MRI features of Balo's concentric sclerosis.

We report MRI findings in a 56-year-old woman with Balo's concentric sclerosis (BCS) who initially presented with a progressive hemiparesis. MRI showed two lesions with a concentric pattern in the left frontoparietal region and a laminated, arcuate pattern in the right frontal region. These patterns were best seen in post-contrast images and were consistent with BCS. In addition, there were several small cerebral multiple sclerosis-like plaques. The clinical symptoms improved and the MR findings regressed after corticosteroid therapy. The patient had completely recovered 12 months later, except for mild right hand numbness. MRI showed further regression of the lesions, but the concentric pattern was still present. This case demonstrated that BCS can run a benign prolonged course and may persist for a long time. Concentric or laminated contrast enhancement in the acute phase may suggest that bands of demyelination in BCS occur synchronously rather than successively.