Bilateral motor and premotor cortex hypometabolism in a case of Mills syndrome

Mills syndrome is a rare condition characterized by slowly progressive upper motor neuron-predominant hemiparesis, belonging to the motor neuron disorder spectrum. Predominantly unilateral primary degeneration of corticospinal pathways is the supposed underlying pathophysiological mechanism. By means of (18)F-Fluorodeoxyglucose Positron Emission Tomography, we found significant (Statistical Parametric Mapping, SPM, analysis versus controls, uncorrected p < 0.005 at voxel level, p < 0.05 at cluster level, corrected for multiple comparisons) hypometabolism in motor and premotor areas of both hemispheres, mainly contralateral to the limbs weakness in a patient with a 10-year history of slowly progressive left-sided hemiparesis. No significant grey matter loss was found on voxel based morphometry (SPM). This supports the hypothesis of a slowly progressive neurodegenerative process involving primary motor and premotor cortex.