Effect of subthalamic nucleus stimulation patterns on motor performance in Parkinson's disease.

We studied different patterns of deep brain stimulation (DBS), but same average rate, in seven Parkinson disease patients performing a wrist flexion/extension task. Movement times were shorter with regular (continuous) stimulation than cycled 'on' and 'off' for 0.1s (mean difference 0.129 s; 95% confidence interval [CI], 0.228-0.029 s; P < 0.007) and tended to be shorter than cycling at 0.5s (mean difference 0.076 s, 95% CI, 0.171 to -0.020 s; P < 0.6). Movement times under stimulation cycling at 0.5 s tended to be shorter than cycling at 0.1 s (mean difference, 0.083 s, 95% CI, 0.188 to -0.022 s, P < 0.12). Any therapeutic mechanisms of action of DBS must account for patterns of stimulation.