Hydrocephalus in the patient with acoustic neuroma RONALD L. STEENERSON, MD, and NETTLETON PAYNE, MD, Atlanta, Georgia
Hydrocephalus can occur in conjunction with large acoustic neuromas. Cerebral tentorial herniation and brainstem compression can be a complication of surgical excision. Three cases of hydrocephalus and acoustic neuroma are presented and therapeutic options are discussed. Ventriculoperitoneal shunting 1 to 2 weeks before translabyrinthine or suboccipital excision of acoustic neuroma is recommended. (OTOLARYNGOL HEAD NECK SURG 1992:10735.]
Hydrocephalus in the Patient With Acoustic Neuroma
Hydrocephalus is occasionally encountered in the patient with acoustic neuroma. It is usually related to tumor size, being more often found in tumors of greater than 3 cm diameter. The surgical management of such patients can be difficult, with potential for severe complications as a result of tentorial herniation, with resultant brainstem injury. We present three patients with large acoustic neuromas and secondary hydrocephalus. The recognition of this condition and the options and potential pitfalls in the management are discussed. CASE REPORTS
Case 1. T.M. was a 56-year-old woman with an 8-year history of progressive hearing loss and tinnitus. For the year before presentation she had severe headaches of increasing intensity. They were worse when she was lying down and early in the morning. She had experienced intermittent poor balance for the past year. Her left face had felt numb for the past 5 months. She did not report memory difficulty, visual abnormalities, or urinary incontinence. The patient saw an otolaryngologist 8 years earlier for the tinnitus and hearing loss. A CT scan was obtained both with and without contrast, and was determined to be normal. The patient had seen numerous physicians in the year before presentation for her increasing headaches with no diagnosis. The patient saw an otolaryngologist who documented a left-sided
From Atlanta Ear Clinic (Dr. Steenerson) and Peachtree Neurosurgical Associates (Dr. Payne). Presented at the Southern Section of the Triological Society. Williamsburg, Va., Jan. 1 1 , 1991. Received for publication Sept. 4, 1991; revision received Feb. 27. 1992; accepted March 5 , 1992. Reprint requests: Ronald L. Steenerson. MD, 980 Johnson Ferry Rd., Suite 470, Atlanta, GA 30342. 231 1 l3Xi57
Fig. 1. MRI scan shows large acoustic neuroma
hearing loss with an 80 dB flat neurosensory deficit with zero discrimination. The right ear was normal. An MRI scan revealed a 3 cm cerebellopontine angle tumor (Fig. I ) on the left side, consistent with an acoustic neuroma. Marked dilatation of the ventricles was thought to be related to basal cistern obstruction (Fig. 2). Examination at the Atlanta Ear Clinic showed hypesthesia on the left side of the face with a diminished corneal reflex. The facial nerve functioned normally. The patient was un-
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Otolaryngology-
36 STEENERSON and PAYNE
Head and N e c k Surgery
Fig. 2. MRI scan shows marked ventricular enlargement.
steady when she stood with her feet together. There was severe bilateral papilledema. Because of the peritumoral edema in the brainstem and the cerebellar hemisphere, the patient was started on a regimen of dexamethasone (4 mg/q6 hours). A ventriculoperitoneal shunt was then placed. A Cordis-Hakim system was chosen because it incorporates a very reliable valve mechanism with an inline reservoir that will allow bidirectional irrigation of the in situ device. The opening pressure of the valve was chosen to be in the 120 to 130 mm of cerebrospinal fluid (CSF) range in order to prevent a shift from too high to too low a pressure and potential related problems, such as the slit ventricle syndrome. The patient was discharged on the first postoperative day after shunting, free of headache. The postoperative CT showed the ventricles to be normal in size (Fig. 3). Two weeks later, a 3 cm acoustic neuroma was removed by a suboccipital approach, with preservation of the facial nerve. Intraoperatively, the facial nerve stimulated well at the brainstem with 0.05 milliamperes, but no function was observed postoperatively. An eyelid spring was inserted on the fifth postoperative day, and the woman was discharged, headachefree, on the sixth postoperative day. The patient recovered without complications and facial function started to return at 6 months.
