Short pulse width widens the therapeutic window of subthalamic neurostimulation.

We explored the impact of pulse durations <60 µsec on the therapeutic window of subthalamic neurostimulation in Parkinson's disease. Current thresholds for full rigidity control and first muscle contractions were evaluated at pulse durations between 20 and 120 µsec during a monopolar review session in four patients. The average therapeutic window was 2.16 mA at 60 µsec, which proportionally increased by 182% at 30 µsec, while decreasing by 46% at 120 µsec. Measured chronaxies and model data suggest, that pulse durations <60 µsec lead to a focusing of the neurostimulation effect on smaller diameter axons close to the electrode while avoiding stimulation of distant pyramidal tract fibers.