Transient improvement induced by motor fatigue in focal occupational dystonia: The handgrip test
✍ Scribed by Alessandra Pesenti; Alberto Priori; Guglielmo Scarlato; Sergio Barbieri
- Publisher
- John Wiley and Sons
- Year
- 2001
- Tongue
- English
- Weight
- 39 KB
- Volume
- 16
- Category
- Article
- ISSN
- 0885-3185
- DOI
- 10.1002/mds.1208
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✦ Synopsis
Abstract
Muscle fatigue induced by a previous sustained contraction temporarily decreases the motor output, transiently worsening motor performance. Whether muscle fatigue alters motor performance also in dystonia—a disorder whose main pathophysiological abnormality is motor overflow—remains unknown. To assess the effects of muscle fatigue in patients with focal occupational upper limb dystonia, we studied the effect of a previous maximum fatiguing voluntary contraction on motor performance in 10 musicians with focal occupational dystonia, in 3 musicians with hand motor impairment due to non‐dystonic disorders, and in 5 normal musicians. The fatiguing task consisted of grasping a spring handgrip as long as possible until the task failed. In dystonic musicians, a fatiguing contraction significantly improved motor performance. The improvement lasted less than 5 minutes and appeared only after fatigue of the affected upper limb. In contrast, in musicians with non‐dystonic motor impairment, motor performance remained unchanged or worsened, and normal musician performance consistently worsened. © 2001 Movement Disorder Society.