Fig. 3. CT scan ventricles.
shows shunt tube in place and normal size
Case 2. H.H. was a 60-year-old man with a several week history of severe headache and unsteadiness of gait. While he did not report tinnitus or hearing loss, examination and ABRs revealed markedly abnormal function. Physical examination demonstrated mild stupor with active nystagmus in all fields of gaze, but slower and coarser nystagmus on looking to the right than in other directions. There was a mild sensory loss over the right side of the face, but there was no loss of the corneal reflex. The patient had weakness in his right lower extremity. The pertinent normal examination included the absence of papilledema and signs of cerebellar dysfunction. An MRI scan showed a large mass in the right cerebellopontine angle with enlargement of the porous acousticus. There was marked hydrocephalus. The patient underwent placement of a ventriculoperitoneal shunt on the day he was first seen, and resection of the acoustic neuroma by means of a posterior fossa approach 1 week later. He made a complete recovery with no residual neurologic deficit except right-sided deafness. Facial function was normal. Case 3. S.M. was a 36-year-old woman who worked for a rock radio station and who had a 5-year history of intermittent popping in her left ear. This seemed to be associated with a gradual hearing loss on the same side. For the past 2
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Volume 107 Number 1 July 1992
Hydrocephalus in patient with acoustic neuroma 37
years she had experienced imbalance, and more recently she noted difficulty controlling her left arm and hand. A tendency to fall toward the left developed. In the 2 years before the recognition of her tumor, she noted vertex headaches, occasionally associated with nausea and vomiting. When the headaches were severe, her vision became blurred. On examination, she had counterclockwise nystagmus, left-sided cerebellar signs, and right lower extremity weakness. Her corneal reflex was decreased on the left, and her hearing was reduced on the same side. The ABRs were absent on the left, as was the ENG. An MRl revealed a large cerebellopontine angle mass enlarging the internal auditory canal. There was secondary hydrocephalus as evidenced by the mild ventricular enlargement. The patient underwent surgical resection of an acoustic neuroma by means of a posterior fossa approach. A catheter was placed into the frontal portion of the right lateral ventricle before the opening of the posterior fossa dura. Postoperatively, the patient made a good recovery with full facial nerve function, and with no need for a long-term shunt.
Table 1. Hydrocephalus
DISCUSSION
the others will survive with arrested hydrocephalus. Only 20% of those with arrested hydrocephalus will have normal cognitive function. In adults, in whom the sutures of the bones of the skull are fused and thus cannot expand with the stress of increased intracranial pressure, the patient may deteriorate to death very quickly with acute obstruction of the CSF flow. More typically, CSF obstruction develops gradually, beginning with intermittent blockage of CSF flow and progressing to a more complete obstruction. The intermittent nature of early blockage is the result of the effect of the pumping action of the heart on: (1) the expansion and contraction of the brain within the skull during the cardiac cycle, and (2) the pulsatile flow of the CSF. Symptoms may include decreased mentation, headache, imbalance, blindness, obtundation, and death. Most CSF is produced by the choroid plexus in the lateral ventricles.‘ The average daily production in an adult is 480 to 600 cc per 24 hours. Most of the CSF is absorbed by the arachnoid villae projecting into the sagittal sinus. CSF circulation starts in lateral ventricles, progresses through the third ventricle, the aqueduct of Sylvius, the fourth ventricle, out the basal cisterns, the subarachnoid space, and finally is reabsorbed by the arachnoid villae of the sagittal sinus. In a normal state, CSF production equals CSF reabsorption. Any condition that alters the ratio of CSF reabsorption to CSF production or blocks the CSF circulation can cause hydrocephalus. A classification of the causes of hydrocephalus is shown in Table 1. Until the twentieth century, treatment of hydrocephalus included diet, leeches, and head binding.’ The
Hydrocephalus is the result of abnormally high cerebral spinal fluid pressure within the ventricles or in subarachnoid space over the surface of the brain. It usually results in the enlargement of the ventricular system within the brain. Hydrocephalus may be caused by: ( I ) increased production of cerebral spinal fluid within the ventricles, as seen in choroid plexus papillomas; (2) decreased absorption of CSF over the cerebral hemispheres by the arachnoid granulations, as seen after subarachnoid hemorrhage; or ( 3 ) blockage of the pathways through which the CSF flows, either within the brain or during its egress out of the brain and through the basal cisterns. Morgagne‘ and Whytt’ described the pathology of hydrocephalus in the 1770s, concomitant with the recognition of the structure of the ventricles and the character of the CSF. Magendie3 described the concept of CSF circulation in the 19th century. In 1918, Walter Dandy4 described ventriculography, in which he filled the ventricles with air and studied their configuration with x-ray. This technique made possible the diagnosis and therapy of hydrocephalus. Dandy’s contributions to the understanding of hydrocephalus include: ( I ) description of CSF formation by the choroid plexus, (2) description of CSF circulation, ( 3 ) development of the concept of communicating and noncommunicating hydrocephalus, and (4) devising a phenolsulfonphthalein test to differentiate between the two forms of hydrocephalus. The natural history of congenital hydrocephalus recognized in infants and children is well k n ~ w n Un.~ treated, approximately 50% of the patients will die and
Causes
