Subthalamic nucleus stimulation in Parkinson's disease patients intolerant to levodopa.

Levodopa responsiveness has been shown to be the best predictor of improvement after subthalamic nucleus (STN) deep brain stimulation (DBS) for Parkinson's disease (PD). The objective of this study was to assess the effect of STN DBS on PD patients intolerant to levodopa due to severe acute side effects such as intolerable nausea. There were 10 patients in the study who received STN DBS for PD. Five patients who were intolerant to levodopa were matched based on age, disease duration, sex and presurgical disease severity to 5 patients taking levodopa and demonstrating a good levodopa response. Both groups had a significant improvement in Unified Parkinson's Disease Rating Scale activities of daily living and motor subscales as well as tremor, rigidity and bradykinesia scores at 3, 6 and 12 months after surgery compared to baseline, and these improvements were equivalent between the two groups. Patient global ratings also indicated significant improvements at all follow-up visits. There were no differences in stimulator settings between the two groups at the 3-, 6- or 12-month follow-up visits. In conclusion, although levodopa responsiveness is the best predictor for outcome after STN DBS, carefully selected PD patients intolerant to levodopa can have significant improvement.