Shabbir Hussain I Merchant1, Tianxia Wu2, Mark Hallett2. 1. Department of Neurology, Division of Movement Disorders, Harvard Medical School Beth Israel Deaconess Medical Center Boston Massachusetts USA. 2. National Institute of Neurological Disorders and Stroke National Institute of Health Bethesda Maryland USA.
Abstract
Background: Task-specific dystonia (TSD) is a challenging clinical diagnosis with no objective diagnostic biomarkers. Objective: The objective of this study was to test 2 neurophysiologic variables using transcranial magnetic stimulation as potential diagnostic biomarkers for TSD. Methods: We tested (1) cortical silent period (CSP) and (2) dorsal inferior parietal lobule-motor cortex (dIPL-M1) physiologic connectivity in 9 patients with the writer's cramp form of TSD and 12 healthy volunteers on 2 separate sessions. Results: CSP was significantly prolonged (P < 0.0001) in TSD and could classify TSD with high sensitivity and specificity with areas under the receiver operating characteristic curve (AUCs) = 0.94 and 0.90, respectively, for 2 separate sessions with an intraclass correlation = 0.79. dIPL-M1 interaction was notable for significant motor cortical inhibition in TSD compared with facilitation in healthy subjects (P < 0.0001) and could classify TSD with high sensitivity and specificity with AUCs = 0.96 and 0.86, respectively. Conclusion: CSP and dIPL-M1 physiologic connectivity can classify TSD with high sensitivity, specificity, reproducibility, and reliability.
Background: Task-specific dystonia (TSD) is a challenging clinical diagnosis with no objective diagnostic biomarkers. Objective: The objective of this study was to test 2 neurophysiologic variables using transcranial magnetic stimulation as potential diagnostic biomarkers for TSD. Methods: We tested (1) cortical silent period (CSP) and (2) dorsal inferior parietal lobule-motor cortex (dIPL-M1) physiologic connectivity in 9 patients with the writer's cramp form of TSD and 12 healthy volunteers on 2 separate sessions. Results: CSP was significantly prolonged (P < 0.0001) in TSD and could classify TSD with high sensitivity and specificity with areas under the receiver operating characteristic curve (AUCs) = 0.94 and 0.90, respectively, for 2 separate sessions with an intraclass correlation = 0.79. dIPL-M1 interaction was notable for significant motor cortical inhibition in TSD compared with facilitation in healthy subjects (P < 0.0001) and could classify TSD with high sensitivity and specificity with AUCs = 0.96 and 0.86, respectively. Conclusion: CSP and dIPL-M1 physiologic connectivity can classify TSD with high sensitivity, specificity, reproducibility, and reliability.
Authors: Shabbir Hussain I Merchant; Eleni Frangos; Jacob Parker; Megan Bradson; Tianxia Wu; Felipe Vial-Undurraga; Giorgio Leodori; M C Bushnell; Silvina G Horovitz; Mark Hallett; Traian Popa Journal: Brain Date: 2020-06-01 Impact factor: 13.501
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