I Obstructive A Ventricular blockage (noncommunicating) 1 Congenital anomalies 2 Postinflammatory blockage 3 Posthemorrhagic blockage 4 Tumors blocking the fourth ventricle, aque duct of Sylvius or foramen of Monro B Cistern blockage (communicating) 1 Congenital anomalies 2 C-P angle tumors I I Nonobstructive A Atrophic III Funct/onal A Hypersecretion B Impaired absorption
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OtolaryngologyHead and Neck Surgery
STEENERSON and PAVNE
latter procedure was reinstated temporarily by some authors for infants in the 1970s. Lumbar puncture’ was introduced in the early part of this century and is still useful if used judiciously in certain cases of hydrocephalus associated with decreased absorption of fluid. Carotid artery ligation’ and various other procedures have been tried since the advent of general anesthesia, but have proved useless. In 1919, Dandy l o introduced choroid plexectomy as a treatment for hydrocephalus. This was performed through a cerebrotomy with an endoscope borrowed from urologic colleagues. Payr” introduced ventricular CSF shunting to the sagittal sinus and jugular vein in 1908, but the methods used invariably became occluded. Nulsen and Spitz’* implanted valve controlled one-way drainage devices in the 1950s, opening the modem era of ventricular shunting as the treatment for hydrocephalus. Today, commonly used shunting procedures include ventriculoperitoneal, ventriculoatrial, ventriculopleural, and lumbar-peritoneal using a myriad of valves, reservoirs, and shunting tubes. Medical treatment has included lumbar puncture and medications. These include drugs to decrease CSF production, to decrease brain water content, and to increase CSF absorption. All of these are temporary measures at best. The diagnosis of hydrocephalus may be made by ultrasound in individuals with an open fontanelle, by computed tomography (CT scanning), and magnetic resonance imaging (MRI). Air or x-ray dense-contrast agents injected into the ventricles are rarely used today. Radioactive iodinated serum albumin or other colloidal isotopes that tend to remain in the CSF may be used to study CSF flow patterns on a scintillation counter. Hydrocephalus as a result of large acoustic neuromas results from interruption in the normal CSF flow through the basal cisterns. The aqueduct of Sylvius and the fourth ventricle remain patent. While hydrocephalus does not occur frequentlyeven with large acoustic tumors, its recognition is necessary in order to prevent severe intraoperative complications. If the elevated pressure within the ventricles is not normalized before the dura is opened over the posterior fossa, the cerebral hemispheres may shift caudally, compressing and damaging the brainstem. The cerebellum may become so tight within the posterior fossa that it is not possible to expose the tumor without tearing important parts of the brain or its blood supply. The precise route of approach to the tumor, whether by the retrosigmoid, translabyrinthine, or a combined approach, does not alter the risk, because they are all below the tentorium.
In order to prevent herniation, a ventriculostomy may be placed into one of the lateral ventricles at the time of tumor surgery before the dura is opened (case 3). It is safest to place it in the nondominant hemisphere. It is left in place during the operation and through the immediate postoperative period. If a catheter is left in for longer than 48 hours, the risk of infection increases greatly. The disadvantages to this approach are that in a very sick patient with stupor, vomiting, dehydration, and poor nutrition, it will not be possible to correct these deficits in advance of the long surgery for tumor removal. In addition, there is the risk of infection because it is often necessary to leave the ventriculostomy in place for longer than 48 hours. It may have to remain for several weeks, until the blood and cellular debris of the operation are cleared from the CSF and the basal cisterns reopen and the fluid flows adequately into the arachnoid granulations. For these reasons, we favor placement of a shunt 7 to 14 days before the surgery for tumor removal (cases 1 and 2). This allows the patient to awaken to mental clarity, regain hydration and nutrition, and therefore tolerate the surgery more easily. The risk of infection is less as the device is never externalized, and it provides the definitive treatment in those cases in which the basal cisterns fail to reopen to allow adequate CSF flow. The drawbacks to the use of a shunt are few, but it is a foreign body, and when left in place for a period of years there is a small risk of infection by hematogenous bacterial seeding. In addition, a shunt may make the patient more dependent on it as time passes. The normal mechanism for CSF resorption seems to atrophy in some individuals and may include complete closure of the aqueduct. If this occurs and the shunt blocks, the patient may become acutely ill from hydrocephalus. It is possible in some cases with only mild ventricular enlargement to remove the tumor without ventricular drainage of any type. We, however, believe this approach creates an additional major risk to which the patient need not be exposed. The presence of the shunt will reduce the risk of incisional and eustachian tube CSF leakage postoperatively. This occurs in as many as 10% of patients operated on by the translabyrinthine approach. While we have not experienced any incisional leaks in patients done by the posterior fossa-retrosigmoid approach who are closed with a watertight dura, it may occur internally through open mastoid air cells into the middle ear cavity, with resultant CSF rhinorrhea. In summary, we have presented three cases of large acoustic neuromas associated with hydrocephalus. A
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Volume 107 Number 1 July 1992
Hydrocephalus in patient with acoustic neuroma 39
brief review of the development of our knowledge of hydrocephalus, its pathophysiology, and the method and the rationale for treatment of the hydrocephalus in these patients are provided.
