title: Gait dynamics in Parkinson's disease: relationship to Parkinsonian features, falls and response to levodopa.
abstract: OBJECTIVE
  Patients with Parkinson's disease (PD) have an increased risk of falling that has yet to be fully explained. To better understand the gait disturbance in PD and the factors that contribute to falls, we quantitatively evaluated: (1) the relationship between gait variability (a marker of fall risk in other populations), fall history, and other parkinsonian features, and (2) the effects of levodopa on these relationships.
  
  
  METHODS
  The average stride time and stride-to-stride variability were measured using force-sensitive insoles during comfortable walking. Fall frequency, motor control, function, and mental health were measured using the Unified Parkinson's Disease Rating Scale (UPDRS), the Mini-Mental State Exam (MMSE), and the timed motor tests of the Core Assessment Program for Intracerebral Transplantations (CAPIT) in 32 subjects with idiopathic PD, in an "off" (unmedicated) state and again in an "on" (medicated) state.
  
  
  RESULTS
  Average stride time was not associated with any UPDRS or CAPIT measure and was similar in fallers and non-fallers in "off" and "on" states (p>0.27). Stride time variability was significantly associated with fall frequency as well as with total scores on the CAPIT and the UPDRS, ADL abilities, and motor function. Stride time variability and falls were not related to tremor, rigidity or bradykinesia in the "off" state. 41% of subjects reported one or more falls. Stride time variability was 8.8+/-7.9% in fallers and 4.2+/-1.3% in non-fallers (p<0.009). Stride time variability significantly improved in response to levodopa, both in fallers and non-fallers, but remained increased in fallers (vs. non-fallers).
  
  
  CONCLUSIONS
  The patho-physiology responsible for impaired stride-to-stride regulation of gait timing is apparently independent of other cardinal features of PD, i.e., tremor, rigidity, or bradykinesia, but is responsive to levodopa. Stride-to-stride variability is especially impaired among PD subjects with a history of falls, suggesting, for the first time, the possibility of exaggerated impairment of internal clock function in PD fallers.
authors.affiliation: Movement Disorders Unit, Department of Neurology, Tel Aviv Sourasky Medical Center, and Sackler School of Medicine, Tel Aviv University, 6 Weizmann Street, Tel Aviv 64239, Israel.
authors.forename: Joanna D
authors.initials: JD
authors.lastname: Schaafsma
authors.forename: Nir
authors.initials: N
authors.lastname: Giladi
authors.forename: Yacov
authors.initials: Y
authors.lastname: Balash
authors.forename: Anna L
authors.initials: AL
authors.lastname: Bartels
authors.forename: Tanya
authors.initials: T
authors.lastname: Gurevich
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Hausdorff
mesh_terms: D000203:Activities of Daily Living; D000368:Aged; D000369:Aged, 80 and over; D000978:Antiparkinson Agents / Q000627:therapeutic use*; D005260:Female; D005684:Gait / Q000502:physiology*; D020233:Gait Disorders, Neurologic / Q000188:drug therapy / Q000503:physiopathology; D006801:Humans; D007980:Levodopa / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009460:Neurologic Examination; D010300:Parkinson Disease / Q000188:drug therapy* / Q000503:physiopathology*; D011569:Psychiatric Status Rating Scales; D012016:Reference Values; D012307:Risk Factors; D013997:Time Factors
chemical_list: D000978:Antiparkinson Agents; D007980:Levodopa