title: Compensatory stepping in Parkinson's disease is still a problem after deep brain stimulation randomized to STN or GPi.
abstract: The effects of deep brain stimulation (DBS) on balance in people with Parkinson's disease (PD) are not well established. This study examined whether DBS randomized to the subthalamic nucleus (STN; n = 11) or globus pallidus interna (GPi; n = 10) improved compensatory stepping to recover balance after a perturbation. The standing surface translated backward, forcing subjects to take compensatory steps forward. Kinematic and kinetic responses were recorded. PD-DBS subjects were tested off and on their levodopa medication before bilateral DBS surgery and retested 6 mo later off and on DBS, combined with off and on levodopa medication. Responses were compared with PD-control subjects (n = 8) tested over the same timescale and 17 healthy control subjects. Neither DBS nor levodopa improved the stepping response. Compensatory stepping in the best-treated state after surgery (DBS+DOPA) was similar to the best-treated state before surgery (DOPA) for the PD-GPi group and the PD-control group. For the PD-STN group, there were more lateral weight shifts, a delayed foot-off, and a greater number of steps required to recover balance in DBS+DOPA after surgery compared with DOPA before surgery. Within the STN group five subjects who did not fall during the experiment before surgery fell at least once after surgery, whereas the number of falls in the GPi and PD-control groups were unchanged. DBS did not improve the compensatory step response needed to recover from balance perturbations in the GPi group and caused delays in the preparation phase of the step in the STN group.
authors.affiliation: Department of Neurology, Oregon Health and Science University, Beaverton, Oregon; Human Motor Control Laboratory, School of Medicine, University of Tasmania, Hobart, Australia.
authors.forename: R J
authors.initials: RJ
authors.lastname: St George
authors.affiliation: Department of Neurology, Oregon Health and Science University, Beaverton, Oregon;
authors.forename: P
authors.initials: P
authors.lastname: Carlson-Kuhta
authors.affiliation: Department of Neurology, Oregon Health and Science University, Beaverton, Oregon;
authors.forename: L A
authors.initials: LA
authors.lastname: King
authors.affiliation: Department of Neurosurgery, Oregon Health and Science University, Beaverton, Oregon;
authors.forename: K J
authors.initials: KJ
authors.lastname: Burchiel
authors.affiliation: Department of Neurology, Oregon Health and Science University, Beaverton, Oregon; Department of Veterans Affairs Portland Health Care System, Portland, Oregon; and horakf@ohsu.edu.
authors.forename: F B
authors.initials: FB
authors.lastname: Horak
mesh_terms: D000368:Aged; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D046690:Deep Brain Stimulation / Q000009:adverse effects*; D005260:Female; D005917:Globus Pallidus / Q000502:physiology*; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology* / Q000628:therapy; D004856:Postural Balance; D020531:Subthalamic Nucleus / Q000502:physiology*; D016138:Walking
chemical_list: D007980:Levodopa
keywords: Parkinson's disease; balance; compensatory stepping; deep brain stimulation