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| Year : 1999 | Volume
: 47
| Issue : 2 | Page : 145-7 |
Association of lower cranial nerve schwannoma with spinal ependymoma in ? NF2.
Kumar R, Sharma KH, Chhabra DK
Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.
Correspondence Address:
Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India.
A 15 year old male, who had earlier been operated for intraspinal intramedullary ependymoma, subsequently developed a right cerebello pontine (CP) angle mass. A diagnosis of right CP angle ependymoma was considered, in view of established histology of previously operated spinal lesion. Histopathological examination of the well defined extra-axial mass, which was attached with ninth cranial nerve, however revealed a schwannoma. A diagnosis of Neurofibromatosis-2 (NF2) is strongly suspected, because of well established fact, that the spinal ependymomas may have association with lower cranial nerve schwannomas in NF2. Cranial and spinal MRI screening for early diagnosis of associated, asymptomatic lesions, in suspected cases of NF2, particularly in children, is recommended.
How to cite this article:
Kumar R, Sharma K H, Chhabra D K. Association of lower cranial nerve schwannoma with spinal ependymoma in ? NF2. Neurol India 1999;47:145 |
Neurofibromatosis-2 (NF-2) is less common than neurofibromatosis-1 (NF-1). The frequency of vestibular schwannomas is 95% in the families affected by NF 2 (1st degrees relative), though other tumours of nervous system like craniospinal meningiomas and gliomas are also common in these cases. The ependymoma and astrocytomas however, are usually intraspinal. According to Thapar et al,[1] in the absence of bilateral vestibular schwannomas, the diagnosis of NF 2 may be suspected in the children having meningiomas, schwannomas or with multiple heterogeneous lesions. The association of other cranial nerve schwannomas and spinal tumours is well known in patients of NF 2, with their reported incidence of 23.8% and 67.4% respectively.[2] But the association of lower cranial nerve schwannoma with spinal ependymoma is extremely rare. The diagnosis of NF 2, was suspected because of suggestive clinico radiological profile, though the molecular genetic analysis (which is otherwise also not helpful in diagnosis of 40-50% cases of sporadic type) has not been done in our case.
A 15 year old boy presented with interscapular pain of moderate severity of 3 years duration. He developed gradually progressive numbness from nipple to groin four months before admission. Neurological examination revealed suspended hypoaesthesia from D4 to L1 dermatome with no other sensory motor deficit. Gadolinium enhanced MRI of dorsal spine showed heterogeneously enhancing intramedullary mass at C7 to D1 vertebral level. Syrinx was present above and below the mass [Figure 1]. C6 to D2 laminectomy and microsurgical decompression of tumour was done. Biopsy revealed it to be ependymoma. There was no improvement in hypoaesthesia at the time of discharge. Four months later he presented with history of gradually increasing headache and vomiting of two month's duration, diplopia of 1" months, difficulty in deglutition for one month and slurring of speech of 15 days duration. There was no history of hearing loss. Neurological examination revealed bilateral papilloedema, right horizontal gaze evoked nystagmus, 25% hypoaesthesia over right V1, V2 and V3 distribution of trigeminal nerve, with diminished right corneal reflex. Right 7th UMN paresis and paresis of right 9th and 10th cranial nerves were also demonstrated. Motor system examination revealed hypotonia on right side with pendular knee jerk. Right cerebellar appendicular signs were present. Cranial CT scan showed a large, well defined, heterodense mass in left cerebello pontine angle with heterogeneous enhancement. MRI showed hypo to isointense extra axial lesion on T1 and iso to hyperintense lesion on T2 weighted images, in right CP angle; shift of 4th ventricle to left and hydrocephalus [Figure 2] [Figure 3]. The mass was extending upto foramen magnum.
