FUNCTIONAL CORRELATES OF CALLOSAL ATROPHY IN RELAPSING-REMITTING MULTIPLE-SCLEROSIS PATIENTS - A PRELIMINARY MRI STUDY

In multiple sclerosis (MS), periventricular lesions produce atrophy of the corpus callosum (CC), as evidenced by magnetic resonance imaging (MRI). We investigated whether CC atrophy in relapsing-remitting MS pa tients is related to functional deficits. We compared 14 mildly disabl ed (mean Expanded Disability Status Scale score 2.7) relapsing-omittin g MS patients with 14 age- und sex-matched controls. CC size was deter mined using sagittal T1-weighted MRI. The function of the CC was studi ed using a neuropsychological battery and neurophysiological evaluatio n based on visual stimulation using a divided visual field paradigm. T he total area of the CC in patients (mean 5.3 cm(2)) was significantly (P=0.002) smaller than in controls (mean 6.6 cm(2)). Patients showed left ear extinction using the dichotic listening test and impaired nam e learning, which was correlated with atrophy of the splenium. There w ere no differences in interhemispheric transfer time between patients and controls. Marked atrophy of the CC can be encountered in relapsing -remitting MS patients. The associated cerebral disconnection correlat ed with atrophy of expected regions of the CC, thus supporting topogra phical organization.