Clinical outcome of deep brain stimulation for Parkinson's disease

Deep brain stimulation is one of the most effective treatments of Parkinson's disease (PD). This report summarizes the state of the art as at January 2013. Stimulation of the subthalamic nucleus is the most commonly used approach. It improves the core motor symptoms better than medication in patients with advanced disease. It also improves the majority of nonmotor symptoms, such as mood, impulse control disorders, sleep, and some autonomic dysfunctions. Quality of life (QoL) is improved significantly more than with medication. Long-term data show that the treatment is effective for up to 10 years, but the late appearance of l-dopa-resistant symptoms is seemingly not influenced. Internal globus pallidus (GPi) stimulation is less well studied but seems to have similar short-term efficacy. Importantly l-dopa use cannot be reduced with GPi DBS, which is a major disadvantage for patients suffering from medication side-effects, although gait may be influenced more positively. Although short-term QoL improvement seems to be similar to that for subthalamic nucleus (STN) DBS - gait and speech may be better improved - long-term data are rare for GPi DBS. Thalamic stimulation in the ventral intermediate nucleus (VIM) is applied only in tremor-dominant elderly patients. The treatment improves the dopa-sensitive symptoms and effectively reduces fluctuations leading to an overall QoL improvement. Although most of the controlled studies have been on advanced PD, the recently published EARLYSTIM study suggests that even patients with a very short duration of their fluctuations and dyskinesia are doing significantly better with neurostimulation in terms of QoL and all major motor outcome parameters.