6.
REFERENCES
8.
7.
1. Morgagne GB. The seats and causes of diseases investigated by
anatomy. London: Miller and Cadell, 1761. 2. Whytt R . Observations on the dropsy in the brain. Edinburgh: J . Balfour, 1768. 3. Magendie F. Memoire sur le liquide qui se trouue dans le crane et I’e’pine del’homme and des animaux. J Physiol Exp Pathol 1825;5:27-37. 4. Dandy WE. Ventriculostomy following in injection of air into the cerebral ventricles. Ann Surg 1918;68:5-11. 5. Foltz EL, Shurtleff DB. Five-year comparative study of hydro-
9. 10. 1 1.
12.
cephalus in children with and without operation in 113 cases. J Neurosurg 1963;20: 1064-8. Milhorat TH, Mosher MB, Hammock MK, et al. Choroid plexus and cerebrospinal fluid production. Science 1969;166:15 14-6. Davidoff LM. Treatment of hydrocephalus. Historical review and description of new method. Arch Surg 1929;18:1737-62. Quinke H. Veber hydrocephalus. Verh Congr Inn Med 189 I ; 10:321-339. Frase J, and Dottnm. Hydrocephalus. Br Surg 1922;23:165-91. Dandy WE. Diagnosis and treatment of structures of the aqueduct of Sylvius (causing hydrocephalus). Arch Surg 1945;51:1-4. Payr. Drainage der Himentrikle Mittelst Frei Transplantirter Blutgefassee. Bemerkungen Ueber Hydrocephalus Arch. Klon Chir 1908;87:80 1-85. Nulsen FE, Spitz EB. Treatment of hydrocephalus by direct shunt from venticle to jugular vein. Surg Forum 1952;2:399-400.
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Otolaryngology Head and Neck Surgery March 1993
News and Announcements
held July 26-30, 1993, at the Tamarron Resort in Durango, Colorado. This 28 hour review and update will encompass all the clinically important areas of MR imaging. Important new concepts and pathological/imaging correlations in the body, musculoskeletal system, ENT, head and neck, brain, and spine will be explored. Daily case presentations will supplement these lectures and will serve to test the registrants' diagnostic abilities in MR imaging. This complete review of MR imaging will be presented by nationally recognized leaders in magnetic resonance imaging. As a result of this comprehensive review, registrants will become familiar with current applications of MR imaging and will be able to integrate many of these applications directly into their practice. Program chairmen for this presentation will be Robert Quencer, MD (University of Miami), Victor Haughton, MD (Medical College of Wisconsin). Twenty-eight credits of Category I will be available. For further information, please contact Marti Carter, CME, Inc., 11011 West Nort Ave., Milwaukee, Wisconsin 53226, or call (414) 771-9520. Ear, Nose, and Throat Diseases: 1993 Update
Children's Hospital of Pittsburgh will hold its 18th Annual Symposium, "Ear, Nose, and Throat Diseases in Children: A 1993 Update." This symposium will be held July 30-31, 1993. CME credits will be awarded.
For further information, please contact the Department of Pediatric Otolaryngology, Children's Hospital of Pittsburgh, 3705 Fifth Avenue at DeSoto St., Pittsburgh, Pennsylvania 15213, or call (412) 692-8577. Twenty-fifth Annual Meeting - Head and Neck Oncologists
The Association of Head and Neck Oncologists of Great Britain will sponsor the Twenty-fifth Annual Meeting of Head and Neck Oncology, to be held in Edinburgh, Scotland, United Kingdom, on August 23-26, 1993. International and local faculty will present extensive social and family programs. For further information, please contact Mr. P. J. Bradley, Honorary Secretary, Department of Otorhinolaryngology-Head and Neck Surgery, University Hospital, Queens Medical Centre, Nottingham, NG7 2UH, England, or phone 0602421421. Sixth International Congress on Interventlonal Ultrasound
The Sixth International Congress on Interventional Ultrasound will be held in Copenhagen, Denmark, on September 7-10, 1993. For further information, please contact Christian Nolsoe, Congress Secretary, Department of Ultrasound, Herlev Hospital, University of Copenhagen, DK-2730 HerlevDenmark, or call + 45/ 44 53 53 00 ext. 3240.
CORRECTION
The Supplement to the December 1992 issue of the JOURNAL (Volume 107, Number 6, Part 2), incorrectly listed Dr. Bruce R. Gordon as Chief of Otolaryngology at the Massachusetts Eye and Ear Institute. Dr. Joseph Nadol is Chief of Otolaryngology at the Massachusetts Eye and Ear Infirmary. Dr. Gordon is Chief of Otolaryngology at Cape Cod Hospital.
