Long-term outcomes of pallidal deep brain stimulation in X-linked dystonia parkinsonism (XDP): Up to 84 months follow-up and review of literature

Introduction: X-linked dystonia-parkinsonism (XDP/DYT3/Lubag) patients had improved dystonia and parkinsonism with bilateral pallidal deep brain stimulation (DBS) in the literature. Method: We reviewed eleven XDP patients who underwent bilateral pallidal DBS from October 2009 to September 2018. The Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) and Unified Parkinson's Disease Rating Scale (UPDRS)-III scores were reviewed from baseline up to the longest follow-up together with the demographic and clinical data. The published case reports on DBS in XDP were also reviewed. Results: The mean age was 39 +/- 9.2 years with a mean disease duration of 3 years (range 1-9 years). An immediate response for dystonia post-DBS (1 month) was seen in all cases, with a mean BFMDRS score of 23.3 +/- 12.12 [from a mean baseline of 36.3 +/- 12.1] and a small change in the mean UPDRS-III score of 20 +/- 10.39 [from a mean baseline of 24.04 +/- 8.74]. At 12 months (n = 10), the mean BFMDRS score was 13.7 +/- 10.63 and the mean UPDRS-III score was 19 +/- 13.19. There was improvement in the clinical and functional stage of the patients, with majority in Stage 1 (n = 3) and Stage 2 (n = 5) at their last follow-up. Conclusion: Bilateral pallidal DBS should be considered as a treatment option for XDP. It is effective in the first 12 months in controlling dystonia with variable response in controlling parkinsonism. It may be effective in up to 72-84 months, as seen in three patients.