Histologic findings in motor neuron disease. Relation to clinically determined activity, duration, and severity of...

Correlation of 18 histologic variables with age and sex of 24 patients with motor neuron disease (MND), and the duration, severity, and activity of their disease, showed that high density of atrophic fibers correlated with degree of muscle weakness and the worst prognosis and that type I grouping correlated with the best prognosis. Although both type I and type II fibers are involved in the majority of patients with MND, the data suggest that involvement of type I fibers is more important in relation to activity of the disease.