Deep brain stimulation in the treatment of secondary dystonia

Dystonia is one of the most challenging movement disorders to treat. Medications and surgeries are the two methods to control dystonic symptoms. For patients with dystonia in whom symptoms are inadequately controlled with pharmacologic measures, the use of deep brain stimulation (DBS) can improve symptoms and enhance functional capacity. The best candidate for DBS is believed to be primary generalized dystonia, especially the DYT-1 type. Here, we report 9 cases of secondary dystonia to explore the feasibility, indications and complications of DBS in the treatment of secondary dystonia.From July 2003 to June 2006, nine patients with secondary dystonia underwent surgery at Beijing Tiantan Hospital. Among them, 2 were diagnosed as having tardive dystonia, 1 had posttraumatic dystonia, 3 had a history of perinatal anoxia, 1 had neonatal pathologic jaundice, and 2 had no exact contributory history; MRI showed bilateral lentiform nuclei degeneration in one patient. Six patients underwent bilateral subthalamic nucleus (STN)-DBS, two underwent unilateral STN-DBS, the other underwent left STN and right globus pallidus internus (GPi)-DBS.With intraoperative microelectrode recording, the targeted nucleus was accurately localized. Tentative stimulation could decrease muscle tension to the same extent, but twisting was not obviously improved. Follow-up for 3 months to 3 years showed satisfactory results in 3 patients with tardive dystonia and posttraumatic dystonia and that Burke-Fahn-Marsden Dystonia Scale (BFMS) decreased by more than 90%. The improvement of symptoms was progressive along with time. The other 6 patients had slight to moderate improvement. None of them had severe surgery-related complications. One had lead fracture 16 months after surgery and the lead was then evacuated.DBS could be an ideal treatment for patients with tardive and posttraumatic dystonia. For patients with perinatal anoxia and diffuse impairment in the basal ganglia, DBS seemed not to be a good choice. STN could be an ideal target. Intraoperative microelectrode recording and mild amelioration of muscle tension are indicators of correct target location. No severe complications occurred.