What is the appropriate evaluation and management for a patient suspected of having a spinal epidural abscess?

Evaluation and Management of Spinal Epidural Abscess

MRI with and without contrast is the gold standard imaging modality for diagnosing spinal epidural abscess, with 96% sensitivity and 94% specificity, and should be performed urgently in all suspected cases to prevent neurological deterioration. 1

Clinical Presentation and Risk Factors

• Patients with spinal epidural abscess commonly present with back pain (70-90% of cases), fever (less common), and neurological deficits (in approximately one-third of cases) 2
• High-risk populations include those with:
  • Intravenous drug use 3, 4
  • Diabetes mellitus 3, 4, 5
  • Immunocompromised states (HIV, cancer, dialysis) 3, 4
  • Recent spinal procedures or surgeries 1, 2
  • Concurrent infections (endocarditis, dental abscesses, soft tissue infections) 2

Diagnostic Algorithm

1. Laboratory Testing:

   • Obtain ESR and CRP (ESR has 100% sensitivity when combined with risk factors) 4, 2
   • Complete blood count (leukocytosis present in ~67% of cases) 4, 2
   • Blood cultures (before antibiotic administration) 4

2. Imaging:

   • First-line: MRI without and with IV contrast of the affected spinal region 1

     • Consider imaging the entire spine in high-risk patients (IV drug users) or if multifocal infection is suspected 1, 3
     • Optimal protocol includes T1-weighted, T2-weighted sequences with fat suppression or STIR, followed by contrast-enhanced T1-weighted sequences 3

   • If MRI contraindicated: CT with IV contrast (sensitivity 79%, specificity 100% for spine infection, but only 6% sensitivity for epidural abscess) 1, 3

   • For equivocal cases: Consider FDG-PET/CT as a complementary examination 1

3. Avoid:

   • Lumbar puncture in suspected epidural abscess (risk of spreading infection) 1, 2
   • Plain radiographs as primary imaging (insensitive in early infection) 1, 3
   • MRI with contrast only without obtaining precontrast images 1, 3

Management

1. Immediate Interventions:

   • Administer appropriate empiric antibiotics at the earliest sign of infection 1
     • Coverage should include vancomycin (for MRSA) and a third/fourth-generation cephalosporin 2
     • Staphylococcus aureus is the causative organism in approximately two-thirds of cases 2

2. Surgical Consultation:

   • Obtain urgent neurosurgical or orthopedic spine consultation to determine need for surgical intervention 1
   • Surgical decompression is typically indicated for patients with:
     • Neurological deficits 5, 6
     • Age >65 years 5
     • MRSA infection 5
     • Diabetes 5

3. Medical Management:

   • Medical management alone may be considered in select patients without the above risk factors 5, 6
   • Patients with higher CRP, longer symptom duration, and concurrent non-spinal infections are at higher risk of failing medical management 6
   • Close neurological monitoring is essential if pursuing non-operative management 5

Pitfalls to Avoid

• Delayed diagnosis due to variable clinical presentation (classic triad of fever, back pain, and neurological deficits is often incomplete) 2, 7
• Relying solely on WBC count, which may be normal in up to 40% of cases 4
• Failing to image the entire spine when indicated, as 9% of cases have non-contiguous (skip) lesions 6
• Underestimating the urgency of treatment, as neurological outcomes correlate with time to intervention 1, 2
• Missing epidural abscess in pediatric patients who may lack traditional risk factors 8

Follow-up

• Antibiotic therapy typically continues for 4-6 weeks 7
• Serial imaging may be necessary to evaluate treatment response 1
• Monitor for development of spinal instability or deformity that may require subsequent surgical stabilization 1