Baló's concentric sclerosis.

Baló's concentric sclerosis is often regarded as a rare variant of multiple sclerosis. Patients with this disorder present with acute or subacute neurological deterioration, with MRI showing one or more concentrically multilayered ring-like lesions usually in the cerebral white matter. Historically, Baló's concentric sclerosis was thought fatal in all cases. However, the availability of MRI has led to a better appreciation of the variable natural history of patients presenting with radiologically evident Baló lesions and the clinical association with multiple sclerosis and, less often, with other neurological disorders. Important advances have increased understanding of the immunopathogenic mechanisms associated with the formation of Baló lesions. However, how to treat an acute lesion and when or whether to start treatment are less well understood, although for patients with Baló lesions who also fulfil standard diagnostic criteria for multiple sclerosis, our opinion is that treatment with multiple sclerosis disease-modifying therapy would seem reasonable.