DIAGNOSIS AND MANAGEMENT OF PRIMARY TUMORS OF THE PETROUS APEX RICHARD R. GACEK, M.D. BOSTON, MASSACHUSETTS
SUMMARY - Five patients with primary tumors of the petrous apex were diagnosed and treated between the years 1968 to 1974; two had congenital epidennoids, two had ehondromyxosarcomas and one had neurofibroma. The embryological development of the foramen lacerurn and the pattern of expansion of these primary tumors support the contention that these three categories of tumors arise in the foramen lacerum. Knowledge of the structures surrounding the foramen lacerum can provide a guide to early diagnosis of petrous apex tumors. Since these tumors cannot be completely removed, the goal of surgery is to obtain histological diagnosis and to produce permanent fistulization of the petrous apex. Although there are several recommended surgical approaches to the petrous apex, the transmastoid-translabyrinthine procedure was used in this series.
Primary neoplasms of the petrous apex are rarely encountered in otological practice. The lack of familiarity with tumors in this area is a handicap to early diagnosis and management. Since these tumors occur infrequently and are located in an inaccessible region of the skull, they are usually not diagnosed until they reach considerable size and cause multiple cranial nerve deficits or intracranial complications. The present study constitutes an evaluation of five patients with the signs and symptoms of three types of tumor (congenital epidermoid, chondromyxosarcoma and neurofibroma) that may arise at the petrous apex. A discussion of the origin and development of these tumors is given with suggested guidelines for early diagnosis and effective surgical management of these neoplasms. CASE REPORTS CASE ONE
Congenital Epidermoid Cust. A thirtytwo-year-old female was first seen in April 1968 with a complaint of a hearing loss in the right ear for four to five months. The hearing loss followed an upper respiratory infection and despite decongestants and myringotomy, there was only temporary improvement in her ser-
ous otitis media. Otolaryngological examination was normal except for a blueappearing right ear drum and a conductive hearing loss on the right. Following myringotomy with insertion of a pressure equalizing tube, the conductive hearing loss was eliminated. Despite this initial improvement, the patient continued to have some discomfort in the right ear and had a brownish mucoid discharge through the pressure equalizing tube, which persisted for two months. Because of increased pain in the right ear, x-rays of the mastoid cell system were taken in early June 1968 and revealed destruction of cell partitions. A course of antibiotic therapy failed to improve the symptoms, and therefore in June 1968 a simple mastoidectomy was performed. Granulation tissue with flecks of keratin which filled the mastoid cells was removed. Histological examination showed cholesterol granuloma. Improvement in symptoms continued until February 22, 1969 when she was seen in the emergency room with severe right-sided temporal parietal headaches and pain in the lower jaw and teeth. X-rays (Fig. 1A) revealed an osteolytic lesion in the petrous apex which was present on previous x-rays but was not identified at that time. The patient was
From the Massachusetts Eye and Ear Infirmary, Harvard Medical School, 243 Charles St. Boston, Mass. '
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RICHARD R. GACEK
Fig. 1. A) Case 1. X-ray view of the base of the skull showing the osteolytic epidermoid cyst (small arrows) at the petrous apex. The cochlea (C) and the internal auditory canal (lAC) are not involved but the Eustachian tube (ET) is compressed. B) Postoperative x-ray taken one year after successful fistulization of the cyst. Note reduction in size of cyst as evidenced by the recalcification of bony margin of foramen ovale (arrow).
PRIMARY TUMORS OF PETROUS APEX
then admitted to the hospital for a complete work-up including an arteriogram, pneumoencephalogram and brain scan. These studies revealed an extradural avascular mass in the petrous apex which displaced the internal carotid artery laterally. In order to establish a diagnosis, the middle cranial fossa was explored on April 11, 1969 and a cystic lesion containing xanthochromic fluid and keratin material was identified and evacuated. The wall of the cyst was adherent to the internal carotid artery and surrounding structures, and therefore could not be removed. Pathological examination of the aspirate revealed old blood and amorphous keratin material. Postoperatively the patient experienced complete relief from her headaches until May 11, 1969 when she was again admitted as an emergency case because of severe headaches and blurred vision. At this time the mandibular condyle was removed and a radical mastoidectomy was performed in order to fistulize the cyst into the ear canal. The fistula was created anterior to the carotid canal in an effort to preserve labyrinthine function. The fistulous tract was lined with skin grafts and a silastic tube was inserted to hold them in place. This tube extruded after five months and the fistula closed spontaneously. The "exploding type" headache and blurred vision recurred. Therefore, in December 1969 a revision mastoidectomy and a labyrinthectomy were performed to create a wider fistulous tract into the cyst. The bone removal included the medial wall of the middle ear, from the carotid- canal anteriorly to the descending portion of the facial canal posteriorly and inferiorly to the level of the jugular bulb. This opening was lined with split-thickness skin grafts. Complete relief from headaches and eye symptoms occurred and recovery from the effects of labyrinthine destruction was sufficient to permit discharge from the hospital after five to six days. The patient has remained completely free of headaches to the present date, a period of 4~ years. Radiological evaluation one year after the last operation has revealed a decrease in size of the
3
cyst as revealed by recalcification of bony landmarks such as the foramen ovale (Fig. 1B). CASE TWO
Congenital Epidermoid Cyst. A twenty-seven-year-old male was first seen in January 1973 with a complaint of short lasting episodic dizziness for ten weeks. He also complained of fluctuating hearing loss and a blocked sensation in the left ear for several months. Numbness over the left dental area and the lower left cheek was also noted for six months, and headache around the left ear was present for one month. The ear, nose and throat examination was entirely normal. Neurological evaluation was also within normal limits except for a slightly diminished left corneal reflex. Audiometric testing revealed bilateral high tone sensorineural loss at 4,000 Hz and normal speech discrimination scores. No conductive hearing loss was found. Electronystagmography revealed a slightly diminished response in the left ear and a type II positional nystagmus which was attributed to a possible brain stem lesion. Conventional and tomographic x-rays of the mastoids and base of the skull revealed an osteolytic lesion of the left petrous apex (Figs. 2 and 3A). Brain scan, arteriography and pneumoencephalography revealed an avascular petrous apex mass with a middle fossa extension. The internal carotid artery was displaced laterally in the region of the petrous apex. The preoperative diagnosis was primary cholesteatoma of the petrous apex, and on February 13, 1973 radical mastoidectomy and fistulization of the petrous apex was performed through the region of the labyrinth. A wide opening into the keratin filled cyst was created after removal of bone from the carotid canal to the vertical portion of the facial nerve canal and from the middle fossa dura to the jugular bulb. Split-thickness skin grafts were placed in the fistula after evacuation of a large amount of keratin debris from the cholesteatoma cyst. The patient was discharged four days following surgery, having made striking improvement from the effects of the labyrinthectomy. He
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RICHARD R. GACEK
Fig. 2. Case 2. Frontal tomograms of the petrous apices demonstrating a complete destruction of the left petrous apex by the epidermoid cyst (arrows). C - Cochlea.
has been completely free of headaches except for one severe headache episode and an elevated temperature one month following surgery which occurred in association with a profuse cerebrospinal fluid leak from the left ear. Hematological and cerebrospinal examinations were normal. Symptoms gradually subsided on nonspecific therapy and there was gradual cessation of the cerebrospinal fluid otorrhea. The cholesteatoma remained marsupialized (Fig. 3B) and the patient has been free of symptoms for 16 months. CASE THREE
Neurofibroma. A seventy-three-yearold white female was first evaluated otologically in January 1962 for hearing loss and tinnitus in the left ear of two years duration. No complaints of vertigo, headache or facial pain were elicited. Complete otolaryngological examination was normal except for a left serous otitis media. Needle paracentesis of the left middle ear produced thin amber fluid and marked improvement in hearing. Following this, audiometric evaluation showed normal hearing in the
right ear and a flat sensorineural hearing loss of about 50 dB with complete recruitment and 56% speech discrimination score in the left ear. Tone decay was normal. Caloric response was present but somewhat reduced in the left ear. Radiological evaluation of the base of skull showed a questionable area of destruction of the floor of the middle fossa. It was felt that no relationship existed between the serous otitis media, sensorineural hearing loss, and questionable x-ray abnormalities. No further therapy was instituted and the patient was instructed to return in six months. The patient next returned in January 1969 with a history of increasing symptoms during the preceding 6-12 months; the left-sided hearing loss was now complete, pulsating tinnitus continued, horizontal diplopia was present, and a vague unsteadiness occurred from time to time. Examination revealed a "blue" drum on the left (brownish fluid on paracentesis), a slight left VI nerve weakness, profound left hearing loss, and markedly reduced caloric response in the left ear. No headache, facial pain or facial weakness were present. Radiological evalua-
PRIMARY TUMORS OF PETROUS APEX
Fig. 3. A) Case 2. Base of skull x-ray demonstrating an osteolytic lesion of the left petrous apex (dark arrows). The bony cochlea (C) has been spared by the lesion but the Eustachian tube (ET) and the foramen ovale (FO) may be encroached upon by the epidermoid cyst. FS - Foramen spinosum. B) Postoperative x-ray demonstrating the surgical fistula into the petrous apex. Radiopaque dye has been instilled into the external ear canal and outlines the tract (arrow) into the petrous apex cyst. ICA - Internal carotid artery, SP ~ Sphenoid sinus.
5
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RICHARD R. GACEK
Fig. 4. A) Case 3. Conventional x-ray demonstrating a very extensive lesion (dark arrows) which has destroyed the petrous apex, the foramen ovale and the foramen spinosum. The tumor has extended into the sphenoid sinus (SP). C - Cochlea. Note normal foramen ovale (FO) and foramen spinosum (FS) on the right side. B) This tomogram clearly shows the extension into the left sphenoid sinus (arrow). C - Cochlea. Note normal petrous apex (AP) on the right.
