Subthalamic DBS-induced diphasic dyskinesias: An overlooked complication?

Deep brain stimulation (DBS) has become the standard of care in patients with Parkinson's Disease (PD) experiencing motor fluctuations. The existing literature suggests that deep-brain stimulation (DBS) of the subthalamic nucleus (STN) alleviates levodopa-induced dyskinesias (LID), particularly those associated with high plasma levels of levodopa (peak dose), through medication reduction.

We report a case of early-onset PD with motor fluctuations and levodopa-induced peak-dose dyskinesias, who developed an interesting phenomenon of diphasic dyskinesias during the monopolar review of DBS. These dyskinesias resolved when the stimulation amplitude was increased to achieve a more stable 'ON' phase.

This rare phenomenon suggests that when predominantly lower-limb dyskinesias occur at low current stimulation, increasing stimulation amplitude might improve the excessive movements. Diphasic dyskinesias are often misdiagnosed and under-reported. Future studies should clarify the frequency.