Skip to content

MOGAD

Summary

fleuron

  • MOGAD (Myelin Oligodendrocyte Glycoprotein Antibody-associated Disease) is an autoimmune demyelinating CNS disorder caused by antibodies against myelin oligodendrocyte glycoprotein (MOG-IgG)
  • Presents with optic neuritis, acute disseminated encephalomyelitis (ADEM), transverse myelitis, or brainstem encephalitis
  • Distinct from multiple sclerosis and NMOSD; generally more steroid-responsive with better prognosis

Pathophysiology

  • Pathogenic IgG1 antibodies target MOG, a glycoprotein expressed on the outer surface of the myelin sheath and oligodendrocyte cell membrane
  • MOG-IgG activates complement and antibody-dependent cellular cytotoxicity, causing demyelination
  • Can be monophasic or relapsing; relapsing course more common in adults
  • Distinct from aquaporin-4 (AQP4)-IgG associated NMOSD, though phenotypic overlap exists

Demographics

  • Affects all age groups; bimodal distribution with peaks in childhood and adulthood
  • Childhood cases more likely to present as ADEM
  • No significant sex predilection in children; slight male predominance in adults
  • Prevalence estimated at 1–2 per 100,000

Diagnosis

  • Clinical syndromes:
    • Optic neuritis: often bilateral, with disc swelling and good visual recovery
    • ADEM-like: multifocal, often with encephalopathy (especially in children)
    • Transverse myelitis: often short segment, conus involvement common
    • Brainstem encephalitis: area postrema syndrome less common than in AQP4-NMOSD
  • Laboratory:
    • MOG-IgG positive in serum (cell-based assay preferred)
    • CSF: lymphocytic pleocytosis in acute attacks; oligoclonal bands typically absent
  • Diagnosis requires compatible clinical syndrome plus seropositivity for MOG-IgG

Imaging

  • MRI Brain:
    • T2/FLAIR: cortical/subcortical and deep white matter lesions; often large and fluffy
    • ADEM pattern: bilateral, asymmetric, poorly marginated T2-hyperintense lesions
    • Cortical lesions: more common than in MS or AQP4-NMOSD
    • T1+C: variable enhancement; leptomeningeal enhancement may be seen
  • MRI Optic Nerves:
    • T2: hyperintensity along optic nerve; often anterior with perineural enhancement
    • T1+C: enhancement of optic nerve sheath complex; bilateral involvement common
  • MRI Spine:
    • T2: conus medullaris involvement; central cord signal change; typically short segment
    • Longitudinally extensive transverse myelitis can occur (≥3 segments)
    • T1+C: patchy or diffuse cord enhancement

panels-1

  • A 30-year-old patient presented with ataxia and optic neuritis.
  • MRI showed multiple enhancing lesions in the cerebellum, cerebral peduncles, corpus callosum and intraorbital right optic nerve.

panels-1

  • A 40 year old presented with confusion and upper and lower limb weakness and sensory disturbance.
  • MRI showed extensive white matter lesions within both cerebral hemispheres associated with diffusion restriction and peripheral enhancement.
  • In the cord, there were multiple swollen mainly central short segment cord lesions.

Treatment

  • Acute attack:
    • High-dose IV methylprednisolone (1g/day for 3–5 days) — highly responsive
    • IV immunoglobulin (IVIG) for steroid-refractory attacks or in children
    • Plasma exchange for severe or steroid-resistant attacks
  • Maintenance (relapsing disease):
    • Prolonged low-dose oral prednisolone (many patients relapse on steroid taper)
    • Azathioprine or mycophenolate mofetil
    • IVIG (regular infusions)
    • Rituximab for refractory cases
  • Monitoring:
    • MOG-IgG titres may correlate with disease activity
    • Regular MRI and visual acuity monitoring
  • Prognosis:
    • Generally better than AQP4-NMOSD and MS
    • Visual recovery usually good
    • Relapsing course in ~50% of adults

Differential diagnosis

Differential Diagnosis Distinguishing Feature
Multiple Sclerosis Dawson fingers and calloso-septal interface lesions; short spinal cord lesions (<2 vertebral segments); no leptomeningeal enhancement
Neuromyelitis Optica spectrum disorder Area postrema and medulla lesions; posterior optic nerve and chiasm involvement; longitudinally extensive transverse myelitis
Acute Disseminated Encephalomyelitis Large, confluent, bilateral T2 lesions involving grey and white matter; often involves basal ganglia and thalami