PRIMARY TUMORS OF PETROUS APEX
tion revealed a definite osteolytic lesion of the left petrous apex and floor of the middle cranial fossa. Carotid arteriography demonstrated marked lateral displacement of the internal carotid artery in the region of the petrous apex. The diagnosis of primary petrous epidermoid cyst was made and surgery recommended. The patient refused surgery and was followed over the next five years. There was no essential progression in symptoms and no new signs appeared. An intermittent discharge of brownish fluid from the left ear provided relief from the pressure and tinnitus during these years. In June 1974 a follow-up radiological examination revealed an extensive area of destruction involving the petrous apex and the sphenoid bone, with extension into the left sphenoid sinus (Figs. 4A and B). Because of the increase in size of the tumor, the patient was referred to the author for surgical management to prevent intracranial complications (meningitis) and further neurological deficits. In November 1974 exploration of the left petrous apex was performed. After a wide field radical mastoidectomy, the carotid canal was identified anteriorly and the bone over the cochlea was removed between the internal carotid artery and the vertical portion of the facial nerve. A solid tumor mass was encountered in the petrous apex. Several biopsies were taken of the firm avascular mass. The area was skin grafted and packing inserted into the cavity. The patient had an uneventful postoperative course. Histological examination of the biopsy material revealed neurofibroma. Surgical removal of this tumor was not attempted because of the risk associated with extirpation of such a large tumor in an elderly patient. Unless signs or symptoms of critical nature occur, no surgical procedure is contemplated in the future. CASE FOUR
Chondrornyxosarcoma. A twenty-seven-year-old female was first seen in No-
7
vember 1971 with a complaint of headache, unsteadiness and a progressive right hearing loss. Otological examination two years previously revealed a right serous otitis media which was treated by the introduction of a middle ear pressure equalizing tube. Six months later, after the tube had extruded, the hearing loss recurred and a second pressure equalizing tube was introduced. After the second tube extruded, the patient had recurrence of hearing loss, unsteadiness with falling to the right and weakness of the right arm. The patient was then referred for consultation. Otological examination at this time showed a right serous otitis media, a reddish mass behind the inferior part of the right tympanic membrane, and a pure conductive hearing loss of 40-50 dB on the right and normal hearing in the left ear. Caloric tests with 5 cc of 26.6 C water revealed bilaterally symmetrical responses of normal duration. There was weakness of the right sternocleidomastoid and trapezius muscles, hemiparesis and hyperreflexia of the right arm and leg, right facial weakness, complete paralysis of the right vocal cord, and deviation of a fasciculating tongue to the right. Radiological studies of the mastoid and skull revealed increased density with destruction of the right petrous apex extending to the region of the jugular foramen. Exploration of the middle ear was carried out under general anesthesia and biopsy of the mass revealed chondromyxosarcoma. Since there were signs of increasing brain stem compression, partial removal of the intracranial component of the tumor was performed neurosurgically. However, the patient followed a progressive downhill course following surgery and died from bronchopneumonia twelve days after surgery. Autopsy revealed a muItilobulated encapsulated tumor mass which involved the right sphenoid and petrous portion of the temporal bone. The tumor extended into the basiocciput as far as the articular cartilage of the first cervical vertebra, and herniated into the middle and posterior cranial fossae, enveloping
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RICHARD R. GACEK
Fig. 5. A) Case 4. Low power horizontal section of the chondromyxosarcoma replacing the petrous apex. The cochlea and internal auditory canal have been spared. The middle ear ( ME ) contains serous fluid. The internal carotid artery (lCA), the mandibular division of the trigeminal nerve (V') and the middle meningeal artery (MA) are compressed by the tumor (T) which has also extended into the posterior fossa. V2 - Second division of trigeminal nerve. (Reproduced from Figure 1 in "Primary Sarcomas of the Temporal Bone" by Pierre Naufal, reprinted from the Archives of Otolaryngology, July, 1973, Volume 98:44-50, Copyright 1973, American Medical Association.) B) High power photomicrograph (195X) of the tumor showing the cartilage tumor cells of chondrosarcoma.
the right III to XII cranial nerves. The temporal bones were removed for study, and the right temporal bone revealed a massive solid tumor which replaced the petrous bone with extension into the middle and posterior cranial fossae (Figs.
SA and B). The tumor extended through the infralabyrinthine cell tract into the hypotympanum, where it was visible on otoscopy. The internal carotid artery and mandibular division of the trigeminal nerve were displaced markedly in an
PRIMARY TUMORS OF PETRO US APEX
9
Fig. 6. Case 5. Frontal tomogram of petrous apices demonstrating the typical osteolytic lesion (arrows) of the apex which spares the cochlea (C). X - Indicates extension of the tumor into the infratemporal fossa.
anterolateral direction. The carotid artery was compressed to the point of occlusion. The lumen of the bony and cartilaginous portions of the Eustachian tube was also compressed by tumor. However, the bony labyrinth capsule was intact; the sensory areas of the cochlea and the vestibular organs were normal. CASE FIVE
Chondromyxosarcoma. A thirty-oneyear-old female was first seen in May 1971 with the complaint of difficulty in speaking and swallowing; a left paralyzed vocal cord was found. An examination including arteriogram was performed in October 1971, but no abnormality was discovered. In November 1971 she developed left-sided headaches. A diagnostic work-up which included polytomography, arteriography, and pneumoencephalography was performed at another hospital. As a result of these studies, the patient underwent a transmastoid exploration of the left jugular foramen and cartilaginous material was removed which was diagnosed histologically as "normal cartilage." The patient
noted some improvement in symptoms postoperatively but continued to have a pulsating feeling in the left ear. She was then reasonably well until November 1972 when she noted blurring of vision on turning her head, and in January 1973 experienced intermittent diplopia. This became constant by February 1973 and at that time it was noted that a left VI nerve palsy was present. In May 1973 she experienced the onset of intermittent tingling over the left mandible. At this time she was seen at the MEEI where a paralyzed left vocal cord, asymmetric elevation of the palate, and a questionable slight weakness of the left shoulder muscles were noted. The tongue was normal in appearance and movement. No extremity weakness was noted. Manual examination revealed a fullness inferior and deep to the left tympanic bone. Hearing evaluation and vestibular testing were normal bilaterally. No evidence of brain stem compression was found on this examination. Polytomography performed in April 1973 revealed a large erosive lesion extending from the petrous apex back to the jugular fora-
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RICHARD R. GACEK TABLE I SUMMARY OF SYMPTOMS AND SIGNS IN PATIENTS WITH PRIMARY TUMORS OF THE PETROUS APEX
Tumor
Patient
Congenital epidermoid cyst
32F 27M
Neurofibroma
73F
Chondromyxosarcoma
24F
±
=
Int. Eusta· Carotid Artery V chian Nerve Tube Ob- ComHeadache Signs struction pression
+ + + +
31F incomplete Eustachian tube obstruction
men and as far posteriorly as the foramen magnum (Fig. 6). Carotid arteriography revealed anterolateral displacement and compression of the petrosal segment of the internal carotid artery. A diagnosis of primary cholesteatoma of the petrous apex or a chondroid tumor was entertained. Surgical exploration of the petrous apex was performed through a mastoid and middle ear approach. In the middle ear a small extension of tumor was noted protruding into the anterior hypotympanum between the exposed internal carotid artery anteriorly and the basal tum of the cochlea posteriorly. This area was enlarged by removing sufficient bone to create a fistula into the petrous apex without injuring the labyrinth. Solid and degenerated bluish cartilaginous material was removed for biopsy purposes. A large amount of degenerated tumor was then aspirated and the bony fistula was lined with split-thickness skin grafts to maintain a permanent tract into the petrous apex. Histologically this was diagnosed as a low-grade chondromyxosarcoma. The patient recovered from the surgery uneventfully and after the ear was completely healed, radiation therapy was administered on the 160 MeV proton beam machine to a dose of 6,125 rads. The patient tolerated radiation therapy well and experienced relief from headaches. Some improvement in the VI nerve palsy was noted. Deficits of cran-
+ + + +
+ ± + + ±
+ +
Other Craniol Nerves none none VI, VIII
+ +
Ill, VI, VII, IX, X, XI, XII IV, VI, IX, X, XI
ial nerves IX, X, and XI remain unchanged. Table I summarizes the findings in these five patients with petrous apex tumors. Except for one patient, these patients were all females and in a young age group. Significantly, four out of five patients experienced severe headaches, signs of involvement of the third division of the trigeminal nerve, and signs of internal carotid compression. While three out of five patients showed signs of complete Eustachian tube obstruction (serous otitis media), the remaining two patients had complained of ear blockage which was interpreted as incomplete tubal obstruction. These findings are associated with the early stage of development of petrous apex tumors. Only when the tumors reached extensive proportions were other cranial nerves involved as demonstrated by the last three cases in the table. DISCUSSION
Although this report discusses an almost equal number of patients with each of these primary tumors of the petrous apex, chondromyxosarcomas and neurofibromas are extremely rare in this area. In an extensive review of the literature on primary sarcomas of the temporal bone, Naufal' found one chondrosarcoma reported by Tucker" and added a second case (Case 4). There are numerous reports describing congenital cholestea-
PRIMARY TUMORS OF PETROUS APEX
toma arising in the middle ear 3 - 8 and in the petrous apex. 9 - 1 8
Clinical Features. Patients with congenital epidermoid cysts and patien~s with chondromyxosarcoma are usually ill the young adult age grouP? the~ ran~ed in age from 24-32 years ill this series, Other reports on congenital epidermoids of the petrous apex consistently report a young adult age group prevalence with these tumors. 1 , 3 - 7 , 9 - 1 9 Neurofibromas can occur in almost any part of the body and have been reported in all age groups. Headache was one of the most prominent symptoms in these patients and was described as a severe headache usually ineffectively treated with medication. The headache pain was usually located in the side of the ear affected, although in Case 1 the patient's headache was sometimes described as a deep exploding headache located in the center of the head. Headache is probably an indication of dural stretching by an expanding tumor at the petrous apex. Another common symptom was involvement of the mandibular division of the trigeminal nerve. Involvement of the third division of the V cranial nerve produced either pain, parasthesia or anesthesia over the distribution of this nerve. Very likely this indicated compression of the mandibular division of the V cranial nerve in the foramen ovale. Varying degrees of occlusion of the Eustachian tube were also found in these patients. In three patients (Cases 1, 3 and 4), complete obstruction of the Eustachian tube produced serous otitis media. In the other two patients (Cases 2 and 5), serous otitis media was not present but the patients complained of some form of blockage of the ear which could be interpreted as incomplete Eustachian tube obstruction. In the patients with complete Eustachian tube obstruction, conductive hearing loss was documented by audiometry. Symptoms related to internal carotid artery compression were also common. Slow compression of the internal carotid artery in young patients probably does not produce hemiparesis. Therefore, in
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Case 4 the right hemiparesis was probably due to direct brain stem compression by the extensive tumor. However, lesser symptoms described as blurring of vision on turning of the head (Cases I and 5), or as dizziness (Case 2) m~y be ischemic effects from internal carotid artery compression. More sign~icant symptoms occurred in the patients WIth a solid malignant tumor (chondromyxosarcoma) as compared to patients with a cystic tumor (congenital epidermoid) or a slow growing benign tumor (neurofibroma) which probably exert a less compressive effect on the artery. The two patients with chondromyxosarcoma presented with a more extensive involvement of the base of the skull. In these patients the nerves of the jugular foramen (IX, X and XI), and the hypoglossal foramen (XII) were involved. Other nerves compressed by anterior extension at the base of the skull were III, IV and VI. While these multiple cranial nerve deficits were more common with solid malignant tumors as chondromyxosarcoma, it is also possible that extensive benign tumors of the petrous apex may involve these cranial nerves (Case 3). Aside from the cranial nerve deficits associated with very extensive tumors, the otolaryngological examination was either normal (C ases 2 and 5), or revealed merely serous otitis media if the tumor was large enough to compress the Eustachian tube (Cases 1, 3 and 4). Only when the tumor is massive may it present otologically (Case 4). In four of these patients both auditory and vestibular labyrinthine function was normal. This was true even in the cases of chondromyxosarcoma where there was extensive destruction of the petrous bone. The preservation of labyrinthine function underlines the resistance of the bony labyrinth to tumor erosion. However, extensive tumors may eventually destroy the bony labyrinth wall and cause loss of auditory and vestibular function as in Case 3.
Radiological Findings. While conventional routine x-rays of the petrous bone
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RICHARD R. GACEK
Int. Carotid Art.
Heart
Ext. Carotid Art.
