A unique case of multiphasic ADEM or what else?

Area of Science:

• Neurology
• Immunology
• Neuroimmunology

Background:

• Acute disseminated encephalomyelitis (ADEM) is typically a monophasic post-infectious demyelinating disease.
• A subset of ADEM patients may develop relapsing disorders, including recurrent DEM (RDEM), multiphasic DEM (MDEM), neuromyelitis optica spectrum disorders (NMOSD), and multiple sclerosis (MS).
• This case presents an adult patient with two ADEM-like episodes separated by an unusually long, 8-year symptom-free interval.

Observation:

• A 48-year-old male experienced initial ADEM-like symptoms (encephalopathy, dysarthria) treated successfully with steroids.
• Eight years later, he presented with recurrent encephalopathy and balance issues, new MRI lesions, and a single CSF-restricted IgG band.
• Despite steroid and apheresis treatments, symptoms persisted, and antibody testing for anti-aquaporin-4 and anti-MOG was negative.

Findings:

• The patient received Rituximab, leading to neurological and radiological stability.
• This case meets diagnostic criteria for MDEM but features an exceptionally long interval between episodes.
• The prolonged interval suggests a potential new nosological entity within the spectrum of demyelinating diseases.

Implications:

• This case expands the known clinical spectrum of multiphasic disseminated encephalomyelitis (MDEM).
• The 8-year gap between ADEM-like episodes challenges conventional timelines for relapsing demyelinating diseases.
• Further research is needed to classify this extended-interval presentation and its place among neuroinflammatory disorders.