Magnetic resonanceimaging ofspinal cordlesions in multiple sclerosis

SUMMARY Theclinical andpathological manifestations ofmultiple sclerosis are duetoareas of demyelination which occurthroughout thewhite matterofthecentral nervous system.MRI ofthe brainfrequently showsabnormalities inthehemispheric subcortical whitematter;these are demonstrable inthemajority ofpatients andsupporttheclinical diagnosis ofmultiple sclerosis. Our studies haveshownthat while MRI identifies suchcerebral lesions innearly allclinically definite multiple sclerosis patients withillness ofduration greater than10years,these areasofabnormal T2 signal arepresent less often inthebrains ofpatients studied within 3yearsofdisease onset.However, symptomsreferable tothelong tracts ofthespinal cord areprominent inmany ofthese patients. Imaging ofthespinal cordhaspresented technical problems because ofthesmall size ofthecord, patient body, heart andrespiratory movements, andlimitations ofsurface coil technology. Thespinal cordof77patients withmultiple sclerosis havebeenimaged, revealing three typesofabnormalities: (1)approximately half thecords showregions ofabnormal T2weighted signal; (2)during acute exacerbation, spinal cordenlargement (swelling) may beobserved; (3)spinal cordatrophy (narrowing) isfoundparticularly inpatients withdisease oflonger duration andgreater disability. Unlikethepresenceofbrainlesions, theexistence ofspinal cordlesions ofhighT2signal isnot associated withincreasing duration ofdisease butiscorrelated withdisability status. Ofpatients with suchlesions about onefifth didnotexhibit brain lesions discernible byMRI. Multiple sclerosis isdiagnosed byuseofclinical criteria,' although neuro-imaging procedures are increasingly usedasparaclinical confirmation of lesions.2 Magnetic resonance imaging (MRI)ofthe brain isconsiderably moresensitive thanX-ray computedtomography, evenwith"double-dose" intravenous contrast, anddemonstrates regions of abnormal T2signal inthecerebral white matter of ultimately morethan90%ofpatients.?'2 However, early inthecourse ofdisease asmaller proportion of patients showfindings onbrain MRI.7"' 31 Prevalent presenting clinical manifestations ofmultiple sclerosis consist ofmotorandsensory long tract signs inthelimbs.5 These primarily reflect spinal cord disease. Fordiagnostic purposes, spinal cordMRI obviates needforX-raymyelography toexclude compressive lesions inthespinal canal,'1'8 andoffers