The Effect of Dual Tasking and Deep Brain Stimulation Frequency Parameters on Gait in Advanced Parkinson's Disease

OBJECTIVE: To study the effect of dual tasking and deep brain stimulation frequency parameters on gait in advanced Parkinson's disease MATERIALS AND METHODS: This is an open label interventional study evaluating 40 post STN-DBS patients with gait disturbances. All patients were diagnosed as PD by a movement disorder specialist using the United Kingdom Parkinson's Disease Society Brain Bank (UKPDSBB) criteria. Patients underwent bilateral subthalamic deep brain stimulation by a qualified neurosurgeon. Patients were managed on a combination of dopamine replacement therapy as well as deep brain stimulation. Patients were assessed by stand walk sit (SWS) test for a 5 meter distance and FOG scoring during medication 'ON' state and device “ON” state, at four frequencies 180, 130, 90, 60 HZ and device “OFF” state. RESULTS: Out of 40 patients, 38 patients showed a significant improvement in gait at a single frequency (best response frequency) which is different for each patient. The mean FOG score showed significant improvement at all stimulation frequencies when compared to OFF stimulation (P < 0.05). The mean number of steps was 18.9 at best response frequency and 21.48 at 130 Hz (P < 0.0001). Number of freezing episodes also were significantly less with best frequency when compared to 130 Hz stimulation (0.28 and 0.65 respectively, (P < 0.0001). The mean FOG score was 6.45 at best frequency and 9.48 at 130 Hz (P < 0.0001). Mean Dual tasking score was 3.53 at best frequency and 5.15 at 130 Hz (P < 0.0002). CONCLUSION: Optimization of frequency setting for each patient can improve gait and that each patient may have a different optimal frequency.