Magnetisation transfer of normal appearing white matter in primary progressive multiple sclerosis

Patients with Primary Progressive multiple sclerosis may develop severe dis ability despite a paucity of lesions on conventional magnetic resonance ima ging, raising the possibility that intrinsic changes in normal appearing wh ite matter (NAWM) contribute to disability This study has measured magnetis ation transfer ratio (MTR), an index of tissue damage, of NAWM in 52 patien ts with primary progressive multiple sclerosis and 26 healthy controls. Abs olute values of MTR were obtained from the genu of the corpus callosum and pens, and mean values were calculated from bilateral regions in the centrum semiovale, frontal white matter parieto-occipital white matter and posteri or limb of the internal capsule. The median MTR was lower in all regions in patients compared to controls. Median values (per cent units) were signifi cantly lower in corpus callosum (39.73 vs 40.63; P=0.01), frontal white mat ter (39.11 vs 39.59; P=0.01) and centrum semiovale (37.21 vs 37.82; P<0.05) . This study has demonstrated smell but widespread decreases in MTR in NAWM in Primary Progressive multiple sclerosis supporting the hypothesis that t here ore intrinsic changes in NAWM which may contribute to disability in th is patient group.