Changed patterns of cerebral activation related to clinically normal hand movement in cervical dystonia

The relief of cervical dystonia by sensory tricks points at complex sensorimotor interaction. The relation between such stimulus-induced normalization of posture and parietal activation [Naumann M, Magyar-Lehmann S, Reiners K, Erbguth F, Leenders KL. Sensory tricks in cervical dystonia: perceptual dysbalance of parietal cortex modulates frontal motor programming. Ann Neurol 2000;47:322-8] further supports the idea of disturbed higher-order motor control and suggests that the organization of movement is affected beyond the level of a local output channel. Dysbalance beyond a restricted output channel is also supported by the spread of focal dystonia to adjacent body parts. In this fMRI study, we aimed to determine whether cervical dystonia patients have indeed different patterns of cerebral activation during clinically normal hand performance.

By means of statistical parametric mapping (SPM) of 3T fMRI results, task-related cerebral activations measured in eight cervical dystonia patients were compared to data of nine healthy volunteers.

Compared to controls, the patient group showed a relative reduction of activations in bilateral parietal, left premotor and cingulate cortex regions during imagining of movement, while activation of right (ipsilateral) putamen, insula and cingulate cortex was impaired during movement execution.

Cervical dystonia appears to concern a general disorganization of cerebral motor control, which indicates a pre-dystonic state of clinically normal hand movements. The latter may imply an increased vulnerability for deteriorating triggers such as minor accidents.