Distortion of the cortical motor map in patients with Unverricht-Lundborg disease: A combined TMS-MRI study.

Objective: To assess functional organization of the motor cortex in patients with Unverricht-Lundborg disease (EPM1A) using a combined neurophysiologic and imaging approach.

Methods: EPM1A patients underwent transcranial magnetic stimulation (TMS)-based cortical mapping of the motor hand area. Moreover, they performed neuroimaging studies to assess functional magnetic resonance imaging (fMRI) activation maps related to motor hand task and cortical thickness (CTH) on T1-weighted 3D images.

Results: The hand cortical representation was different in EPM1A patients from that of the control subjects both in TMS and in fMRI brain mapping, characterized by a posterior dislocation and a mild reduction in the activation of motor areas. CTH analysis revealed a thinning of both precentral and paracentral areas in the patients.

Conclusions: We hypothesize that the altered cortical motor map reflects a functional reorganization of the residual cortical neuronal pool of the sensorimotor hand areas driven by plastic reorganization and/or pathophysiological mechanisms.

Significance: Both pathophysiological process and plastic changes may represent two sides of the same phenomenon in the EPM1A patients; structural and functional brain mapping may help to identify functional reorganization of the cortical motor system.