A Case of Neurofibromatosis 2 Presenting with a Mononeuritis Multiplex

Journal of Neurology, Neurosurgery, and Psychiatry 1992;55:391-393 391 SHORT REPORT J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.5.391 on 1 May 1992. Downloaded from A case of neurofibromatosis 2 presenting with a mononeuritis multiplex T J Kilpatrick, R J Hjorth, M F Gonzales Abstract forearm extensors. There was weakness of the A patient with neurofibromatosis 2 had an intrinsic muscles of the right hand and gener- asymmetrical peripheral neuropathy. A alised weakness of the left arm. The legs were nerve biopsy specimen revealed neuro- also wasted with symmetrical distal weakness. fibromatous changes, and the neuropathy The reflexes were depressed on the right but may have been a direct consequence of normal on the left, except for a depressed ankle neurofibromatosis. An apparent clinical jerk. The right plantar was flexor and the left response to immunosuppressive treat- unresponsive. There was a mild impairment of ment and plasma exchange is also repor- all sensory modalities in the hands and legs, ted. extending to the right knee and to the left anterior superior iliac spine. There were no palpable enlargements along the course of any The term neurofibromatosis defines two peripheral nerves. genetically and phenotypically distinct dis- The results of tests for urea, electrolytes and orders.' Neurofibromatosis 1, or von Reck- liver function, full blood examination and linghausen's disease, is an autosomal domi- random blood glucose and serum calcium, nant disorder with the genetic abnormality phosphate, vitamin B12, and folate concentra- localised to chromosome 17. Typical abnor- tions were all normal. There was no para- malities include cafe-au-lait spots, neuro- proteinaemia, antinuclear antibodies were not fibromas, and Lisch nodules in the iris. Neuro- detected and the erythrocyte sedimentation fibromatosis 2 is also an autosomal dominant rate was 27 mm in the first hour. Serological disorder, but the genetic abnormality is a tests for syphilis and HIV 1 yielded negative deletion on chromosome 22. The characteristic results. The CSF contained 5 x 106/1, the feature is bilateral acoustic neuromas, and loss glucose concentration was 3-8 mmol/l, and the of hearing is often the first symptom. Other protein was elevated at 1-39 g/l. Nerve conduc- CNS tumours, including meningiomas and tion studies showed mild slowing of the left gliomas, also occur. Cafe-au-lait spots and ulnar motor conduction velocity to 40 mls, and peripheral tumours, although less common the left median and ulnar and the right lateral http://jnnp.bmj.com/ than in neurofibromatosis 1, may also be popliteal nerve amplitudes were at the lower found.2 The tumours range from discrete limits of the normal ranges. The corresponding Schwannomas to poorly delineated plexiform F wave latencies were also mildly prolonged. neurofibromas.3 Even in neurofibromatosis 1, The ulnar, median, and left sural nerve sensory however, peripheral tumours are usually potentials were absent, but the right sural asymptomatic, with deficits occurring in only nerve action potential was preserved. A left 4-3% of cases in the series reported by Cannale sural nerve biopsy specimen showed loss of et al.4 some myelinated fibres without active axonal on September 29, 2021 by guest. Protected copyright. We have found there are five previous degeneration or demyelination. reports of peripheral neuropathy associated A provisional diagnosis of subacute, asym- with neurofibromatosis, and two of the cases metrical, sensorimotor peripheral neuropathy had neurofibromatosis 2.` We describe a was made. Although the nerve conduction further patient who had neurofibromatosis 2, studies did not show either a conduction block Royal Melbourne Hospital, Gratton the first to our knowledge to present initially or gross slowing ofthe conduction velocity, the Street, Parkville, with an asymmetrical sensorimotor neuro- clinical presentation and CSF findings sug- Victoria 3050, pathy and subsequently to develop more char- gested the possibility of an inflammatory Australia Department of acteristic features. demyelinating neuropathy, and the patient was Neurology treated with prednisolone (50mg/day). Two T J Kilpatrick months later, however, there had been progres- R J Hjorth Case report sion of symptoms and signs. Azathioprine was Department of A 24 year old male presented with four months started (100mg/day), and seven plasma Anatomical Pathology (Neuropathology of progressive peripheral numbness and weak- exchanges were given. Considerable clinical Laboratory) ness, beginning with paraesthesiae in the fin- improvement occurred over the next three M F Gonzales gers and weakness of the left foot, followed by months. In particular, the sensory