Eight‐year follow‐up outcome of subthalamic deep brain stimulation for Parkinson’s disease: Maintenance of therapeutic efficacy with a relatively low levodopa dosage and stimulation intensity

AIMS: This follow‐up study aimed to examine the 8‐year efficacy and safety of subthalamic nucleus (STN) deep brain stimulation (DBS) for patients with Parkinson's disease (PD) in southern China. METHODS: The follow‐up data of 10 patients with PD undergoing STN‐DBS were analyzed. Motor symptoms were assessed before and 1, 3, 5, and 8 years after the surgery with stimulation‐on in both off‐medication (off‐med) and on‐medication (on‐med) status using the Unified Parkinson's disease Rating Scale Part III. The quality of life was assessed using the 39‐item Parkinson's Disease Questionnaire. The sleep, cognition, and emotion were evaluated using a series of nonmotor scales. Levodopa equivalent daily dose (LEDD) and stimulation parameters were recorded at each follow‐up. RESULTS: The motor symptoms were improved by 50.9%, 37.7%, 36.7%, and 37.3% in 1, 3, 5, and 8 years, respectively, in the off‐med / stimulation‐on status compared with the baseline. The quality of life improved by 39.7% and 56.1% in 1 and 3 years, respectively, but declined to the preoperative level thereafter. The sleep, cognition, and emotion were mostly unchanged. LEDD reduced from 708.1 ± 172.5 mg to 330 ± 207.8 mg in 8 years. The stimulation parameters, including amplitude, pulse width, and frequency, were 2.77 ± 0.49 V, 71.3 ± 12.8 μs, and 121.5 ± 21 Hz, respectively, in 8 years. CONCLUSION: Long‐term therapeutic efficacy of STN‐DBS could be achieved even with relatively low stimulation intensity and medication dosage for PD patients in southern China. Motor improvement and medication reduction were maintained through the 8‐year follow‐up, but improvement in quality of life lasted for only 3 years. No definite changes was found in nonmotor symptoms after STN‐DBS.