Spin turns in advanced Parkinson's disease: A new clinical gait sign?

Two strategies are known for turning while walking: step turns (the direction change is performed with 3 steps or more) and spin turns (turning on one/both feet simultaneously). It is unknown which strategy patients with Parkinson's disease (PD) choose and if l-dopa and STN-DBS are influencing this strategy.

Video-recordings of 171 PD patients that completed 180° turns were analyzed by two blinded raters before surgery, both off and on l-dopa, and one year after STN-DBS-implantation. The strategies were classified: 1) spin 2) step and 3) mixed (spin plus step) strategy. The characteristics of the patients with different strategies were compared.

Interrater reliability for classification of turning strategy showed high agreement (κ = 0.894). The distribution of the preferred strategy differed significantly between treatment conditions (untreated, treated with l-dopa, l-dopa plus stimulation; X²(4) = 67.2, p < 0.0001). The spin turn was found in 10.5% of patients OFF-drug, 23.5% ON-drug and in 38.8% ON-drug/ON-stim condition. In the three treatment conditions patients with spin turns had significantly lower UPDRS III scores compared to people with step turns (p = 0.017, p = 0.001, p = 0.006, respectively); step turn patients had poorer postural instability and gait disorders (PIGD) scores (p = 0.04, p = 0.002, p = 0.04, respectively).

The turn strategy can be reliably identified in clinical settings and is a simple motor sign. The spin turn is associated with better motor performance. Since improvements in motor score in patients with fluctuations are also related to behavioral changes, we cannot exclude that the turn strategy also represents a feature of psycho-motor interaction.