Effects of relative low-frequency bilateral globus pallidus internus stimulation for treatment of cervical dystonia

Objective: To assess the effect of relative lower amplitude and frequency for globus pallidus internus (GPi) deep brain stimulation (DBS) of cervical dystonia (CD). Materials and Methods: Between February 2005 and October 2008, 14 patients diagnosed with CD underwent bilateral GPi DBS and all the patients received low-frequency stimulation and were followed for more than 2 years. We activated the implantable pulse generator 3-4 days postoperatively and initial amplitude, pulse width, and frequency were set at 1.5 V, 120 μs, and 70 Hz. The Toronto Western Spasmodic Torticolis Rating Scale (TWSTRS) was applied preoperatively and at 1, 6, 12 and 24 months postoperatively. Results: The overall TWSTRS scores improved 71.2% 2 years postoperatively (p = 0.001). The mean improvement was 78.4% in severity subscores, 68.4% in disability, and 66.8% in pain scores for the 2-year follow-up period. The TWSTRS scores were significantly reduced (p < 0.05), suggesting that the most significant improvement of the TWSTRS scores occurred within 1 month. The final amplitude was 2.9/2.7 V with the pulse width of 147.9/147.9 μs and the frequency of 101.1/100 Hz. Conclusion: According to our results, the initial settings of low amplitude and especially relatively low frequency are safe and effective for treatment of CD.