Medication dose reductions after pallidal versus subthalamic stimulation in patients with Parkinson's disease

Objective- To compare the medication dose reduction between deep brain stimulation (DBS) of the globus pallidus interna (GPi) vs subthalamic nucleus (STN) in matched patients with Parkinson's disease (PD). Materials and methods- Records of 12 patients with PD who underwent GPi-DBS at our institution from 2002 to 2008 were matched by pre-operative PD medication doses and pre-operative motor Unified Parkinson's Disease Rating Scale (UPDRS) scores to 12 cases of STN-DBS. PD medication doses were converted to levodopa equivalent doses (LEDs). Results- GPi and STN groups had similar mean pre-operative LEDs and motor UPDRS scores. At 6months post-DBS, there was no significant difference in percent reduction in LEDs between the GPi (47.95%) and STN (37.47%) groups (P=0.52). The mean post-operative 'medication off/stimulation on' motor UPDRS scores did not differ significantly between GPi (15.33) and STN (16.25) groups (P=0.74). The mean percent reduction in motor UPDRS scores was also similar between GPi (58.44%) and STN (58.98%) patients (P=0.94). Conclusions- We conclude that in disease-matched patients with PD undergoing DBS, both GPi and STN may result in similar reduction in PD medication doses.