CNS Demyelinating Disease Evaluation Profile, Serum

Neuromyelitis optica spectrum disorders (NMOSDs), classified as immune-mediated chronic and frequently recurring inflammatory conditions, primarily impact the optic nerve and spinal cord. While NMOSDs can occur in any demographic, they tend to be more prevalent in middle-aged and elderly women. Due to the presence of similar symptoms such as optic neuritis and transverse myelitis, NMOSDs are sometimes misdiagnosed as multiple sclerosis (MS). However, distinguishing factors between the two conditions include the clinical progression, the location and size of lesions in the brain and/or spinal cord, the occurence of optic neuritis, and the detection of specific autoantibodies like aquaporin-4 receptor (AQP4) or myelin oligodendrocyte glycoprotein (MOG) IgG. Once initial non-specific tests have been conducted to exclude infections, vasculitis and other conditions that may resemble NMOSDs in their presentation, it is recommended to assess the serum antibody status for AQP4 IgG and MOG IgG. The detection of AQP4 IgG antibodies in the appropriated clinical context confirms the presence of NMOSDs. In patients with MS, AQP4 IgG testing generally yields negative results, whereas around 75% of NMOSD patients show antibodies targeting the AQP4 receptor. Although a small percentage of individuals with clinical symptoms suggestive of NMOSDs may test negative for AQP4 IgG, they may still have detectable serum MOG IgG antibodies. It is important to note that the absence of both AQP4 IgG and MOG IgG antibodies does not exclude the diagnosis of NMOSD, and it is advisable to consider retesting before initiating antibody-targeted therapies.