Bilateral Oculomotor Nerve Schwannomas Presenting With Ptosis And Occulomotor Nerve Palasy- A Rare Presentation Of Neurofibromatosis-2

摘要

Neurofibromatosis 2 (NF2) is a rare autosomal dominant disorder characterized by the development of multiple nervous system tumors. The presence of bilateral vestibular schwannomas is a defining feature, but patients with NF2 also develop other cranial, spinal, peripheral schwannomas, cranial and spinal meningiomas, and cataracts. Other associated intracranial lesions are non neoplastic calcifications with involvement of the Choroid plexus being most common. Cerebellar andcerebral cortical calcifications may also be seen .Though schwanomas other than 8th nerve schwannomas are known to occur but third nerve schwannomas are a rare presentation of NF-2.We at our institution report a rare case of bilateral occulomotor nerve schwannomas associted with massive 5th nerve schwannoma which presented with unilateral ptosis and third nerve palsy. Introduction Neurofibromatosis-2 previously also known as central neurofibromatosis is characterized by bilateral acoustic schwannomas. Other cranial nerve schwannomas such as 5th, 7th 9th 10th are also known to occur but they generally occur in combination with 8th nerve schwannomas(1-3). Oculomotor nerve schwannomas are a rare clinical occurrence. Bilateral oculomotor nerve schwannomas are extremely rare occurrence with no case reported in literature. We report a rare case of bilateral oculomotor nerve schwannomas presenting with ptosis and third nerve palsy and discuss management options in such patients. Case report A 40 year old male presented in our out patient department with gradually progressive ptosis of right eye of one month duration. There was no history of trauma, headache or history of diabetes mellitus or hypertension. On careful examination patient was found to have right sided occulomotor nerve palsy. Examination of the rest of the cranial nerves revealed decreased sensations on left half of the face, weakness of muscles of mastication on left side. Examination of rest of the cranial nerves was normal. Patient also had spasticity in all four limbs with exaggerated deep tendon reflexes. Planters were extensor bilaterally.A provisional diagnosis of right sided intracranial mass lesion was made and a contrast MRI brain was ordered, which revealed bilateral 3rd nerve tumours with a massive left sided 5th nerve tumour. MRI also revealed empty sella and enlarged choroid plexus in fourth ventricle. A diagnosis of multiple cranial nerve schwannomas with NF-2 was made. Two days following admission patient complained of radicular pain in dorsal region with increased weakness in lower limbs. MRI spine revealed an intra dural extramedullary mass in dorsal region causing cord compression at D-4 level.Since patients’ paraplegia was progressive he underwent D4-5 laminectomy with microsurgical removal of IDEM mass. Histopathology was suggestive of neurofibroma. This was followed by microsurgical removal of left 5th nerve mass in two stages Intracranial mass was removed by extended middle cranial fossa approach and extra cranial portion was removed via osteoplastic maxillotomy approach. Post operatively the patient had mild deterioration of 5th nerve function. His spasticity and weakness improved remarkably Since bilateral occulomotor nerve tumors were small and their removal is generally indicated for large tumours causing mass effect, patient was explained the prognosis and it was decided to follow these tumours clinically and radiologically.