Neuromyelitis optica.

An 11-year-old girl developed sudden visual loss in her left eye, preceding subacute myelitis by 9 months. Multifocal lesions in the central nervous system were demonstrated by magnetic resonance imaging. Although unilateral blindness is unusual, the clinical findings predominantly involving the optic nerve and spinal cord were consistent with the diagnosis of neuromyelitis optica (NMO). This case provides additional evidence to support the view that NMO is a variant of multiple sclerosis.