Infratentorial atrophy on magnetic resonance imaging and disability in multiple sclerosis

Loss of tissue volume in the central nervous system may provide an index of fixed neurological dysfunction in multiple sclerosis, Recent magnetic reso nance studies have shown a modest relationship between clinical disability rating scores and transverse sectional area of the cervical spinal cord. To explore further the relationship between atrophy and disability in multipl e sclerosis, we estimated the volumes of infratentorial structures from MRI s in a cross-sectional study of 41 patients, 21 with relapsing-remitting mu ltiple sclerosis and 20 with secondary progressive multiple sclerosis, We u sed the Cavalieri method of modern design stereology with point counting to estimate the volume of brainstem, cerebellum and upper cervical spinal cor d from three-dimensional MRIs acquired with an MPRAGE (Magnetization-prepar ed Rapid Acquisition Gradient Echo) sequence, The volume of the upper (C1-C 3) cervical spinal cord was significantly correlated with a composite spina l cord score derived from the appropriate Functional Scale scores of the Ex panded Disability Status Scale (r = -0.50, P < 0.01), The cerebellar (r = 0 .49, P < 0.01) and brainstem (r = 0.34, P < 0.05) volumes correlated with t he Scripp's Neurological Disability Rating Scale scores, The upper cervical cord volumes (r = -0.39, P < 0.01), but not the brainstem or cerebellar vo lumes, were significantly associated with disease duration. MRI-estimated s tructural volumes may provide a simple index of axonal and/or myelin loss, the presumed pathological substrates of irreversible impairment and disabil ity in multiple sclerosis.