Ambulatory measurement of gait parameters in Parkinson's disease: Effects of subthalamic stimulation

Introduction: In this study the effect of subthalamic nucleus neep brain Stimulation (STN-DBS) on the gait parameters of patients with Parkinson's disease (PD) was examined using an ambulatory gait analysis system based on miniature gyroscopes. The aim was twofold: to characterize gait with and without stimulation (ON and OFF states) and to understand how STN-DBS improves motor performance in PD patients.Methods: Ten PD patients, 20±3 months after implantation of bilateral STN-DBS were asked to walk 20m. Patients did the test twice: once STN-DBS was ON and once 180 minutes after turning it OFF. Six miniature gyroscopes were attached on each wrist, thigh and shank respectively. A light data-logger (Physilog®) carried by the patients recorded angular velocities measured by gyroscopes, during each walking trial. Spatio-temporal gait parameters were estimated using a method described earlier [1]. In addition, the range of the movements of lower limbs in the sagittal plane and hands in 3D were estimated based on the integration of angular velocity during each gait cycle. Mean and stride-stride variability of all parameters were obtained for each patients. The same protocol was used to measure ten normal, age matched control subjects. Unified Parkinson's Disease Score (UPDRS III) was obtained for each patient in the ON and OFF states.Results: Compared to controls, PD patients (OFF state) had significantly shorter normalized stride length and velocity (SL=0.40 vs. 0.79, p