Blood-Brain Barrier Disruption is More Severe in Neuromyelitis Optica than in Multiple Sclerosis and Correlates with Clinical Disability

OBJECTIVES: This study evaluated blood brain barrier (BBB) integrity, using blood and cerebrospinal fluid (CSF) markers, and assessed the practicality of these markers in the differential diagnosis of neuromyelitis optica (NMO) and multiple sclerosis (MS). METHODS: This was a retrospective observational study of consecutive patients presenting with acute phase NMO or MS (first attack or relapse). Haematological tests (including antiaquaporin-4 antibody levels) and CSF parameters (using primary component analyses) were undertaken; the correlation between BBB permeability and disease severity (by Expanded Disability Status Scale [EDSS] score) was examined. RESULTS: Levels of several markers of BBB permeability were higher in patients with NMO (n = 21) than in those with MS (n = 52). The CSF : serum albumin ratio (AR) was the one of the main differentiators of NMO and MS. Additionally, there was a significant correlation between AR and clinical severity for NMO but not for MS. CONCLUSIONS: Markers of BBB permeability were significantly higher in NMO patients than in MS patients. AR was the best marker for differentiating NMO and MS. Thus, measurement of BBB disruption markers (such as AR) might help to differentiate the diagnosis of NMO and MS in acute clinical settings.