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Functional significance of upper and lower motor neuron impairment in amyotrophic lateral sclerosis
Author(s) -
KentBraun Jane A.,
Walker Christie H.,
Weiner Michael W.,
Miller Robert G.
Publication year - 1998
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/(sici)1097-4598(199806)21:6<762::aid-mus8>3.0.co;2-5
Subject(s) - amyotrophic lateral sclerosis , isometric exercise , upper motor neuron , lower motor neuron , motor neuron , physical medicine and rehabilitation , weakness , medicine , muscle weakness , cardiology , neuroscience , psychology , anatomy , disease
The objective of this study was to examine the contribution of lower motor neuron (LMN) and upper motor neuron (UMN) dysfunction to weakness and impaired motor control in 27 patients with amyotrophic lateral sclerosis (ALS). Isometric strength was measured by dorsiflexor maximum voluntary contraction force (MVC). LMN function was measured by tetanic force, twitch force, and the amplitude of the compound muscle action potential. UMN function was measured by the speed of rapid foot taps, the maximum rate of rise of voluntary force, and the central activation ratio [CAR = MVC/(MVC + superimposed tetanic force)]. The results suggest that (1) LMN loss appears to be the primary cause of progressive weakness in ALS; while (2) UMN impairment in ALS leads to slowing of contraction speed and rapid movements, and modest decreases in central activation; and (3) during 6 months of progression, LMN changes were greater than UMN changes. © 1998 John Wiley & Sons, Inc. Muscle Nerve 21:762–768, 1998.