Deep brain stimulation for treatment of dystonia and tremor

Deep brain stimulation (DBS) is a safe and successful therapeutic option for patients with dystonia and tremor syndrome who do not respond sufficiently to conservative therapies. The most common target of DBS in patients with dystonia is the internal region of the globus pallidus (GPI). DBS of the GPI leads to long-lasting and remarkable improvement of dystonic movements in about 80% of patients. Recently it could be shown that not only patients with idiopathic dystonia but also patients with secondary dystonia can benefit from DBS although to a somewhat lesser extent. In patients with tremor syndromes, such as essential tremor, tremor-dominant Parkinson's disease or tremor in multiple sclerosis (MS) the intermediate ventral nucleus of the thalamus (VIM) as well as the subthalamic region proved to be promising targets for DBS electrodes. Especially in patients with essential tremor VIM-DBS leads to an often acute reduction of the tremor syndrome. In long-term observations, however, patients with essential tremor showed some tolerability to VIM-DBS leading to a slow increase of stimulation parameters to maintain a stable effect. VIM-DBS in patients with Parkinson's disease is rare and is reserved for elderly patients with pronounced tremor syndrome and little disease progression. Controlled studies and data on DBS in MS tremor are lacking and data are sparse and heterogeneous. Therefore, VIM-DBS in MS tremor patients has to be evaluated individually with caution. In summary patients with tremor syndromes as well as dystonia who cannot be adequately controlled with conservative therapy are good candidates for deep brain stimulation, a therapeutic option with moderate complications and risks and very good outcome for most patients.