title: Split-belt locomotion in Parkinson's disease links asymmetry, dyscoordination and sequence effect.
abstract: The pathophysiology behind gait impairments seen in Parkinson's disease (PD), in particular freezing of gait (FOG), is not fully understood. Here we study the interplay between several gait features related to FOG during different split-belt treadmill (SBTM) conditions.
  
  
  
  We investigated the spatiotemporal properties, the phenomenon of sequence effect and the inter-limb symmetry and temporal coordination of gait during different split-belt conditions in 20 patients with advanced Parkinson's disease and different severities of freezing. Subjects were tested in four belt configurations: tied, split while reducing the velocity of leg with the shorter (worst side reduction, WSR) and longer (best side reduction, BSR) step length, and tied again to measure the after-effect.
  
  
  
  We found that in spite of an improvement of spatial symmetry, the BSR led to a worsening of coordination (i.e. the left-right anti-phased stepping) and an increased sequence effect (i.e. progressive shortening of the step length). By contrast, in spite of a worsened spatial symmetry, WSR improved inter-limbs coordination and reduced the sequence effect. After prolonged split-belt walking gait was differently modulated according to the reduction of the best or worst leg velocity: BSR led to positive after effects in symmetry, bilateral coordination and sequence effect.
  
  
  
  These findings support the hypothesis that the irregularity of inter-limb coordination and defective amplitude generation leading to sequence effect might be coupled and result from the same maladaptive motor behavior. Furthermore, our results show that SBTM can be an effective tool to improve parkinsonian gait.
authors.affiliation: Department of Neurology, Christian-Albrechts-University, Kiel, Germany; Morton and Gloria Shulman Movement Disorders Clinic and the Edmond J. Safra Program in Parkinson's Disease, Toronto Western Hospital and Division of Neurology, University of Toronto, Toronto, Ontario, Canada. Electronic address: alfonso.fasano@gmail.com.
authors.forename: Alfonso
authors.initials: A
authors.lastname: Fasano
authors.affiliation: Department of Neurology, Christian-Albrechts-University, Kiel, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Schlenstedt
authors.affiliation: Department of Neurology, Christian-Albrechts-University, Kiel, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Herzog
authors.affiliation: Advanced Technologies Center, Department of Neurological Rehabilitation, Rehabilitation Hospital, Sheba Medical Center, Tel Hashomer, Israel; Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel; Gonda Brain Research Center, Bar Ilan University, Ramat Gan, Israel.
authors.forename: Meir
authors.initials: M
authors.lastname: Plotnik
authors.affiliation: Department of Neurology, Christian-Albrechts-University, Kiel, Germany.
authors.forename: Franziska E M
authors.initials: FEM
authors.lastname: Rose
authors.affiliation: Department of Neurology, Christian-Albrechts-University, Kiel, Germany; Department of Neurology, University of Würzburg, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Volkmann
authors.affiliation: Department of Neurology, Christian-Albrechts-University, Kiel, Germany.
authors.forename: Günther
authors.initials: G
authors.lastname: Deuschl
mesh_terms: D001259:Ataxia / Q000503:physiopathology; D005080:Exercise Test; D005260:Female; D005684:Gait; D020233:Gait Disorders, Neurologic / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology*; D016138:Walking
keywords: Asymmetry; Freezing; Gait; Parkinson's disease; Split-belt