Hydrocephalus can occur in conjunction with large acoustic neuromas. Cerebral tentorial herniation and brainstem compression can be a complication of surgical excision. Three cases of hydrocephalus and acoustic neuroma are presented and therapeutic options are discussed. Ventriculoperitoneal shunting 1 to 2 weeks before translabyrinthine or suboccipital excision of acoustic neuroma is recommended. (OTOLARYNGOL HEAD NECK SURG 1992:10735.]
Hydrocephalus in the Patient With Acoustic Neuroma
Hydrocephalus is occasionally encountered in the patient with acoustic neuroma. It is usually related to tumor size, being more often found in tumors of greater than 3 cm diameter. The surgical management of such patients can be difficult, with potential for severe complications as a result of tentorial herniation, with resultant brainstem injury. We present three patients with large acoustic neuromas and secondary hydrocephalus. The recognition of this condition and the options and potential pitfalls in the management are discussed. CASE REPORTS
Case 1. T.M. was a 56-year-old woman with an 8-year history of progressive hearing loss and tinnitus. For the year before presentation she had severe headaches of increasing intensity. They were worse when she was lying down and early in the morning. She had experienced intermittent poor balance for the past year. Her left face had felt numb for the past 5 months. She did not report memory difficulty, visual abnormalities, or urinary incontinence. The patient saw an otolaryngologist 8 years earlier for the tinnitus and hearing loss. A CT scan was obtained both with and without contrast, and was determined to be normal. The patient had seen numerous physicians in the year before presentation for her increasing headaches with no diagnosis. The patient saw an otolaryngologist who documented a left-sided
From Atlanta Ear Clinic (Dr. Steenerson) and Peachtree Neurosurgical Associates (Dr. Payne). Presented at the Southern Section of the Triological Society. Williamsburg, Va., Jan. 1 1 , 1991. Received for publication Sept. 4, 1991; revision received Feb. 27. 1992; accepted March 5 , 1992. Reprint requests: Ronald L. Steenerson. MD, 980 Johnson Ferry Rd., Suite 470, Atlanta, GA 30342. 231 1 l3Xi57
Fig. 1. MRI scan shows large acoustic neuroma
hearing loss with an 80 dB flat neurosensory deficit with zero discrimination. The right ear was normal. An MRI scan revealed a 3 cm cerebellopontine angle tumor (Fig. I ) on the left side, consistent with an acoustic neuroma. Marked dilatation of the ventricles was thought to be related to basal cistern obstruction (Fig. 2). Examination at the Atlanta Ear Clinic showed hypesthesia on the left side of the face with a diminished corneal reflex. The facial nerve functioned normally. The patient was un-
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35
Otolaryngology-
36 STEENERSON and PAYNE
Head and N e c k Surgery
Fig. 2. MRI scan shows marked ventricular enlargement.
steady when she stood with her feet together. There was severe bilateral papilledema. Because of the peritumoral edema in the brainstem and the cerebellar hemisphere, the patient was started on a regimen of dexamethasone (4 mg/q6 hours). A ventriculoperitoneal shunt was then placed. A Cordis-Hakim system was chosen because it incorporates a very reliable valve mechanism with an inline reservoir that will allow bidirectional irrigation of the in situ device. The opening pressure of the valve was chosen to be in the 120 to 130 mm of cerebrospinal fluid (CSF) range in order to prevent a shift from too high to too low a pressure and potential related problems, such as the slit ventricle syndrome. The patient was discharged on the first postoperative day after shunting, free of headache. The postoperative CT showed the ventricles to be normal in size (Fig. 3). Two weeks later, a 3 cm acoustic neuroma was removed by a suboccipital approach, with preservation of the facial nerve. Intraoperatively, the facial nerve stimulated well at the brainstem with 0.05 milliamperes, but no function was observed postoperatively. An eyelid spring was inserted on the fifth postoperative day, and the woman was discharged, headachefree, on the sixth postoperative day. The patient recovered without complications and facial function started to return at 6 months.
