Outcome of deep brain stimulation of the globus pallidus pars interna in genetic dystonia syndromes

Dystonia is a complex neurological movement disorder characterized by involuntary muscle contractions causing abnormal movements and posture. Deep Brain Stimulation (DBS) is an accepted treatment for drug-refractory dystonia. Despite the overall efficacy of DBS in dystonia, variability has been reported in its outcome [1]. Herein, we investigated pre-implant factors that could be predictive of DBS effect comprising genetic profiles, distribution of symptoms, age at onset, disease duration and severity.This study involved thirty-one dystonia patients who underwent DBS surgery in the globus pallidus pars interna (GPi), assessed by neurologists before and after surgery using the Burke–Fahn–Marsden (BFM) scale. Follow-ups were scheduled at 1, 3 and 5 years after surgery. The total BFM scales show an overall significant improvement in dystonia symptoms which remain stable over time (47.8%, p<1e-8). Changes in cranial scores (mean of normalized, 0.07) were substantially less than those in trunk (0.24), lower (0.20) and upper limbs (0.16). However, there was not a significant difference between lower limbs and cranial scores at baseline. The improvement of the total motor score did not differ significantly across genetic groups. Finally, we evaluated the performance of multiple linear regression and results showed that by considering all factors it can be predicted with the Pearson’s correlation coefficient of 0.90 (p<1e-11).These results may assist for the selection of patients for surgery and prediction of surgical outcomes.[1] Tsuboi, T., et al., 2020. Secondary worsening following DYT1 dystonia deep brain stimulation: a multi-country cohort. Frontiers in human neuroscience, 14, p.242.