Cortical Activation in the Primary Somatosensory Cortex: Healthy and Diagnosed Focal Hand Dystonia

Abstract

Current documentation on the pathophysiology of focal hand dystonia (FHD) is not conclusive regarding cortical activation. Most importantly, previous studies have not focused reports on the relative activation between hemispheres with stimulation of both hands. Purpose: to determine and compare the blood oxygen level dependent (BOLD) signal changes within primary somatosensory cortex (S1) during individual digit movement in subjects with FHD and healthy subjects. Methods: Eight healthy and five individuals diagnosed with FHD, all right hand dominant, participated in one session of functional magnetic resonance imaging (fMRI) while performing a specific finger tapping task. The BOLD response within the S1 was labeled as the region of interest and beta weights were exported for statistical analysis. Results: BOLD signal changes exhibited a significant hemisphere x hand x group interaction. Age was a significant covariate (p<0.001). Assessing BOLD signal changes for the right hemisphere, there was a group to hemisphere interaction (p<0.001). In post-hoc t-test comparison regarding contralateral hand control between groups there was a significant difference between groups (p<0.001). Conclusion: Limited studies have examined the ipsilateral and contralateral activation of both hands during individual digit movement in FHD. These results point to a somatosensory difference between healthy and individuals with dystonia. Specifically the results suggest a contralateral control difference within S1 cortical activation in the left hemisphere between healthy and diagnosed FHD.