Strength, physical activity, and fasciculations in patients with ALS.

Fasciculations are a nearly universal feature in people with amyotrophic lateral sclerosis (ALS). The prognostic value of fasciculations remains uncertain. Twenty-four patients with ALS were evaluated for the effects of atrophy, limb weakness, disease duration, and physical activity on fasciculation frequency (as measured by surface electromyography and clinical counting). Variables were compared by multiple linear regression. As strength of the limb deteriorated, the number of fasciculations in the same limb increased, as long as physical activity was maintained or increased. Fasciculation frequency was not associated with the duration of ALS (r = 0.22; p = 0.30) and was independent of the degree of limb weakness (p>0.05) and limb atrophy (p>0.05). No prediction of disease duration could be made based on fasciculation frequency alone. Fasciculations therefore appear to have diagnostic, but not prognostic, utility in the care of people with ALS.