Transcanal infracochlear approach to the petrous apex NEIL A. GIDDINGS, MD, DERALD E. BRACKMANN, MD, and JED A. KWARTLER, MD, Danville, Pennsylvania,
Los Angeles, California, and Newark, New Jersey
Computerized tomography and magnetic resonance imaging have now made it possible to reliably differentiate cholesteatoma from cholesterol granuloma of the petrous apex. The treatment for cholesteatoma is complete surgical excision when possible, whereas cholesterol granuloma needs only adequate drainage for control. A new transcanal infracochlear approach for drainage of cholesterol granuloma involving the anterior petrous apex is described. Absolute measurements from 10 cadaveric temporal bones were obtained to determine the distances between the cochlea, jugular bulb, carotid artery, and facial nerve. In all specimens the petrous apex was entered without invading the cochlea, carotid, or jugular bulb. Advantages of this technique include a more direct route to the petrous apex, dependent drainage, and preservation of the normal hearing mechanism, including the tympanic membrane. Clincial indications for this technique include failure of other treatment approaches and a high jugular bulb obstructing an infralabyrinthineapproach. Experienceto date shows that patients experience little difficulty from the procedure. (OTOLARYNGOL HEAD NECK SURG 1991;104:29.)
Cholesterol granuloma frequently occurs in the middle ear and mastoid in association with chronic ear disease as a result of poor aeration in a mucosa-lined cavity. On rare occasions it may arise in the petrous apex without middle ear disease and produce symptoms through slow expansion. In the last 5 years, numerous clinical reports have documented a rising awareness of this lesion and the sometimes frustrating results of its treatment. Cholesterol granuloma was first described by Manasse' in 1917. Since then it has been frequently described. Sometimes it is confused with cholesteat ~ m a .Cholesteatoma ~.~ and cholesterol granuloma, two distinct pathologic entities, may appear independently or in conjunction. Cholesteatoma arises from trapped skin in an abnormal anatomic location, whereas cho-
From the Department of Otolaryngology-Head and Neck Surgery (Dr. Giddings), Geisinger Medical Center, Danville; House Ear Clinic and House Ear Institute, Los Angeles (Dr. Brackmann); and the Division of Otolaryngology (Dr. Kwartler), New Jersey University of Medicine and Dentistry, Newark. Supported by research funds from the House Ear Institute and Geisinger Medical Center. Presented at the Annual Meeting of the American Neurotology Society, West Palm Beach, Fla., April 27, 1990. Received for publication April 20, 1990; accepted Aug. 14, 1990. Reprint requests: Derald E. Brackmann, MD, House Ear Clinic, 2122 West 3rd St., Los Angeles, CA 90057. 231 1124561
lesterol granuloma is a granulomatous structure formed in nonspecific reaction to cholesterol crystals.' These cholesterol crystals are probably derived from local tissue breakdown or blood.4 Cholesterol granuloma may develop in any aerated portion of the temporal bone, but it most commonly occurs in the mastoid air cells some distance from a lesion preventing normal aeration. Cholesterol granuloma of the petrous apex probably develops when a pathologic process or trauma obstructs the air-cell tracts to a well-pneumatized petrous apex." The treatment for cholesterol granuloma of the temporal bone is drainage and reestablishment of adequate aeration to the involved area. The cyst wall is composed of a fibrous connective tissue. It is free of the keratinizing squamous epithelium that characterizes cholesteatoma, and complete removal of the cyst is not necessary. The petrous apex can be approached by way of a number of routes, including through the middle fossa, translabyrinthine, or along lines of developed air cell tracts. The middle fossa approach does not allow adequate ventilation of the petrous apex after drainage, making recurrence of cholesterol granuloma likely. The translabyrinthine approach provides continued drainage but obviously destroys hearing. Following established air cell tract offers the possibility of continued drainage, aeration of the petrous apex, and preserved hearing. Most of the routes of drainage for the petrous apex 29
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Fig. 1. The external auditory canal is completely transected.
