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

To study the effect of dual tasking and deep brain stimulation frequency parameters on gait in advanced Parkinson's disease.

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.

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).

Optimization of frequency setting for each patient can improve gait and that each patient may have a different optimal frequency.