Rathke's Pouch Optic Vesicle
Fig. 7. Drawing of the cephalic flexure and relationship to the internal carotid artery at the one-month embryo stage. Note the location of Seessel's pocket and Rathke's pouch adjacent to the stomodeal plate (broken line). Roman numerals I-IV identify branchial pouches. (Redrawn from Figure 74 in Patten, B. M., Human Embryology, McGraw-Hill, 1953. Used with permission of McGraw-Hill Book Company.)
and the base of the skull may occasionally provide clear evidence of an osteolytic lesion at the petrous apex, frequently when the tumor is small the findings on plain views are equivocal and confirmatory evidence may be obtained with polytomography and arteriography. In all cases in this series, there was radiological evidence of bone destruction at the petrous apex. Plain views and tomograms of the petrous bone demonstrated this radiologic defect. In the extensive tumors, the area of bone destruction extended posteriorly to include the jugular foramen and the hypoglossal canal and anteriorly to involve the sphenoid sinus. Arteriography in all cases consistently showed lateral displacement of the petrous segment of the internal carotid artery by an avascular mass. Pneumoencephalography showed these tumors to be extradural in location. Origin of Tumors. It seems likely that these tumors of the petrous apex arose from the foramen lacerum. The foramen lacerum is the name given to the space (occupied by the basal fibrocartilage) with jagged margins between the pars basilaris of the occipital bone and the
temporal wing of the sphenoid bone on the one hand, and the apex of the petrous segment of the temporal bone on the other. Several reasons may be given as support for the hypothesis that these tumors arose from the foramen lacerum. 1. The foramen lacerum normally contains fibrocartilage, a mesenchymal derivative of embryonic development. This fibrocartilage appears the most likely source for the origin of chondroid tumors, although other cartilage rests are located in the enchondral bone layer of the bony labyrinth. However, if the cartilage tumors arose in the enchondral layer, loss of labyrinthine function would be an expected early sign.
2. While no structures pass through the foramen lacerum, there are two types of structures that course across the foramen. These are the internal carotid artery and the nerves which merge to form the vidian nerve ( greater superficial petrosal and deep petrosal). Therefore, tumors of neural origin can arise in the foramen lacerum with little or no ob-
PRIMARY TUMORS OF PETROUS APEX
13
Epithelium pinched off from Seessel's pocket
Eye
Hypophysis from Rathke's pouch
Fig. 8. This drawing illustrates the proposed mechaJ.lism whereby epithelial res~s from Seessel's pocket are trapped in the mesenchyme (sttp~led area) of, the cephalic flexure, Dotted arrows indicate the deepening of the cephahc flexure which promotes the entrapment of epithelial rests.
vious signs or symptoms related to the involved nerve, 3. The foramen lacerum appears to be a likely area for epithelial remnants to be trapped during embryonic development and then develop later into congenital epidermoid cysts.
Early in embryonic developme~t OI~e of the important changes occw:mg IS flexion of the embryo from a straight to a semicircular shape in order to conform to the limited space in utero.P? Bending of the ectodermal tube which will form the central nervous system produces the cephalic flexure (Fig. 7), In a one-month embryo the internal carotid artery, which ascends through the cephalic flexure, is recognizable after absorption of the intersegmental arterial branches between pharyngeal pouches. An invagination at the stomodeum reaches toward the primitive gut to the point where a stomodeal plate is formed marking the transition between ectodermal and entodermal epithelium. Resorption of this stomodeal plate occurs early in embryonic development. Concomitant with the resorption of the stomodeal plate is the lengthening of the cephalic flexure and an associated shift of the mesenchyme filling the flex-
ure. Accompanying this movement is a withdrawal of the epithelium adjacent to the stomodeal plate into the cephalic flexure. The most external of these epithelial invaginations is Rathke's pouch and the internal one is Seessel's pocket (Fig. 7). As these two epithelial invaginations are drawn up into the mesenchymal tissue filling the cephalic flexure, isolated epithelial remnants of Rathke's pouch or Seessel's pocket may remain. Epithelial remnants derived from Rathke's pouch in the midline form a portion of the adult hypophysis. It seems possible that isolated epithelial islands from the lateral recesses of a deep Seessel's pocket may also remain trapped in condensing mesenchyme at the base of the cephalic flexure ( Fig. 8) . While most of the mesenchyme in the cephalic flexure undergoes resorption, a small portion at the base forms the fibrocartilage filling the foramen lacemm. Support for the contention that the base of the cephalic flexure is identical with the foramen lacerum is shown in Figure 9, where the trigeminal ganglion can be seen stretching across from the petrous apex to the mandibular region, and in Figure 10,
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RICHARD R. GACEK
Cephalic F~le:::x.:::ur::::e==:::::---.
Cephalic Flexure
Foramen Lacerum
Fig. 9. Drawing which shows the relationship of the trigeminal nerve and ganglion to the cephalic flexure, the eye and the ear, and the other cranial nerves. Note how the ganglion is located anterolateral to the base of the flexure, indicating that this area is located at the apex of the petrous pyramid. (Redrawn from Figure 66 in Patten, B. M., Human Embryology. McGraw-Hill, 1953. Used with permission of McGraw-Hill Book Company.)
where the ossification of bones at the base of the skull in the embryo can be seen. The ossification of the temporal bone and the temporal wing of the sphenoid surrounds the base of the cephalic flexure. Incomplete fusion of these ossification centers and retention of mesenchyme as fibrocartilage form the adult foramen lacerum. Retained epithelial remnants of Seessel's pocket may be entrapped in this fibrocartilage and give rise to congenital epidermoid cysts or cholesteatomas later in life. 4. Finally, the pattern of expansion and involvement of structures surrounding the base of the skull suggests that these primary tumors of the petrous apex arise from the foramen lacerum. Figure 11 demonstrates the relationship of the foramen ovale, Eustachian tube, and the internal carotid artery to the foramen lacerum. Expanding tumors from the foramen lacerum would most likely involve these structures before other structures at the base of the skull. Tumors
Internal Auditory Canal
Fig. 10. Drawing of the ossification of the bones at the base of the skull (heavy stipple) and their relationship to the cephalic flexure. Note how the base of the flexure is located between the apex of the petrous bone and the temporal wing of the sphenoid bone. The mesenchyme in the cephalic flexure ( light stipple) forms the cartilage in the foramen lacerum. Upper drawing represents side view, lower drawing is a base view of the skull. (Redrawn from Figure 165 in Patten, B. M., Human Embryology, McGraw-Hill, 1953. Used with permission of McGraw-Hill Book Company.)
arising in more distant areas such as the jugular foramen or the middle ear would involve other structures such as the tympanic membrane, the facial nerve or the nerves of the jugular foramen before involving structures at the petrous apex. Lateral displacement of the internal carotid artery by tumors in this region would argue against epithelial rests from the Eustachian tube (branchial pouch I) as the source of congenital cholesteatoma of the apex. If the epidermoid arose from Eustachian tube elements, the internal
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PRIMARY TUMORS OF PETROUS APEX
Eustachian Tube
Foramen Spinosum Foramen Lacerum
Jugular Foramen
Fig. 11. Half photograph and half drawing of structures at the base of the skull. Note relationship of Eustachian tube, foramen ovale, and internal carotid artery to the foramen lacerurn.
carotid artery would be displaced medially. Stages in Growth of TUTTWT. In the otological and neurosurgical literature, primary epidermoids of the petrous apex have been described in three clinical forms. 1. Olivecrona'" and Revilla1 3 • 1 4 have emphasized the association of mandibular division of the trigeminal nerve signs along with normal VIII and VII nerve function in patients with primary epidermoid of the petrous apex. Normal radiological and neurological examinations were also usually present. It is likely that these patients are seen pri-
marily by the neurosurgeon because of the large number of patients with tic douloureaux treated by this specialty. 2. In the otological literature the characteristic clinical presentation of primary petrous apex epidermoid consists of VII and VIII nerve deficits either with or without cholesteatoma in the middle ear or mastoid.v-v-" This association is undoubtedly related to the presence of otological functional deficits at the time of diagnosis. Otological reports of patients with petrous apex congenital cholesteatoma having normal VII and VIII nerve function are rare." 3. Primary epidermoids are included
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RICHARD R. GACEK
in the classifications of cerebellopontine angle tumors when there is encroachment of the nerves in the internal auditory canal by a mass lesion which is usually located anterior to the VII and VIII nerves in the posterior cranial fossa. Trigeminal nerve involvement is sometimes used to differentiate clinically epidermoid from other cerebellopontine angle tumors. This description of primary epidermoid is present in both the neurosurgica1'3,14,19 and otologicaI15,16,18 literature. An analysis of the patients described in this report and in the literature points to a common pattern of expansion in the petrous apex. The bone of the apex contains marrow spaces and would more likely allow for expansion of a tumor than the other solid bony components of the skull. Knowledge of the structures surrounding the foramen lacerum provides a guideline for early detection of expanding tumors in this area. Based on the involvement of surrounding structures at the base of the skull, primary tumors at the petrous apex may be divided clinically into three stages which more or less correspond to the clinical types described in the literature. Stage I. Tumors at this stage involve those structures in the immediate vicinity of the foramen lacerum. These are: the middle or posterior fossa dura attached to the petrous apex, the mandibular division of the trigeminal (V) nerve, the Eustachian tube, and the internal carotid artery. Symptoms resulting from encroachment on these structures are: headache, pain, anesthesia or paresthesia in the distribution of the third division of the V nerve, hearing loss or a blocked feeling in the ear, and various complaints related to cerebral ischemia such as blurred vision or faintness.
At this stage only one or two of these structures may be clinically involved and otolaryngological examination including evaluation of labyrinthine function may be entirely normal. Therefore, a high index of suspicion is necessary in order to make the diagnosis of tumor at the petrous apex. Careful radiological eval-
uation of the base of the skull is the simplest and most informative diagnostic study to carry out. Failure to suspect a lesion at the petrous apex at this early stage may lead to unnecessary surgical treatment for Eustachian tube obstruction (myringotomy with insertion of ventilating tubes, simple mastoidectomy) and potentially dangerous delays in diagnosis. Stage II. As the tumors enlarge, extension is usually in a posterior or anterior direction because the bone in these areas at the base of the skull offers the least resistance. Compression of the VII and VIII nerves at the internal auditory meatus, cranial nerves IX, X and XI in the jugular foramen, and the XII nerve in the hypoglossal foramen may occur with posterior extension. Cranial nerves III, IV, and VI may become involved with anterior extension of the tumor toward the cavernous sinus. These neurological deficits make the diagnosis of petrous apex tumor more apparent. Stage III. Further extension of an expanding neoplasm at the petrous apex may involve a region where the tumor mass can be detected by clinical examination. These areas are: the nasopharynx, the middle and posterior cranial fossae, the middle ear, or the infratemporal fossa. Detection of tumor in such areas may be by direct visualization and palpation (nasopharynx, middle ear or neck) or by the effects of tumor compression on vital structures such as the brain stem (the posterior cranial fossa). When such extension involves the posterior fossa, a cerebellopontine angle tumor mass is present.
The bony labyrinth resists erosion from the enlargement of these tumors." Therefore, normal labyrinthine function is frequently found on clinical evaluation. However, this resistance is not absolute and with extensive erosion, loss of labyrinthine function and facial paralysis may occur. Seventh and VIII cranial nerve function may be impaired by direct compression of the nerves as they course toward the brain stem or by erosion of the bony labyrinth wall. When
17
PRIMARY TUMORS OF PETROUS APEX External Auditory Canal
Facial Nerve
Eustachian Tube
Antrum
Internal Carotid Artery
Fig. 12. Drawing of the temporal bone showing the otologic approach to fistulize (heavy solid lines) a tumor located in the petrous apex. Areas surrounding the cochlea (dashed + dotted lines) indicate bone removal necessary to reach the tumor after exposure with radical mastoidectomy.
these signs are present they are late indications of a petrous apex tumor. DIAGNOSIS
Since tumors at the petrous apex are inaccessible to direct clinical detection, early diagnosis must rest on a high index of suspicion based on recognition of the early signs and symptoms of expanding tumors at the petrous apex. When there is an indication of involvement of the dura of the cranial fossae, the mandibular division of the V cranial nerve, the Eustachian tube, or the internal carotid artery, then conventional radiological views and tomography of the petrous apices and the base of the skull should be obtained. If no abnormality is found, then careful follow-up examination at five to six month intervals should be carried out if symptoms persist.