were developed during the preantibiotic era for drainage of petrous apex abscesses and cure of Gradenigo’s syndrome. These same approaches may be equally effective in draining cholesterol granuloma. Air cell tracts may be followed from the root of the zygoma, the sinodural angle, the attic, or through the arch of the superior semicircular Inferiorly based approaches may follow the carotid artery anterior to the cochlea or infralabyrinthine.’-’* Ghorayeb and Jahrsdoerfer* presented at the 1988 meeting of the American Neurotologic Society an infracochlear approach to the petrous apex requiring a canal wall-down mastoidectomy. All of these approaches have been effective in the drainage of petrous apicitis, but their effectiveness in drainage of cholesterol granuloma remains undetermined. We describe a new transcanal approach to the petrous apex for the drainage of cholesterol granuloma, including results of a temporal bone study and several case reports. OPERATIVE TECHNIQUE
In 1984, F a r r i ~ rdescribed ’~ a transcanal approach to small glomus jugulare tumors of the hypotympanum. Our infracochlear approach to the petrous apex is a *Ghorayeb BY, Jahrsdoerfer RA. Subcochlear approach for cholesterol granulomas of the inferior petrous apex [Personal communication]. 1989.
combination of this technique and the subcochlear approach described by Ghorayeb and Jahrsdoerfer. 1. A postauricular incision is made and the auricle is reflected anteriorly. 2 . The membranous external auditory canal is completely transected laterally (Fig. 1). 3. A tympanomeatal flap is elevated from the 2o’clock position to the 10-o’clockposition, leaving the tympanic membrane attached at the umbo and the superior canal wall. 4. The external auditory canal is enlarged anteriorly and inferiorly to expose the hypotympanum. The chorda tympani is followed inferiorly, posterior to lateral, to define the extent of posterior dissection possible without injuring the facial nerve (Fig. 2). 5. Air cells are removed below the cochlea in the hypotympanum to expose the course of the carotid artery and the jugular bulb. The round window provides the superior line of dissection, and Jacobson’s nerve leads to the “crutch” of the carotid and jugular bulb (Fig. 3). 6. Removal of air cells continues medially. If the plane of dissection remains below the round window, the internal auditory canal structures will not be at risk (Fig. 4). 7. The cholesterol granuloma cyst is entered and drained. The newly created “window” is enlarged anteriorly to the carotid artery, inferiorly
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Transcanal infracochlear approach to petrous apex 31
Fig. 2. External auditory canal skin is elevated, exposing the lower half of the middle ear space. Bone is removed from the anterior and inferior aspects of the canal to expose the hypotympanum with the chorda tympani as a landmark for the posterior limit of dissection.
/ Fig. 3. Bone is removed, exposing the carotid artery and jugular bulb.
to the jugular bulb, and superiorly to the inferior aspect of the basal turn of the chochlea. 8. A silicone rubber catheter of appropriate size is introduced if necessary to provide support for the opening.
9. The soft tissue of the external auditory canal is returned to its normal position, and Gelfoam is packed within the external auditory canal and between the canal wall and the newly enlarged bony canal (Fig. 5).
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.
_--
Fig. 4. Dissection proceeds medially in the triangle formed by the inferior aspect of the basal turn of the chochlea. the carotid artery, and the jugular bulb until the cyst is entered and drained.
Fig. 5. The external auditory canal skin is returned to its normal position and packed with Gelfoam.
10. The postauricular incision is closed and a mastoid dressing is applied. TEMPORAL BONE RESULTS
Ten cadaveric temporal bones were dissected with the surgical technique described previously. After completion of the dissections, a graduated ocular was used to measure the anterior-posterior and inferior-superior dimensions of each surgically created fenestra. Most of
the fenestrae were shaped like triangles or rectangles (Fig. 6). Cross-sectional area was calculated by the formulas % x Base x Height for triangular fenestrae and Length x Width for rectangular fenestrae (Table 1). The mean area of the fenestrae was 25.6 f 16.3 mm2, with a maximum area of 67.2 mm2 and a minimum area of 7.4 mm2,The median area was 22.1 mm’. In all bones it was possible to enter either petrous
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Transcanal infracochlear approach to petrous apex 33
Fig. 6. Temporal bone specimens showing relative positions of major vessels and cochlea. Arrows indicate lines of measurement.
