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Year : 2001  |  Volume : 49  |  Issue : 4  |  Page : 380--3

Medulloblastomas of the cerebellopontine angle.

R Kumar, G Achari, A Mishra, DK Chhabra 
 Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow - 226014, India., India

Correspondence Address:
R Kumar
Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow - 226014, India.


It is unusual for a medulloblastoma to occur in the cerebellopontine angle (CPA). Four of the total 63 cases of medulloblastoma managed in our department between 1988 to 1998, presented with a mass in the cerebellopontine angle. There were two children amongst these four patients, aged eight and nine years. The other two patients were young adults. Three patients had primary CPA medulloblastoma, while the fourth case had a recurrence in this region, following the excision of the primary vermian tumour. All the four cases were managed by gross total microsurgical excision and craniospinal irradiation. One of the two children, developed subfrontal recurrence after 1 year and 8 months of initial treatment, while the other child developed a large recurrence at primary site, within three months of post-operative irradiation. However, the adult patient developed CPA recurrence and subsequent cervical intramedullary metastasis within two and a half years of diagnosis. These three cases succumbed to their disease, between three months to thirty months of their initial management. However the fourth patient, a 20 years female with desmoplastic variant, was well at two and a half years of follow up.

How to cite this article:
Kumar R, Achari G, Mishra A, Chhabra D K. Medulloblastomas of the cerebellopontine angle. Neurol India 2001;49:380-3

How to cite this URL:
Kumar R, Achari G, Mishra A, Chhabra D K. Medulloblastomas of the cerebellopontine angle. Neurol India [serial online] 2001 [cited 2021 Jan 19 ];49:380-3
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  ::   IntroductionTop

Children with medulloblastomas, present with a midline mass, arising from the vermis and associated with clinical syndrome of headache, vomiting, letharginess and gait ataxia, while in adults, the laterally placed masses arising from the cerebellar hemispheres are more common.[1],[2],[3] The medulloblastomas may develop at an atypical and uncommon site like cerebellopontine angle cistern. Out of total 15 cases reported, in the world literature so far, only two presented with the typical features of the CPA syndrome.[4],[5] Four such cases of CPA medulloblastoma are reported here, with clinical and radiological details, problems in management and ultimate outcome of these cases.

  ::   Material and methodsTop

Out of 63 cases of medulloblastoma operated from 1988 to 1998, in the department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, four cases were encountered in the cerebellopontine angle cistern (CPA). On account of their unusual location, these cases were studied reasonably well in detail and followed up regularly, after surgery and radiotherapy. Three of these cases were males and one was female. CT scan (plain and contrast) was available for all the cases and MRI in two cases only, during their initial work up.

  ::   Case reportsTop

Case 1 : A 9 year old boy, presented with three weeks history of neck pain, vertigo and a tendency to sway to left side while walking. He had bilateral gross papilloedema, bilateral 6th nerve paresis, left sided 7th nerve paresis of lower motor neuron type, mild left sensorineural deafness and left sided gross cerebellar signs. CT scan showed a hyperdense, heterogeneously enhancing mass in left CPA, compressing the pons and shifting the fourth ventricle to contralateral side. On MRI, the mass was hypointense on T1WI and heterointense on T2WI with contrast enhancement, without any intracanalicular extension [Figure. 1]. Gross total microsurgical excision of the mass was achieved via a retromastoid suboccipital craniectomy. At surgery the mass was very vascular, fleshy, greyish, firm (soft at places), encircling the 7th and 8th nerve complex, but was easily separable. Medially, it was free from brain stem. The patient received 3600 cGy whole brain irradiation, 6000 cGy to local site and 3000 cGy for the spinal cord. Postoperatively and after radiation therapy, he showed improvement in neck pain, vertigo and cerebellar signs. But, after one year and 8 months, he came back with a large subfrontal metastasis [Figure. 2], which was excised completely. The biopsy turned out to be medulloblastoma. In the post operative period, he developed malignant meningitis and malignant subdural effusion, which was proved by cytological examination of the aspirate following CT scan study. A six cycle course of vincristine, etoposide and cisplatin was started. The drugs were given in their usual doses. After two cycles, patient showed minimal clinical improvement but his parents refused further treatment because of financial constraints and poor prognostic implications of the disease.

Case 2 : An 8 year old boy was admitted with history of headache, vomiting and gait ataxia of one year duration. Examination revealed bilateral papilloedema, left 7th nerve paresis of lower motor neuron type and gross cerebellar signs on left side. CT scan showed isodense to hypodense mass, enhancing heterogeneously on contrast, in left CPA with hydrocephalus and brain stem compression. A left retromastoid suboccipital craniectomy and gross total microsurgical excision of the tumour was achieved. Histopathology confirmed it to be medulloblastoma. He was given radiotherapy of 3600 cGys to whole brain, 5500 Gys to local site and 3000 cGys to his spinal cord. There was remarkable improvement in headache, vomiting and gait ataxia. Three months later, he came back with a large recurrence at primary site having significant mass effect [Figure. 3]. He required artificial ventilation, but kept on deteriorating and ultimately succumbed to his illness.