If an area of bone destruction at the petrous apex is detected, then pneumoencephalography, brain scan, and carotid arteriography are the most helpful diagnostic studies that may be performed. These studies along with a complete oto-
laryngologic and neurologic examination are usually sufficient to rule out other entities in the differential diagnosis such as petrositis, metastatic nasopharyngeal carcinoma, metastatic carcinoma from a distant primary (such as breast, thyroid and prostate), glomus jugulare tumor, meningioma, internal carotid artery aneurysm, and eosinophilic granuloma. If the lesion is one of the primary neoplasms of the foramen lacerum discussed in this study, the diagnostic studies would demonstrate an avascular extradural mass lesion at the petrous apex which displaces the internal carotid artery laterally. SURGICAL MANAGEMENT
Delay in diagnosis of petrous apex tumors resulted in no treatment (Case 5) or in treatment for a relatively benign condition secondary to tumor growth such as serous otitis media (Cases 1, 3 and 4). This delay can probably be attributed to a lack of awareness of the early signs and symptoms of these tumors and as a result inadequate radio-
18
RICHARD R. GACEK
logical evaluation of the petrous apex of the temporal bone. Once the radiological diagnosis of a destructive lesion at the petrous apex was made, exploration of the petrous apex was carried out in Cases 1, 2 and 5. It was clear from the experience with Case 1 that simple exploration and evacuation of the primary epidermoid cyst of the petrous apex does not result in permanent relief of symptoms. Permanent fistulization was then the goal in the treatment of congenital cholesteatomas of the petrous apex. A conservative approach to fistulizing the congenital epidermoid in Case 1 met with failure. In this patient, a fistula into the cyst was created anterior to the carotid canal and skin grafted with preservation of labyrinthine function; the fistula closed eventually because it was not wide enough. The successful operation in Case 1 consisted of complete labyrinthectomy and removal of the bony labyrinth from the internal auditory canal to the internal carotid artery (Fig. 12) and lining the bony fistula with split-thickness skin grafts. The effectiveness of this approach was again demonstrated in Case 2 where, at the initial surgical procedure, the transmastoid and translabyrinthine fistulization of the congenital cholesteatoma was successful. Surgical exploration of the petrous apex tumor in Case 3 was carried out to prevent the Occurrence of complications from rupture of an extensive primary epidermoid cyst. Instead, exploration and biopsy via the translabyrinthine route revealed a solid benign tumor which was too extensive to remove safely. The surgical procedure in this case served a diagnostic purpose. In Case 4 the chondromyxosarcoma was too extensive at its initial recognition to permit effective surgical or radiotherapeutic management. The surgical procedures performed provided 1) histological diagnosis and 2) neurosurgical decompression of the expanding tumor. The patient eventually died from an intracranial complication of the primary tumor. In Case 5 where the tumor was diagnosed histologically, following the
approach to the petrous apex through a large infralabyrinthine cell tract, a drainage procedure was accomplished by fistulizing the tumor mass. Radiation therapy has been administered. SURGICAL APPROACHES TO THE PETROUS APEX
Because of the inaccessible location of the tumors in the petrous apex, complete extirpative surgery is usually not possible. Therefore, the surgical management consists of diagnostic exploration and fistulization of the expanding mass. Biopsy is necessary to obtain tissue diagnosis; fistulization either may form the definitive treatment, as in the case of primary epidermoid cysts, or may act as a drainage procedure for necrotic tumor cells follOWing radiation therapy for chondromyxosarcoma. There are several surgical approaches to the petrous apex. M.iddle Fossa Extradural. This approach to the petrous apex via the middle cranial fossa can serve to reach the tumor for diagnostic purposes. Biopsy of a solid tissue mass or aspiration of a cystic lesion may be accomplished via this route but permanent fistulization is not possible. Thus in the case of primary epidermoid cysts, recurrence is frequently the case as demonstrated in Case 1 in the present series. An advantage of this procedure is that labyrinthine function may be preserved. Posterior Fossa Craniotomy. The morbidity associated with this approach limits its usefulness to those tumors of the cerebellopontine angle where the neoplasm may be intracranial in origin, thus requiring intracranial removal. This approach may also be necessary as a decompression procedure where intracranial extension of a petrous apex tumor may produce signs of brain stem compression (as in Case 4). However, some neurosurgical reports have described complete or near complete removal of epidermoids using this approach. Transethmoidosphenoid. This approach through the ethmoid and sphenoid sinus to the petrous apex has been described to successfully fistulize con-
PRIMARY TUMORS OF PETROUS APEX
genital epidermoid cysts at the petrous apex." While this can be accomplished via this route, the space limitation may add difficulty to the maintenance of a permanent fistula into the cyst. It is not possible to apply skin grafts to the fistula, and one must depend on the opening of the fenestra in the sphenoid sinus to maintain a fistula. Furthermore, the risk of an ascending infection into the pennanently fistulized lesion from a potentially contaminated area such as the nasopharynx must be considered. The difficulty of evacuating a keratin filled mass through the nasal cavity may also be a minor disadvantage of this procedure. On the other hand, the preservation of labyrinthine function is a major advantage of this approach to the petrous apex.
Transmastoul - Translabyrinthine. In this approach, a wide field mastoidectomy and removal of the cochlea is essential in order to expose the tumor. Meticulous removal of all vestibular sensory tissue is also necessary to assure complete elimination of all vestibular function and a satisfactory recovery from the labyrinthectomy. Purposeful destruction of the cochlear and vestibular labyrinth is justified in order to successfully expose a life-threatening lesion at the apex of the temporal bone. A wide bony fistula into the petrous apex is created by exenterating the bone from the carotid canal anteriorly to the descending facial nerve posteriorly and from the jugular bulb inferiorly to the middle cranial fossa superiorly (Fig. 12). As the petrous apex is exposed, solid tissue may be obtained for biopsy or the contents of an epidermoid cyst may be evacuated completely. The bony fistula is then lined with split-thickness skin grafts that are held in place with packing. Packing for 10-14 days is sufficient to allow for the implantation of skin grafts. After a large fistulous tract into the petrous apex has been created, the cystic space can be easily aspirated on an outpatient basis and little chance of ascending infection is present. The most significant disadvantage of this procedure is the loss of labyrinthine function. However, this is justifiable in order to achieve relief of
19
symptoms and the complete control of a potentially life-threatening tumor. In the case of solid tumors as chondromyxosarcoma, a wide fistulous opening may provide satisfactory drainage of necrotic tumor following radiation therapy.
Factors Influencing Choice of Surgical Approach. Regardless of approach, the fundamental aim of surgery is to reach the tumor and to form a permanent fistula into it. Since a lesion at the petrous apex cannot be marsupialized via the middle or posterior fossa route, the effective choice is either the nasal or the middle ear approach. This choice can be guided by several factors. Preference of the Surgeon. Familiarity with the anatomical variations and surgical technique associated with sphenoid or middle ear surgery must be considered by the surgeon. Experience with surgical anatomy and its variations are essential to approaching the petrous apex safely and the surgeon should choose the route with which he feels most confident. The otologic approach is favored over the rhinologic one in this report for several reasons: 1) The middle ear route is more direct and the working distance to the apex is less. Therefore, the contents of the cholesteatoma or solid tumor can be aspirated more easily. 2) Split-thickness skin grafts may be applied to the bony fistula by means of the middle ear route. 3) There is less chance for ascending infection from the middle ear into a fistulized cyst as compared to the nasopharynx.
Degree of Labyrinthine Function in the Involved and Uninvolved Ear. If the hearing on the side with tumor is profoundly depressed, the otologic approach is clearly indicated. However, if the involved ear represents an only-hearing ear, then the nasal approach to fistulize the petrous apex tumor through the sphenoid sinus should be considered. Additional Incidental Factors. If both ears have normal inner ear function, then other anatomical and pathological factors gUide the decision. These may be
20
RICHARD R. GACEK
real or potential factors. The presence of a sclerotic sphenoid sinus or of chronic sinusitis would contraindicate the nasal approach. Even the potential risk of ascending infection into a fistulized cyst may favor the otologic approach. The sacrifice of labyrinthine function in one MASSACHUSETTS EYE AND EAR INFIRMARY,
ear is justified by the serious nature of an expanding cholesteatoma or solid tumor in the petrous apex. In petrous apex tumors that have extended outside the apex (Stage III), the extension into the sphenoid sinus or middle ear may dictate the logical approach. 243
CHARLES ST., BOSTON, MASS.
02114.
REFERENCES
1. Naufal PM: Primary sarcomas of the temporal bone. Arch Otolaryngol 98:44-50, 1973
12. Cole TB, McCoy G: Congenital cholesteatoma of temporal bone and sphenoid sinus. Arch Otolaryngol 87 :576-579, 1968
2. Tucker WN: Cancer of the middle ear. Cancer 18:642-650, 1965
13. Revilla AG: Tic douloureaux and its relationship to tumors of the posterior fossa. J Neurosurg 4:233-239, 1947
3. Day KM: A primary cholesteatoma of the middle ear. Ann Otol Rhinol Laryngol 64: 161-163, 1955 4. Derlacki EL, Clemis JD: Congenital cholesteatoma of the middle ear and mastoid. Ann Otol Rhinol Laryngol 74:706-727, 1965 5. Derlacki EL: Congenital cholesteatoma of the middle ear and mastoid. Arch Otolaryngol 97: 177-182, 1972 6. House HP: An apparent primary cholesteatoma. Laryngoscope 63:712-713, 1953 7. Kerr AG, Smyth GD: Congenital cholesteatoma of the temporal bone. Laryngoscope 77 :86-88, 1967
14. Revilla AG: Differential diagnosis of tumors -at the cerebellopontile recess. Bull Johns Hopk Hosp 83:187-212, 1948 15. Hitselberger WE, House WF: Tumors of the cerebellopontine angle. Arch Otolaryngol 80:720-731, 1964 16. House WF, Doyle JB Jr: Early diagnosis and removal of primary cholesteatoma causing pressure to eighth nerve. Laryngoscope 72:1053-1062, 1962 17. Jefferson G, Smalley AA: Progressive facial palsy produced by intratemporal dermoids. J Laryngol Otol 53:417, 1938
8. Sheehy JL: True cholesteatoma. Arch Otolaryngol 69:57-60, 1959
18. Lewis ML, Echols DH: Pearly tumor of the cerebellopontine angle. Report of a case with reversible deafness. Laryngoscope 61: 1123-1125, 1951
9. Brookler KH, Pulec JL and Hallberg OE: Congenital cholesteatoma of the temporal bone. Arch Otolaryngol 90:71-74, 1969
19. Olivecrona H: Cholesteatomas of the cerebellopontine angle. Acta Psychiat et Neurol 24:639-643, 1949
10. Cawthorne E, Griffith A: Primary cholesteatoma of the temporal bone. Arch Otolaryngol 73:252-261, 1961
20. Patten BM: Human Embryology, ed. 2. New York, McGraw-Hill, 1953
11. Cawthorne T: Congenital cholesteatoma. Arch Otolaryngol 78:248-252, 1963
21. Proctor B, Lindsay JR: Tumors involving the petrous pyramid of the temporal bone. Arch Otolaryngol 46: 180-194, 1947
SUMMARY - Five patients with primary tumors of the petrous apex were diagnosed and treated between the years 1968 to 1974; two had congenital epidennoids, two had ehondromyxosarcomas and one had neurofibroma. The embryological development of the foramen lacerurn and the pattern of expansion of these primary tumors support the contention that these three categories of tumors arise in the foramen lacerum. Knowledge of the structures surrounding the foramen lacerum can provide a guide to early diagnosis of petrous apex tumors. Since these tumors cannot be completely removed, the goal of surgery is to obtain histological diagnosis and to produce permanent fistulization of the petrous apex. Although there are several recommended surgical approaches to the petrous apex, the transmastoid-translabyrinthine procedure was used in this series.
