Effect of frequency on subthalamic nucleus deep brain stimulation in primary dystonia

Background: Subthalamic nucleus deep brain stimulation (DBS) is an alternative target choice for treating primary dystonia, but little is known about the most effective programming parameters. Objective: Here we prospectively evaluate the effect of low versus high frequency subthalamic nucleus DBS in patients with predominantly cervical or upper extremity primary dystonia. Methods: Seven patients were stimulated at low frequency stimulation (60 Hz) for the first three months and then switched to high frequency stimulation (130 Hz) until month six. Severity of dystonia was determined by a blinded rater (unaware of the patient’s pre or post-operative status) who scored the Burke Fahn Marsden dystonia rating scale movement score (BFMDRS-M) and the Toronto Western Spasmodic Torticollis Rating Scale severity score (TWSTRS-S) preoperatively, three, six, and twelve months post-surgery. Results: Patients had a lower mean improvement of 16.6% in BFMDRS-M and 9.5% in TWSTRS-S at three months using low frequency stimulation compared to a 52.3% (p ¼ 0.018) and 45.2% (p ¼ 0.028), respectively, noted at six months using high frequency stimulation. At 12 months (using 130 Hz), the BFMDRS-M and TWSTRS-S improved by 51.8% (p ¼ 0.022) and 56% (p ¼ 0.034). Patients developed transient dyskinesia (during low and high frequency stimulation) which improved with programming adjustments. Conclusion: This study offers further support of the effectiveness of subthalamic nucleus DBS in the treatment of primary dystonia and finds that high frequency stimulation was more effective than low frequency stimulation. Published by Elsevier Ltd.