Retrobulbar optic neuritis in a two-year-old boy.

We report a 2-year-4-month-old boy with retrobulbar optic neuritis. He had a sudden onset of impaired vision, which progressed to total blindness within a day. The visual evoked potential (VEP) showed no activity, but the electroretinogram was normal. Computed tomography (CT) and magnetic resonance imaging (MRI) showed no abnormal findings in the visual tract. The cerebrospinal fluid (CSF) myelin basic protein (MBP) level was elevated and serum anti-myelin antibody was positive. These findings suggested that optic neuritis in our patient was induced by retrobulbar demyelination, perhaps as a result of an autoimmune process. His visual impairment recovered gradually, but not completely, following oral prednisolone therapy. We have followed him for one year since discharge and have found neither recurrence of optic neuritis nor any other neurological disorders. Optic neuritis in children is rare and, to our knowledge, this patient is one of the youngest to be reported. This case suggests that autoimmune mechanisms may induce optic neuritis even in early childhood. In addition to VEP and MRI studies, the CSF MBP and serum anti-myelin antibody can be useful in the diagnosis and follow-up the patients with optic neuritis.