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 »  Introduction
 »  Case report
 »  Discussion
 »  References

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Year : 2000  |  Volume : 48  |  Issue : 4  |  Page : 385-7

Facial nerve neurinoma presenting as middle cranial fossa and cerebellopontine angle mass : a case report.


Departments of Neurosurgery and Neuropathology, National Institute of Mental Health and Neurosciences, Bangalore, 560029, India.

Correspondence Address:
Departments of Neurosurgery and Neuropathology, National Institute of Mental Health and Neurosciences, Bangalore, 560029, India.

  »  Abstract

Facial nerve neurinomas are rare. The tumours arising from the geniculate ganglion may grow anteriorly and superiorly and present as a mass in the middle cranial fossa. Only a few cases of facial nerve neurinomas presenting as middle cranial fossa mass have so far been reported. These tumours present with either long standing or intermittent facial palsy along with cerebellopontine angle syndrome.

How to cite this article:
Devi B I, Panigrahi M, Jaiswal V K, Bhat D I, Das S, Das B. Facial nerve neurinoma presenting as middle cranial fossa and cerebellopontine angle mass : a case report. Neurol India 2000;48:385


How to cite this URL:
Devi B I, Panigrahi M, Jaiswal V K, Bhat D I, Das S, Das B. Facial nerve neurinoma presenting as middle cranial fossa and cerebellopontine angle mass : a case report. Neurol India [serial online] 2000 [cited 2019 Nov 22];48:385. Available from: http://www.neurologyindia.com/text.asp?2000/48/4/385/1493




   »   Introduction Top

Facial nerve neurinomas are relatively uncommon.[1] Though the tumour may arise anywhere along the course of the nerve, facial nerve neurinoma presenting as a large middle cranial fossa mass is very rare. Less than half a dozen cases have been reported so far. We present a case of seventh nerve neurinoma who presented with features suggestive of both middle cranial fossa mass and cerebellopontine angle mass.


   »   Case report Top

A 25 year old female presented with asymmetry of the angle of mouth of 5 years duration, proptosis of right eye and facial pain on right side of 6 months duration and headache of 4 months. She had hearing loss on right side and 2 episodes of generalised tonic/clonic seizures. Physical examination revealed axial proptosis of right eye. There was no evidence of neurofibromatosis. She had bilateral papilloedema and reduced visual acuity. Corneal reflex was sluggish. There was minimal wasting of masseter on right side but power was adequate. She had lower motor neuron type facial nerve palsy on right side. Audiometry revealed profound sensori-neural hearing loss with secondary middle ear pathology. Neuropsychological assessment revealed impaired visual learning. Contrast enhanced CT scan of head demonstrated a 8 cm diameter isodense, globular lesion having well defined border with speckled calcification, enhancing well with contrast. There was no perilesional oedema. There was associated midline shift and erosion of mid-third of petrous bone [Figure. 1a]. Coronal CT scan delineated the lesion arising from the floor of the middle fossa and the associated bone erosion with vertical extension upto parietal region [Figure. 1b] and [Figure. c]. Angiography revealed a large infrasylvian mass with blush seen from external carotid circulation only.
She underwent a right posterior temporal craniotomy, subtemporal extradural approach and total excision of an extradural tumour. The lesion had eroded the midportion of petrous bone. Part of the bone was scooped out. Nerve fibres of 5th nerve were identified medially. Histopathologic examination revealed neurinoma. Post operatively she had dense facial nerve palsy of lower motor neuron type but there was no worsening of deficit of trigeminal nerve.


