Prefrontal and parietal adaptations in cervical dystonia after parietal TMS interleaved with fMRI

80 Abstract Clinically normal hand movement associated with altered cerebral activation patterns in CD may imply cerebral adaptation. Since impaired sensorimotor integration appears to play a role in dystonia, left superior parietal cortex modulation with TMS was employed to further challenge adaptation mechanisms reflected by a change in cerebral activation. Seven CD patients and ten HC were scanned on a 3T MRI scanner with interleaved TMS. They executed and imagined right wrist flexion/ extension movements. Each task was preceded by a 10-second period either with or without TMS. TMS in HC showed a similar task-related activation pattern as found in CD without TMS influence, i.e. increases of activation in bilateral prefrontal and posterior parietal regions during both tasks and decreases in right anterior parietal cortex during movement imagery (P<0.001). The TMS effect in CD was weaker but with a similar trend in activation changes. Only in the right angular gyrus, TMS significantly failed to induce an increase of activation in CD as was seen in the control subjects (P<0.001). The similarity between TMS effects on the distribution of cerebral activations in controls and the pattern seen in CD supports the concept that CD patients make use of compensatory circuitry enabling clinically normal hand movement. The fact that a similar but weaker TMS effect occurred in CD suggests that the capacity of compensation is reduced. Particularly for the right angular gyrus, this reduction was statistically significant.