Focal amyotrophy in neurofibromatosis 2

Neurofibromatosis type 2 (NF2) is an autosomal dominant disorder characteri sed by bilateral vestibular schwannomas and other CNS tumours including men ingiomas and spinal schwannomas. Occasionally, peripheral neuropathy occurs in these patients but this is the first report of focal amyotrophy. Clinic al, electrophysiological, and imaging data from four NF2 patients seen at a specialist neurofibromatosis clinic over a 4 year period are described in whom symptomatic focal amyotrophy preceded the diagnosis of NF2. Two presen ted with wasting and weakness of a single muscle group, several years befor e NF2 was diagnosed. In one patient a mononeuritis multiplex was the presen ting feature of NF2, and in one patient focal wasting and weakness develope d after the diagnosis of NF2 was made. In none of the four cases could a fo cal peripheral nerve or root neurofibroma be identified despite extensive i maging with MRI, and the Limitations of neuroimaging for identifying a stru ctural cause in patients with NF2 with a focal peripheral nerve lesion is d iscussed. It is likely that NF2 may affect peripheral nerve structures in a manner distinct from a compressive schwannoma.