Neuropathy and motor neuron syndromes associated with plasma cell disease.

Increasing numbers of patients are being recognized with neurological abnormalities associated with the immunochemical changes of plasma cell disease. To illustrate the wide spectrum of clinical disorders that can be found, I discuss in detail 5 patients: 2 with neuropathy, 3 with amyotrophic lateral sclerosis (ALS), all of whom had serum monoclonal paraproteinemia. In addition, I report in tabular form 6 patients with paraproteinemia and the following clinical presentations: 1) systemic lupus with polyneuropathy and severe cerebritis, 2) myasthenia gravis with thymoma, 3) polymyositis, 4) polymyositis, arthritis and Grave's disease, 5) relapsing polyneuritis (one of the original patients diagnosed by Austin) and 6) ALS, dystonia and parkinsonism. Major improvements in clinical condition occurred sometimes, but not always, coincident with reductions in the levels of the paraprotein using prednisone, cyclophosphamide, chlorambucil and plasma exchange treatments even in some of the patients who had the clinical appearance of ALS. Patients with neuromuscular diseases should be routinely screened with serum immunoelectrophoresis for monoclonal gammopathy. If a monoclonal gammopathy is found and if the disease is serious, then those patients should be treated as if they had an autoimmune disorder.