Fig. 3. CT scan ventricles.
shows shunt tube in place and normal size
Case 2. H.H. was a 60-year-old man with a several week history of severe headache and unsteadiness of gait. While he did not report tinnitus or hearing loss, examination and ABRs revealed markedly abnormal function. Physical examination demonstrated mild stupor with active nystagmus in all fields of gaze, but slower and coarser nystagmus on looking to the right than in other directions. There was a mild sensory loss over the right side of the face, but there was no loss of the corneal reflex. The patient had weakness in his right lower extremity. The pertinent normal examination included the absence of papilledema and signs of cerebellar dysfunction. An MRI scan showed a large mass in the right cerebellopontine angle with enlargement of the porous acousticus. There was marked hydrocephalus. The patient underwent placement of a ventriculoperitoneal shunt on the day he was first seen, and resection of the acoustic neuroma by means of a posterior fossa approach 1 week later. He made a complete recovery with no residual neurologic deficit except right-sided deafness. Facial function was normal. Case 3. S.M. was a 36-year-old woman who worked for a rock radio station and who had a 5-year history of intermittent popping in her left ear. This seemed to be associated with a gradual hearing loss on the same side. For the past 2
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Volume 107 Number 1 July 1992
Hydrocephalus in patient with acoustic neuroma 37
years she had experienced imbalance, and more recently she noted difficulty controlling her left arm and hand. A tendency to fall toward the left developed. In the 2 years before the recognition of her tumor, she noted vertex headaches, occasionally associated with nausea and vomiting. When the headaches were severe, her vision became blurred. On examination, she had counterclockwise nystagmus, left-sided cerebellar signs, and right lower extremity weakness. Her corneal reflex was decreased on the left, and her hearing was reduced on the same side. The ABRs were absent on the left, as was the ENG. An MRl revealed a large cerebellopontine angle mass enlarging the internal auditory canal. There was secondary hydrocephalus as evidenced by the mild ventricular enlargement. The patient underwent surgical resection of an acoustic neuroma by means of a posterior fossa approach. A catheter was placed into the frontal portion of the right lateral ventricle before the opening of the posterior fossa dura. Postoperatively, the patient made a good recovery with full facial nerve function, and with no need for a long-term shunt.
Table 1. Hydrocephalus
DISCUSSION
the others will survive with arrested hydrocephalus. Only 20% of those with arrested hydrocephalus will have normal cognitive function. In adults, in whom the sutures of the bones of the skull are fused and thus cannot expand with the stress of increased intracranial pressure, the patient may deteriorate to death very quickly with acute obstruction of the CSF flow. More typically, CSF obstruction develops gradually, beginning with intermittent blockage of CSF flow and progressing to a more complete obstruction. The intermittent nature of early blockage is the result of the effect of the pumping action of the heart on: (1) the expansion and contraction of the brain within the skull during the cardiac cycle, and (2) the pulsatile flow of the CSF. Symptoms may include decreased mentation, headache, imbalance, blindness, obtundation, and death. Most CSF is produced by the choroid plexus in the lateral ventricles.‘ The average daily production in an adult is 480 to 600 cc per 24 hours. Most of the CSF is absorbed by the arachnoid villae projecting into the sagittal sinus. CSF circulation starts in lateral ventricles, progresses through the third ventricle, the aqueduct of Sylvius, the fourth ventricle, out the basal cisterns, the subarachnoid space, and finally is reabsorbed by the arachnoid villae of the sagittal sinus. In a normal state, CSF production equals CSF reabsorption. Any condition that alters the ratio of CSF reabsorption to CSF production or blocks the CSF circulation can cause hydrocephalus. A classification of the causes of hydrocephalus is shown in Table 1. Until the twentieth century, treatment of hydrocephalus included diet, leeches, and head binding.’ The
Hydrocephalus is the result of abnormally high cerebral spinal fluid pressure within the ventricles or in subarachnoid space over the surface of the brain. It usually results in the enlargement of the ventricular system within the brain. Hydrocephalus may be caused by: ( I ) increased production of cerebral spinal fluid within the ventricles, as seen in choroid plexus papillomas; (2) decreased absorption of CSF over the cerebral hemispheres by the arachnoid granulations, as seen after subarachnoid hemorrhage; or ( 3 ) blockage of the pathways through which the CSF flows, either within the brain or during its egress out of the brain and through the basal cisterns. Morgagne‘ and Whytt’ described the pathology of hydrocephalus in the 1770s, concomitant with the recognition of the structure of the ventricles and the character of the CSF. Magendie3 described the concept of CSF circulation in the 19th century. In 1918, Walter Dandy4 described ventriculography, in which he filled the ventricles with air and studied their configuration with x-ray. This technique made possible the diagnosis and therapy of hydrocephalus. Dandy’s contributions to the understanding of hydrocephalus include: ( I ) description of CSF formation by the choroid plexus, (2) description of CSF circulation, ( 3 ) development of the concept of communicating and noncommunicating hydrocephalus, and (4) devising a phenolsulfonphthalein test to differentiate between the two forms of hydrocephalus. The natural history of congenital hydrocephalus recognized in infants and children is well k n ~ w n Un.~ treated, approximately 50% of the patients will die and
Causes
