• E De Bruijn, S W R Nijmeijer, P A Forbes, KoelmanJ H T MJHTMAcademic Medical Center, Neurology/Clinical Neurophysiology, Meibergdreef 9, 1105AZ Amsterdam, The Netherlands., F C T Van Der Helm, TijssenM A JMAJUniversity Groningen, University Medical Centre of Groningen, Department of Neurology, Hanzeplein 1, 9713GZ Groningen, The Netherlands., and R Happee.
• Biomechanical Engineering, Delft University of Technology, Mekelweg 2, 2628CD Delft, The Netherlands.
• Clin Neurophysiol. 2017 Oct 1; 128 (10): 1937-1945.

ObjectiveTo identify effects of a deviant motor drive in the autospectral power of dystonic muscles during voluntary contraction in cervical dystonia patients.MethodsSubmaximal (20%) isometric head-neck tasks were performed with the head fixed, measuring surface EMG of the sternocleidomastoid, splenius capitis and semispinalis capitis in CD patients and controls. Autospectral power of muscle activity, and head forces was analyzed using cumulative distribution functions (CDF). A downward shift between the theta/low alpha-band (3-10Hz) and the high alpha/beta-band (10-30Hz) was detected using the CDF10, defined as the cumulative power from 3 to 10Hz relative to power from 3 to 30Hz.ResultsCDF10 was increased in dystonic muscles compared to controls and patient muscles unaffected by dystonia, due to a 3-10Hz power increase and a 10-30Hz decrease. CDF10 also increased in patient head forces.ConclusionsSubmaximal isometric contractions with the head fixed provided a well-defined test condition minimizing effects of reflexive feedback and tremor. We associate shifts in autospectral power with prokinetic sensorimotor control.SignificanceAnalysis of autospectral power in isometric tasks with the head fixed is a promising approach in research and diagnostics of cervical dystonia.Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

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