Does Mycoplasma infection cause Acute Disseminated Encephalomyelitis (ADEM)?

Mycoplasma Infection Can Cause Acute Disseminated Encephalomyelitis (ADEM)

Yes, Mycoplasma pneumoniae infection is a recognized trigger for Acute Disseminated Encephalomyelitis (ADEM), which requires prompt treatment with immunomodulatory therapy to reduce morbidity and mortality.

Pathophysiological Connection

Mycoplasma pneumoniae is one of several infectious agents that can trigger ADEM through post-infectious immune-mediated mechanisms. ADEM represents an autoimmune demyelinating process that occurs following an infection outside the central nervous system 1.

The pathophysiology involves:

• Initial Mycoplasma infection (typically respiratory)
• Subsequent immune-mediated demyelination of the brain parenchyma
• Development of neurological dysfunction

Diagnostic Approach

When evaluating a patient with suspected ADEM following Mycoplasma infection:

1. Clinical presentation:

   • Altered mental status (required criterion)
   • Neurological dysfunction following a recent respiratory infection
   • Symptoms may include focal neurological deficits, seizures, behavioral changes 1

2. Laboratory investigations:

   • CSF analysis showing mild mononuclear pleocytosis
   • Elevated CSF protein with normal glucose
   • Serological testing for Mycoplasma pneumoniae (IgM antibodies)
   • PCR testing of respiratory specimens for Mycoplasma 2

3. Neuroimaging:

   • MRI showing multifocal T2-weighted hyperintense lesions in the white matter
   • Lesions typically in periventricular regions 3

Treatment Recommendations

The management of ADEM secondary to Mycoplasma infection requires a stepwise approach:

1. First-line therapy: High-dose corticosteroids

   • Methylprednisolone 500-1000 mg IV daily for 3-5 days 1

2. Second-line therapy (if inadequate response to corticosteroids):

   • Intravenous immunoglobulin (IVIG) 2 g/kg divided over 2-5 days 1

3. Third-line therapy (for refractory cases):

   • Plasma exchange (plasmapheresis) for 5-7 treatments 2

4. Antimicrobial therapy:

   • Macrolide antibiotics (azithromycin or clarithromycin) should be administered concurrently to treat the underlying Mycoplasma infection 2, 4

Evidence from Case Reports

Multiple case reports document the association between Mycoplasma pneumoniae and ADEM:

• A 21-year-old female with ADEM secondary to Mycoplasma pneumoniae showed marked improvement with azithromycin and plasmapheresis after failing to respond to steroids and IVIG 2

• A 17-year-old boy with severe ADEM and documented Mycoplasma pneumoniae in CSF improved significantly with erythromycin, immunoglobulins, and corticosteroids 4

• A 28-year-old man with fulminant ADEM following Mycoplasma pneumonia required hypothermia therapy after failing to respond to surgical decompression and corticosteroids 5

Clinical Pearls and Pitfalls

• Diagnostic pitfall: Failure to consider Mycoplasma as an etiology for ADEM, especially in patients with preceding respiratory symptoms

• Treatment pitfall: Delaying immunomodulatory therapy while waiting for confirmatory test results can worsen outcomes

• Important consideration: Some patients may not respond to first-line corticosteroid therapy and require escalation to IVIG or plasmapheresis 2

• Monitoring: Serial neuroimaging is important to assess treatment response and disease progression 3

• Differential diagnosis: Consider other causes of encephalitis including direct viral infections, other post-infectious processes, and antibody-mediated encephalitis 1