Neuromuscular diseases associated with benign monoclonal gammopathy. Study of CSF and serum proteins by isoelectric focusing.

In over 1200 cases examined by isoelectric focusing of CSF and serum proteins, 4 patients had benign monoclonal gammopathy. These patients were affected by amyotrophic lateral sclerosis of bulbar onset, sensitive neuropathy of Thevenard type, myasthenia gravis, and limb-girdle muscular dystrophy, respectively. The difficulty to relate the differences in the clinical features of these cases to a common physiopathological mechanism and the incidence of this finding (0.4% in 873 cases ranging from 21-60 years of age) do not seem to suggest any pathogenetic relationship between benign monoclonal gammopathy and the different neurological disorders encountered in these patients.