OBJECTIVE: For dystonic patients who have failed medical therapy, stereotactic deep brain stimulation (DBS) of the globus pallidus interna (Gpi) or subthalamic nucleus (STN) can provide significant symptom improvement, but it is not known which site provides maximum benefit or the physiologic mechanisms by which these improvements may occur. The study goals are to determine if DBS of Gpi or STN provides significant clinical improvement in patients with primary generalized dystonia, whether the anatomic DBS site (if either) provides optimal improvement, and to gain deeper insight into the underlying pathophysiology of this disorder. STUDY POPULATION: Adult and pediatric patients with medically refractory primary generalized dystonia will make-up the study population. Patients with primary generalized dystonia suffer a wide range of symptoms including physical deformity, speech difficulties, swallowing dysfunction, visual problems, and intractable pain, which can result in an inability to care for themselves. Moreover, pediatric primary generalized dystonia patients will often have abnormal skeletal development (scoliosis) resulting from the abnormal forces placed on the skeleton by dystonic muscle contractions. DESIGN: We propose placing DBS electrodes (using microelectrode guidance) bilaterally into either the Gpi or STN of medically refractory dystonia patients. Physiological studies will be performed and compared with clinical changes to understand the mechanism of action of DBS and underlying pathophysiology of dystonia. OUTCOME MEASURES: Clinical effectiveness of DBS of the Gpi or STN will be measured by the Burke-Fahn-Marsden Scale (BFM) and monitored over time to determine the effectiveness of DBS and if there is an ideal anatomic stimulation site. Electrophysiologic outcome measures will be obtained to determine the underlying pathophysiology of dystonia, and the mechanism of action of DBS.
- INCLUSION CRITERIA: To be eligible for entry into the study, candidates must meet all the following criteria: 1. Patients greater than 7 years of age with generalized primary dystonia. 2. Patients who are refractory to medical treatment (including levodopa, anticholinergics, benzodiazepines, Baclofen) who are considered surgical candidates. Patients will be determined to have medical refractory dystonia after having been treated by at least two medications of two different groups at the maximum recommended dose for a duration of at least two months. 3. In case of treatment by intrathecal Baclofen delivered by a pump, a change to oral Baclofen must be performed, so that the pump can be taken out. 4. Patients must have a minimum BFM score of 20 on optimal medical therapy. 5. Adults must be mentally competent to consent for entrance into the protocol at the time of admission. 6. Patients must have a signed DPA for research purposes. EXCLUSION CRITERIA: Candidates will be excluded if: 1. The patient has had previous lesioning surgery including radiofrequency lesioning of deep nuclei (thalamus, pallidum, STN). 2. The patient currently has a functioning and effective stimulator in deep brain nuclei (thalamus, pallidum, STN). 3. The patient is not able to tolerate surgery, as determined by the preoperative evaluation. 4. The patient has a coagulopathy demonstrated by an abnormal prothrombin time, activated partial thromboplastin time, or thrombocytopenia (platelet count less than 150,000 platelets/mm(3)). 5. The patient has an acute or untreated infection (viral, bacterial or fungal). 6. The patient has a contraindication to MR-imaging such as previous surgery that involved placement of metal objects that could cause tissue damage or produce image artifacts. 7. The patient has another chronic neurologic disorder. 8. The patient is pregnant at the time of surgery. 9. The patient has epilepsy. 10. The patient does not have access to proper follow-up care at home and may not be eligible for the study.