Long-Term Efficacy of Globus pallidus Stimulation for the Treatment of Parkinson’s Disease

Abstract

Objective: To determine the long-term efficacy and safety of globus pallidus internus (GPi) stimulation for Parkinson’s disease (PD). Background: We previously reported 3-month data for 5 patients who underwent GPi stimulation for PD. We now report long-term data on these 5 patients and 4 additional patients. Methods: Nine PD patients, 5 men and 4 women, with an average age of 49 years and disease duration of 10 years, underwent GPi stimulation. Six patients had staged bilateral implants and 3 patients had unilateral implants. The mean follow-up was 48.5 months. All patients were evaluated with the Unified Parkinson’s Disease Rating Scale (UPDRS) and completed 2-day diaries before and after surgery. Results: There was a 21% improvement in UPDRS Part II (activities of daily living; ADL) scores and a 37% improvement in UPDRS Part III (motor) scores when the longest follow-up in the ‘stimulation-on/medication-off’ state was compared to the ‘medication-off’ state at baseline. The UPDRS Part II (ADL) scores improved by 30% and the UPDRS Part III (motor) scores improved by 39% when the longest follow-up in the ‘stimulation-on/mediation-on’ state was compared to the ‘medication-on’ state at baseline. As measured by patient diaries, ‘on’ time increased from 25 to 59% and ‘on with dyskinesia’ decreased from 42 to 15%. Surgical- and device-related complications included transient hemiparesis in the operating room, postoperative seizures, and implantable pulse generator and lead problems. There were seven device-related events requiring additional surgical procedures. Conclusions: GPi stimulation continues to be effective for the long-term treatment of the disabling symptoms of PD; however, the physician and patient should be aware that device-related problems are not uncommon and additional surgery may be necessary.