title: Rate of force production and relaxation is impaired in patients with focal hand dystonia.
abstract: One factor, which may contribute to slowed movement in dystonia, is impairment in controlling the voluntary rate of motor output. This study examined the ability of patients with focal hand dystonia to rapidly turn force on and off at the wrist and elbow joints. Dystonic patients were slower than controls in rapidly turning on force from rest at both joints, passively relaxing force and rapidly reversing force output from a steady-state flexion contraction. Adding a preload did not improve the ability of dystonic subjects to rapidly turn on force. These results support the idea that dystonia is a disorder of impaired motor cortical activation, possibly due to basal ganglia dysfunction.
authors.affiliation: Department of Movement Sciences (M/C 994), College of Applied Health Sciences, University of Illinois at Chicago, 808 South Wood Street, 690 CME, Chicago, IL 60612, USA. jwildi1@uic.edu
authors.forename: Janey
authors.initials: J
authors.lastname: Prodoehl
authors.forename: Colum D
authors.initials: CD
authors.lastname: MacKinnon
authors.forename: Cynthia L
authors.initials: CL
authors.lastname: Comella
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Corcos
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D003627:Data Interpretation, Statistical; D020821:Dystonic Disorders / Q000175:diagnosis / Q000503:physiopathology*; D004551:Elbow Joint / Q000503:physiopathology; D005260:Female; D006225:Hand / Q000294:innervation / Q000503:physiopathology; D006236:Handwriting; D006801:Humans; D007537:Isometric Contraction; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology; D009119:Muscle Contraction / Q000502:physiology; D009126:Muscle Relaxation / Q000502:physiology; D018482:Muscle, Skeletal / Q000503:physiopathology*; D014955:Wrist Joint / Q000503:physiopathology