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Table of Contents    
Year : 2020  |  Volume : 68  |  Issue : 2  |  Page : 257-261

Surgical Experience with Eighty Cases of Acoustic Neurinoma

Department of Neurology and Neurosurgery, Christian Medical College and Hospital, Vellore, Tamil Nadu, India

Date of Web Publication15-May-2020

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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0028-3886.284346

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How to cite this article:
Sambasivan M, Mathai K V, Chandy J. Surgical Experience with Eighty Cases of Acoustic Neurinoma. Neurol India 2020;68:257-61

How to cite this URL:
Sambasivan M, Mathai K V, Chandy J. Surgical Experience with Eighty Cases of Acoustic Neurinoma. Neurol India [serial online] 2020 [cited 2022 Jul 6];68:257-61. Available from: https://www.neurologyindia.com/text.asp?2020/68/2/257/284346

  Historical Notes Top

Surgery for cerebellopontine angle tumours began in the wake of the 20th century, but results of surgery were poor at that time. Berecharht collected 18 cases of cerebellopontine angle tumours of whom 13 died subsequent to surgery.[1] Eiselberg reported 16 similar cases with 12 fatalities and Krause reported 31 cases with 26 deaths.[1],[2] Cushing attributed the high rate of surgical fatality to hasty attempts at tumour removal.[1] He described the crossbow incision for better exposure of posterior fossa and easier accessibility to cerebellopontine angle. He also suggested uncapping of the tumour by excising the lateral third of cerebellum to facilitate easier approach to the tumour. Removal of tumour intracapsularly as against total excision was practised by him in an attempt to reduce surgical mortality. By these techniques he reported a mortality rate of 15 per cent. Elsberg advocated a combined suboccipital and temporal approach for tumours of the cerebellopontine angle.[1]

Frazier adopted unilateral suboccipital craniectomy to remove tumour from the cerebellopontine angle.[1] In 1922, Dandy reported total excision of acoustic tumours; all his first five cases survived.[1] Horrax and Poppen advocated total removal of acoustic tumour and followed Dandy's technique.[1] Cairns attempted to save the facial nerve during the excision of acoustic neurinoma.[1] Olivecrona is another pioneer who contributed much to the management of acoustic neurinomas.[3],[1]

  Age and Sex Incidence Top

Cushing stated, that, “symptoms of acoustic tumour rarely occur before the third decade of life. Hence one may be justified in the conclusion that a patient under the age of 20 with a cerebellopontine angle syndrome in all likelihood has a lesion other than an acoustic tumour.[1] Although this is generally true it may be stated that, rarely, acoustic neurinomas occur in childhood also. Bilateral acoustic tumours are commoner in children with multiple neurofibromatosis.

Mark and Sweet[12] reported a case of unilateral acoustic neurinoma occurring at the age of 6 years. Perhaps this is the only case of unilateral acoustic neurinoma reported as occurring in the first decade. Keith, Craig and Kernohan[4] reported 427 cases of brain tumour in children below 15 years; there were no cases of acoustic neurinoma in this series. Of the 410 cases of intracranial tumour reported from Mayo Clinic only two cases of acoustic tumour were seen below 15 years of age. Craig, et al.[5] reported two cases of acoustic neurinoma, one in an 11-year-old child and the other in a 14-year-old child. [Table 1] shows the age incidence in the present series. The maximum age incidence is between 20-50 years. There are five cases below 15 years; of these one patient was 9 years of age and had bilateral acoustic neurinoma.
Table 1: Age incidence

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  Clinical Features Top

The pathological syndrome of the cerebellopontine angle is well known. In the present series the first symptom complained of in 50 per cent of cases was headache. Order of occurrence of symptoms is given in [Table 2]. In 3 per cent of cases trigeminal neuralgia was the only symptom, without any neurological deficit. One patient had trigeminal ganglion decompression done on him with adequate relief of pain. He came back with recurrence of trigeminal neuralgia and corneal anaesthesia. Clinically there was no hearing deficit and X-ray of petrous pyramids did not show asymmetry or widening of the auditory canal. Exploration of the cerebellopontine angle revealed a small acoustic neurinoma which was excised. Three per cent of patients presented with generalised seizures and one with behavioural changes. The most frequent symptom for which they sought medical help was deterioration of vision. Twenty two per cent of patients were admitted with secondary optic atrophy.
Table 2: First symptom

