MOTOR-NEURON DISEASE AND MONOCLONAL GAMMOPATHY

In a study to determine the prevalence of monoclonal gammopathy (MG) a mong patients with motor neuron disease (MND), 6 out of 56 (10.7%) wer e found to have a monoclonal paraprotein. Of these 6 patients, 4 had a n IgG and 2 had an IgA paraprotein. The clinical syndromes consisted o f amyotrophic lateral sclerosis in 2 patients, lower motor neuron synd rome with preserved reflexes in at least one limb in 3 patients, and m otor neuropathy with multifocal conduction block in 1 patient. The pre sence of gammopathy appears to correlate with the absence of marked up per motor neuron involvement and with elevated CSF protein concentrati on. An underlying malignant disorder was ruled out in all 6 patients, and they were considered to have MG of undetermined significance (MGUS ). In a control group of 121 age-matched patients with other neuroimmu nological disorders, 5 patients (4.13%) had MG. Four of these had gamm opathy associated with malignant myeloma, and 1 had MGUS. These result s support previous reports of increased prevalence of MGUS in patients with MND and suggest that an autoimmune mechanism may play a role in the disease.