Abnormal surface EMG during clinically normal wrist movement in cervical dystonia

Authors: de Vries, P. M.; Leenders, K. L.; van der Hoeven, J. H.¹; de Jong, B. M.; Kuiper, A. J.²; Maurits, N. M.

Source: European Journal of Neurology, Volume 14, Number 11, November 2007 , pp. 1244-1250(7)

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Abstract:

We investigated whether patients with cervical dystonia (CD) have abnormal muscle activation in non-dystonic body parts. Eight healthy controls and eight CD patients performed a flexion-extension movement of the right wrist. Movement execution was recorded by surface electromyography (EMG) from forearm muscles. Although patients had no complaints concerning wrist movement and had no apparent difficulty in executing the task, they demonstrated lower mean EMG amplitude (flexor: 0.32 mV and extensor: 0.61 mV) than controls (flexor: 0.67 mV; P = 0.021 and extensor: 1.18 mV; P = 0.068; borderline significant). Mean extensor muscle contraction was prolonged in patients (1860 ms) compared with controls (1334 ms; P = 0.026). Variation in mean EMG amplitude over movements tended to be higher in patients (flexor: 43% and extensor: 35%) than controls (flexor: 34%; P = 0.072 and extensor: 26%; P = 0.073). These results suggest that CD patients also have abnormal muscle activation in non-dystonic body parts at a subclinical level. This would support the concept that in dystonia, non-dystonic limbs are in a `pre-dystonic state'.

Keywords: cervical dystonia; electromyography; wrist movement

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1468-1331.2007.01955.x

Affiliations: 1: Department of Neurology, University Medical Center Groningen, University of Groningen, The Netherlands 2: BCN-Neuroimaging Center, University of Groningen, The Netherlands

Publication date: 2007-11-01