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Clinical signs were characteristic in most, of the cases [Table 3] and [Table 4]. Ninety per cent had deafness on the affected sideither shown clinically or by audiometry. Vestibular function was either absent or markedly hypoactive in the same number of cases. A few patients mentioned that, they were not able to hear the voices of females or high pitched tones. Many cases were seen with secondary optic atrophy or severe papilloedema. Severe neurological deficit, such as glossopharyngeal, vagus or hypoglossal paralysis or long tract involvement in decating the large size of the tumour, was seen in a few cases.
Table 3: Subsequent symptoms

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Table 4: Signs

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  Diagnosis Top

In addition to the routine laboratory investigations 90 per cent of the cases were subjected to audiometry and vestibular function studies. All these cases showed hearing and vestibular function deficit.

Towne's and Stenver's views of skull were of diagnostic value in 85 per cent of the cases. Enlargement of the internal auditory meatus and canal was the early change. Loss of sharpness of the superior margin and erosion of the tip of the petrous bone were seen in some cases. In a few cases fractional pneumoencephalogram was done to demonstrate the cerebellopontine angle cisterns. Non-filling of the cistern was not considered of any diagnostic value unless it showed a filling defect. Few cases were subjected to vertebral angiography by retrograde brachial artery injection of dye under pressure. Gross shift of basilar artery to one side was seen in one case and up- ward displacement of posterior cerebral and superior cerebellar artery was seen in another case. In two cases tumour staining was noted. The most characteristic feature in many of the cases was anterior displacement of the basilar artery in the lateral view. In 9 per cent of cases where diagnosis was in doubt ventriculograms were done.

In 90 per cent of cases a preoperative diagnosis of acoustic neurinoma was made; in the rest a pathological diagnosis was made only after operation.

Two patients presented with signs suggestive of midline cerebellar lesion. One was a child aged 12 years and the other was an adult aged 28 years. In both cases, at operation, the vermis was found widened. Exploration revealed vascular tumours. Biopsy from the tumour showed a histopathological pattern typical of neurilemmoma. On further exploration in both cases acoustic tumours were removed.

  Management Top

All 80 patients were subjected to surgery. In the majority tumour was totally excised in one stage. In some two or three stages were required to achieve complete removal of tumour. In a few cases it was not possible to excise the tumour completely. In the present series of 80 cases 96 operations were carried out [Table 5].
Table 5: Operation and mortality

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Fifty-four patients were treated by primary extracapsular total excision of tumour; their post-operative period was relatively smooth. Morbidity resulting from glossopharyngeal and vagus palsy necessitated prolonged hospitalization in some cases. The overall mortality rate in this group was 16.5 per cent. In the surviving cases cerebellar deficit recovered fairly rapidly. In 26 cases tumour could be removed only sub-totally because of the very large size and vascülarity of the tumour or because of marked adherence to vital structures. Eleven required secondary operation and 5 needed tertiary operation. In the group of cases with subtotal excision of tumour, recurrence of symptoms necessitating re-exploration occurred within 2½ years. Buey[6] has emphasized the superiority of total excision over partial excision. The comparative mortality figures are shown in [Table 6].[16]
Table 6: Comparative mortality rates

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After subtotal excisions many patients had a stormy post-operative course. This may have been due to brain stem distortion. A possible explanation may be that during mobilisation of the tumour almost all the venous channels are interrupted as they are peripherally situated. At the same time arterial twigs arising from vertebro- basilar system supplying the tumour, are intact. The unsupported tumour with its severed lateral attachments swells and hangs from the brain stem. This causes central cardio-respiratory depression, altered consciousness, cranial nerve palsies and long tract signs, resulting in morbidity and mortality.

