Disturbances in the voluntary recruitment order of anterior tibial motor units in ataxia. Issue 1 (January 1975)

• Record Type: Journal Article
• Authors: Grimby, L; Hannerz, J
• Is Part Of: Journal of neurology, neurosurgery and psychiatry. Volume 38:Issue 1(1975)
• Page Start: 46
• Page End: 51
• Publication Date: 1975-01
• Subjects: Neurology -- Periodicals; Nervous system -- Surgery -- Periodicals; Psychiatry -- Periodicals; 616.8
• DOI: 10.1136/jnnp.38.1.46
• Languages: English
• ISSNs: 0022-3050

Abstract

Abstract : The recruitment order of motor units was studied with an electromyographic technique for secure identification of single motor unit potentials. It has been shown in previous studies of normal subjects that the recruitment order in sustained voluntary contraction is predominantly stable, and that motor units which increase slowly in discharge rate with increasing contraction strength and which already attain regular discharge intervals at low frequencies are always recruited before motor units which increase more rapidly in discharge rate and which do not attain regular discharge intervals until at higher frequencies. In this study 15 patients with severe cerebellar ataxia were examined. It was shown that the recruitment order in sustained voluntary contraction in attaxia is unstable and that low- and high-frequency motor units may alternate as the unit of lowest threshold.