Bilateral deep brain stimulation of subthalamic nucleus in patients with Parkinson’s disease

Abstract

Ninetyfour patients with advanced Parkinson’s disease were assessed retrospectively one, two, three and four years after bilateral surgery for Deep Brain Stimulation of the subthalamic nucleus. The patients were treated with bilateral subthalamic nucleus stimulation and assessed under different conditions with levodopa (“medication on”) and without levodopa (“medication off”) with use of the Unified Parkinson’s Disease Rating Scale and were compared with the preoperative “medication off” condition. In addition, the symptoms depression, cognition, dysphagia and dysarthria were monitored during the follow-up period. One year after surgery, the motor disability scores showed a neurostimulation induced improvement of 56% and 41% in the “medication on” and “medication off” conditions respectively. Four years after surgery, accompanied with the progression of Parkinson’s disease, the improvement was at 45% and 25% in the “medication on” and “medication off” conditions respectively. The neurostimulation induced improvement was 57% and 45% over baseline at one year after surgery on the body side dominantly affected by Parkinson’s disease in the “medication on” and “medication off” conditions respectively. At four years, the improvement was sustained at 56% in “medication on” and slightly reduced to 35% in “medication off”. Symptoms tremor, akinesia and rigidity showed a markedly sustained improvement in “medication on” condition, with the improvement at four year being 57%, 40% and 50% respectively. The improvement was at 43%, 20% and 34% in “medication off” condition. Gait showed a sustained improvement only up to three years (43% at year 3) in “medication on” condition, with the improvement in “medication off” being 28% at three years. The medication related complications were markedly improved, with the improvement at one year being 39% and at four years being 34%. The motor activities of daily life showed a significant improvement of 39% and 14% in “medication on” and “medication off” conditions respectively up to three years after surgery. Levodopa dosage was drastically decreased by 33% at four years. Depression scores did not worsen during the follow-up period. Cognitive performance showed slight but significant decline in the fourth year. Mean scores for dysphagia and dysarthria increased at four years after surgery. Persistent adverse events related to the brain surgery were observed in 3% of the patients. A few patients experienced eyelid-opening apraxia. In conclusion, this study demonstrates the efficacy of bilateral stimulation of the subthalamic nucleus in patients with advanced Parkinson’s disease. The results are aligned with previous studies. Moreover, the safety of the treatment, which was assessed by carefully monitoring the adverse events, was in the acceptable range, similar to results from other studies.