title: Subthalamic nucleus deep brain stimulation does not improve visuo-motor impairment in Parkinson's disease.
abstract: OBJECTIVE
  To evaluate how bilateral subthalamic nucleus deep brain stimulation (STN-DBS) affects visuo-motor coordination (VMC) in patients with Parkinson's disease (PD).
  
  
  BACKGROUND
  VMC involves multi-sensory integration, motor planning, executive function and attention. VMC deficits are well-described in PD. STN-DBS conveys marked motor benefit in PD, but pyscho-cognitive complications are recognized and the effect on VMC is not known.
  
  
  METHODS
  Thirteen PD patients with bilateral STN-DBS underwent neurological, cognitive, and mood assessment before VMC testing with optimal DBS stimulation parameters ('on-stimulation') and then, on the same day without any medication changes, after DBS silencing and establishing motor function deterioration ('off-stimulation'). Twelve age-matched healthy controls performed 2 successive VMC testing sessions, with a break of similar duration to that of the PD group. The computer cursor was controlled with a dome-shaped 'mouse' hidden from view that minimized tremor effects. Movement duration, hand velocity, tracking continuity, directional control variables, and feedback utilization variables were measured. MANOVA was performed on (1) clinically measured motor function, (2) VMC performance and (3) mood and attention, looking for main and interaction effects of: (1) group (controls/PD), (2) test-order (controls: first/second, PD: on-stimulation/off-stimulation), (3) path (sine/square/circle) and (4) hand (dominant/non-dominant).
  
  
  RESULTS
  Unified PD Rating Scale (UPDRS) Part III worsened off-stimulation versus on-stimulation (mean: 42.3 versus 21.6, p = 0.02), as did finger tapping (p = 0.02), posture-gait (p = 0.01), upper limb function (p<0.001) and backwards digit span (p = 0.02). Stimulation state did not affect mood. PD patients performed worse in non-velocity related VMC variables than controls (F(5,18) = 8.5, p<0.001). In the control group there were significant main effects of hand (dominant/non-dominant), path (sine/square/circle) and test-order (Test_1/Test_2). In the PD group, hand and path effects, but no test-order (on-stimulation/off-stimulation), were found.
  
  
  CONCLUSIONS
  'Low-level' clinically-measured motor function responds to STN-DBS but 'high-level' motor and cognitive functions relating to VMC may be unresponsive to STN-DBS.
authors.affiliation: Parkinson's Disease and Movement Disorders Clinic, Sagol Neuroscience Center and Department of Neurology, Sheba Medical Center, Tel Hashomer, Israel. simon.korn@gmail.com
authors.forename: Simon D
authors.initials: SD
authors.lastname: Israeli-Korn
authors.forename: Shraga
authors.initials: S
authors.lastname: Hocherman
authors.forename: Sharon
authors.initials: S
authors.lastname: Hassin-Baer
authors.forename: Oren S
authors.initials: OS
authors.lastname: Cohen
authors.forename: Rivka
authors.initials: R
authors.lastname: Inzelberg
mesh_terms: D000368:Aged; D046690:Deep Brain Stimulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology* / Q000628:therapy*; D020531:Subthalamic Nucleus