Dysfunctional turning in Parkinson's disease

Purpose. People with Parkinson's disease (PD) frequently freeze or fall turning: They turn slowly taking numerous steps. We aimed to describe more fully the differences observed on turning between people with and without PD, in particular the extent of left-right asymmetry and the correlations between turning and age, balance and PD severity, using a simple clinical test. Method. Twenty-eight people with PD (median age 71; median years since diagnosis eight) and 12 controls (median age 70) performed the video-based Standing Start 180 Turn Test. We counted turning steps (n), evaluated turn time (sec), type and quality (0-5, based on independence, ground clearance, stability, continuity and posture) and calculated the 95% limits of left-right agreement. Results. The groups differed (p<0.004) on step count (medians 4.5 vs. 3), time (2.3 sec vs. 1.7 sec) and quality (4 vs. 5). In the PD group, 75% turned 'on-the-spot' and differences turning left and right were marked (e.g., 95% upper limit for step count 6.6). Among controls, 42% turned 'on-the-spot' and turning was symmetrical (e.g., 95% upper limit for step count 1.7). Step count was most closely correlated with self-assessed disability in PD (r=0.67; p=0.001) and with age among controls (r=0.87; p=0.001). Conclusions. People having difficulty turning are likely to have trouble with many everyday activities and thus may benefit from rehabilitation. Directional asymmetry in turning is easily identifiable and future studies should explore its diagnostic value.