In a young female patient with progressive visual disturbance and increased signal foci involving the optic nerve and surrounding the cerebral aqueduct, what is the favoured diagnosis?
Neuromyelitis optica
What is the most specific laboratory test to confirm the diagnosis?
NMO-IgG targeted to water channel AQP4 (aquaporin 4), it is present in ~ 70% of NMO patients and is ~99% specificity.
Subtle foci of increased FLAIR signal surrounding the cerebral aqueduct. The right optic nerve has diffuse increased signal on STIR. The remainder brain is unremarkable.