May 16, 2024
A 4-year-old boy with known autism spectrum disorder and developmental delay at baseline is admitted to the ICU with subacute progressive encephalopathy, ataxia, autonomic instability, and subacute intractable emesis.
Myelin Oligodendrocyte Glycoprotein Antibody-associated Disease (MOGAD)
- Background:
- Recently defined distinct inflammatory disorder of the CNS with immune-mediated demyelination characterized by antibody against myelin oligodendrocyte glycoprotein (MOG). MOG is a glycoprotein expressed on the outer membrane of myelin and is solely found within the CNS.
- Clinical Presentation:
- Mainly presents in children and young adults
- Common phenotype in children is with ADEM-like presentation, while adults can present with varying combination of cortical involvement, optic neuritis, transverse myelitis
- Infectious prodrome is common
- Key Diagnostic Features:
- Varying involvement of:
- Deep white matter (confluent or patchy multifocal changes)
- Deep gray nuclei and/or along the corticospinal tracts
- Involvement of middle cerebellar peduncles has been characteristically associated
- Screening of optic apparatus and spinal imaging is warranted if such pattern of neuroinflammatory disease is seen
- Optic nerves: uni-/bilateral, extensive lesions (>50% length), mainly anterior segments sparing the chiasm, with perineural enhancement
- Spine: longitudinally extensive, >1 lesion, conus medullaris frequently involved, axial H-sign, enhancement in 50% of patients
- Resolution of findings in 50%–80% of cases, which is unique among CNS demyelinating disorders
- Serum MOG-IgG antibody testing utilizing a cell-based assay is recommended, however the disease course in MOGAD may be monophasic or relapsing. Serum MOG-IgG may be transiently positive at time of initial attack and antibody-negative on follow-up testing.
- Varying involvement of:
- Differential Diagnosis:
- MOGAD can mimic a wide variety of conditions depending on the pattern of involvement
- Leukodystrophy mimic (as in the first case): when there is greater white matter involvement
- Viral encephalitis: if there is predominant deep gray matter involvement
- Parainfectious transverse myelitis (TM): An inflammatory condition associated with rapidly progressive motor, sensory, or autonomic dysfunction within 4 weeks of an infectious prodrome. A number of viral infections including, but not limited to, enteroviruses, herpesvirus, neuroborreliosis (Lyme),and Epstein Barr virus are implicated. MR imaging manifestations are variable but may include long-segment T2 hyperintensity with variable patterns of enhancement and/or expansion.
- Neuromyelitis optica spectrum disorders (NMOSD): NMOSD includes neurologic disorders associated with serum aquaporin-4 IgG antibody. Characteristically, these occur in younger females. MR imaging of optic nerve may demonstrate uni-/bilateral lesions of mainly posterior segments including chiasm. Spinal cord may show a longitudinally extensive single lesion, central/diffuse on axial images, elongated ring, or patchy enhancement. MR imaging of the brain is often nonspecific but may include area postrema, peri-third/fourth ventricle, corticospinal tracts, and extensive white matter lesions.
- Treatment:
- Management of MOGAD attacks includes high-dose intravenous steroids followed by an oral steroid taper. Patients who do not respond adequately to steroids may be treated with intravenous immunoglobulin or plasma exchange.
- In patients with a relapsing disease course, maintenance therapy is recommended and includes the selection of specific therapeutic agents such as intravenous immunoglobulin, rituximab, azathioprine, or mycophenolate mofetil.
- Multiple sclerosis disease-modifying therapies do not appear to be efficacious for preventing MOGAD relapses.
