Asymmetrical weakness in polymyositis associated with neuropathic involvement.

Peripheral nerve involvement is rare in polymyositis and dermatomyositis. We describe a patient in whom the clinical appearance was suggestive of a markedly asymmetrical presentation of polymyositis. Nerve conduction studies, however, were consistent with multiple neuropathies and suggest that neurological involvement may have been the basis of the asymmetrical weakness. Both the muscle weakness and the neurological abnormalities resolved with corticosteroid therapy. This case illustrates a previously undescribed neurological complication of polymyositis.