apex air cells or marrow without invading the cochlea. carotid, or jugular bulb. In no specimen was damage to the internal auditory canal seen after operation. CASE REPORTS Case I. A 50-year-old woman was well until September 1987, when she had a sudden left sensorineural licaring loss. After treatment with oral steroids. her condition returned to baseline. Results of computerized tomographic (CT) scan of the temporal bones, performed at another institution. were reportedly unremarkable. In October 1987, she experienced a left-sided palsy involving cranial nerve VI and diplopia. These resolved without treatment. In March 1988. the diplopia recurred. CT and magnetic resonance imaging (MRI) scans revealed a left petrous apex lesion consistcnt with cholesterol granuloma (Fig. 7). The patient was first seen at the House Ear Clinic in October 1988, at which time she reported diplopia and left-sided tinnitus. Physical examination was unremarkable at that time except for a left-sided palsy involving cranial nerve VI. An audiogram was unremarkable. MRI scan at that time revealed an increase in the lesion’s size to greater than 2 cm. as compared with the size noted at the previous examination in March 1988. Because of a high jugular bulb. an infralabyrinthine approach to the lesion was not attempted and a craniotomy through the left middle fossa with drainage of the cholesterol granuloma was performed on October 21, 1988. The patient had a good postoperative course, with resolution of her diplopia until May 1989, when she once again began to expcrience diplopia. CT scan at that time revealed persistent petrous apex lesion with continued expansion. There was an infracochlear patent air cell tract. The patient returned to the operating room June 13. 1989. for a transcanal infracochlear drainage of the cholesterol granuloma. Her postoperative course was good and she remains free of symptoms. A CT scan 6 months after operation ( Fig.
Table I.Measurements of infracochlear fenestra size from 10 cadaveric temporal bones Temporal
Height
Width
Area
bone
(mml
(mm]
(mmzl
62 56 74 35 56 39 57 52 42 63
98 50 84 63 60 70 50 46 35 61
30 4 14 0 62 2 22 1 33 6 22 0 14 3 11 8 74 38 4
1
2 3 4 5 6 7 8 9 10
8) reveals a persistent patent avenue for drainage in the infracochlear region. Case 2. A 17-year-old girl was well until 1984. when she noticed decreased hearing in the right ear. Physical cxamination at that time revealed a bluish mass behind the right tympanic membrane. A CT scan revealed a “congenital cholesteatoma” of tlie right petrous apex. and she undenvent a middle fossa craniotomy for removal of the cholesteatonia at an outside institution. Despite otherwise satisfactory healing. she once again noticed decreased hearing in her right ear. Fluid collectcd again behind tlie right tympanic membrane. requiring insertion of a pressure equalization tube. In November 1985. she began to have continuous drainage from the tube. She was seen at the House Ear Clinic for the first time on June 19, 1989. At that time she did not have diplopia but did have decreased hearing and otorrhea on the right side. CT scan revealed a persistent cholesterol granuloma of the right pctrous apex that had enlarged since the middle fossa dccomprcssion.
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Fig. 7. Case 1. MRI scan shows cholesterol granuloma expanding t h e petrous apex. Note t h e wellpneumatized opposite petrous apex.
Fig. 8. Case 1. Postoperative CT scan of temporal bane. Arrow points to patent infrocochlear tract.
Physical examination revealed a scarred right tympanic membrane with a tube in place. There was no activc drainage. Therc was a dccreased corneal reflex on the right side. but the cranial ncrve examination and head and neck examination were otherwise unremarkable.
The patient was taken to the operating room July 24, 1989, for a transcanal infracochlear drainage of the petrous apex. She experienced no difficulties from the procedure and continues to be in good condition. Case 3. A 26-year-old man was well until 1987. when he
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Transcanai infracochlear approach to petrous apex 35
Fig. 9. Case 3. Postoperatwe CT scan of temporal bone demonstrates silicone rubber catheter (SC) inserted from middle ear to area of cholesterol granuloma. Note the relationship to the carotid artery (C) and jugular bulb (J). Dofted line indicates plane of reconstruction for Fig. 10.
Fig. 10. Case 3. Sagittal reconstructon of CT scan from Fig. 9 shows triangulor fenestra created belween basal turn of the cochlea (co), jugular bulb (J), and carotid artery [C).
awoke with diplopia. He was found on examination to have a right-sided palsy of cranial nerve VI. This palsy resolved over a 4-month period and no evaluation was done at that time. In 1788, he once again experienced palsy. which lasted 5 months. In September 1789, he again experienced diplopia that resolved over several days until its return I month later. At this time CT and MRI scans revealed a petrous apex lesion that was diagnosed as a cholesterol granuloma. On January 24. 1990. he underwent a transmastoid infralabyrinthine Iiurgical procedure that was unsuccessful because of a high jugular bulb. He was then referred to the House Ear Clinic for further evaluation. The patient reported mild blurred vision but no diplopia. Physical examination revealed a postauricular incision healing well and a small amount of fluid behind the tympanic membrane. Audiogram revealed a mild conductive
hearing loss in the right ear but was otherwise unremnrkable. Review of CT and MRI scans revealed no infralabyrinthine air cell tract but did reveal a well-developed infracochlear air cell tract to the petrous apex lesion. On February 13. 1970, the patient was taken to the operating room for transcanal infracochlear drainage of a cholesterol granuloma. The patient experienced no difficulty from the procedure and was discharged 1 day later (Figs. 9 and 10).
