If there's concern for an epidural abscess, is a lumbar puncture (LP) the first step?

Epidural Abscess Diagnosis: MRI is Essential, Not Lumbar Puncture

No, a lumbar puncture (LP) should NOT be performed when there is concern for an epidural abscess. MRI without and with IV contrast is the diagnostic procedure of choice. 1

Diagnostic Approach for Suspected Epidural Abscess

Initial Evaluation

• Epidural abscess is a medical emergency with incidence of 2.5-3 per 10,000 hospital admissions 1
• Clinical presentation often includes:
  • Back pain (most common symptom, 70-90% of cases) 2
  • Fever (least frequent presenting symptom) 2
  • Neurological deficits (only present in about one-third of cases) 2

Imaging Recommendations

1. First-line imaging: MRI without and with IV contrast

   • Sensitivity: 96%, Specificity: 94% for spine infection 1
   • Provides excellent tissue characterization and anatomic delineation 1
   • Can identify epidural abscess, define its size/extent, and determine presence of cord compression 1
   • Contrast enhancement is crucial for identifying epidural fluid collections 1

2. Alternative if MRI contraindicated: CT with myelography

   • Note: Standard CT has very low sensitivity (6%) for epidural abscess 1

Why LP is Contraindicated

• Lumbar puncture is NOT recommended due to risk of:
  • Iatrogenic spread of infection 2
  • Potential seeding of the CSF space 3
  • Worsening neurological status by introducing pathogens deeper into the CNS 3
  • Possible spinal cord injury if needle passes through the abscess 2

Management Considerations

Laboratory Testing

• Blood cultures (should be obtained before antibiotics) 2
• Inflammatory markers:
  • Elevated ESR has 100% sensitivity when combined with risk factors 2
  • C-reactive protein (CRP) 2
  • Complete blood count (leukocytosis present in ~2/3 of cases) 2

Treatment Approach

1. Prompt antibiotic therapy

   • Empiric coverage should include:
     • Vancomycin (for MRSA coverage)
     • Third or fourth-generation cephalosporin 2
   • S. aureus is the causative organism in approximately 2/3 of cases 2

2. Urgent surgical consultation

   • Early surgical decompression is often necessary 4
   • Surgical evacuation combined with 6-12 weeks of antibiotics is optimal therapy 4

Common Pitfalls to Avoid

• Delayed diagnosis (leads to worse neurological outcomes) 4
• Performing LP when epidural abscess is suspected 2
• Failing to obtain appropriate imaging (MRI) promptly 1
• Missing subtle neurological deficits that may indicate spinal cord compression 2
• Underestimating the urgency of treatment (epidural abscess is a medical emergency) 4

Early diagnosis with appropriate imaging and prompt treatment with antibiotics and surgical consultation is associated with excellent prognosis 4. Delays in diagnosis and treatment can lead to devastating neurological sequelae including permanent paralysis 5.