[Long-term efficacy of deep brain stimulation in patients with dystonia].

In patients with primary generalized or segmental dystonia controlled studies have shown that bilateral pallidal deep brain stimulation (DBS) can reduce disability scores by 40 to 60 %. Up to now, the data base on the therapeutic effects of DBS in selected patients with focal dystonia is less extensive. Long-term efficacy of DBS in dystonia has been demonstrated, but reports have focused mainly on patients with primary generalized dystonia so far, with a mean observation period of approximately 5 years. Predictors of a favourable long-term efficacy of DBS in primary generalized dystonia patients are young age at surgery, a shorter duration of the disease, a lower severity of disability, and a posteroventrolateral localization of the DBS electrode within the globus pallidus internus (GPi). Controlled studies are needed to identify also the factors determining the best long-term outcome of non-generalized dystonia patients treated with DBS.