title: Abnormalities and cue dependence of rhythmical upper-limb movements in Parkinson patients with freezing of gait.
abstract: BACKGROUND
  Freezing of gait (FOG) is a significant clinical problem in Parkinson disease (PD). Similar freezing-like episodes occur during finger movements, but little is known about ongoing motor problems during repetitive hand movements.
  
  
  OBJECTIVE
  To investigate if the regulation of bimanual movements is impaired in those with FOG and if withdrawal of an auditory cue amplifies this problem.
  
  
  METHODS
  A total of 23 PD patients (11 with and 12 without FOG) and 11 controls (CTRLs) performed repetitive finger movements, either externally paced or following cue withdrawal. Movement frequency, amplitude, and coordination pattern were manipulated. The stability and accuracy of movement were evaluated after exclusion of freezing trials.
  
  
  RESULTS
  With auditory pacing present, movement performance was comparable between groups. Following cue withdrawal, motor control deteriorated in those with FOG, resulting in smaller and less stable amplitudes, hastened and more variable frequency, and decreased coordination stability. Conversely, the performance of those without FOG remained mostly similar to that of CTRLs.
  
  
  CONCLUSIONS
  Compared with those without FOG, those with FOG show greater continuous dyscontrol of bimanual movements, similar to the continuous timing and scaling difficulties during locomotion. Those with FOG also benefit from auditory cueing during upper-limb movements, but these are highly cue dependent. This implies that internal timekeeping functions are more disturbed in those with FOG, who may require rehabilitation strategies for repetitive upper-extremity tasks that include cueing and imagery.
authors.affiliation: Katholieke Universiteit Leuven, Leuven, Belgium. sarah.vercruysse@faber.kuleuven.be
authors.forename: Sarah
authors.initials: S
authors.lastname: Vercruysse
authors.forename: Joke
authors.initials: J
authors.lastname: Spildooren
authors.forename: Elke
authors.initials: E
authors.lastname: Heremans
authors.forename: Jochen
authors.initials: J
authors.lastname: Vandenbossche
authors.forename: Nicole
authors.initials: N
authors.lastname: Wenderoth
authors.forename: Stephan P
authors.initials: SP
authors.lastname: Swinnen
authors.forename: Wim
authors.initials: W
authors.lastname: Vandenberghe
authors.forename: Alice
authors.initials: A
authors.lastname: Nieuwboer
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D003463:Cues; D004185:Disability Evaluation; D005260:Female; D005385:Fingers / Q000503:physiopathology*; D020233:Gait Disorders, Neurologic / Q000209:etiology* / Q000473:pathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications*; D010507:Periodicity; D011597:Psychomotor Performance