Differentiation of neuromyelitis optica from multiple sclerosis on spinal magnetic resonance imaging

In order to examine the accuracy of magnetic resonance imaging (MRI)-based diagnosis of neuromyelitis optica (NMO) versus multiple sclerosis (MS), we performed a retrospective, rater-blinded review of 29 cases of NMO and 30 cases of MS using the criteria of long (more than three vertebral levels), continuous lesions with a central cord location for NMO and more peripheral and patchy lesions for MS. Using these criteria, two raters were able to distinguish the two conditions with a good degree of confidence, particularly when the imaging was performed at the time of an acute cord attack. The sensitivity and specificity for diagnosis of NMO were 86.2% and 93.3%, respectively, for Rater A and 96.4% and 78.6%, respectively, for Rater B, with a kappa value of 0.72. Thus there are significant differences in lesion characteristics that allow the distinction on spinal cord imaging between MS and NMO with a moderately high degree of confidence. The location of the lesion as evident on MRI of the spine can be regarded as a distinguishing diagnostic feature between MS and NMO.