Treatment of Dystonia Caused by Several Etiologies with DBS

Abstract

Introduction: This meta-analysis of reported cases of deep brain stimulation (DBS) for dystonia evaluates the effect using the globus pallidus internus (GPi) as target, and the factors that significantly have influenced the outcome related to the target. The Burke-Fahn-Marsden (BFM) movement scale, the most reported measure, was chosen as the primary outcome measure for this analysis. Material and Methods: MEDLINE searches on English literature identified 137 patients who underwent DBS for dystonia in 24 studies that had individual BFM scores. The study was done with statistical analysis by intention to treat. Statistical analysis was made with a significant p-value of 0.05. For the comparison of pre- and postoperative scores, a Wilcoxon signed-rank test was used. Results: The mean BFM percentage change (improvement in postoperative score from baseline) was 46.3% (range 34% to 100%). At last follow-up, disease severity and degree of disability and pain on the BFM were significantly improved by 70.4%, and 67.8%, respectively (p < 0.05, Wilcoxon signed-rank test). Significantly better outcomes were achieved with stimulation of the GPI than with stimulation of the posterior portion of the ventral lateral (VLp) nucleus of the thalamus (p < 0.05). The etiology of the dystonia also had a significant effect on outcomes. Statistically significant improvements in outcomes were seen for all etiologic categories, except encephalitis. Dystonia due to birth injury and encephalitis had significantly worse outcomes of patients who were DYT1, or had pantothenate-kinase-associated neurodegeneration (PKAN), tardive dyskinesia, and idiopathic and posttraumatic dystonias. Longer duration of dystonia symptoms correlated negatively with surgical outcome. Conclusion: Deep Brain Stimulation of the GPi provides improvement in BFM scores in a variety of dystonic conditions.