DISCUSSION The transcanal infracochlear approach to the petrous apex appears safe and efficacious for the drainage of cholesterol granuloma. Evidence for its safety is pro-
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vided by the temporal bone laboratory studies and by cases in which failure of other treatments or approaches to the petrous apex led to its clinical use. Long-term results for this procedure are not yet available, but the three patients whose cases are presented in this article all remain without symptoms. A recent report4 has revealed disappointing long-term results for drainage of cholesterol granuloma of the petrous apex by a number of other approaches. The transcanal infracochlear approach to the petrous apex offers several advantages over other drainage procedures: 1. The transcanal infracochlear approach can be used when a high jugular bulb obstructs the infralabyrinthine approach to the apex. 2 . With this approach, there is dependent drainage of the cholesterol granuloma. 3. This drainage is to a well-aerated area near the entrance of the eustachian tube into the middle ear. 4. A normal external auditory canal and middle ear conductive mechanism are preserved with this approach. 5. Should the infracochlear fenestra become occluded, it could theoretically be opened by means of an inferior myringotomy with minimal associated morbidity. CONCLUSIONS
The transcanal infracochlear approach to the petrous apex is an efficient route to the petrous apex for drainage of cholesterol granuloma. It can be used in temporal bones with high jugular bulbs preventing an infracochlear approach to the petrous apex. It offers the additional benefit of dependent drainage near the entrance of the eustachian tube into the middle ear with preservation of normal middle ear anatomy and function.
REFERENCES
1. Manasse P. Otitis media catarrhalis chronica (otitis media chronica fibrosa). In: Mamasse P, Korner H, eds. Handbuch der pathologischen Anatomie des menschlichen Ohres. Die Ohrenheilkunde der Gegenwart und ihre Grenzgebiete, Bd IX. Wiesbaden: JF Bergmann, 1917:46-53. 2. Friedmann I. Epidermoid cholesteatoma and cholesterol granuloma: experimental and human. Ann Otol Rhinol Laryngol 1959;68:57-79. 3. Birrell JF. Black cellular cholesteatosis in childhood. J Laryngol Otol 1956;70:260-82. 4. Sade J, Teitz A. Cholesterol in cholesteatoma and in the otitis media syndrome. Am J Otol 1982;3:203-8. 5 . Gherini SG, Brackmann DE, Lo WW, Solti-Bohman LG. Cholesterol granuloma of the petrous apex. Laryngoscope 1985i9516.59-64. 6. Mawson SR. Complications of otitis media. In: Mawson SR, ed. Diseases of the ear Baltimore: Williams and Wilkins Co, 1963:347-52. 7. Eagleton WP. Unlocking of the petrous pyramid for localized bulbar (pontile) meningitis secondary to suppuration of the petrous apex. Arch Otolaryngol 1931;13:386-422. 8. Frenckner P. Some remarks on the treatment of apicitis (petrositis) with or without Gradenigo’s syndrome. Acta Otolaryngol (Stockh) 1932;17:97-120. 9. Ramadier J. Exploration de la pointe du rocher par la voie du canal carotidien. Ann d’Otolaryngo1 1933:4:422-44. 10. Dearmin RM. A logical approach to the tip cells of the petrous pyramid. Arch Otolaryngol 1937;26:3 14-20. 1 1. Fanior JB. The sublabyrinthine exenteration of the petrous apex. Ann Otol Rhinol Laryngol 1942;5:1007-16. 12. Kopetzky SJ, Almour R. The suppuration of the petrous pyramid: pathology, symptomatology and surgical treatment (part 111).Ann Otol Rhinol Laryngol 1931;40:396-4 14. 13. Fanior JB. Anterior hypotympanic approach for glomus tumor of the infratemporal fossa. Laryngoscope 1984;94:1016-20. 14. Thedinger BA, Nadol JB, Montgomery WW, Thedinger BS, Greenberg JJ. Radiographic diagnosis, surgical treatment, and long-term follow-up of cholesterol granulomas of the petrous apex. Laryngoscope 1989:99:896-907.
The authors would like to thank Karen Berliner, PhD, of the House Ear Institute, for her assistance in manuscript preparation.