I Obstructive A Ventricular blockage (noncommunicating) 1 Congenital anomalies 2 Postinflammatory blockage 3 Posthemorrhagic blockage 4 Tumors blocking the fourth ventricle, aque duct of Sylvius or foramen of Monro B Cistern blockage (communicating) 1 Congenital anomalies 2 C-P angle tumors I I Nonobstructive A Atrophic III Funct/onal A Hypersecretion B Impaired absorption
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OtolaryngologyHead and Neck Surgery
STEENERSON and PAVNE
latter procedure was reinstated temporarily by some authors for infants in the 1970s. Lumbar puncture’ was introduced in the early part of this century and is still useful if used judiciously in certain cases of hydrocephalus associated with decreased absorption of fluid. Carotid artery ligation’ and various other procedures have been tried since the advent of general anesthesia, but have proved useless. In 1919, Dandy l o introduced choroid plexectomy as a treatment for hydrocephalus. This was performed through a cerebrotomy with an endoscope borrowed from urologic colleagues. Payr” introduced ventricular CSF shunting to the sagittal sinus and jugular vein in 1908, but the methods used invariably became occluded. Nulsen and Spitz’* implanted valve controlled one-way drainage devices in the 1950s, opening the modem era of ventricular shunting as the treatment for hydrocephalus. Today, commonly used shunting procedures include ventriculoperitoneal, ventriculoatrial, ventriculopleural, and lumbar-peritoneal using a myriad of valves, reservoirs, and shunting tubes. Medical treatment has included lumbar puncture and medications. These include drugs to decrease CSF production, to decrease brain water content, and to increase CSF absorption. All of these are temporary measures at best. The diagnosis of hydrocephalus may be made by ultrasound in individuals with an open fontanelle, by computed tomography (CT scanning), and magnetic resonance imaging (MRI). Air or x-ray dense-contrast agents injected into the ventricles are rarely used today. Radioactive iodinated serum albumin or other colloidal isotopes that tend to remain in the CSF may be used to study CSF flow patterns on a scintillation counter. Hydrocephalus as a result of large acoustic neuromas results from interruption in the normal CSF flow through the basal cisterns. The aqueduct of Sylvius and the fourth ventricle remain patent. While hydrocephalus does not occur frequentlyeven with large acoustic tumors, its recognition is necessary in order to prevent severe intraoperative complications. If the elevated pressure within the ventricles is not normalized before the dura is opened over the posterior fossa, the cerebral hemispheres may shift caudally, compressing and damaging the brainstem. The cerebellum may become so tight within the posterior fossa that it is not possible to expose the tumor without tearing important parts of the brain or its blood supply. The precise route of approach to the tumor, whether by the retrosigmoid, translabyrinthine, or a combined approach, does not alter the risk, because they are all below the tentorium.
In order to prevent herniation, a ventriculostomy may be placed into one of the lateral ventricles at the time of tumor surgery before the dura is opened (case 3). It is safest to place it in the nondominant hemisphere. It is left in place during the operation and through the immediate postoperative period. If a catheter is left in for longer than 48 hours, the risk of infection increases greatly. The disadvantages to this approach are that in a very sick patient with stupor, vomiting, dehydration, and poor nutrition, it will not be possible to correct these deficits in advance of the long surgery for tumor removal. In addition, there is the risk of infection because it is often necessary to leave the ventriculostomy in place for longer than 48 hours. It may have to remain for several weeks, until the blood and cellular debris of the operation are cleared from the CSF and the basal cisterns reopen and the fluid flows adequately into the arachnoid granulations. For these reasons, we favor placement of a shunt 7 to 14 days before the surgery for tumor removal (cases 1 and 2). This allows the patient to awaken to mental clarity, regain hydration and nutrition, and therefore tolerate the surgery more easily. The risk of infection is less as the device is never externalized, and it provides the definitive treatment in those cases in which the basal cisterns fail to reopen to allow adequate CSF flow. The drawbacks to the use of a shunt are few, but it is a foreign body, and when left in place for a period of years there is a small risk of infection by hematogenous bacterial seeding. In addition, a shunt may make the patient more dependent on it as time passes. The normal mechanism for CSF resorption seems to atrophy in some individuals and may include complete closure of the aqueduct. If this occurs and the shunt blocks, the patient may become acutely ill from hydrocephalus. It is possible in some cases with only mild ventricular enlargement to remove the tumor without ventricular drainage of any type. We, however, believe this approach creates an additional major risk to which the patient need not be exposed. The presence of the shunt will reduce the risk of incisional and eustachian tube CSF leakage postoperatively. This occurs in as many as 10% of patients operated on by the translabyrinthine approach. While we have not experienced any incisional leaks in patients done by the posterior fossa-retrosigmoid approach who are closed with a watertight dura, it may occur internally through open mastoid air cells into the middle ear cavity, with resultant CSF rhinorrhea. In summary, we have presented three cases of large acoustic neuromas associated with hydrocephalus. A
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Volume 107 Number 1 July 1992
Hydrocephalus in patient with acoustic neuroma 39
brief review of the development of our knowledge of hydrocephalus, its pathophysiology, and the method and the rationale for treatment of the hydrocephalus in these patients are provided.
