A pilot magnetoencephalographic study of coherence in cervical dystonia and meige syndrome
Mahajan A, Bowyer S, Zillgitt A, LeWitt P, Kaminski P, and Sidiropoulos C. A pilot magnetoencephalographic study of coherence in cervical dystonia and meige syndrome. Mov Disord 2017; 32(9):e2.
Objectives: To explore functional connectivity at a network level with MEG, pre-and post-administration of medications, in cervical dystonia and Meige syndrome. Background: Mechanisms thought to play a critical role in dystonia include reduced intracortical inhibition and distorted somatotopic cortical representation. Prior studies showed altered functional connectivity within the sensorimotor, the executive control and the primary visual network. Methods: MEG Data on 5 patients, 4 with cervical dystonia and 1 with Meige syndrome (age: 16-70 years) were matched to 5 (age and sex matched) healthy controls. All patients (4 on Botulinum toxin, 1 on Diazepam) showed clinical benefit with medications. Two 15-minute MEG scans pre and post intervention were obtained. Synchronization of neuronal activity was quantified by calculating coherence source imaging (CSI) between cortical sites from MEG imaged brain activations. A region-of-interest (ROI) tool was used to identify 54 regions in the brain (27 in each hemisphere). Within the frequency band 3-50Hz, a t-test was conducted to assess group difference in average CSI values for each pair of brain regions (N51,431). A P value was produced for each region pair. Only statistically significant coherence values (p<0.05) with a large effect size were considered. Results: Using group based analysis, in both pre-treatment and posttreatment groups, the biggest difference in coherence between patients and controls was seen in the fronto-striatal and occipito-striatal regions, with some differences in the parieto-striatal and striato-parietal regions. On comparing pre-and post-treatment dystonia patients, an increase in coherence was observed in these regions post treatment. Conclusion: Our exploratory study using MEG showed increased neuronal connectivity in regions associated with visuospatial and executive function, with an increase post medication in patients with cervical dystonia and Meige syndrome. The latter may be a biomarker for normalization of aberrant connectivity and merits further exploration.