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Los Angeles, California, and Newark, New Jersey
Computerized tomography and magnetic resonance imaging have now made it possible to reliably differentiate cholesteatoma from cholesterol granuloma of the petrous apex. The treatment for cholesteatoma is complete surgical excision when possible, whereas cholesterol granuloma needs only adequate drainage for control. A new transcanal infracochlear approach for drainage of cholesterol granuloma involving the anterior petrous apex is described. Absolute measurements from 10 cadaveric temporal bones were obtained to determine the distances between the cochlea, jugular bulb, carotid artery, and facial nerve. In all specimens the petrous apex was entered without invading the cochlea, carotid, or jugular bulb. Advantages of this technique include a more direct route to the petrous apex, dependent drainage, and preservation of the normal hearing mechanism, including the tympanic membrane. Clincial indications for this technique include failure of other treatment approaches and a high jugular bulb obstructing an infralabyrinthineapproach. Experienceto date shows that patients experience little difficulty from the procedure. (OTOLARYNGOL HEAD NECK SURG 1991;104:29.)
Cholesterol granuloma frequently occurs in the middle ear and mastoid in association with chronic ear disease as a result of poor aeration in a mucosa-lined cavity. On rare occasions it may arise in the petrous apex without middle ear disease and produce symptoms through slow expansion. In the last 5 years, numerous clinical reports have documented a rising awareness of this lesion and the sometimes frustrating results of its treatment. Cholesterol granuloma was first described by Manasse' in 1917. Since then it has been frequently described. Sometimes it is confused with cholesteat ~ m a .Cholesteatoma ~.~ and cholesterol granuloma, two distinct pathologic entities, may appear independently or in conjunction. Cholesteatoma arises from trapped skin in an abnormal anatomic location, whereas cho-
From the Department of Otolaryngology-Head and Neck Surgery (Dr. Giddings), Geisinger Medical Center, Danville; House Ear Clinic and House Ear Institute, Los Angeles (Dr. Brackmann); and the Division of Otolaryngology (Dr. Kwartler), New Jersey University of Medicine and Dentistry, Newark. Supported by research funds from the House Ear Institute and Geisinger Medical Center. Presented at the Annual Meeting of the American Neurotology Society, West Palm Beach, Fla., April 27, 1990. Received for publication April 20, 1990; accepted Aug. 14, 1990. Reprint requests: Derald E. Brackmann, MD, House Ear Clinic, 2122 West 3rd St., Los Angeles, CA 90057. 231 1124561
lesterol granuloma is a granulomatous structure formed in nonspecific reaction to cholesterol crystals.' These cholesterol crystals are probably derived from local tissue breakdown or blood.4 Cholesterol granuloma may develop in any aerated portion of the temporal bone, but it most commonly occurs in the mastoid air cells some distance from a lesion preventing normal aeration. Cholesterol granuloma of the petrous apex probably develops when a pathologic process or trauma obstructs the air-cell tracts to a well-pneumatized petrous apex." The treatment for cholesterol granuloma of the temporal bone is drainage and reestablishment of adequate aeration to the involved area. The cyst wall is composed of a fibrous connective tissue. It is free of the keratinizing squamous epithelium that characterizes cholesteatoma, and complete removal of the cyst is not necessary. The petrous apex can be approached by way of a number of routes, including through the middle fossa, translabyrinthine, or along lines of developed air cell tracts. The middle fossa approach does not allow adequate ventilation of the petrous apex after drainage, making recurrence of cholesterol granuloma likely. The translabyrinthine approach provides continued drainage but obviously destroys hearing. Following established air cell tract offers the possibility of continued drainage, aeration of the petrous apex, and preserved hearing. Most of the routes of drainage for the petrous apex 29
Downloaded from oto.sagepub.com at DALHOUSIE UNIV on June 5, 2016
30
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GlDDlNGS et al.
Fig. 1. The external auditory canal is completely transected.
were developed during the preantibiotic era for drainage of petrous apex abscesses and cure of Gradenigo’s syndrome. These same approaches may be equally effective in draining cholesterol granuloma. Air cell tracts may be followed from the root of the zygoma, the sinodural angle, the attic, or through the arch of the superior semicircular Inferiorly based approaches may follow the carotid artery anterior to the cochlea or infralabyrinthine.’-’* Ghorayeb and Jahrsdoerfer* presented at the 1988 meeting of the American Neurotologic Society an infracochlear approach to the petrous apex requiring a canal wall-down mastoidectomy. All of these approaches have been effective in the drainage of petrous apicitis, but their effectiveness in drainage of cholesterol granuloma remains undetermined. We describe a new transcanal approach to the petrous apex for the drainage of cholesterol granuloma, including results of a temporal bone study and several case reports. OPERATIVE TECHNIQUE
In 1984, F a r r i ~ rdescribed ’~ a transcanal approach to small glomus jugulare tumors of the hypotympanum. Our infracochlear approach to the petrous apex is a *Ghorayeb BY, Jahrsdoerfer RA. Subcochlear approach for cholesterol granulomas of the inferior petrous apex [Personal communication]. 1989.
