[Isolated sixth nerve palsy--presenting sign of multiple myeloma].

Multiple myeloma is a disease caused by neoplastic plasma cells. Initial symptoms in most cases described in the literature include chest and lumbar pain, paresthesia, paraplegia, general weakness and renal failure. We report a case of isolated sixth nerve palsy causing diplopia as the presenting sign of multiple myeloma. Awareness of such a rare clinical presentation - especially when the existence of multiple myeloma is ignored after visualization of a cranial mass with magnetic resonance imaging (MRI) and computerized tomography (CT)--can prevent unnecessary surgical intervention and delay the appropriate treatment.