The diagnosis of cranial ependymoma was considered in view of already operated spinal ependymoma, with the presumption that either the cranial ependymoma did not manifest earlier (before the operation) because of its insignificant size or the diagnosis had been missed initially. Considering the malignant potential of tumour and its probable downward extension in the spine, the option of irradiation of cranial tumour was thought to be practicable. However, in view of academic curiosity and for the sake of histopathological verification of the mass, as well as to achieve decompression, the operation was planned. Right retromastoid suboccipital craniectomy with removal of foramen magnum rim and posterior arch of atlas was done. On opening the dura, a greyish tumour was seen bulging, at the level of foramen magnum and posterior arch of atlas. The tumour was soft to firm, vascular with defined plain of cleavage all around. Brain stem was pushed towards left side. Rootlets of 9th cranial nerve were adherent to tumour capsul. Fifth,7th, 8th and other lower cranial nerves were seen separately and preserved. Histopathology revealed it to be schwannoma. Post operatively, at six months follow up the patient had shown improvement in cerebellar signs and cranial nerve paresis, but the hypoaesthesia of D4-L1 dermatome was still persisting.
Association of spinal and intracranial tumours, specially bilateral vestibular schwannomas, is a common finding in patients of NF 2.[2],[3] 70-89% of patients of NF 2 may have spinal tumours and approximately one third of these tumours are intramedullary astrocytomas and ependymomas.[3] 15% cases of NF 2 diagnosed according to NIH criteria[4] may not have vestibular schwannoma.[5] 11% of these patients were found to be clinically asymptomatic. Basic molecular research over the last decade has led to development of genetic tests for both NF 1 and NF 2.[6] These tests require blood samples from both parents or two close relatives with NF. These tests are however very costly and are available in few centers only. These tests can not be used to detect the sporadic (non-inherited) forms of the disease which accounts for 40-50 % cases.[7]
The diagnosis of NF 2 in children, who do not have family history requires high degree of suspicion. Mautner et al suggested following criterias for probable diagnosis of NF 2 in paediatric age group; - (i) unilateral vestibular schwannomas, (ii) multiple central nervous system tumours, (iii) juvenile cataract, (iv) multiple spinal tumours without leisch nodules or cafe-au-let spots, (v) multiple skin schwannomas.[8] NF is defined by the association and multiplicity of cranial and spinal, meningeal, nerve sheath and glial (astrocytoma and ependymoma) neoplasms.[9] Central NF is also characterized by very frequent (9 out of 11) incidence of distinctive malformative CNS lesions, which include intramedullary and perivascular schwannomas, meningeal angiomatosis, discrete ependymal ectopias, atypical glial cell nests in the grey matter and less frequently syringomyelia.[9] Parry et al[2] demonstrated 62 bilateral vestibular schwannomas out of 63 patients of NF 2. Schwannomas of other cranial nerves were demonstrated in 23.8% and were seen in all cranial nerves except 1st, 2nd and 6th nerve. In sixty seven percent of these patients, the spinal tumours have been documented with preponderance to the cervical spine. Out of 14% neoplasms with confirmed histopathology (in NF 2), 2 patients had ependymomas.[2] Mautner et al described 3 patients of NF 2 without acoustic neuromas, in whom NF 2 gene carrier status was diagnosed by spinal tumour, cataract and schwannomas of cranial and peripheral nerves.[3] Family history and clinical criterias can be met with in only 40-50% cases. NF 2 can also be suspected in patients, who do not meet the NIH criteria as discussed above.[7]
Parry et al performed MR study of entire spine in 40 of 49 patients with NF 2, and observed spinal tumours in 30 patients (75%).[2] MR imaging study confirmed similar observations in 65 of 73 NF 2 patients, who were found to have spinal tumours.[3] As the vestibular schwannomas are unlikely to produce the clinical features at the time of admission, careful examination of skin and eyes is necessary and should be followed by gadolinium enhanced MRI imaging of brain and spine,[8] in order to diagnose NF 2.
The present case, who presented with 3 years history of spinal neoplasm, was subsequently detected to have cranial schwannoma, when it became symptomatic. We strongly suspect the diagnosis of NF 2 in this case, as the association of lower cranial nerve schwannoma with spinal ependymoma, is one of its presentations. Though molecular genetic study in this patient was not done but clinical, radiological and histopathological data is a strong pointer. We also support the view, that MR imaging of spine may be particularly worthwhile in patients found to have a unilateral schwannoma and multiple meningioma or schwannoma of other cranial nerves, to confirm the diagnosis of NF 2.
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