A pre-operative ventriculo-atrial shunt by Pudenz valve was done in 28 patients. Of them 20 had total excision and 8 had subtotal excision of tumour. It was found that this preparation prior to definitive surgery was very useful.[7] With adequate decompression and partial restoration of CSF dynamics, the operation was easier and post-operative management was simpler. None of the cases needed post-operative ventricular punctures. In this group mortality rate for total excision was 14 per cent and that for subtotal excision was 26 percent.

Of the 80 tumours, 5 were partially cystic.

No deliberate attempt was made to preserve the facial nerve. This was because of the large size of the tumour and its extension into the internal auditory canal. However, unless involved in the tumour, 5th, 9th and 10th cranial nerves were deliberately identified and preserved. Tracheostomy was not done post-operatively unless indicated. A lateral tarsorrhaphy on the affected side was done in most patients. All patients were fed by nasogastric tube even where it was certain that no damage was done to the 9th and 10th nerves. If the patients were able to swallow sips of water without gagging the tube was removed in 48 to 72 hours. In the few cases where there was swallowing difficulty the tube was used as long as necessary.

  Some Interesting Case Reports Top

Case 1

Male, aged 26 years, was admit- ted with symptoms diagnostic of right cerebellopontine angle lesion. X-ray of the skull showed erosion of the petrous pyramid. A ventriculo-atrial shunt was done prior to definitive surgery. At operation a vascular solid acoustic neurinoma was excised partially because the tumour was very adherent to brain stem. In the immediate post-operative period he regained consciousness, but after 24 hours his condition deteriorated and respirations became shallow and laboured. Tracheostomy was performed. His conscious level deteriorated and he was not responding even to deep pain.

Re-exploration at this stage showed no clot in the tumour bed, but the tumour that was left behind appeared markedly swollen. More tumour was excised, including a piece that was lodged in the tentorial hiatus; a portion adherent to the medulla was left behind. By now breathing was better and general condition improved. Post-operative course was stormy; intermittently, the respiration stopped and he was tided over these phases with assisted respiration. After 24 hours he was breathing normally and became Improvement continuedand he was dis- charged 2 months later. One month after discharge he developed sudden respiratory distress at home for which tracheostomy was performed in another hospital and he was readmitted. He had marked palatal was paralysis on the right side in addition to the pevious findings. A third attempt was made to excise the tumour; this could not be achieved and the patient expired.

This case illustrates one of the problems associated with partial excision of a large acoustic neuroma.

Case 2

Male, aged 29 years, was admitted on 1st May, 1963 for a left acoustic neurinoma which was partially excised. He was admitted again on 27th August 1963 with recurrence of symptoms, and more tumour was excised, though total excision was not possible as the tumour was adherent to the medulla. After a stormy post- operative period he recovered and was sent home. One month later he was admitted again in very poor general condition. He was semiconscious with all the signs of a left cerebellopontine angle lesion, dysphgia and bilateral long tract signs. Bed sores were present. Another attempt at tumour excision was made. The tumour was now larger than seen at the first operation. Most of its extension was into the ten- torial hiatus and foramen magnum. Total excision was achieved and the patient made an uneventful recovery although his cerebellar deficit and motor signs persisted.

Case 3

An 18-year-old male was admitted with proptosis of the left eye, and evidence of increased intracranial tension. Examination showed that his sense of smell was impaired. There was bilateral papilloedema. Lateral rectus paralysis was present in the right side; all movements of the left eye were restricted; there was no nystagmus. Upper motor neurone facial weakness was present on the left side. Slight left hemi- Paresis with hyperactive tendon reflexes was noted. X-ray of the skull showed sutural diastasis and Towne's view showed bony erosion in the region of right internal auditory meatus. Right retrograde brachial angio gram showed a right frontoparietal meningioma. A diagnosis of right frontoparietalmeningioma and right acoustic neurinoma was made. Surgery was planned in stage. In the first stage an attempt was made to excise the meningioma. Possibly due to some coagulation defect there was a steady ooze from the wound and bone, surface. Tumour could not be approached. Autopsy showed a right fronto-parietal meningioma, a right acoustic neurinoma and a left third nerve neurinoma.

