Task-specific interhemispheric hypoconnectivity in writer's cramp – An EEG study. Issue 5 (May 2020)

• Record Type: Journal Article
• Authors: Thirugnanasambandam, Nivethida; Zimmerman, Tyler; Pillai, Ajay S; Shields, Jessica; Horovitz, Silvina G; Hallett, Mark
• Is Part Of: Clinical neurophysiology. Volume 131:Issue 5(2020:May)
• Page Start: 985
• Page End: 993
• Publication Date: 2020-05
• Subjects: Writer's cramp -- Interhemispheric coherence -- Functional connectivity -- Focal task specific dystonia -- EEG; ANOVA analysis of variance -- CSD current source density -- EEG electroencephalography -- EOI electrodes of interest -- fMRI Functional Magnetic Resonance Imaging -- FTSD focal task specific dystonia -- IHC interhemispheric coherence -- MANOVA multivariate analysis of variance -- TRP task-related power -- TRC task-related coherence -- WC writer's cramp; Neurophysiology -- Periodicals; Electroencephalography -- Periodicals; Electromyography -- Periodicals; Neurology -- Periodicals; 612.8
• DOI: 10.1016/j.clinph.2020.01.011
• Languages: English
• ISSNs: 1388-2457

Abstract

Highlights: We examined task-specific changes in functional connectivity during motor and motor imagery tasks. Writer's cramp patients show reduction in interhemispheric alpha connectivity during handwriting. Low beta power and parietal-premotor connectivity are non-task-specific changes in writer's cramp. Abstract: Objective: Writer's cramp (WC) is a focal task-specific dystonia characterized by abnormal posturing of the hand muscles during handwriting, but not during other tasks that involve the same set of muscles and objects such as sharpening a pencil. Our objective was to investigate the pathophysiology underlying the task specificity of this disorder using EEG. We hypothesized that premotor-parietal connectivity will be lower in WC patients specifically during handwriting and motor imagery of handwriting. Methods: We recruited 15 WC patients and 15 healthy controls. EEG was recorded while participants performed 4 tasks – writing with a pencil, sharpening a pencil, imagining writing and imagining sharpening. We determined the connectivity changes between relevant brain regions during these tasks. Results: We found reduced interhemispheric alpha coherence in the sensorimotor areas in WC patients exclusively during handwriting. WC patients also showed less reduction of task-related beta spectral power and a trend for reduced premotor-parietal coherence during motor tasks. Conclusion: We could not confirm an abnormality in premotor-parietal connectivity specific to handwriting by this method. However, there was a task-specific reduction in interhemispheric alpha connectivity in WC patients, whose behavioral correlate remains unknown. Significance: Interhemispheric alpha connectivity can be a potential interventional target in WC.