title: Off-period dystonia in Parkinson's disease but not generalized dystonia is improved by high-frequency stimulation of the subthalamic nucleus.
abstract: STN-HFS is well known to improve patients with IPD. Because off-period dystonia mimics focal or generalized dystonia of other causes, we proposed bilateral STN-HFS to some patients with generalized dystonia. The aim of this study was to compare the efficacy of STN stimulation on off-period dystonia and generalized dystonia. From a larger series of patients with IPD, we selected 22 patients based on the presence of severe preoperative off-period dystonia rated > or = 3 in least one limb on a severity score ranging from 0 to 4. Four patients with generalized dystonia (Hallervorden-Spatz disease, n = 3; primary, n = 1) underwent bilateral STN-HFS. Dystonia of the four limbs was rated on video recordings in all patients before surgery and 3 months after surgery. In IPD, bilateral STN stimulation reduced the severity of off-period dystonia by 70% on the four limbs (preoperative mean severity score = 2.03 +/- 1.49; postoperative mean severity score = 0.60 +/- 0.78). In contrast, bilateral STN-HFS had no effect on generalized dystonia (preoperative mean severity score = 3.25 +/- 0.77; postoperative mean severity score = 3.12 +/- 0.62). Despite clinical similarities between off-period dystonia in Parkinson's disease and generalized dystonia in certain cases, the effect of chronic bilateral STN-HFS differs. STN stimulation is highly effective in off-period dystonia of IPD, whereas it does not improve generalized dystonia. The pathophysiologic mechanisms underlying dystonia in these two disorders are still unknown. Assuming that the mechanism of action of STN-HFS is similar regardless of the cause of dystonia, our findings suggest that the STN is not similarly involved in off-period dystonia of IPD and others dystonias.
mesh_terms: D000328:Adult; D017668:Age of Onset; D002648:Child; D004421:Dystonia / Q000145:classification / Q000150:complications / Q000628:therapy*; D004558:Electric Stimulation; D004599:Electric Stimulation Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D006211:Pantothenate Kinase-Associated Neurodegeneration / Q000628:therapy; D010300:Parkinson Disease / Q000150:complications / Q000628:therapy*; D012720:Severity of Illness Index; D013238:Stereotaxic Techniques; D020531:Subthalamic Nucleus; D013514:Surgical Procedures, Operative