6.
REFERENCES
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7.
1. Morgagne GB. The seats and causes of diseases investigated by
anatomy. London: Miller and Cadell, 1761. 2. Whytt R . Observations on the dropsy in the brain. Edinburgh: J . Balfour, 1768. 3. Magendie F. Memoire sur le liquide qui se trouue dans le crane et I’e’pine del’homme and des animaux. J Physiol Exp Pathol 1825;5:27-37. 4. Dandy WE. Ventriculostomy following in injection of air into the cerebral ventricles. Ann Surg 1918;68:5-11. 5. Foltz EL, Shurtleff DB. Five-year comparative study of hydro-
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cephalus in children with and without operation in 113 cases. J Neurosurg 1963;20: 1064-8. Milhorat TH, Mosher MB, Hammock MK, et al. Choroid plexus and cerebrospinal fluid production. Science 1969;166:15 14-6. Davidoff LM. Treatment of hydrocephalus. Historical review and description of new method. Arch Surg 1929;18:1737-62. Quinke H. Veber hydrocephalus. Verh Congr Inn Med 189 I ; 10:321-339. Frase J, and Dottnm. Hydrocephalus. Br Surg 1922;23:165-91. Dandy WE. Diagnosis and treatment of structures of the aqueduct of Sylvius (causing hydrocephalus). Arch Surg 1945;51:1-4. Payr. Drainage der Himentrikle Mittelst Frei Transplantirter Blutgefassee. Bemerkungen Ueber Hydrocephalus Arch. Klon Chir 1908;87:80 1-85. Nulsen FE, Spitz EB. Treatment of hydrocephalus by direct shunt from venticle to jugular vein. Surg Forum 1952;2:399-400.
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Otolaryngology Head and Neck Surgery March 1993
News and Announcements
held July 26-30, 1993, at the Tamarron Resort in Durango, Colorado. This 28 hour review and update will encompass all the clinically important areas of MR imaging. Important new concepts and pathological/imaging correlations in the body, musculoskeletal system, ENT, head and neck, brain, and spine will be explored. Daily case presentations will supplement these lectures and will serve to test the registrants' diagnostic abilities in MR imaging. This complete review of MR imaging will be presented by nationally recognized leaders in magnetic resonance imaging. As a result of this comprehensive review, registrants will become familiar with current applications of MR imaging and will be able to integrate many of these applications directly into their practice. Program chairmen for this presentation will be Robert Quencer, MD (University of Miami), Victor Haughton, MD (Medical College of Wisconsin). Twenty-eight credits of Category I will be available. For further information, please contact Marti Carter, CME, Inc., 11011 West Nort Ave., Milwaukee, Wisconsin 53226, or call (414) 771-9520. Ear, Nose, and Throat Diseases: 1993 Update
Children's Hospital of Pittsburgh will hold its 18th Annual Symposium, "Ear, Nose, and Throat Diseases in Children: A 1993 Update." This symposium will be held July 30-31, 1993. CME credits will be awarded.
For further information, please contact the Department of Pediatric Otolaryngology, Children's Hospital of Pittsburgh, 3705 Fifth Avenue at DeSoto St., Pittsburgh, Pennsylvania 15213, or call (412) 692-8577. Twenty-fifth Annual Meeting - Head and Neck Oncologists
The Association of Head and Neck Oncologists of Great Britain will sponsor the Twenty-fifth Annual Meeting of Head and Neck Oncology, to be held in Edinburgh, Scotland, United Kingdom, on August 23-26, 1993. International and local faculty will present extensive social and family programs. For further information, please contact Mr. P. J. Bradley, Honorary Secretary, Department of Otorhinolaryngology-Head and Neck Surgery, University Hospital, Queens Medical Centre, Nottingham, NG7 2UH, England, or phone 0602421421. Sixth International Congress on Interventlonal Ultrasound
The Sixth International Congress on Interventional Ultrasound will be held in Copenhagen, Denmark, on September 7-10, 1993. For further information, please contact Christian Nolsoe, Congress Secretary, Department of Ultrasound, Herlev Hospital, University of Copenhagen, DK-2730 HerlevDenmark, or call + 45/ 44 53 53 00 ext. 3240.
CORRECTION
The Supplement to the December 1992 issue of the JOURNAL (Volume 107, Number 6, Part 2), incorrectly listed Dr. Bruce R. Gordon as Chief of Otolaryngology at the Massachusetts Eye and Ear Institute. Dr. Joseph Nadol is Chief of Otolaryngology at the Massachusetts Eye and Ear Infirmary. Dr. Gordon is Chief of Otolaryngology at Cape Cod Hospital.
