VARIABILITY IN SPATIOTEMPORAL GAIT CHARACTERISTICS OVER THE COURSE OFTHE L-DOPA CYCLE IN PEOPLE WITH ADVANCED PARKINSON-DISEASE

Background and Purpose. Understanding the nature and extent of fluctua tions in spatial and temporal variables of gait (eg, speed, stride len gth [SL], stride time [ST])over the course of the levodopa (L-dopa) cy cle of individuals with advanced Parkinson disease (PD) is important i n order to assess patients and examine the effectiveness of interventi ons. The purpose of this study was to determine whether gait variables are sufficiently stable to be used as outcome measures in a clinical trial involving patients with advanced PD. Subjects. Five volunteers ( 3 male, 2 female; mean age=67.8 years; Hoehn and Yahr stages 3-4) with idiopathic PD of a mean duration of 15.0 years participated. Methods. Gait speed, Si,, and ST were measured as the subjects walked 7.2 m at self-selected speeds. To evaluate the full ''on-off'' sequence of the L-dopa response, this analysis was repeated 11 times, at intervals of 10% of the L-dopa cycle. Each subject was analyzed on 3 separate days , with approximately 1 month between tests. Two-way repeated-measures analyses of covariance, with 2 within-subject factors (percentage of L -dopa cycle and day) and 1 covariate (height), were applied, and coeff icients of variation were calculated to determine the extent of change in speed, Si,, and ST over the L-dopa cycle and over the 3 days. Resu lts. The subjects' overall mean gait speed was 70.39 cm/s, representin g 55.4% of the age-related normative values. There were no effects of percentage of the L-dopa cycle or day or of the interaction of percent age of the L-dopa cycle and day on speed, Si,, and ST. The coefficient s of variation for speed and SL were consistently higher than the norm ative values, ranging from 13.5% to 23.8% and from 13.9% to 23.3% at 2 0% of the L-dopa cycle, respectively. Conclusion and Discussion. When interpreting spatiotemporal measurements of gait of patients with adva nced PD, fluctuations can be extensive and may not follow a predictabl e pattern.