ISOLATED U-FIBER INVOLVEMENT IN MS - PRELIMINARY-OBSERVATIONS

We studied the frequency and location of isolated U-fiber involvement in MS and correlated these findings exploratively with physical disabi lity and neuropsychological impairment. Fifty-three MS patients were e xamined. Three-millimeter-thick, fast spin-echo T2-weighted MR images and spin-echo postgadolinium T1-weighted images were obtained. Compute r software that which had been validated previously for quantitation o f MS lesions was used to detect lesions on the T2-weighted images. The Expanded Disability Status Scale (EDSS), Ambulation Index (AI), and a battery of neurocognitive tests were performed on each patient. Forty -two arcuate hyperintensities along the U-fiber were detected by the s oftware in 28 patients (53%). Twenty-seven lesions (64.3%) were seen i n the frontal lobe, eight (19.0%) in the temporal lobe, three (7.1%) i n the parietal lobe, three (7.1%) in the occipital lobe, and one (2.4% ) in both frontal and parietal lobes. Four lesions (9.5%) showed gadol inium enhancement. Seventeen lesions (40%) were hypointense on the T1- weighted images. Scores of three of the 11 neuropsychological tests re flecting performance in executive control and memory were significantl y different at least at the p = 0.05 level between the eight patients with multiple, isolated U-fiber lesions and the 45 patients without Rn v or with only a single U-fiber lesion. No significant difference was noted for EDSS or AI. Isolated U-fiber involvement is an underapprecia ted MR finding in MS. Our preliminary hypothesis is that U-fiber lesio ns may contribute to neuropsychological impairment, although our obser vation requires confirmation.