combination of this technique and the subcochlear approach described by Ghorayeb and Jahrsdoerfer. 1. A postauricular incision is made and the auricle is reflected anteriorly. 2 . The membranous external auditory canal is completely transected laterally (Fig. 1). 3. A tympanomeatal flap is elevated from the 2o’clock position to the 10-o’clockposition, leaving the tympanic membrane attached at the umbo and the superior canal wall. 4. The external auditory canal is enlarged anteriorly and inferiorly to expose the hypotympanum. The chorda tympani is followed inferiorly, posterior to lateral, to define the extent of posterior dissection possible without injuring the facial nerve (Fig. 2). 5. Air cells are removed below the cochlea in the hypotympanum to expose the course of the carotid artery and the jugular bulb. The round window provides the superior line of dissection, and Jacobson’s nerve leads to the “crutch” of the carotid and jugular bulb (Fig. 3). 6. Removal of air cells continues medially. If the plane of dissection remains below the round window, the internal auditory canal structures will not be at risk (Fig. 4). 7. The cholesterol granuloma cyst is entered and drained. The newly created “window” is enlarged anteriorly to the carotid artery, inferiorly
Downloaded from oto.sagepub.com at DALHOUSIE UNIV on June 5, 2016
Volume 104 Number 1 January 1991
Transcanal infracochlear approach to petrous apex 31
Fig. 2. External auditory canal skin is elevated, exposing the lower half of the middle ear space. Bone is removed from the anterior and inferior aspects of the canal to expose the hypotympanum with the chorda tympani as a landmark for the posterior limit of dissection.
/ Fig. 3. Bone is removed, exposing the carotid artery and jugular bulb.
to the jugular bulb, and superiorly to the inferior aspect of the basal turn of the chochlea. 8. A silicone rubber catheter of appropriate size is introduced if necessary to provide support for the opening.
9. The soft tissue of the external auditory canal is returned to its normal position, and Gelfoam is packed within the external auditory canal and between the canal wall and the newly enlarged bony canal (Fig. 5).
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.
_--
Fig. 4. Dissection proceeds medially in the triangle formed by the inferior aspect of the basal turn of the chochlea. the carotid artery, and the jugular bulb until the cyst is entered and drained.
Fig. 5. The external auditory canal skin is returned to its normal position and packed with Gelfoam.
10. The postauricular incision is closed and a mastoid dressing is applied. TEMPORAL BONE RESULTS
Ten cadaveric temporal bones were dissected with the surgical technique described previously. After completion of the dissections, a graduated ocular was used to measure the anterior-posterior and inferior-superior dimensions of each surgically created fenestra. Most of
the fenestrae were shaped like triangles or rectangles (Fig. 6). Cross-sectional area was calculated by the formulas % x Base x Height for triangular fenestrae and Length x Width for rectangular fenestrae (Table 1). The mean area of the fenestrae was 25.6 f 16.3 mm2, with a maximum area of 67.2 mm2 and a minimum area of 7.4 mm2,The median area was 22.1 mm’. In all bones it was possible to enter either petrous
Downloaded from oto.sagepub.com at DALHOUSIE UNIV on June 5, 2016
Volume 104 Number 1 January 1991
Transcanal infracochlear approach to petrous apex 33
Fig. 6. Temporal bone specimens showing relative positions of major vessels and cochlea. Arrows indicate lines of measurement.