Primary neoplasms of the petrous apex are rarely encountered in otological practice. The lack of familiarity with tumors in this area is a handicap to early diagnosis and management. Since these tumors occur infrequently and are located in an inaccessible region of the skull, they are usually not diagnosed until they reach considerable size and cause multiple cranial nerve deficits or intracranial complications. The present study constitutes an evaluation of five patients with the signs and symptoms of three types of tumor (congenital epidermoid, chondromyxosarcoma and neurofibroma) that may arise at the petrous apex. A discussion of the origin and development of these tumors is given with suggested guidelines for early diagnosis and effective surgical management of these neoplasms. CASE REPORTS CASE ONE
Congenital Epidermoid Cust. A thirtytwo-year-old female was first seen in April 1968 with a complaint of a hearing loss in the right ear for four to five months. The hearing loss followed an upper respiratory infection and despite decongestants and myringotomy, there was only temporary improvement in her ser-
ous otitis media. Otolaryngological examination was normal except for a blueappearing right ear drum and a conductive hearing loss on the right. Following myringotomy with insertion of a pressure equalizing tube, the conductive hearing loss was eliminated. Despite this initial improvement, the patient continued to have some discomfort in the right ear and had a brownish mucoid discharge through the pressure equalizing tube, which persisted for two months. Because of increased pain in the right ear, x-rays of the mastoid cell system were taken in early June 1968 and revealed destruction of cell partitions. A course of antibiotic therapy failed to improve the symptoms, and therefore in June 1968 a simple mastoidectomy was performed. Granulation tissue with flecks of keratin which filled the mastoid cells was removed. Histological examination showed cholesterol granuloma. Improvement in symptoms continued until February 22, 1969 when she was seen in the emergency room with severe right-sided temporal parietal headaches and pain in the lower jaw and teeth. X-rays (Fig. 1A) revealed an osteolytic lesion in the petrous apex which was present on previous x-rays but was not identified at that time. The patient was
From the Massachusetts Eye and Ear Infirmary, Harvard Medical School, 243 Charles St. Boston, Mass. '
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RICHARD R. GACEK
Fig. 1. A) Case 1. X-ray view of the base of the skull showing the osteolytic epidermoid cyst (small arrows) at the petrous apex. The cochlea (C) and the internal auditory canal (lAC) are not involved but the Eustachian tube (ET) is compressed. B) Postoperative x-ray taken one year after successful fistulization of the cyst. Note reduction in size of cyst as evidenced by the recalcification of bony margin of foramen ovale (arrow).
PRIMARY TUMORS OF PETROUS APEX
then admitted to the hospital for a complete work-up including an arteriogram, pneumoencephalogram and brain scan. These studies revealed an extradural avascular mass in the petrous apex which displaced the internal carotid artery laterally. In order to establish a diagnosis, the middle cranial fossa was explored on April 11, 1969 and a cystic lesion containing xanthochromic fluid and keratin material was identified and evacuated. The wall of the cyst was adherent to the internal carotid artery and surrounding structures, and therefore could not be removed. Pathological examination of the aspirate revealed old blood and amorphous keratin material. Postoperatively the patient experienced complete relief from her headaches until May 11, 1969 when she was again admitted as an emergency case because of severe headaches and blurred vision. At this time the mandibular condyle was removed and a radical mastoidectomy was performed in order to fistulize the cyst into the ear canal. The fistula was created anterior to the carotid canal in an effort to preserve labyrinthine function. The fistulous tract was lined with skin grafts and a silastic tube was inserted to hold them in place. This tube extruded after five months and the fistula closed spontaneously. The "exploding type" headache and blurred vision recurred. Therefore, in December 1969 a revision mastoidectomy and a labyrinthectomy were performed to create a wider fistulous tract into the cyst. The bone removal included the medial wall of the middle ear, from the carotid- canal anteriorly to the descending portion of the facial canal posteriorly and inferiorly to the level of the jugular bulb. This opening was lined with split-thickness skin grafts. Complete relief from headaches and eye symptoms occurred and recovery from the effects of labyrinthine destruction was sufficient to permit discharge from the hospital after five to six days. The patient has remained completely free of headaches to the present date, a period of 4~ years. Radiological evaluation one year after the last operation has revealed a decrease in size of the
3
cyst as revealed by recalcification of bony landmarks such as the foramen ovale (Fig. 1B). CASE TWO
Congenital Epidermoid Cyst. A twenty-seven-year-old male was first seen in January 1973 with a complaint of short lasting episodic dizziness for ten weeks. He also complained of fluctuating hearing loss and a blocked sensation in the left ear for several months. Numbness over the left dental area and the lower left cheek was also noted for six months, and headache around the left ear was present for one month. The ear, nose and throat examination was entirely normal. Neurological evaluation was also within normal limits except for a slightly diminished left corneal reflex. Audiometric testing revealed bilateral high tone sensorineural loss at 4,000 Hz and normal speech discrimination scores. No conductive hearing loss was found. Electronystagmography revealed a slightly diminished response in the left ear and a type II positional nystagmus which was attributed to a possible brain stem lesion. Conventional and tomographic x-rays of the mastoids and base of the skull revealed an osteolytic lesion of the left petrous apex (Figs. 2 and 3A). Brain scan, arteriography and pneumoencephalography revealed an avascular petrous apex mass with a middle fossa extension. The internal carotid artery was displaced laterally in the region of the petrous apex. The preoperative diagnosis was primary cholesteatoma of the petrous apex, and on February 13, 1973 radical mastoidectomy and fistulization of the petrous apex was performed through the region of the labyrinth. A wide opening into the keratin filled cyst was created after removal of bone from the carotid canal to the vertical portion of the facial nerve canal and from the middle fossa dura to the jugular bulb. Split-thickness skin grafts were placed in the fistula after evacuation of a large amount of keratin debris from the cholesteatoma cyst. The patient was discharged four days following surgery, having made striking improvement from the effects of the labyrinthectomy. He
4
RICHARD R. GACEK
Fig. 2. Case 2. Frontal tomograms of the petrous apices demonstrating a complete destruction of the left petrous apex by the epidermoid cyst (arrows). C - Cochlea.
has been completely free of headaches except for one severe headache episode and an elevated temperature one month following surgery which occurred in association with a profuse cerebrospinal fluid leak from the left ear. Hematological and cerebrospinal examinations were normal. Symptoms gradually subsided on nonspecific therapy and there was gradual cessation of the cerebrospinal fluid otorrhea. The cholesteatoma remained marsupialized (Fig. 3B) and the patient has been free of symptoms for 16 months. CASE THREE
Neurofibroma. A seventy-three-yearold white female was first evaluated otologically in January 1962 for hearing loss and tinnitus in the left ear of two years duration. No complaints of vertigo, headache or facial pain were elicited. Complete otolaryngological examination was normal except for a left serous otitis media. Needle paracentesis of the left middle ear produced thin amber fluid and marked improvement in hearing. Following this, audiometric evaluation showed normal hearing in the
right ear and a flat sensorineural hearing loss of about 50 dB with complete recruitment and 56% speech discrimination score in the left ear. Tone decay was normal. Caloric response was present but somewhat reduced in the left ear. Radiological evaluation of the base of skull showed a questionable area of destruction of the floor of the middle fossa. It was felt that no relationship existed between the serous otitis media, sensorineural hearing loss, and questionable x-ray abnormalities. No further therapy was instituted and the patient was instructed to return in six months. The patient next returned in January 1969 with a history of increasing symptoms during the preceding 6-12 months; the left-sided hearing loss was now complete, pulsating tinnitus continued, horizontal diplopia was present, and a vague unsteadiness occurred from time to time. Examination revealed a "blue" drum on the left (brownish fluid on paracentesis), a slight left VI nerve weakness, profound left hearing loss, and markedly reduced caloric response in the left ear. No headache, facial pain or facial weakness were present. Radiological evalua-
PRIMARY TUMORS OF PETROUS APEX
Fig. 3. A) Case 2. Base of skull x-ray demonstrating an osteolytic lesion of the left petrous apex (dark arrows). The bony cochlea (C) has been spared by the lesion but the Eustachian tube (ET) and the foramen ovale (FO) may be encroached upon by the epidermoid cyst. FS - Foramen spinosum. B) Postoperative x-ray demonstrating the surgical fistula into the petrous apex. Radiopaque dye has been instilled into the external ear canal and outlines the tract (arrow) into the petrous apex cyst. ICA - Internal carotid artery, SP ~ Sphenoid sinus.
5
6
RICHARD R. GACEK
Fig. 4. A) Case 3. Conventional x-ray demonstrating a very extensive lesion (dark arrows) which has destroyed the petrous apex, the foramen ovale and the foramen spinosum. The tumor has extended into the sphenoid sinus (SP). C - Cochlea. Note normal foramen ovale (FO) and foramen spinosum (FS) on the right side. B) This tomogram clearly shows the extension into the left sphenoid sinus (arrow). C - Cochlea. Note normal petrous apex (AP) on the right.
