LAUSR

Introduction Dystonia patients express less effective intracortical inhibition, which can potentially be restored with pallidal deep brain stimulation (DBS). The DBS-related clinical benefit in dystonia increases relatively slowly, suggesting an induction of slow plastic processes in regions involved with motor control. In our study, we explored the relationship between intracortical inhibition of the motor cortex, brain morphology, and DBS-related clinical effects. Methods Twenty-two patients (mean age 51 ± (SD)17 years) with dystonia of various distribution and etiology treated by chronic pallidal DBS and 22 healthy subjects were included in the study. Voxel-based morphometry of postoperative T1-weighted images (MPRAGE, 1 × 1 × 1 mm) was calculated for gray matter (GM) density in each voxel using CAT12/SPM12 software. Paired TMS with subthreshold conditioning stimulus followed by a supratreshold testing stimulus were applied to the motor cortex to elicit short-latency intracortical inhibition (SICI) of the motor evoked potential. The clinical effect of DBS was expressed as a change in the dystonic score (BFMDS or TWSTRS) between actual DBS ON condition and the preoperative state. Results Dystonia patients showed increased GM density in the supplementary motor area (SMA) and middle cingulate in comparison with healthy controls (p  Conclusion Good responders to pallidal DBS treatment exhibited a similar level of SICI as healthy controls but non-responders were unable to increase it. Brain changes of treated patients possibly underwent grey matter rebuilding with cerebellar hypertrophy quantitatively related to the improvement of intracortical inhibition and with hypertrophy in the cortex involved in motor act preparation. All these results support the multilevel impact of effective DBS on motor networks in dystonia. Supported by the grants GACR 16-13323S.