Magnetic resonance imaging of spinal cord lesions in multiple sclerosis.

The clinical and pathological manifestations of multiple sclerosis are due to areas of demyelination which occur throughout the white matter of the central nervous system. MRI of the brain frequently shows abnormalities in the hemispheric subcortical white matter; these are demonstrable in the majority of patients and support the clinical diagnosis of multiple sclerosis. Our studies have shown that while MRI identifies such cerebral lesions in nearly all clinically definite multiple sclerosis patients with illness of duration greater than 10 years, these areas of abnormal T2 signal are present less often in the brains of patients studied within 3 years of disease onset. However, symptoms referable to the long tracts of the spinal cord are prominent in many of these patients. Imaging of the spinal cord has presented technical problems because of the small size of the cord, patient body, heart and respiratory movements, and limitations of surface coil technology. The spinal cord of 77 patients with multiple sclerosis have been imaged, revealing three types of abnormalities: (1) approximately half the cords show regions of abnormal T2 weighted signal; (2) during acute exacerbation, spinal cord enlargement (swelling) may be observed; (3) spinal cord atrophy (narrowing) is found particularly in patients with disease of longer duration and greater disability. Unlike the presence of brain lesions, the existence of spinal cord lesions of high T2 signal is not associated with increasing duration of disease but is correlated with disability status. Of patients with such lesions about one fifth did not exhibit brain lesions discernible by MRI.