Acute optic neuritis. A cognitive and magnetic resonance imaging study.

Forty-two patients with acute optic neuritis (ON) (mean duration of symptoms 14.5 d) were compared with a matched, normal control group on a battery of tests of attention and information processing speed. Approximately half the sample (55%) had brain abnormalities shown by magnetic resonance imaging (MRI) and were more impaired across a variety of tests compared with those patients without brain lesions or normal controls. There was no difference in psychometric performance other than the pegboard task between the normal control group and those ON patients without brain involvement. Significant correlations were found between total lesion area in the brain and some tests of attention. Results from the Symbol Digit-Substitution Test were particularly sensitive in this regard and could correctly identify 70% of the sample with brain lesions.