Objective: To investigate functional brain networks underlying focal embouchure dystonia (FED) using resting-state functional connectivity (FC) magnetic resonance imaging and to correlate abnormal connectivity with functional impairment and quantitative measures of FED severity.

Background: FED impairs orofacial motor control in wind instrument musicians and causes professional disability. Little is known about its pathophysiology, but striatal abnormalities and altered sensorimotor cortical plasticity have been identified in many forms of dystonia. Across focal dystonia subtypes, striatal changes may be restricted to somatotopically distinct subregions, but many of these studies had participants perform dystonia-eliciting tasks during imaging and thus were confounded by secondary responses to abnormal movement. Imaging in the resting-state minimizes this confound of interpretation. We hypothesized that participants with FED would have altered functional connectivity (FC) in a striatal subregion implicated in laryngeal dystonia (LD) and lateral sensorimotor cortex.

Method: Fourteen brass musicians with and eleven without FED underwent 30 minutes of resting-state BOLD scans. We defined seeds in putamen subregions implicated in LD and writer’s cramp (WC), pallidum, lateral sensorimotor cortex, and posterior cingulate cortex (PCC) and computed the correlations between seed average time courses and BOLD activity in every voxel across the brain. Group-level differences in seed-voxel BOLD correlations (i.e. FC) were assessed on a cluster-wise basis.

Results: FED is characterized by an abnormal functional network comprising the putamen LD subregion, right superior temporal sulcus and surrounding cortex, and PCC. Intra-network FC correlated with functional impairment and an objective, quantitative measure of FED severity. FC patterns of the putamen WC subregion, pallidum, and lateral sensorimotor cortex seeds were unaffected.

Conclusion: We identified an abnormal striatal-temporal-PCC network in musicians with FED that is sensitive and specific for musicians with FED and correlates with functional and objective impairment metrics, suggesting clinical relevance. Altered FC for the LD but not WC striatal subregion adds cross-modal support for differential somatotopically-distinct striatal subregion abnormalities in focal dystonia.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/an-aberrant-embouchure-dystonia-network-predicts-objective-and-functional-measures-of-severity/