Stimulation-Induced Dyskinesia After Subthalamic Nucleus Deep Brain Stimulation in Patients With Meige Syndrome.

OBJECTIVES: Deep brain stimulation of the subthalamic nucleus (STN-DBS) is increasingly used to treat Meige syndrome (MS) and markedly improves symptoms. Stimulation-induced dyskinesia (SID), which adversely affects surgical outcomes and patient satisfaction, may, however, occur in some patients. This study attempts to explore possible causes of SID. MATERIALS AND METHODS: Retrospectively collected clinical data on 32 patients who underwent STN-DBS between October 2016 and April 2019 were analyzed. Clinical outcomes were assessed pre- and post-surgery, using the Burke-Fahn-Marsden dystonia rating scale (BFMDRS). Patients were divided into a dyskinesia group and a non-dyskinesia group, according to whether or not they experienced persistent SID during follow-up. The coordinates of the active contacts were calculated from post-operative computerized tomography or magnetic resonance imaging, using the inter-commissural line as a reference. At final follow-up, the main stimulatory parameters for further study included pulse width, voltage, and frequency. RESULTS: At final follow-up (mean = 16.3 ± 7.2 months), MS patients had improved BFMDRS total scores compared with pre-surgical scores (mean improvement = 79.0%, p < 0.0001). The mean improvement in BFMDRS total scores in the dyskinesia (n = 10) and non-dyskinesia (n = 22) groups were 81.6 ± 8.8% and 77.9 ± 14.2%, respectively. The mean minimum voltage to induce dyskinesia was 1.7 ± 0.3 V. The programmed parameters of both groups were similar. When compared with the non-dyskinesia group, active stimulatory contact coordinates in the dyskinesia group were inferior (mean left side: z = -2.3 ± 1.7 mm vs. z = -1.2 ± 1.5 mm; p = 0.0282; mean right side: z = -2.7 ± 1.9 mm vs. z = -2.3 ± 1.7 mm; p = 0.0256). The x and y coordinates were similar. CONCLUSION: STN-DBS is an effective intervention for MS, providing marked improvements in clinical symptoms; SID may, however occur in the subsequent programming control process. Comparing patients with/without dyskinesia, the active contacts were located closer to the inferior part of the STN in patients with dyskinesia, which may provide an explanation for the dyskinesia.

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 ±â€¯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 ±â€¯1.2 mm, y = -13.3 ±â€¯1.7 mm, z = -5.5 ±â€¯2.5 mm; mean right side: x = 12.7 ±â€¯1.4 mm, y = -12.7 ±â€¯1.7 mm, z = -6.4 ±â€¯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.