title: The effect of medication and the role of postural instability in different components of freezing of gait (FOG).
abstract: Freezing of gait (FOG) is associated with gait asymmetry and arrhythmicity, cognitive impairment in Parkinson's disease (PD). However, the role of postural instability (PI) in and the effect of dopaminergic medication (meds) on FOG are unclear. We investigated the effect of meds on FOG using a validated metric, Stepping in Place (SIP) and the relationship between PI and FOG.
  
  
  METHODS
  We assessed static posturography (off meds), SIP, UPDRS-III (off/on meds) and the FOG-questionnaire (FOG-Q) in 15 freezers/15 non-freezers and 14 healthy controls.
  
  
  RESULTS
  UPDRS-III, rigidity, tremor (P < 0.01) and axial subscores (P < 0.05) improved with meds in freezers. Only UPDRS-III and tremor improved in non-freezers (P < 0.01). Meds improved freezing episode (FE) frequency, duration and stride duration in freezers (P < 0.01). Over 73% of freezers did not freeze on meds, although one freezer had more and longer duration FEs. Meds did not improve SIP cycle asymmetry and arrhythmicity, which remained greater in freezers compared to other groups on and off meds (P < 0.01, P < 0.05 respectively). Center of pressure (CoP) mediolateral displacement and velocity (VCoP) in both directions were larger in freezers (P < 0.05). FOG-Q was correlated with CoP anteroposterior displacement and mediolateral VCoP (R = 0.42; R = 0.40, P < 0.05). The improvement of FOG frequency and duration but not of gait asymmetry and arrhythmicity on meds suggests that both dopaminergic and non-dopaminergic networks contribute to FOG. The correlations between postural instability and FOG severity and SIP asymmetry on meds, suggest that as the disease progresses, postural instability interferes with gait symmetry and lead to on meds FOG and falls.
authors: School of Human Kinetics, Faculty of Health Sciences, Ottawa University, Canada.
authors: Julie
authors: J
authors: Nantel
authors: Department of Neurology and Neurological Sciences, Stanford University, CA, USA; Department Neurosurgery, Stanford University, CA, USA. Electronic address: hbs@stanford.edu.
authors: Helen
authors: H
authors: Bronte-Stewart
mesh_terms: D000978:Antiparkinson Agents / Q000627:therapeutic use*; D005260:Female; D005684:Gait / Q000187:drug effects*; D020233:Gait Disorders, Neurologic / Q000209:etiology*; D006801:Humans; D008297:Male; D010300:Parkinson Disease / Q000150:complications* / Q000188:drug therapy*; D004856:Postural Balance / Q000187:drug effects
chemical_list: D000978:Antiparkinson Agents
keywords: Dopaminergic networks; Freezing of gait; Medication; Parkinson's disease; Postural instability