A patient presents with recurrent optic neuritis of both eyes with extensive transverse myelitis. Visual acuity in right eye is 6/60 and visual acuity in left eye is 6/18. Patient showed 50% response to steroids. Diagnosis is:
Neuromyelitis optica (NMO) Subacute combined degeneration of spinal cord (SACD) Posterior cerebral artery stroke Neurosyphilis