apex air cells or marrow without invading the cochlea. carotid, or jugular bulb. In no specimen was damage to the internal auditory canal seen after operation. CASE REPORTS Case I. A 50-year-old woman was well until September 1987, when she had a sudden left sensorineural licaring loss. After treatment with oral steroids. her condition returned to baseline. Results of computerized tomographic (CT) scan of the temporal bones, performed at another institution. were reportedly unremarkable. In October 1987, she experienced a left-sided palsy involving cranial nerve VI and diplopia. These resolved without treatment. In March 1988. the diplopia recurred. CT and magnetic resonance imaging (MRI) scans revealed a left petrous apex lesion consistcnt with cholesterol granuloma (Fig. 7). The patient was first seen at the House Ear Clinic in October 1988, at which time she reported diplopia and left-sided tinnitus. Physical examination was unremarkable at that time except for a left-sided palsy involving cranial nerve VI. An audiogram was unremarkable. MRI scan at that time revealed an increase in the lesion’s size to greater than 2 cm. as compared with the size noted at the previous examination in March 1988. Because of a high jugular bulb. an infralabyrinthine approach to the lesion was not attempted and a craniotomy through the left middle fossa with drainage of the cholesterol granuloma was performed on October 21, 1988. The patient had a good postoperative course, with resolution of her diplopia until May 1989, when she once again began to expcrience diplopia. CT scan at that time revealed persistent petrous apex lesion with continued expansion. There was an infracochlear patent air cell tract. The patient returned to the operating room June 13. 1989. for a transcanal infracochlear drainage of the cholesterol granuloma. Her postoperative course was good and she remains free of symptoms. A CT scan 6 months after operation ( Fig.
Table I.Measurements of infracochlear fenestra size from 10 cadaveric temporal bones Temporal
Height
Width
Area
bone
(mml
(mm]
(mmzl
62 56 74 35 56 39 57 52 42 63
98 50 84 63 60 70 50 46 35 61
30 4 14 0 62 2 22 1 33 6 22 0 14 3 11 8 74 38 4
1
2 3 4 5 6 7 8 9 10
8) reveals a persistent patent avenue for drainage in the infracochlear region. Case 2. A 17-year-old girl was well until 1984. when she noticed decreased hearing in the right ear. Physical cxamination at that time revealed a bluish mass behind the right tympanic membrane. A CT scan revealed a “congenital cholesteatoma” of tlie right petrous apex. and she undenvent a middle fossa craniotomy for removal of the cholesteatonia at an outside institution. Despite otherwise satisfactory healing. she once again noticed decreased hearing in her right ear. Fluid collectcd again behind tlie right tympanic membrane. requiring insertion of a pressure equalization tube. In November 1985. she began to have continuous drainage from the tube. She was seen at the House Ear Clinic for the first time on June 19, 1989. At that time she did not have diplopia but did have decreased hearing and otorrhea on the right side. CT scan revealed a persistent cholesterol granuloma of the right pctrous apex that had enlarged since the middle fossa dccomprcssion.
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34 GlDDlNGS et at.
Fig. 7. Case 1. MRI scan shows cholesterol granuloma expanding t h e petrous apex. Note t h e wellpneumatized opposite petrous apex.
Fig. 8. Case 1. Postoperative CT scan of temporal bane. Arrow points to patent infrocochlear tract.
Physical examination revealed a scarred right tympanic membrane with a tube in place. There was no activc drainage. Therc was a dccreased corneal reflex on the right side. but the cranial ncrve examination and head and neck examination were otherwise unremarkable.
The patient was taken to the operating room July 24, 1989, for a transcanal infracochlear drainage of the petrous apex. She experienced no difficulties from the procedure and continues to be in good condition. Case 3. A 26-year-old man was well until 1987. when he
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Transcanai infracochlear approach to petrous apex 35
Fig. 9. Case 3. Postoperatwe CT scan of temporal bone demonstrates silicone rubber catheter (SC) inserted from middle ear to area of cholesterol granuloma. Note the relationship to the carotid artery (C) and jugular bulb (J). Dofted line indicates plane of reconstruction for Fig. 10.
Fig. 10. Case 3. Sagittal reconstructon of CT scan from Fig. 9 shows triangulor fenestra created belween basal turn of the cochlea (co), jugular bulb (J), and carotid artery [C).
awoke with diplopia. He was found on examination to have a right-sided palsy of cranial nerve VI. This palsy resolved over a 4-month period and no evaluation was done at that time. In 1788, he once again experienced palsy. which lasted 5 months. In September 1789, he again experienced diplopia that resolved over several days until its return I month later. At this time CT and MRI scans revealed a petrous apex lesion that was diagnosed as a cholesterol granuloma. On January 24. 1990. he underwent a transmastoid infralabyrinthine Iiurgical procedure that was unsuccessful because of a high jugular bulb. He was then referred to the House Ear Clinic for further evaluation. The patient reported mild blurred vision but no diplopia. Physical examination revealed a postauricular incision healing well and a small amount of fluid behind the tympanic membrane. Audiogram revealed a mild conductive
hearing loss in the right ear but was otherwise unremnrkable. Review of CT and MRI scans revealed no infralabyrinthine air cell tract but did reveal a well-developed infracochlear air cell tract to the petrous apex lesion. On February 13. 1970, the patient was taken to the operating room for transcanal infracochlear drainage of a cholesterol granuloma. The patient experienced no difficulty from the procedure and was discharged 1 day later (Figs. 9 and 10).