PRIMARY TUMORS OF PETROUS APEX
tion revealed a definite osteolytic lesion of the left petrous apex and floor of the middle cranial fossa. Carotid arteriography demonstrated marked lateral displacement of the internal carotid artery in the region of the petrous apex. The diagnosis of primary petrous epidermoid cyst was made and surgery recommended. The patient refused surgery and was followed over the next five years. There was no essential progression in symptoms and no new signs appeared. An intermittent discharge of brownish fluid from the left ear provided relief from the pressure and tinnitus during these years. In June 1974 a follow-up radiological examination revealed an extensive area of destruction involving the petrous apex and the sphenoid bone, with extension into the left sphenoid sinus (Figs. 4A and B). Because of the increase in size of the tumor, the patient was referred to the author for surgical management to prevent intracranial complications (meningitis) and further neurological deficits. In November 1974 exploration of the left petrous apex was performed. After a wide field radical mastoidectomy, the carotid canal was identified anteriorly and the bone over the cochlea was removed between the internal carotid artery and the vertical portion of the facial nerve. A solid tumor mass was encountered in the petrous apex. Several biopsies were taken of the firm avascular mass. The area was skin grafted and packing inserted into the cavity. The patient had an uneventful postoperative course. Histological examination of the biopsy material revealed neurofibroma. Surgical removal of this tumor was not attempted because of the risk associated with extirpation of such a large tumor in an elderly patient. Unless signs or symptoms of critical nature occur, no surgical procedure is contemplated in the future. CASE FOUR
Chondrornyxosarcoma. A twenty-seven-year-old female was first seen in No-
7
vember 1971 with a complaint of headache, unsteadiness and a progressive right hearing loss. Otological examination two years previously revealed a right serous otitis media which was treated by the introduction of a middle ear pressure equalizing tube. Six months later, after the tube had extruded, the hearing loss recurred and a second pressure equalizing tube was introduced. After the second tube extruded, the patient had recurrence of hearing loss, unsteadiness with falling to the right and weakness of the right arm. The patient was then referred for consultation. Otological examination at this time showed a right serous otitis media, a reddish mass behind the inferior part of the right tympanic membrane, and a pure conductive hearing loss of 40-50 dB on the right and normal hearing in the left ear. Caloric tests with 5 cc of 26.6 C water revealed bilaterally symmetrical responses of normal duration. There was weakness of the right sternocleidomastoid and trapezius muscles, hemiparesis and hyperreflexia of the right arm and leg, right facial weakness, complete paralysis of the right vocal cord, and deviation of a fasciculating tongue to the right. Radiological studies of the mastoid and skull revealed increased density with destruction of the right petrous apex extending to the region of the jugular foramen. Exploration of the middle ear was carried out under general anesthesia and biopsy of the mass revealed chondromyxosarcoma. Since there were signs of increasing brain stem compression, partial removal of the intracranial component of the tumor was performed neurosurgically. However, the patient followed a progressive downhill course following surgery and died from bronchopneumonia twelve days after surgery. Autopsy revealed a muItilobulated encapsulated tumor mass which involved the right sphenoid and petrous portion of the temporal bone. The tumor extended into the basiocciput as far as the articular cartilage of the first cervical vertebra, and herniated into the middle and posterior cranial fossae, enveloping
8
RICHARD R. GACEK
Fig. 5. A) Case 4. Low power horizontal section of the chondromyxosarcoma replacing the petrous apex. The cochlea and internal auditory canal have been spared. The middle ear ( ME ) contains serous fluid. The internal carotid artery (lCA), the mandibular division of the trigeminal nerve (V') and the middle meningeal artery (MA) are compressed by the tumor (T) which has also extended into the posterior fossa. V2 - Second division of trigeminal nerve. (Reproduced from Figure 1 in "Primary Sarcomas of the Temporal Bone" by Pierre Naufal, reprinted from the Archives of Otolaryngology, July, 1973, Volume 98:44-50, Copyright 1973, American Medical Association.) B) High power photomicrograph (195X) of the tumor showing the cartilage tumor cells of chondrosarcoma.
the right III to XII cranial nerves. The temporal bones were removed for study, and the right temporal bone revealed a massive solid tumor which replaced the petrous bone with extension into the middle and posterior cranial fossae (Figs.
SA and B). The tumor extended through the infralabyrinthine cell tract into the hypotympanum, where it was visible on otoscopy. The internal carotid artery and mandibular division of the trigeminal nerve were displaced markedly in an
PRIMARY TUMORS OF PETRO US APEX
9
Fig. 6. Case 5. Frontal tomogram of petrous apices demonstrating the typical osteolytic lesion (arrows) of the apex which spares the cochlea (C). X - Indicates extension of the tumor into the infratemporal fossa.
anterolateral direction. The carotid artery was compressed to the point of occlusion. The lumen of the bony and cartilaginous portions of the Eustachian tube was also compressed by tumor. However, the bony labyrinth capsule was intact; the sensory areas of the cochlea and the vestibular organs were normal. CASE FIVE
Chondromyxosarcoma. A thirty-oneyear-old female was first seen in May 1971 with the complaint of difficulty in speaking and swallowing; a left paralyzed vocal cord was found. An examination including arteriogram was performed in October 1971, but no abnormality was discovered. In November 1971 she developed left-sided headaches. A diagnostic work-up which included polytomography, arteriography, and pneumoencephalography was performed at another hospital. As a result of these studies, the patient underwent a transmastoid exploration of the left jugular foramen and cartilaginous material was removed which was diagnosed histologically as "normal cartilage." The patient
noted some improvement in symptoms postoperatively but continued to have a pulsating feeling in the left ear. She was then reasonably well until November 1972 when she noted blurring of vision on turning her head, and in January 1973 experienced intermittent diplopia. This became constant by February 1973 and at that time it was noted that a left VI nerve palsy was present. In May 1973 she experienced the onset of intermittent tingling over the left mandible. At this time she was seen at the MEEI where a paralyzed left vocal cord, asymmetric elevation of the palate, and a questionable slight weakness of the left shoulder muscles were noted. The tongue was normal in appearance and movement. No extremity weakness was noted. Manual examination revealed a fullness inferior and deep to the left tympanic bone. Hearing evaluation and vestibular testing were normal bilaterally. No evidence of brain stem compression was found on this examination. Polytomography performed in April 1973 revealed a large erosive lesion extending from the petrous apex back to the jugular fora-
10
RICHARD R. GACEK TABLE I SUMMARY OF SYMPTOMS AND SIGNS IN PATIENTS WITH PRIMARY TUMORS OF THE PETROUS APEX
Tumor
Patient
Congenital epidermoid cyst
32F 27M
Neurofibroma
73F
Chondromyxosarcoma
24F
±
=
Int. Eusta· Carotid Artery V chian Nerve Tube Ob- ComHeadache Signs struction pression
+ + + +
31F incomplete Eustachian tube obstruction
men and as far posteriorly as the foramen magnum (Fig. 6). Carotid arteriography revealed anterolateral displacement and compression of the petrosal segment of the internal carotid artery. A diagnosis of primary cholesteatoma of the petrous apex or a chondroid tumor was entertained. Surgical exploration of the petrous apex was performed through a mastoid and middle ear approach. In the middle ear a small extension of tumor was noted protruding into the anterior hypotympanum between the exposed internal carotid artery anteriorly and the basal tum of the cochlea posteriorly. This area was enlarged by removing sufficient bone to create a fistula into the petrous apex without injuring the labyrinth. Solid and degenerated bluish cartilaginous material was removed for biopsy purposes. A large amount of degenerated tumor was then aspirated and the bony fistula was lined with split-thickness skin grafts to maintain a permanent tract into the petrous apex. Histologically this was diagnosed as a low-grade chondromyxosarcoma. The patient recovered from the surgery uneventfully and after the ear was completely healed, radiation therapy was administered on the 160 MeV proton beam machine to a dose of 6,125 rads. The patient tolerated radiation therapy well and experienced relief from headaches. Some improvement in the VI nerve palsy was noted. Deficits of cran-
+ + + +
+ ± + + ±
+ +
Other Craniol Nerves none none VI, VIII
+ +
Ill, VI, VII, IX, X, XI, XII IV, VI, IX, X, XI
ial nerves IX, X, and XI remain unchanged. Table I summarizes the findings in these five patients with petrous apex tumors. Except for one patient, these patients were all females and in a young age group. Significantly, four out of five patients experienced severe headaches, signs of involvement of the third division of the trigeminal nerve, and signs of internal carotid compression. While three out of five patients showed signs of complete Eustachian tube obstruction (serous otitis media), the remaining two patients had complained of ear blockage which was interpreted as incomplete tubal obstruction. These findings are associated with the early stage of development of petrous apex tumors. Only when the tumors reached extensive proportions were other cranial nerves involved as demonstrated by the last three cases in the table. DISCUSSION
Although this report discusses an almost equal number of patients with each of these primary tumors of the petrous apex, chondromyxosarcomas and neurofibromas are extremely rare in this area. In an extensive review of the literature on primary sarcomas of the temporal bone, Naufal' found one chondrosarcoma reported by Tucker" and added a second case (Case 4). There are numerous reports describing congenital cholestea-
PRIMARY TUMORS OF PETROUS APEX
toma arising in the middle ear 3 - 8 and in the petrous apex. 9 - 1 8
Clinical Features. Patients with congenital epidermoid cysts and patien~s with chondromyxosarcoma are usually ill the young adult age grouP? the~ ran~ed in age from 24-32 years ill this series, Other reports on congenital epidermoids of the petrous apex consistently report a young adult age group prevalence with these tumors. 1 , 3 - 7 , 9 - 1 9 Neurofibromas can occur in almost any part of the body and have been reported in all age groups. Headache was one of the most prominent symptoms in these patients and was described as a severe headache usually ineffectively treated with medication. The headache pain was usually located in the side of the ear affected, although in Case 1 the patient's headache was sometimes described as a deep exploding headache located in the center of the head. Headache is probably an indication of dural stretching by an expanding tumor at the petrous apex. Another common symptom was involvement of the mandibular division of the trigeminal nerve. Involvement of the third division of the V cranial nerve produced either pain, parasthesia or anesthesia over the distribution of this nerve. Very likely this indicated compression of the mandibular division of the V cranial nerve in the foramen ovale. Varying degrees of occlusion of the Eustachian tube were also found in these patients. In three patients (Cases 1, 3 and 4), complete obstruction of the Eustachian tube produced serous otitis media. In the other two patients (Cases 2 and 5), serous otitis media was not present but the patients complained of some form of blockage of the ear which could be interpreted as incomplete Eustachian tube obstruction. In the patients with complete Eustachian tube obstruction, conductive hearing loss was documented by audiometry. Symptoms related to internal carotid artery compression were also common. Slow compression of the internal carotid artery in young patients probably does not produce hemiparesis. Therefore, in
11
Case 4 the right hemiparesis was probably due to direct brain stem compression by the extensive tumor. However, lesser symptoms described as blurring of vision on turning of the head (Cases I and 5), or as dizziness (Case 2) m~y be ischemic effects from internal carotid artery compression. More sign~icant symptoms occurred in the patients WIth a solid malignant tumor (chondromyxosarcoma) as compared to patients with a cystic tumor (congenital epidermoid) or a slow growing benign tumor (neurofibroma) which probably exert a less compressive effect on the artery. The two patients with chondromyxosarcoma presented with a more extensive involvement of the base of the skull. In these patients the nerves of the jugular foramen (IX, X and XI), and the hypoglossal foramen (XII) were involved. Other nerves compressed by anterior extension at the base of the skull were III, IV and VI. While these multiple cranial nerve deficits were more common with solid malignant tumors as chondromyxosarcoma, it is also possible that extensive benign tumors of the petrous apex may involve these cranial nerves (Case 3). Aside from the cranial nerve deficits associated with very extensive tumors, the otolaryngological examination was either normal (C ases 2 and 5), or revealed merely serous otitis media if the tumor was large enough to compress the Eustachian tube (Cases 1, 3 and 4). Only when the tumor is massive may it present otologically (Case 4). In four of these patients both auditory and vestibular labyrinthine function was normal. This was true even in the cases of chondromyxosarcoma where there was extensive destruction of the petrous bone. The preservation of labyrinthine function underlines the resistance of the bony labyrinth to tumor erosion. However, extensive tumors may eventually destroy the bony labyrinth wall and cause loss of auditory and vestibular function as in Case 3.
Radiological Findings. While conventional routine x-rays of the petrous bone
12
RICHARD R. GACEK
Int. Carotid Art.
Heart
Ext. Carotid Art.
