Status of diagnostic approaches to AQP4-IgG seronegative NMO and NMO/MS overlap syndromes.

The diagnosis in AQP4-IgG-negative NMO/MS overlap syndromes is challenging and diverse. The classification of such patients currently requires new diagnostic categories, which incorporate lesser degrees of diagnostic confidence. Long-term follow-up may identify early features or biomarkers, which can more accurately distinguish the underlying disorder.