Case 3 : A 20 year old female presented with headache, vomiting and swaying while walking of 6 months durations. She had gross papilloedema, bilateral 6th nerve paresis, diminution of right corneal reflex and right 7th nerve paresis of lower motor neuron type. MRI showed a heterointense mass on T1WI and T2WI, with heterogeneous contrast enhancement in right CP angle with brain stem compression. A retromastoid suboccipital craniectomy, without CSF diversion was performed to achieve gross total microsurgical excision of the tumour. The biopsy was suggestive of desmoplastic variant of medulloblastoma. Postoperatively she received radiotherapy of 3600 cGYs, 6000 cGys, 3500 cGys to whole brain, local site and spinal cord respectively. At 2.5 years follow up, she continued to be symptom free.

Case 4 : A 24 year old male, operated and treated for a small vermian medulloblastoma in 1994 (gross total microsurgical excision and postoperative craniospinal irradiation) came back in January 1997 with features of raised ICP, bilateral cerebellar signs and right sided seventh nerve paresis of lower motor neuron type. CT scan showed a sizeable recurrence in right CPA, extending and infiltrating into ipsilateral hemisphere. He was explored by retromastoid route and near total excision of recurrence was done. There had been improvement in features of raised intracranial pressure after surgery. Three months later, he again presented with clinical syndrome of CPA mass. His CECT confirmed a large recurrence, in the CPA [Figure. 4]. This time he was put on combination chemotherapy of vincristine, etoposide and cisplatin. Six courses of chemotherapy were planned. But after 2 cycles, he developed cervical intramedullary metastasis with quadriparesis and dissociated sensory loss. Finally due to progressive cachexia and compromised respiration, he succumbed to his illness.

  ::   DiscussionTop

Medulloblastomas can have a very variable clinicoradiological pattern and biological behaviour with occurrence at unusual sites. The cerebellopontine angle (CPA) is one such rare location. Only 15 cases of CPA medulloblastoma have been reported in the world literature.[4],[5] Unfortunately, there are no definite clinical, neuro-otological or neuroradiological findings peculiar to CPA medulloblastoma which would help to clinically differentiate this neoplasm from other CPA tumours, like acoustic schwannomas, meningiomas or epidermoids. The diminution of hearing or 7th nerve involvement is uncommon and may help to differentiate medulloblastoma from acoustic schwannoma of the same size. Only two of the 15 reported cases in the world literature, presented with diminution of hearing, as the initial symptom. One of these two developed acute labyrinthine failure as well.[4] When a CPA medulloblastoma presents with such acute onset sensorineural deafness, it is very difficult to differentiate on clinical grounds alone and occasionally on radiology as well. Out of four cases presented here, two presented with diminution of hearing, but acute onset sensorineural deafness was not seen in any of these two patients. Early onset of progressive cerebellar signs and gait ataxia may indicate an axial origin of tumour, while positional nystagmus, may be an early sign suggestive of medulloblastoma as compared to acoustic schwannoma, meningioma or epidermoid cysts.[6],[7] Inspite of these subtle clinical signs, the diagnosis of CPA medulloblastoma is difficult. So far, all the 15 cases of CPA medulloblastoma have been reported in adults only, leading to the assumption that, these neoplasms can occur in adults only. However, two of the cases in present series were children aged [eight] and nine years, which indicates, that this tumour can occur in children as well.

The site of origin of medulloblastomas in the CPA is debatable. It has been speculated to arise from the remnants of the external granular layer in the cerebellar hemisphere, mainly the flocullus, which faces the CPA.[4],[5],[9] It may also develop from proliferating residue of the lateral medullary velum from where it may project into CPA.[5],[7] Only one of our patients, who is still alive at two and a half years follow up, had a histopathological picture of desmoplastic variant. This variant is believed to have a better prognosis because of its stable DNA pattern.[8]

A 30% five year survival has been reported for medulloblastomas of this location after surgery and radiotherapy,[4] while there have been cases who improved with the use of combination chemotherapy, having vincristine based regimens.[9] Chemotherapy has also been combined with radiotherapy, with improvement in a few cases. But it seems that, the surgery along with radiotherapy is the main treatment modality. So far, there is no clear cut consensus as to whether the CPA medulloblastomas are more aggressive as compared to their vermian counterpart. In the present series, only one of the four patients is alive and symptom free while others have succumbed to their disease within a short follow up of 30 months only. This may suggest the higher malignant potential of CPA medulloblastomas in relation to the vermian tumours. Surgery via the retromastoid route followed by radiotherapy remained the main treatment modality to manage these cases. Cordon et al[9] have reported the use of cisplatin based chemotherapy in recurrent disease in children but ototoxicity due to high dose of cisplatin in this age group could be a problem. At surgery in our patients, tumours had been very vascular and was encircling the 7th and 8th nerves, though no intrameatal extension could be seen in any of these. This may explain the 7th and 8th nerve involvement seen in our cases.

In conclusion, CPA medulloblastomas are a very rare group of aggressive tumours with probably higher malignant potential. These occur commonly in adults but can also occur in children. Clinically it is very difficult to distinguish these neoplasms from other intrinsic CPA tumours, though they may be considered in the differential diagnosis of a mass in this region.


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