Rathke's Pouch Optic Vesicle
Fig. 7. Drawing of the cephalic flexure and relationship to the internal carotid artery at the one-month embryo stage. Note the location of Seessel's pocket and Rathke's pouch adjacent to the stomodeal plate (broken line). Roman numerals I-IV identify branchial pouches. (Redrawn from Figure 74 in Patten, B. M., Human Embryology, McGraw-Hill, 1953. Used with permission of McGraw-Hill Book Company.)
and the base of the skull may occasionally provide clear evidence of an osteolytic lesion at the petrous apex, frequently when the tumor is small the findings on plain views are equivocal and confirmatory evidence may be obtained with polytomography and arteriography. In all cases in this series, there was radiological evidence of bone destruction at the petrous apex. Plain views and tomograms of the petrous bone demonstrated this radiologic defect. In the extensive tumors, the area of bone destruction extended posteriorly to include the jugular foramen and the hypoglossal canal and anteriorly to involve the sphenoid sinus. Arteriography in all cases consistently showed lateral displacement of the petrous segment of the internal carotid artery by an avascular mass. Pneumoencephalography showed these tumors to be extradural in location. Origin of Tumors. It seems likely that these tumors of the petrous apex arose from the foramen lacerum. The foramen lacerum is the name given to the space (occupied by the basal fibrocartilage) with jagged margins between the pars basilaris of the occipital bone and the
temporal wing of the sphenoid bone on the one hand, and the apex of the petrous segment of the temporal bone on the other. Several reasons may be given as support for the hypothesis that these tumors arose from the foramen lacerum. 1. The foramen lacerum normally contains fibrocartilage, a mesenchymal derivative of embryonic development. This fibrocartilage appears the most likely source for the origin of chondroid tumors, although other cartilage rests are located in the enchondral bone layer of the bony labyrinth. However, if the cartilage tumors arose in the enchondral layer, loss of labyrinthine function would be an expected early sign.
2. While no structures pass through the foramen lacerum, there are two types of structures that course across the foramen. These are the internal carotid artery and the nerves which merge to form the vidian nerve ( greater superficial petrosal and deep petrosal). Therefore, tumors of neural origin can arise in the foramen lacerum with little or no ob-
PRIMARY TUMORS OF PETROUS APEX
13
Epithelium pinched off from Seessel's pocket
Eye
Hypophysis from Rathke's pouch
Fig. 8. This drawing illustrates the proposed mechaJ.lism whereby epithelial res~s from Seessel's pocket are trapped in the mesenchyme (sttp~led area) of, the cephalic flexure, Dotted arrows indicate the deepening of the cephahc flexure which promotes the entrapment of epithelial rests.
vious signs or symptoms related to the involved nerve, 3. The foramen lacerum appears to be a likely area for epithelial remnants to be trapped during embryonic development and then develop later into congenital epidermoid cysts.
Early in embryonic developme~t OI~e of the important changes occw:mg IS flexion of the embryo from a straight to a semicircular shape in order to conform to the limited space in utero.P? Bending of the ectodermal tube which will form the central nervous system produces the cephalic flexure (Fig. 7), In a one-month embryo the internal carotid artery, which ascends through the cephalic flexure, is recognizable after absorption of the intersegmental arterial branches between pharyngeal pouches. An invagination at the stomodeum reaches toward the primitive gut to the point where a stomodeal plate is formed marking the transition between ectodermal and entodermal epithelium. Resorption of this stomodeal plate occurs early in embryonic development. Concomitant with the resorption of the stomodeal plate is the lengthening of the cephalic flexure and an associated shift of the mesenchyme filling the flex-
ure. Accompanying this movement is a withdrawal of the epithelium adjacent to the stomodeal plate into the cephalic flexure. The most external of these epithelial invaginations is Rathke's pouch and the internal one is Seessel's pocket (Fig. 7). As these two epithelial invaginations are drawn up into the mesenchymal tissue filling the cephalic flexure, isolated epithelial remnants of Rathke's pouch or Seessel's pocket may remain. Epithelial remnants derived from Rathke's pouch in the midline form a portion of the adult hypophysis. It seems possible that isolated epithelial islands from the lateral recesses of a deep Seessel's pocket may also remain trapped in condensing mesenchyme at the base of the cephalic flexure ( Fig. 8) . While most of the mesenchyme in the cephalic flexure undergoes resorption, a small portion at the base forms the fibrocartilage filling the foramen lacemm. Support for the contention that the base of the cephalic flexure is identical with the foramen lacerum is shown in Figure 9, where the trigeminal ganglion can be seen stretching across from the petrous apex to the mandibular region, and in Figure 10,
14
RICHARD R. GACEK
Cephalic F~le:::x.:::ur::::e==:::::---.
Cephalic Flexure
Foramen Lacerum
Fig. 9. Drawing which shows the relationship of the trigeminal nerve and ganglion to the cephalic flexure, the eye and the ear, and the other cranial nerves. Note how the ganglion is located anterolateral to the base of the flexure, indicating that this area is located at the apex of the petrous pyramid. (Redrawn from Figure 66 in Patten, B. M., Human Embryology. McGraw-Hill, 1953. Used with permission of McGraw-Hill Book Company.)
where the ossification of bones at the base of the skull in the embryo can be seen. The ossification of the temporal bone and the temporal wing of the sphenoid surrounds the base of the cephalic flexure. Incomplete fusion of these ossification centers and retention of mesenchyme as fibrocartilage form the adult foramen lacerum. Retained epithelial remnants of Seessel's pocket may be entrapped in this fibrocartilage and give rise to congenital epidermoid cysts or cholesteatomas later in life. 4. Finally, the pattern of expansion and involvement of structures surrounding the base of the skull suggests that these primary tumors of the petrous apex arise from the foramen lacerum. Figure 11 demonstrates the relationship of the foramen ovale, Eustachian tube, and the internal carotid artery to the foramen lacerum. Expanding tumors from the foramen lacerum would most likely involve these structures before other structures at the base of the skull. Tumors
Internal Auditory Canal
Fig. 10. Drawing of the ossification of the bones at the base of the skull (heavy stipple) and their relationship to the cephalic flexure. Note how the base of the flexure is located between the apex of the petrous bone and the temporal wing of the sphenoid bone. The mesenchyme in the cephalic flexure ( light stipple) forms the cartilage in the foramen lacerum. Upper drawing represents side view, lower drawing is a base view of the skull. (Redrawn from Figure 165 in Patten, B. M., Human Embryology, McGraw-Hill, 1953. Used with permission of McGraw-Hill Book Company.)
arising in more distant areas such as the jugular foramen or the middle ear would involve other structures such as the tympanic membrane, the facial nerve or the nerves of the jugular foramen before involving structures at the petrous apex. Lateral displacement of the internal carotid artery by tumors in this region would argue against epithelial rests from the Eustachian tube (branchial pouch I) as the source of congenital cholesteatoma of the apex. If the epidermoid arose from Eustachian tube elements, the internal
15
PRIMARY TUMORS OF PETROUS APEX
Eustachian Tube
Foramen Spinosum Foramen Lacerum
Jugular Foramen
Fig. 11. Half photograph and half drawing of structures at the base of the skull. Note relationship of Eustachian tube, foramen ovale, and internal carotid artery to the foramen lacerurn.
carotid artery would be displaced medially. Stages in Growth of TUTTWT. In the otological and neurosurgical literature, primary epidermoids of the petrous apex have been described in three clinical forms. 1. Olivecrona'" and Revilla1 3 • 1 4 have emphasized the association of mandibular division of the trigeminal nerve signs along with normal VIII and VII nerve function in patients with primary epidermoid of the petrous apex. Normal radiological and neurological examinations were also usually present. It is likely that these patients are seen pri-
marily by the neurosurgeon because of the large number of patients with tic douloureaux treated by this specialty. 2. In the otological literature the characteristic clinical presentation of primary petrous apex epidermoid consists of VII and VIII nerve deficits either with or without cholesteatoma in the middle ear or mastoid.v-v-" This association is undoubtedly related to the presence of otological functional deficits at the time of diagnosis. Otological reports of patients with petrous apex congenital cholesteatoma having normal VII and VIII nerve function are rare." 3. Primary epidermoids are included
16
RICHARD R. GACEK
in the classifications of cerebellopontine angle tumors when there is encroachment of the nerves in the internal auditory canal by a mass lesion which is usually located anterior to the VII and VIII nerves in the posterior cranial fossa. Trigeminal nerve involvement is sometimes used to differentiate clinically epidermoid from other cerebellopontine angle tumors. This description of primary epidermoid is present in both the neurosurgica1'3,14,19 and otologicaI15,16,18 literature. An analysis of the patients described in this report and in the literature points to a common pattern of expansion in the petrous apex. The bone of the apex contains marrow spaces and would more likely allow for expansion of a tumor than the other solid bony components of the skull. Knowledge of the structures surrounding the foramen lacerum provides a guideline for early detection of expanding tumors in this area. Based on the involvement of surrounding structures at the base of the skull, primary tumors at the petrous apex may be divided clinically into three stages which more or less correspond to the clinical types described in the literature. Stage I. Tumors at this stage involve those structures in the immediate vicinity of the foramen lacerum. These are: the middle or posterior fossa dura attached to the petrous apex, the mandibular division of the trigeminal (V) nerve, the Eustachian tube, and the internal carotid artery. Symptoms resulting from encroachment on these structures are: headache, pain, anesthesia or paresthesia in the distribution of the third division of the V nerve, hearing loss or a blocked feeling in the ear, and various complaints related to cerebral ischemia such as blurred vision or faintness.
At this stage only one or two of these structures may be clinically involved and otolaryngological examination including evaluation of labyrinthine function may be entirely normal. Therefore, a high index of suspicion is necessary in order to make the diagnosis of tumor at the petrous apex. Careful radiological eval-
uation of the base of the skull is the simplest and most informative diagnostic study to carry out. Failure to suspect a lesion at the petrous apex at this early stage may lead to unnecessary surgical treatment for Eustachian tube obstruction (myringotomy with insertion of ventilating tubes, simple mastoidectomy) and potentially dangerous delays in diagnosis. Stage II. As the tumors enlarge, extension is usually in a posterior or anterior direction because the bone in these areas at the base of the skull offers the least resistance. Compression of the VII and VIII nerves at the internal auditory meatus, cranial nerves IX, X and XI in the jugular foramen, and the XII nerve in the hypoglossal foramen may occur with posterior extension. Cranial nerves III, IV, and VI may become involved with anterior extension of the tumor toward the cavernous sinus. These neurological deficits make the diagnosis of petrous apex tumor more apparent. Stage III. Further extension of an expanding neoplasm at the petrous apex may involve a region where the tumor mass can be detected by clinical examination. These areas are: the nasopharynx, the middle and posterior cranial fossae, the middle ear, or the infratemporal fossa. Detection of tumor in such areas may be by direct visualization and palpation (nasopharynx, middle ear or neck) or by the effects of tumor compression on vital structures such as the brain stem (the posterior cranial fossa). When such extension involves the posterior fossa, a cerebellopontine angle tumor mass is present.
The bony labyrinth resists erosion from the enlargement of these tumors." Therefore, normal labyrinthine function is frequently found on clinical evaluation. However, this resistance is not absolute and with extensive erosion, loss of labyrinthine function and facial paralysis may occur. Seventh and VIII cranial nerve function may be impaired by direct compression of the nerves as they course toward the brain stem or by erosion of the bony labyrinth wall. When
17
PRIMARY TUMORS OF PETROUS APEX External Auditory Canal
Facial Nerve
Eustachian Tube
Antrum
Internal Carotid Artery
Fig. 12. Drawing of the temporal bone showing the otologic approach to fistulize (heavy solid lines) a tumor located in the petrous apex. Areas surrounding the cochlea (dashed + dotted lines) indicate bone removal necessary to reach the tumor after exposure with radical mastoidectomy.
these signs are present they are late indications of a petrous apex tumor. DIAGNOSIS
Since tumors at the petrous apex are inaccessible to direct clinical detection, early diagnosis must rest on a high index of suspicion based on recognition of the early signs and symptoms of expanding tumors at the petrous apex. When there is an indication of involvement of the dura of the cranial fossae, the mandibular division of the V cranial nerve, the Eustachian tube, or the internal carotid artery, then conventional radiological views and tomography of the petrous apices and the base of the skull should be obtained. If no abnormality is found, then careful follow-up examination at five to six month intervals should be carried out if symptoms persist.