Two cases with multiple tumours, illustrating the association of meningioma and neurinoma were reported earlier8.

  Results and Follow-Up Top

Total excisions seemed to have fairly smooth post-operative period, except when there was operative trauma or ischaemia to the brain stem. Subtotal excision of tumour was often followed by a stormy post- operative phase.

In the group of 54 patients who had total excision of tumour immediate mortality rate was 16.5 per cent. Among the survivors 78 per cent were contacted [Table 7]. They were fairly well rehabilitated at the time of the follow-up. Some who were blind prior to surgery remained blind. In 7 per cent that died at home the cause of death was not known.
Table 7: Follow-up of sixty-four cases

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Among the group of 26 patients who had subtotal excision of tumour the immediate mortality rate was 27 per cent. Of the survivors 11 came back within years for secondary operation.

  Summary Top

Clinical features and results of surgical treatment of 80 cases of acoustic neurinoma are described. A one-stage total primary excision, when feasible, offers the best chance of cure. This has not been possible in some because of the large size of the tumour, extension into tentorial hiatus, ex- treme vascularity and adherence to the brain stem. In such cases tumour removal had to be carried out in two or three stages resulting in a higher mortality and morbidity. No deliberate attempt at preservation of the facial nerve has been made because of the large size of these tumours. A pre- operative ventriculo-atrial shunt improved the results of surgery.

  References Top

Walker AE. A History of Neurological Surgery. Williams and Wilkins, Baltimore; 1951, p.126.   Back to cited text no. 1
Mark V, Sweet W. Unusaual case of Unilateral English Nerve Tumour. J Neurosurg 1952;9:395.  Back to cited text no. 2
Givre A, Olivecrona H. Surgical Experience with Acoustic Tumours. J Neurosurg 1949;6:396.  Back to cited text no. 3
Keith HM, Craig WM, Kernohan JW. Brain Tumours in Children pediatrics 1949;3:839.  Back to cited text no. 4
Craig WM, Dodge HW, Ross PJ. Acoustic Tumours in Children. J Neurosurg 1954;II:505.  Back to cited text no. 5
Bucy PC. Surgical Treatment of Acoustic Tumour. J Neurosurg 1951;8:547.  Back to cited text no. 6
Abraham J, Chandy J. Ventrículoatrial Shunt in the Management of Posterior Fossa Tumours. J Neurosurg 1963;20:252.  Back to cited text no. 7
Mathai KV, Chandy J. Multiple Intracranial Tumours. Neurology (India) 1956;7:21.  Back to cited text no. 8
Balasubramaniam V, Ramamurthy B. Experiences with Auditory Neurofibromas. Neurology (India) 1962;10:29.  Back to cited text no. 9
Hullay J, Tomits GH. Experiences with Total Removal of Tumours of Acoustic Nerve. J Neurosurg 1965;22:127.  Back to cited text no. 10
German WJ. Acoustic Neurinomas, in Clinical Neurosurgery, Williams and Wilkins. Baltimore 1961;7:21.  Back to cited text no. 11
Jefferson G. Symposium on Acoustic Tumours. J Neurol Neurosurg Psychiat 1950;13:279.  Back to cited text no. 12
Olivecrona H. Analysis of Results of complete and partial Removal of Acoustic Neuromas. J Neurosurg Psychiat 1950;13:271.  Back to cited text no. 13
Pennybacker JB, Cairns H. Result in 130 Cases of Acoustic Neuromas. J Neurol Neurosurg Psychiat 1950;13:272.  Back to cited text no. 14
Northfield DW. Acoustic Neurinoma. J Neural Psychiat 1950;12:277.  Back to cited text no. 15
Horrax G. Comparison of Results after Intracapsular Enucleation and Total Extirpation of Acoustic Tumours. J Neurol Neurosurg Psychiat 1950;13:268.  Back to cited text no. 16


  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6], [Table 7]


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