The long-term efficacy of deep brain stimulation for medically refractory primary generalized dystonia

Abstract

Objective To evaluate the long-term efficacy of deep brain stimulation (DBS) in treatment of medically refractory primary generalized dystonia (PGD) and to compare the effect of stimulation of subthalamic nucleus (STN) with that of globus pallidus internus (GPi) in the treatment of dystonia. Methods Twenty-one cases of PGD underwent STN-DBS or GPi-DBS at Department of Neurosurgery, Tangdu Hospital, the Fourth Military Medical University from December 2004 to April 2013 and were enrolled into this study. Among them, 11 patients underwent STN stimulation (STN-DBS group) and the other 10 cases received GPi stimulation (GPi-DBS group). Pre- and postoperative severity of dystonia were assessed by using the Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS). Results The average improvement rates of BFMDRS movement subscale in the 21 cases of PGD were 63.7±14.2 % and 66.5±13.7 % at 1 and 3 years post operation, respectively. Meanwhile, the disability scores were reduced by 43.7±13.8 % and 49.1±12.4 %, respectively. The movement scores in STN-DBS group were 56.9±20.9 prior to surgery and 18.3±6.8 at 3 years post operation, and the average improvement rate was 64.6±15.2 %. Their disability scores were 20.0(11.0) prior to surgery and 8.0(4.0) points at 3 years post operation, and the average improvement rate was 54.5 %(15.0 %). In the GPi-DBS group, the movement scores were 60.8±19.3 before surgery and 18.3±7.9 at 3 years post surgery, and the average improvement rate was 68.6±12.5 %. Their disability scores were 17.5±5.4 before surgery and 8.9±2.5 post surgery, and the average improvement rate was 47.2±12.8 %. There was no statistically significant difference in the improvement rates of BFMDRS movement and disability scores between 2 targets at 1 year and 3 years after surgery (both P>0.05). Conclusions The effect of DBS in the treatment of medically refractory seems to be significant and sustained. Our preliminary results suggest that there is no significant difference in the long-term efficacy between stimulation of STN and stimulation of GPi for dystonia. Key words: Deep brain stimulation; Subthalamic nucleus; Globus pallidus; Primary dystonia; Treatment outcome