Visuoperceptual impairment in multiple sclerosis patients diagnosed with neuropsychological tasks

Abstract

A comprehensive set of 31 binocular neuropsychological tasks assessing a series of spatial and non-spatial visuoperceptual abilities was used to study visuoperceptual impairment in a representative group of 49 MS-clinic patients exhibiting neither diagnosed ophthalmological afflictions nor major psychiatric diagnoses. Among these patients, true frequency rate of visuoperceptual impairment, i.e. of subjects failing four or more tasks, was estimated at 26%. The pattern of visuoperceptual impairment was non-uniform, non-selective, restricted and idiosyncratic. Only four tasks yielded significant rates of impairment. They concerned colour discrimination, the perception of the Müller-Lyer illusion and object recognition in two separate conditions. Each of the four factors identified by factor analysis had an important representative (with factor loading 40.35) among these four tasks. Failures on these tasks correlated poorly. Together, the four tasks satisfactorily predicted visuoperceptual impairment as defined by the comprehensive set of tasks (sensitivity 86.7%; specificity 81.3%), but with regard to an uncontaminated criterion, their aggregate sensitivity and specificity was only 75 and 56% respectively. Visuoperceptual neuropsychological task performance related significantly but weakly to cognitive status, physical disability and to pyramidal, cerebellar and brain stem neurological signs, and did not correlate with other clinical neurological signs, disease duration, type of MS, a history of optic neuritis, depression or medication status.