Cognitive dysfunction 24–31 years after isolated optic neuritis

Abstract

Objective Cognitive dysfunction is common in multiple sclerosis (MS), but long-term data on cognition in patients with clinically isolated syndromes are sparse. Methods We determined cognitive functions in 22 patients 44–75 years old diagnosed with optic neuritis 24–31 years earlier but had no further clinical bouts and had not progressed clinically to MS. We used a neuropsychological test battery covering nine cognitive domains. Magnetic resonance imaging (MRI) of the brain had been performed earlier and was normal in six patients and showed two or more white matter abnormalities compatible with demyelinating lesions in 16 patients. Results On neuropsychological testing, one patient was within normal range on all tests, six subjects showed borderline results, and 15 patients (68%) showed significantly impaired performance in at least one cognitive domain. Seven patients showed significant impairment in two or more domains. Executive function, visuo-spatial ability, and information processing speed were the most frequently affected domains. There was no apparent correlation between MRI findings and cognitive function. Conclusions We conclude that cognitive dysfunction is common in patients many years after clinically isolated optic neuritis. Cognitive dysfunction was found even in patients who had no apparent demyelinating lesions on follow-up MRI.