Post-operative electrode location and clinical efficacy of subthalamic nucleus deep brain stimulation in Meige syndrome

Background Subthalamic nucleus (STN) deep brain stimulation (DBS) has recently been shown to be an effective treatment for Meige syndrome but efficacy of symptomatic improvement and its relationship to factors in DBS remains to be explored. Objectives: This study explored the relationship of electrode contact location in bilateral STN-DBS with clinical efficacy in Meige syndrome patients through retrospective analysis. Methods: Pre- and post-operative magnetic resonance (MR) images of Meige syndrome patients (n = 15) were analysed. Clinical outcomes were evaluated with the Burke-Fahn-Marsden Dystonia Scale (BFMDRS). The location of active contacts in Montreal Neurological Institute (MNI) standard space and volume of activated STN tissue were determined and related to clinical outcomes. Results: At the last follow up (mean = 14.8 +/- 4.0 months; range = 11-24 months), Meige syndrome patients (n = 14) showed improved BFMDRS scores (mean improvement = 70.9%, p = 0.001) compared to pre-operative assessment. Active contacts of stimulation given from coordinates in the MNI space (mean left side: x =- 12.5 +/- 1.2 mm, y = -13.3 +/- 1.7 mm, z = - 5.5 +/- 2.5 mm; mean right side x = 12.7 +/- 1.4 mm, y = -12.7 +/- 1.7 mm, z = - 6.4 +/- 2.4 mm) were found mainly clustered in the dorsolateral STN. While there were no significant differences in patients grouped by their degree of symptomatic improvement ( < 30%, 30-70% and > 70%) with their respective coordinates, the volume of activated tissue within the STN of patients was significantly correlated to the BFMDRS improvement (R = 0.6, p = 0.02). Conclusions: These findings further support the stimulation of the dorsolateral STN for effective alleviation of symptoms in Meige syndrome patients and indicate that specific factors of DBS can be considered to predict clinical efficacy.