Can migraine symptoms mimic those of meningitis or encephalitis?

Migraine Can Mimic Symptoms of Meningitis and Encephalitis

Yes, migraine can cause symptoms that mimic meningitis or encephalitis, making differential diagnosis crucial to avoid unnecessary invasive procedures and treatments. 1

Overlapping Symptoms Between Migraine and Meningitis/Encephalitis

Common Overlapping Symptoms

• Headache: Severe, often bilateral headache is present in both conditions
• Photophobia: Sensitivity to light occurs in both migraine and meningitis
• Nausea and vomiting: Common in both conditions
• Neck stiffness: Can occur in severe migraine, mimicking meningeal signs

Key Differences for Differential Diagnosis

• Altered mental status: A major criterion for encephalitis diagnosis that persists ≥24 hours 1
• Fever: Temperature ≥38°C (100.4°F) is typically present in meningitis/encephalitis but absent in migraine 1
• CSF abnormalities: Increased WBC count ≥5/mm³ and elevated protein are found in meningitis/encephalitis but not in migraine 1
• Focal neurological deficits: More common and persistent in encephalitis than in migraine (where they are transient if present) 1

Diagnostic Approach When Symptoms Overlap

When a patient presents with headache and associated symptoms that could represent either migraine or meningitis/encephalitis:

1. Assess for red flags:

   • Fever ≥38°C (100.4°F)
   • Altered mental status lasting >24 hours
   • Seizures not attributable to pre-existing conditions
   • New persistent focal neurological findings
   • Immunocompromised status
   • Abrupt onset/"worst headache of life"

2. Perform thorough neurological examination:

   • Evaluate for meningeal signs (neck stiffness, Kernig's and Brudzinski's signs)
   • Note that meningeal signs have high specificity but sensitivity as low as 5% 1
   • Check for focal neurological deficits and cranial nerve abnormalities

3. Consider diagnostic testing if red flags present:

   • Neuroimaging (MRI brain with and without contrast)
   • Lumbar puncture for CSF analysis
   • EEG if encephalitis is suspected

Important Clinical Considerations

• In cases reported in the literature, migraine-like headaches have been documented in patients who were later diagnosed with aseptic meningitis 2
• Headache of abrupt onset or described as "the worst headache of life" warrants investigation for meningitis or subarachnoid hemorrhage, even if it resembles migraine 3
• The presence of fever strongly suggests meningitis/encephalitis rather than migraine 1

Management Algorithm

1. If typical migraine presentation without red flags:

   • Treat according to migraine protocols
   • Monitor for any change in symptoms

2. If any red flags present:

   • Proceed with neuroimaging and consider lumbar puncture
   • Start empiric treatment for encephalitis/meningitis while awaiting results if high clinical suspicion 1
   • Include acyclovir (10 mg/kg IV every 8 hours) and appropriate antibiotics 1

3. If diagnostic tests are negative but symptoms persist:

   • Consider consultation with neurology
   • Re-evaluate for other causes of headache

Pitfalls to Avoid

• Misdiagnosing meningitis as migraine: Can lead to delayed treatment and poor outcomes
• Misdiagnosing migraine as meningitis: Can lead to unnecessary hospitalization, procedures, and antimicrobial treatment
• Incomplete assessment: Failing to perform a complete neurological examination in all headache patients
• Overlooking atypical features: New or different headache characteristics in a patient with known migraine should raise suspicion

Remember that while migraine can mimic some symptoms of meningitis and encephalitis, the presence of altered mental status, fever, and abnormal CSF findings strongly favor an infectious or inflammatory process of the central nervous system rather than migraine.