Bedside evaluation of large motor units in childhood spinal muscular atrophy.

One hundred patients with motor unit disease were examined to determine the diagnostc reliability of several clinical signs of large motor units. These signs were high-intensity, low-pitched rumbling on skeletal muscle auscultation, voluntary contraction fasciculations, contraction fasciculation trembling, and palpable contraction fasciculations. Among 22 cases of spinal muscular atrophy, contration fasciculation trembling was noted in 86 percent, abnormal muscle auscultation in 68 percent, palpable contraction fasciculations in 64 percent, and voluntary contraction fasciculations in 50 percent.