Functional MRI connectivity of the primary motor cortex in functional dystonia patients

Background Functional movement disorders include a wide spectrum of clinically documented movement disorders without an apparent organic substrate. Objective To explore the functional connectivity (FC) of the primary motor (M1) cortex in functional dystonia (FD) patients relative to healthy controls, with a focus on different clinical phenotypes. Methods Forty FD patients (12 fixed [FixFD]; 28 mobile [MobFD]) and 43 healthy controls (14 young FixFD-age-matched [yHC]; 29 old MobFD-age-matched [oHC]) underwent resting state fMRI. A seed-based FC analysis was performed using bilateral M1 as regions of interest. Results Compared to controls, FD patients showed reduced FC between left M1 and left dorsal anterior cingulate cortex, and between right M1 and left M1, premotor/supplementary motor area (SMA), dorsal posterior cingulate cortex (PCC), and bilateral precuneus. Relative to yHC, FixFD patients showed reduced FC between M1 and precuneus bilaterally. Compared to oHC, MobFD patients revealed reduced FC between right M1 and left M1, premotor/SMA, dorsal-PCC, bilateral primary sensory cortices and parieto-occipital areas, and increased FC of right M1 with right associative visual cortex and bilateral ventral-PCC. FixFD patients, relative to MobFD, showed lower FC between the right M1 and right associative visual area, and bilateral precuneus and ventral-PCC. Conclusions This study suggests an altered brain FC of the motor circuit with areas involved in emotional processes and sense of agency in FD. FixFD patients showed FC abnormalities mainly in areas related to sense of agency, while MobFD in regions involved in sensorimotor functions (reduced FC) and emotional processing (increased FC).

Automated summary

This study found altered brain functional connectivity (FC) in the motor circuit of patients with functional dystonia (FD), involving areas related to emotional processes and sense of agency. Compared to young healthy controls, fixed FD patients showed decreased FC between M1 and bilateral precuneus. On the other hand, compared to old healthy controls, mobile FD patients exhibited decreased FC between bilateral primary sensory cortices and parieto-occipital areas, as well as increased FC with right associative visual cortex and bilateral ventral-PCC.