If an area of bone destruction at the petrous apex is detected, then pneumoencephalography, brain scan, and carotid arteriography are the most helpful diagnostic studies that may be performed. These studies along with a complete oto-
laryngologic and neurologic examination are usually sufficient to rule out other entities in the differential diagnosis such as petrositis, metastatic nasopharyngeal carcinoma, metastatic carcinoma from a distant primary (such as breast, thyroid and prostate), glomus jugulare tumor, meningioma, internal carotid artery aneurysm, and eosinophilic granuloma. If the lesion is one of the primary neoplasms of the foramen lacerum discussed in this study, the diagnostic studies would demonstrate an avascular extradural mass lesion at the petrous apex which displaces the internal carotid artery laterally. SURGICAL MANAGEMENT
Delay in diagnosis of petrous apex tumors resulted in no treatment (Case 5) or in treatment for a relatively benign condition secondary to tumor growth such as serous otitis media (Cases 1, 3 and 4). This delay can probably be attributed to a lack of awareness of the early signs and symptoms of these tumors and as a result inadequate radio-
18
RICHARD R. GACEK
logical evaluation of the petrous apex of the temporal bone. Once the radiological diagnosis of a destructive lesion at the petrous apex was made, exploration of the petrous apex was carried out in Cases 1, 2 and 5. It was clear from the experience with Case 1 that simple exploration and evacuation of the primary epidermoid cyst of the petrous apex does not result in permanent relief of symptoms. Permanent fistulization was then the goal in the treatment of congenital cholesteatomas of the petrous apex. A conservative approach to fistulizing the congenital epidermoid in Case 1 met with failure. In this patient, a fistula into the cyst was created anterior to the carotid canal and skin grafted with preservation of labyrinthine function; the fistula closed eventually because it was not wide enough. The successful operation in Case 1 consisted of complete labyrinthectomy and removal of the bony labyrinth from the internal auditory canal to the internal carotid artery (Fig. 12) and lining the bony fistula with split-thickness skin grafts. The effectiveness of this approach was again demonstrated in Case 2 where, at the initial surgical procedure, the transmastoid and translabyrinthine fistulization of the congenital cholesteatoma was successful. Surgical exploration of the petrous apex tumor in Case 3 was carried out to prevent the Occurrence of complications from rupture of an extensive primary epidermoid cyst. Instead, exploration and biopsy via the translabyrinthine route revealed a solid benign tumor which was too extensive to remove safely. The surgical procedure in this case served a diagnostic purpose. In Case 4 the chondromyxosarcoma was too extensive at its initial recognition to permit effective surgical or radiotherapeutic management. The surgical procedures performed provided 1) histological diagnosis and 2) neurosurgical decompression of the expanding tumor. The patient eventually died from an intracranial complication of the primary tumor. In Case 5 where the tumor was diagnosed histologically, following the
approach to the petrous apex through a large infralabyrinthine cell tract, a drainage procedure was accomplished by fistulizing the tumor mass. Radiation therapy has been administered. SURGICAL APPROACHES TO THE PETROUS APEX
Because of the inaccessible location of the tumors in the petrous apex, complete extirpative surgery is usually not possible. Therefore, the surgical management consists of diagnostic exploration and fistulization of the expanding mass. Biopsy is necessary to obtain tissue diagnosis; fistulization either may form the definitive treatment, as in the case of primary epidermoid cysts, or may act as a drainage procedure for necrotic tumor cells follOWing radiation therapy for chondromyxosarcoma. There are several surgical approaches to the petrous apex. M.iddle Fossa Extradural. This approach to the petrous apex via the middle cranial fossa can serve to reach the tumor for diagnostic purposes. Biopsy of a solid tissue mass or aspiration of a cystic lesion may be accomplished via this route but permanent fistulization is not possible. Thus in the case of primary epidermoid cysts, recurrence is frequently the case as demonstrated in Case 1 in the present series. An advantage of this procedure is that labyrinthine function may be preserved. Posterior Fossa Craniotomy. The morbidity associated with this approach limits its usefulness to those tumors of the cerebellopontine angle where the neoplasm may be intracranial in origin, thus requiring intracranial removal. This approach may also be necessary as a decompression procedure where intracranial extension of a petrous apex tumor may produce signs of brain stem compression (as in Case 4). However, some neurosurgical reports have described complete or near complete removal of epidermoids using this approach. Transethmoidosphenoid. This approach through the ethmoid and sphenoid sinus to the petrous apex has been described to successfully fistulize con-
PRIMARY TUMORS OF PETROUS APEX
genital epidermoid cysts at the petrous apex." While this can be accomplished via this route, the space limitation may add difficulty to the maintenance of a permanent fistula into the cyst. It is not possible to apply skin grafts to the fistula, and one must depend on the opening of the fenestra in the sphenoid sinus to maintain a fistula. Furthermore, the risk of an ascending infection into the pennanently fistulized lesion from a potentially contaminated area such as the nasopharynx must be considered. The difficulty of evacuating a keratin filled mass through the nasal cavity may also be a minor disadvantage of this procedure. On the other hand, the preservation of labyrinthine function is a major advantage of this approach to the petrous apex.
Transmastoul - Translabyrinthine. In this approach, a wide field mastoidectomy and removal of the cochlea is essential in order to expose the tumor. Meticulous removal of all vestibular sensory tissue is also necessary to assure complete elimination of all vestibular function and a satisfactory recovery from the labyrinthectomy. Purposeful destruction of the cochlear and vestibular labyrinth is justified in order to successfully expose a life-threatening lesion at the apex of the temporal bone. A wide bony fistula into the petrous apex is created by exenterating the bone from the carotid canal anteriorly to the descending facial nerve posteriorly and from the jugular bulb inferiorly to the middle cranial fossa superiorly (Fig. 12). As the petrous apex is exposed, solid tissue may be obtained for biopsy or the contents of an epidermoid cyst may be evacuated completely. The bony fistula is then lined with split-thickness skin grafts that are held in place with packing. Packing for 10-14 days is sufficient to allow for the implantation of skin grafts. After a large fistulous tract into the petrous apex has been created, the cystic space can be easily aspirated on an outpatient basis and little chance of ascending infection is present. The most significant disadvantage of this procedure is the loss of labyrinthine function. However, this is justifiable in order to achieve relief of
19
symptoms and the complete control of a potentially life-threatening tumor. In the case of solid tumors as chondromyxosarcoma, a wide fistulous opening may provide satisfactory drainage of necrotic tumor following radiation therapy.
Factors Influencing Choice of Surgical Approach. Regardless of approach, the fundamental aim of surgery is to reach the tumor and to form a permanent fistula into it. Since a lesion at the petrous apex cannot be marsupialized via the middle or posterior fossa route, the effective choice is either the nasal or the middle ear approach. This choice can be guided by several factors. Preference of the Surgeon. Familiarity with the anatomical variations and surgical technique associated with sphenoid or middle ear surgery must be considered by the surgeon. Experience with surgical anatomy and its variations are essential to approaching the petrous apex safely and the surgeon should choose the route with which he feels most confident. The otologic approach is favored over the rhinologic one in this report for several reasons: 1) The middle ear route is more direct and the working distance to the apex is less. Therefore, the contents of the cholesteatoma or solid tumor can be aspirated more easily. 2) Split-thickness skin grafts may be applied to the bony fistula by means of the middle ear route. 3) There is less chance for ascending infection from the middle ear into a fistulized cyst as compared to the nasopharynx.
Degree of Labyrinthine Function in the Involved and Uninvolved Ear. If the hearing on the side with tumor is profoundly depressed, the otologic approach is clearly indicated. However, if the involved ear represents an only-hearing ear, then the nasal approach to fistulize the petrous apex tumor through the sphenoid sinus should be considered. Additional Incidental Factors. If both ears have normal inner ear function, then other anatomical and pathological factors gUide the decision. These may be
20
RICHARD R. GACEK
real or potential factors. The presence of a sclerotic sphenoid sinus or of chronic sinusitis would contraindicate the nasal approach. Even the potential risk of ascending infection into a fistulized cyst may favor the otologic approach. The sacrifice of labyrinthine function in one MASSACHUSETTS EYE AND EAR INFIRMARY,
ear is justified by the serious nature of an expanding cholesteatoma or solid tumor in the petrous apex. In petrous apex tumors that have extended outside the apex (Stage III), the extension into the sphenoid sinus or middle ear may dictate the logical approach. 243
CHARLES ST., BOSTON, MASS.
02114.
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1. Naufal PM: Primary sarcomas of the temporal bone. Arch Otolaryngol 98:44-50, 1973
12. Cole TB, McCoy G: Congenital cholesteatoma of temporal bone and sphenoid sinus. Arch Otolaryngol 87 :576-579, 1968
2. Tucker WN: Cancer of the middle ear. Cancer 18:642-650, 1965
13. Revilla AG: Tic douloureaux and its relationship to tumors of the posterior fossa. J Neurosurg 4:233-239, 1947
3. Day KM: A primary cholesteatoma of the middle ear. Ann Otol Rhinol Laryngol 64: 161-163, 1955 4. Derlacki EL, Clemis JD: Congenital cholesteatoma of the middle ear and mastoid. Ann Otol Rhinol Laryngol 74:706-727, 1965 5. Derlacki EL: Congenital cholesteatoma of the middle ear and mastoid. Arch Otolaryngol 97: 177-182, 1972 6. House HP: An apparent primary cholesteatoma. Laryngoscope 63:712-713, 1953 7. Kerr AG, Smyth GD: Congenital cholesteatoma of the temporal bone. Laryngoscope 77 :86-88, 1967
14. Revilla AG: Differential diagnosis of tumors -at the cerebellopontile recess. Bull Johns Hopk Hosp 83:187-212, 1948 15. Hitselberger WE, House WF: Tumors of the cerebellopontine angle. Arch Otolaryngol 80:720-731, 1964 16. House WF, Doyle JB Jr: Early diagnosis and removal of primary cholesteatoma causing pressure to eighth nerve. Laryngoscope 72:1053-1062, 1962 17. Jefferson G, Smalley AA: Progressive facial palsy produced by intratemporal dermoids. J Laryngol Otol 53:417, 1938
8. Sheehy JL: True cholesteatoma. Arch Otolaryngol 69:57-60, 1959
18. Lewis ML, Echols DH: Pearly tumor of the cerebellopontine angle. Report of a case with reversible deafness. Laryngoscope 61: 1123-1125, 1951
9. Brookler KH, Pulec JL and Hallberg OE: Congenital cholesteatoma of the temporal bone. Arch Otolaryngol 90:71-74, 1969
19. Olivecrona H: Cholesteatomas of the cerebellopontine angle. Acta Psychiat et Neurol 24:639-643, 1949
10. Cawthorne E, Griffith A: Primary cholesteatoma of the temporal bone. Arch Otolaryngol 73:252-261, 1961
20. Patten BM: Human Embryology, ed. 2. New York, McGraw-Hill, 1953
11. Cawthorne T: Congenital cholesteatoma. Arch Otolaryngol 78:248-252, 1963
21. Proctor B, Lindsay JR: Tumors involving the petrous pyramid of the temporal bone. Arch Otolaryngol 46: 180-194, 1947
