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Amyotrophic lateral sclerosis: Macro–EMG and twitch forces of single motor units
Author(s) -
Dengler Reinhard,
Konstanzer Annette,
Küther Gerald,
Hesse Stefan,
Wolf Werner,
Strupplerdr Albrecht
Publication year - 1990
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.880130612
Subject(s) - amyotrophic lateral sclerosis , motor unit , medicine , electromyography , dorsum , physical medicine and rehabilitation , anatomy , neuroscience , psychology , disease
Macro–EMG potentials (MEP)s and twitch contractions (spike–triggered–averaging) of single motor units (MUs) have been recorded in the first dorsal interosseus muscle (FDI) of 10 control subjects and 20 patients with amyotrophic lateral sclerosis (ALS). MUs over the full range of voluntary recruitment thresholds were studied. Patients with slightly affected FDIs (5) mainly showed MUs with enlarged MEPs and increased twitch forces. Incontrast, the patients with more severely affected FDIs (15) revealed decreased twitch forces, especially in the MUs with higher thresholds. The corresponding MEPs could be enlarged as well as normal. It apperas that MU sprouting and the resulting increase of twitch force can compensate for the loss of motoneuron in early stages of ALS. In more advanced stages, however, a decline of the force of the surviving MUs, especialy of those with higher thresholds, seems to contribute to the progressive muscle weakness, in addition to the corticospinal degeneration and the reduction in the number of motoneurons.