Motor neuron disease and plasma cell dyscrasia

In the years 1977 to 1984, 10 of 206 patients (4.8%) with motor neuron disease (MND) had M proteins; 4 had IgM and 6 had IgG. Among 100 control patients with other neurologic diseases, only 1 had an M protein. We later added six cases of MND and M proteins, as well as three with polyclonal IgM elevations and two with Bence-Jones proteins. Including other reports, there are now 37 known cases of MND with monoclonal and 5 with polyclonal gammopathy. There is evidence that plasma cell dyscrasia is often undetected; the actual incidence of serum immunoglobulin abnormality in patients with MND may be greater than our figure.