Unilateral battery depletion in Parkinson's disease patients treated with bilateral subthalamic nucleus deep brain stimulation may require urgent surgical replacement.

We describe 2 patients with advanced Parkinson's disease (PD) treated with bilateral deep brain stimulation of the subthalamic nucleus in whom unilateral stimulator battery depletion resulted in the rapid appearance of disabling PD symptoms (severe rigidity, bradykinesia and gait difficulty). Both patients did not respond to high doses of dopaminergic medications and were restored to their previous level of function only with battery replacement. One patient developed a deep vein thrombosis and pulmonary emboli as a result of prolonged immobility. Although extreme worsening of PD secondary to battery depletion may be rare, such patients should have their stimulators replaced promptly.