title: Motor switching and motor adaptation deficits contribute to freezing of gait in Parkinson's disease.
abstract: BACKGROUND
  Patients with freezing of gait (FOG) have more difficulty with switching tasks as well as controlling the spatiotemporal parameters of gait than patients without FOG. Objective. To compare the ability of patients with and without FOG to adjust their gait to sudden speed switching and to prolonged walking in asymmetrical conditions.
  
  
  METHODS
  Gait characteristics of 10 freezers, 12 non-freezers, and 12 controls were collected during tied-belt conditions (3 and 4 km/h), motor switching and reswitching (increase of speed in one belt from 3 to 4 km/h and vice versa), and adaptation (adjustment to asymmetrical gait) and re-adaptation (returning to symmetrical gait) on a split-belt treadmill.
  
  
  RESULTS
  Following switching, freezers showed the largest increase of step length asymmetry (P = .001). All groups gradually adapted their gait to asymmetrical conditions, but freezers were slower and demonstrated larger final asymmetry than the other 2 groups (P = .001). After reswitching, freezers again showed the largest step length asymmetry (P = .01). During re-adaptation, both controls and non-freezers reached symmetrical levels, but freezers did not. Interestingly, only immediately after switching did one episode of FOG and one episode of festination occur in 2 different patients.
  
  
  CONCLUSIONS
  Freezers have more difficulties adapting their gait during both suddenly triggered and continued gait speed asymmetry. The impaired ability of freezers during both switching and reswitching would suggest that they have an adaptive deficit rather than difficulties with asymmetry per se. Future work needs to address whether these adaptation problems can be ameliorated with rehabilitation.
authors.forename: Farshid
authors.initials: F
authors.lastname: Mohammadi
authors.forename: Sjoerd M
authors.initials: SM
authors.lastname: Bruijn
authors.forename: Griet
authors.initials: G
authors.lastname: Vervoort
authors.forename: Erwin E
authors.initials: EE
authors.lastname: van Wegen
authors.forename: Gert
authors.initials: G
authors.lastname: Kwakkel
authors.forename: Sabine
authors.initials: S
authors.lastname: Verschueren
authors.forename: Alice
authors.initials: A
authors.lastname: Nieuwboer
mesh_terms: D000222:Adaptation, Physiological; D001696:Biomechanical Phenomena; D005260:Female; D007839:Functional Laterality; D005684:Gait; D020233:Gait Disorders, Neurologic / Q000503:physiopathology*; D006801:Humans; D007866:Leg; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000503:physiopathology*; D010812:Physical Stimulation; D016138:Walking