Brain abnormalities in neuromyelitis optica

Background: Differentiating neuromyelitis optica (NMO) from multiple sclerosis (MS) is a real challenge in the clinical field. In the past, NMO (not MS), was inferred when abnormality was not detected in the brain magnetic resonance imaging (MRI). Recently, some studies have reported abnormalities in the brain MRIs of NMO, but only few among the Asian population. The aim of this study was to evaluate the frequency of brain MRI among Korean NMO patients and characterize findings that might be helpful to distinguish NMO from MS.

Methods: Medical records, NMO-IgG, and brain MRI of 17 patients diagnosed with NMO by the revised diagnostic criteria of Wingerchuk et al. (2006) [6] from 2008 to 2010, were reviewed.

Results: 11 out of 17 patients (64.7%) had abnormal MRI findings. More than two lesions were detected in most patients. The majority of patients with brain MRI abnormality showed nonspecific (5 patients) or atypical (6 patients) findings. Cerebral white matter was most frequently involved (58.8%). 3 patients (17.6%) involved corpus callosum, 4 (23.5%) with internal capsule, 2 (11.8%) with cerebellum, and 3 (17.6%) with brainstem. There were 5 (29.4%) patients who met the Paty et al. criteria (1988) [15] and 3 patients (35.3%) who met the multiple sclerosis (MS) spatial distribution diagnostic criteria of Barkhof et al. (1997) [14] in their brain MRI.

Conclusions: Brain abnormalities have been frequently found among Korean NMO patients and the frequencies have been reported to be higher than that of Caucasians. Current MS spatial distribution criteria, such as Paty et al. (1988) [15] or Barkhof et al. (1997) [14], are not sufficient to discriminate NMO from MS in brain MRI findings. Our results will provide valuable information that would be useful in establishing future revising criteria for NMO.