deficit Correspondence to: the of truncal ataxia and multiple diminished, his ataxia resolved, and he was Dr Kilpatrick development Received 15 October 1990 falls. There was bilateral wasting of the peri- able to return to his previous employment. and in final revised form and intrinsic hand muscles and wast- Two years later he presented with a hoarse 25 June 1991. scapular Accepted 9 July 1991 ing of the left deltoid, brachioradialis, and voice, right tinnitus, and impaired vision in the 392 Kilpatrick, Hjorth, Gonzales right eye. There was a right fundal astrocytic S-l00 staining was performed and immuno- J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.55.5.391 on 1 May 1992. Downloaded from hamartoma. Examination also showed right reactivity was detected within the whorled lower motor neuron facial nerve, accessory structures comprising the endoneurial neuro- nerve, and vocal cord pareses and bilateral fibroma. The upper cervical tumour was sensorineural deafness. The pattern of weak- removed surgically and identified as a neuro- ness in the limbs was unchanged but in the legs fibroma by histopathology. At the operation, the sensory abnormalities were now confined numerous tumours on multiple cervical nerve to the feet. The ankle jerks were absent and roots were also detected. The patient made a both plantar responses were extensor. A good recovery after the operation cerebral CT scan showed multiple meningio- mata and bilateral acoustic neuromas. MRI of the cerebrum and cervical cord confirmed this and also revealed tumours on the second and Discussion seventh cervical nerve roots, the former caus- This patient initially presented with signs ing cervical cord compression. An MRI of the suggestive of an asymmetrical peripheral lower cord and the cauda equina was normal, neuropathy, and there was objective improve- with no evidence of tumours on the lumbar- ment after starting immunosuppressive treat- sacral nerve roots. A diagnosis of neuro- ment. The subsequent development of cranial fibromatosis 2 was made and, on review, small nerve palsies led to the identification of multi- cutaneous neurofibromas were found and con- ple central nervous system tumours and to the firmed histologically. There was no known ultimate diagnosis of neurofibromatosis 2. relevant family history. There are five previous reports of gener- The original sural nerve biopsy specimen alised neuropathy associated with neuro- was reviewed, and further sectioning detected fibromatosis but the clinical features, histo- changes in one fasciculus suggestive of a logical findings, and postulated pathogenetic neurofibroma (figure). As part of the review, mechanisms differ. Bradley et al reported a family with a predominantly motor axonal neuropathy resembling peroneal muscular atrophy, in which the propositus had neurofibromatosis 1. A sural nerve biopsy specimen revealed multiple tumours, but because one of ..; % ': \ -z; two daughters with subclinical neuropathy did .. not have clinical neurofibromatosis, the neuro- .k 1~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.... logical deficits in the kindred were attributed to an unrelated neuronal degeneration. Bosch et /~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~i al6 also described four patients, three from one family, with neurofibromatosis 1 and clinical features resembling peroneal muscular atrophy. Nerve biopsy specimens showed axonal degeneration and concentric Schwann cell hyperplasia but lacked classical neurofibromatous changes. The neuropathy was attributed http://jnnp.bmj.com/ to a primary neuronal degeneration with reac- tive Schwann cell proliferation. Ohnishi and Nada7 reported a patient with neurofibromatosis 2 and a six year history of a progressive, distal sensorimotor neuropathy. A nerve biopsy specimen showed large myelinated fibre loss and lamellated structures interpreted as areas of Schwann cell hyper- on September 29, 2021 by guest. Protected copyright. plasia. Thomas et al,8 however, reviewed the histology and suggested that these structures were of perineurial origin and characteristic of neurofibromatous changes, making a com- pressive cause for the neuropathy more likely. They also reported three further patients. The third had neurofibromatosis 2, palpable nerves, and presented with a six month history of a progressive and symmetrical sensorimotor neuropathy. Neurofibromas were identified on a nerve biopsy specimen in this patient, and the authors concluded that the neuropathy was the direct consequence of neurofibromatosis.8 Our case differs from the above reports in that an apparent asymmetrical peripheral neuropathy of subacute onset was the initial manifestation. Although individual subcuta- neous neurofibromas are often

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