Multiple sclerosis. Coloured magnetic resonance imaging (MRI) scan of the head of a patient with multiple sclerosis (MS). This is an axial scan that has passed horizontally through the head, as seen from below. The front of the head is at top. The scan is at the level of the ventricles (central dark areas), and shows the brain and its outer folds, and the brain membranes, and the skull. The white areas are hypersignals where the MRI scan shows plaques of demyelinisation, areas where the nerve insulating material myelin is absent. This is what causes the nervous system to malfunction in MS. This is a young patient.