DISCUSSION The transcanal infracochlear approach to the petrous apex appears safe and efficacious for the drainage of cholesterol granuloma. Evidence for its safety is pro-
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vided by the temporal bone laboratory studies and by cases in which failure of other treatments or approaches to the petrous apex led to its clinical use. Long-term results for this procedure are not yet available, but the three patients whose cases are presented in this article all remain without symptoms. A recent report4 has revealed disappointing long-term results for drainage of cholesterol granuloma of the petrous apex by a number of other approaches. The transcanal infracochlear approach to the petrous apex offers several advantages over other drainage procedures: 1. The transcanal infracochlear approach can be used when a high jugular bulb obstructs the infralabyrinthine approach to the apex. 2 . With this approach, there is dependent drainage of the cholesterol granuloma. 3. This drainage is to a well-aerated area near the entrance of the eustachian tube into the middle ear. 4. A normal external auditory canal and middle ear conductive mechanism are preserved with this approach. 5. Should the infracochlear fenestra become occluded, it could theoretically be opened by means of an inferior myringotomy with minimal associated morbidity. CONCLUSIONS
The transcanal infracochlear approach to the petrous apex is an efficient route to the petrous apex for drainage of cholesterol granuloma. It can be used in temporal bones with high jugular bulbs preventing an infracochlear approach to the petrous apex. It offers the additional benefit of dependent drainage near the entrance of the eustachian tube into the middle ear with preservation of normal middle ear anatomy and function.
REFERENCES
1. Manasse P. Otitis media catarrhalis chronica (otitis media chronica fibrosa). In: Mamasse P, Korner H, eds. Handbuch der pathologischen Anatomie des menschlichen Ohres. Die Ohrenheilkunde der Gegenwart und ihre Grenzgebiete, Bd IX. Wiesbaden: JF Bergmann, 1917:46-53. 2. Friedmann I. Epidermoid cholesteatoma and cholesterol granuloma: experimental and human. Ann Otol Rhinol Laryngol 1959;68:57-79. 3. Birrell JF. Black cellular cholesteatosis in childhood. J Laryngol Otol 1956;70:260-82. 4. Sade J, Teitz A. Cholesterol in cholesteatoma and in the otitis media syndrome. Am J Otol 1982;3:203-8. 5 . Gherini SG, Brackmann DE, Lo WW, Solti-Bohman LG. Cholesterol granuloma of the petrous apex. Laryngoscope 1985i9516.59-64. 6. Mawson SR. Complications of otitis media. In: Mawson SR, ed. Diseases of the ear Baltimore: Williams and Wilkins Co, 1963:347-52. 7. Eagleton WP. Unlocking of the petrous pyramid for localized bulbar (pontile) meningitis secondary to suppuration of the petrous apex. Arch Otolaryngol 1931;13:386-422. 8. Frenckner P. Some remarks on the treatment of apicitis (petrositis) with or without Gradenigo’s syndrome. Acta Otolaryngol (Stockh) 1932;17:97-120. 9. Ramadier J. Exploration de la pointe du rocher par la voie du canal carotidien. Ann d’Otolaryngo1 1933:4:422-44. 10. Dearmin RM. A logical approach to the tip cells of the petrous pyramid. Arch Otolaryngol 1937;26:3 14-20. 1 1. Fanior JB. The sublabyrinthine exenteration of the petrous apex. Ann Otol Rhinol Laryngol 1942;5:1007-16. 12. Kopetzky SJ, Almour R. The suppuration of the petrous pyramid: pathology, symptomatology and surgical treatment (part 111).Ann Otol Rhinol Laryngol 1931;40:396-4 14. 13. Fanior JB. Anterior hypotympanic approach for glomus tumor of the infratemporal fossa. Laryngoscope 1984;94:1016-20. 14. Thedinger BA, Nadol JB, Montgomery WW, Thedinger BS, Greenberg JJ. Radiographic diagnosis, surgical treatment, and long-term follow-up of cholesterol granulomas of the petrous apex. Laryngoscope 1989:99:896-907.
The authors would like to thank Karen Berliner, PhD, of the House Ear Institute, for her assistance in manuscript preparation.
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