Cognitive impairment in patients with clinically isolated lesions of the type seen in multiple sclerosis. A psychometric and MRI study.

This study reports the performance on psychometric tests of a group of 48 patients with clinically isolated lesions of the type seen in multiple sclerosis (optic neuritis, brainstem and cord lesions). The cognitive functions studied were: 'IQ deficit', verbal and visual memory, abstracting ability, visual and auditory attention, and naming ability. The presence of brain pathology was investigated by means of magnetic resonance imaging (MRI). A group of 46 patients with rheumatic and neurological conditions not known to cause brain disease was used for comparison. Normative MRI data were obtained from a group of 40 normal volunteers. An overall 'Cognitive Ability Index' was significantly worse in patients with clinically isolated lesions when compared with physically disabled controls. IQ deficit and defective auditory attention were the more severely affected parameters. These deficits were significantly correlated with the duration of neurological symptoms and with the degree of brain pathology detected by MRI.