Autoimmune Demyelinating Syndromes

Neuromyelitis optica Spectrum Disorder (NMOSD)

What is NMOSD?

Neuromyelitis Optic (NMO) was once thought to be a form of multiple sclerosis (MS). NMO has now been defined as a distinct clinical–pathological disorder, although the initial clinical presentation often mimics MS (1). In 2004, Neuromyelitis Opticia (or NMO) was defined by the finding of a positive aquaporin-4 antibody (AQP4-IgG), also known at the NMO antibody. Before the discovery of this antibody, neurologists speculated about whether or not NMO and MS were the same or different disease. It is very clear now however that NMO is a distinct clinical–pathological disorder, although the initial clinical presentation may mimic MS. It is very important to differentiate between these two diseases because they have different treatments.

What are the treatment options?
There are now three new FDA-approved therapies for NMOSD since 2019, including Soliris (eculizumab), Uplizna (inebilizumab-cdon), and Enspryng (satralizumab-mwge).  When a patient presents acutely, steroids are commonly used to treat urgently and if the attack is severe often plasma exchange (PLEX) is added. The use of these acute therapies is similar to approaches used in multiple sclerosis.  To avoid future attacks or relapses, just like multiple sclerosis, chronic disease modifying therapies are used, although these longer-term disease-modifying treatments are different.

MOG Antibody Disease (MOGAD)

What is MOG Antibody Disease (MOGAD)?

MOG Antibody Disease (MOGAD) has a similar presentation to NMOSD and includes recurrent optic neuritis and spinal cord lesions (2) (3).  Importantly, it also includes the presence of anti-MOG antibody found in the blood. The full clinical spectrum of MOGAD continues to described in the literature, as the ability to accurately and widely test for this antibody did not occur until 2017. Clinical syndromes seen with MOGAD include: optic neuritis (inflammation of the optic nerve), encephalitis (inflammation of the brain), myelitis (inflammation of the spinal cord), and ADEM (acute disseminated encephalomyelitis; a syndrome often seen in children).

What are the treatment options?

We continue to learn more about this disease and the best treatment approaches. MOG antibody testing became commercially available in 2017. It is apparent however, that traditional MS disease-modifying agents appear to be ineffective.  Often similar treatment approaches to NMOSD are used, however we do not yet know whether B cell therapies are truly the best treatment approach or not. A retrospective study published in 2020 of 121 MOGAD patients treated with rituximab showed a reduction in relapse rates by 37%. Another large retrospective, multicenter study suggested that maintenance IVIg therapy might be helpful to reduce recurrent attacks. Prospective controlled studies are needed.