title: Somatosensory-related limitations for bimanual coordination after stroke.
abstract: BACKGROUND
  Bimanual coordinated movements may be impaired after stroke, so an assessment of causes is necessary to optimize rehabilitation strategies.
  
  
  OBJECTIVE
  We assessed the role of afference-based sources of coordination, including phase entrainment and error correction based on visual and somatosensory feedback.
  
  
  METHODS
  In all, 10 persons with unilateral chronic stroke and 8 age-matched controls participated in a kinesthetic tracking protocol, in which the hemiparetic upper limb was passively driven by the machine. The task consisted of matching the trajectory of the driven limb as accurately as possible with the freely moving limb in 2 conditions: eyes closed and eyes open. We analyzed the continuous relative phase (CRP), the mean absolute difference between positions (ADP) between the positions of the 2 limbs, and the jerk of the matching limb.
  
  
  RESULTS
  Coordination instability (CRP standard deviation) and mean ADP were significantly higher for patients with eyes closed, compared with patients with eyes open, controls with eyes closed, and controls with eyes open. Moreover, the jerk was higher for the nonparetic limb of patients than for the control group. Thus, the nonparetic limb did not produce optimally smooth movements even as the motor-driven paretic limb did.
  
  
  CONCLUSIONS
  Besides deficits caused by interhemispheric competition and motor execution of the paretic limb, somatosensory feedback is a limiting factor in bimanual coordination after stroke. The findings have clinical implications pertaining to the design and individualization of efficient bimanual movement therapy.
authors.affiliation: Montpellier-1 University, EuroMov, Montpellier, France. kjerstin.torre@univ-montp1.fr
authors.forename: Kjerstin
authors.initials: K
authors.lastname: Torre
authors.forename: Nadhir
authors.initials: N
authors.lastname: Hammami
authors.forename: Julien
authors.initials: J
authors.lastname: Metrot
authors.forename: Liesjet
authors.initials: L
authors.lastname: van Dokkum
authors.forename: Flavia
authors.initials: F
authors.lastname: Coroian
authors.forename: Denis
authors.initials: D
authors.lastname: Mottet
authors.forename: Mohamed
authors.initials: M
authors.lastname: Amri
authors.forename: Isabelle
authors.initials: I
authors.lastname: Laffont
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D004185:Disability Evaluation; D056228:Feedback, Sensory / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006225:Hand / Q000294:innervation*; D006801:Humans; D007699:Kinesthesis; D008297:Male; D008875:Middle Aged; D011596:Psychomotor Disorders / Q000209:etiology*; D020521:Stroke / Q000150:complications*
keywords: bimanual coordination; error correction; phase entrainment; somatosensory feedback; unilateral stroke; visual feedback