Unilateral Extradural Motor Cortex Stimulation Is Safe and Improves Parkinson Disease at 1 Year

BACKGROUND: The primary motor cortex, which is part of the corticobasal ganglia loops, may be an alternative option for the surgical treatment of Parkinson disease. OBJECTIVE: To report on the 1-year safety and efficacy of unilateral extradural motor cortex stimulation in Parkinson disease. METHODS: A quadripolar electrode strip was extradurally implanted over the motor cortex. Stimulation was continuously delivered through the electrode paddle contralateral to the most affected clinical side. Subjects were prospectively evaluated by the Unified Parkinson's Disease Rating Scale (UPDRS) and the Parkinson's Disease Quality of Life Questionnaire. In addition, an extensive cognitive and behavioral assessment and electroencephalogram recording were performed. RESULTS: Nine patients were included in this study. No surgical complications or adverse events occurred. Moreover, no cognitive or behavioral changes were observed. Under the off-medication condition, the UPDRS III at baseline was decreased by 14.1%, 23.3%, 19.9%, and 13.2%, at 1, 3, 6, and 12 months, respectively. The motor effects were bilateral, appeared after 3 to 4 weeks of stimulation, and outlasted the stimulation itself for 3 to 4 weeks in 1 case of stimulator accidental switching off. The UPDRS IV was decreased by 40.8%, 42.1%, and 35.5% at 1, 3, and 12 months, respectively. The scores on the Parkinson's Disease Quality of Life Questionnaire were increased at months 3, 6, and 12. CONCLUSION: Extradural motor cortex stimulation is a safe procedure. After 12 months, the patients demonstrated a moderate improvement of motor symptoms (particularly axial symptoms) and quality of life.