   »   Discussion Top

Facial nerve neurinoma is a rare cause of facial palsy accounting for less than 5% of cases.[4] Insidious onset of facial palsy, recurrent facial palsy and persistent facial palsy after 12 weeks[4],[5],[6] are probably suggestive of tumour as a cause of the palsy. In our patient, it was the initial and persistent symptom.
The clinical presentation of facial nerve schwannomas originating in the geniculate ganglion is well known. These consist of facial paralysis, hearing loss without other cranial nerve involvement or long tract signs or raised intracranial signs (ICP). Presentation in our patient is slightly different from the cases described earlier in that she had in addition mild fifth nerve involvement, proptosis and raised ICP.
Proptosis may be one of the symptoms when the tumour grows into the middle cranial fossa selectively. Exact cause of proptosisis is unknown. Proptosis due to the presence of the tumour usually resolves after surgery, as was the case with our patient. Proptosis as one of the symptoms of 7th nerve tumour has not been reported previously. Hearing impairment may be of conductive or sensorineural type depending on whether the nerve is compressed by the tumour or the conduction is impaired by the growth of the tumour into the middle ear. In our patient the hearing had not shown any improvement after surgery, so the hearing loss may have been due to compression of the 8th nerve.
Intratemporal course of the nerve is a common site for facial schwannomas without neurofibromatosis. The tumour may erode the mid portion of the petrous and grow anteriorly and superiorly to present in the middle cranial fossa. Small extradural middle cranial fossa extension has been reported before.[6] Our patient in contrast had presented with middle cranial fossa mass, which was large and all extradural.
The differential diagnosis of a large extra axial middle cranial fossa tumour is meningioma, fifth nerve schwannoma and skull base tumours such as chondroma and chondrosarcoma. Our patient had predominantly lower motor neuron type of facial palsy which was long standing and mixed hearing fossa and with subtle fifth nerve involvement. The 5th nerve involvement can be explained by raised intracranial pressure and due to the pressure over the fifth nerve at the Meckle's cave by the tumour.
These tumours are generally solid tumours. CT scan and pluridirectional tomography demonstrate the probable site of origin and extent.[5],[6],[8] Because the tumour can become extra canalicular at the geniculate ganglion level, both cerebello-pontine angle and middle fossa spread can occur. This type of extension has been termed as 'trans mid petrosal' extension by Inove et al,[3] in contrast to trans-apicopetrosal extension of trigeminal nerve schwannoma, or transhiatal extension of acoustic neuromas.
The need for surgery, timing of surgery and route of surgery are decided by the presence or absence of seventh and [eight] nerve deficits and raised ICP signs.
In the absence of facial palsy, and raised ICP with or without hearing loss, it is probably better to defer the surgery in both very elderly or young patients. Some amount of facial paresis is common postoperatively. The indications for surgery in our patient have been presence of a large tumour with raised ICP and an already established facial palsy and hearing loss with a progressive proptosis. It has been possible to treat two of the symptoms. Symon et al[9] recommend complete excision of the tumour. They also advocate restoration of nerve functions by various methods. In conclusion, a rare case of facial nerve schwannoma with unusual feature of proptosis and raised ICT has been presented.

 

  »   References Top

1.King TT, Morrison AW : Primary facial nerve tumours within the skull. J Neurosurg1990; 72 : 1-8.   Back to cited text no. 1    
2.Kienzle GD, Goldenberg MH, Just NWM et al : Facial nerve neurinoma presenting as middle cranial fossa mass. CT appearance. J Comput Assist Tomogr1986; 10 : 391-394.   Back to cited text no. 2    
3.Inove Y, Tabuchi T, Hakuba A et al : Facial nerve neuromas. CT findings. J Comput Assist Tomogr 1987; 11 : 942-947.   Back to cited text no. 3    
4.May M : Facial paralysis: differential diagnosis and indications for surgical therapy. Clin Plast Surg 1979; 6 : 275-291.   Back to cited text no. 4    
5.Lidov M, Som PM, Stacy C et al : Eccentric cystic facial schwannoma: CT and MR features. J Comput Assist Tomogr 1991; 15 : 1065-1067.   Back to cited text no. 5    
6.O'Donoghue GM, Brackman DE, House JW et al : Neuromas of the facial nerve. Am J Otol 1989; 10 : 49-54.   Back to cited text no. 6    
7.Ismat F, Bontimeus F, Miranda AM et al : Neurinomas of the facial nerve. Report of three Cases. J Neurosurg1975; 43 : 608-613.   Back to cited text no. 7    
8.Martin N, Strekers O, Mompoint D et al : Facial nerve neuromas : MR imaging. Report of four cases. Neuroradiology 1992; 34 : 62-67.   Back to cited text no. 8    
9.Symon L, Chessman DA, Kavanchi M et al : Neuromas of the facial nerve: a report of 12 cases. Br J Neurosurg1993; 7 : 13-22.   Back to cited text no. 9    

 

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