emDOCs Podcast – Episode 63: Spinal Epidural Abscess

Today on the emDOCs cast with Brit Long, MD (@long_brit), we cover spinal epidural abscess.

Episode 63: Spinal Epidural Abscess

Background:

• Definition: SEA is a pyogenic infection within the epidural space; may involve 3-5 vertebral spaces.
• Many patients with SEA have multiple visits before diagnosis is made. It is a challenging diagnosis because back pain is a frequent condition evaluated in the ED, but SEA is rare overall.
• Accounts for 1-2/10,000 inpatient admissions; 1/350 patients who present with back pain to an ED will have a spinal emergency.
• The mortality for SEA approximates 5%; 50% have residual deficits, with worse outcomes the longer the delay in diagnosis.

Pathophysiology:

• SEA an occur due to hematogenous, direct extension from infected contiguous tissue, direct inoculation.
  • Spinal cord damage occurs due to direct compression, thrombosis/thrombophlebitis of nearby veins, arterial supply disruption, bacterial toxins/inflammatory mediators.
  • Neurologic deficits may develop due to these factors.

Risk Factors:

• Diabetes, HIV, cancer, renal disease, liver disease, dialysis/recurrent vascular access, alcoholism, IV drug use, immunocompromise, spinal instrumentation/surgery, older age

Presentation:

• Many patients have a nonspecific presentation, contributing to its misdiagnosis.
• The most common symptom is back pain.
  • Triad of back pain, fever, and neurologic deficit present in < 15%
  • Fever is present in < 50%
  • 4 stages: back pain, radiculopathy, weakness (motor/sensory changes, bowel/bladder incontinence), paralysis
  • Neurologic symptoms indicate spinal compression and can occur in up to one third of patients
  • Paralysis is often irreversible once it develops
• Differential for flu/COVID-like symptoms: endocarditis, myocarditis, meningitis, toxic shock syndrome, CO toxicity, SEA, and others

ED Evaluation:

• WBC elevated in 50-66% of patients, but this should not rule out SEA if normal.
• ESR/CRP sensitive (High 90’s), but nonspecific.
• Blood cultures positive in up to 60%.
• Imaging modality of choice is MRI of whole spine with contrast.
  • Skip lesions occur in about 15%. They occur more frequently in those with older age, extremely elevated ESR, concomitant area of infection outside of spine, longer symptom duration.
• CT myelogram can be used but may underestimate abscess size.
• Approach:
  • Perform history and exam to determine pretest probability
    • Low risk (no or few risk factors => No further evaluation
    • Moderate risk (no motor deficits, risk factors present) => Obtain inflammatory markers. If elevated => obtain MRI. If negative => Stop workup
    • Motor deficit => MRI

Management:

• Components are source control, blood cultures, antibiotics, early consultation with spine specialist.
• Surgery indications:
  • Developing or worsening neurologic deficits (paralysis upon presentation may be treated with antibiotics alone due to low likelihood of improvement with surgery)
  • Cervical or thoracic region = higher risk of neurologic sequelae
  • Potential CT-guided needle aspiration + antibiotics for posterior SEA, lack of neurologic deficit, high surgical risk,
  • Phlegmon = may not benefit from surgery
• Antibiotics: Most common causes are Staphylococcus aureus, followed by gram negative bacilli, streptococcal species, coagulase negative staphylococci
  • If stable: obtain blood cultures, consult specialist (may want to obtain cultures of material in OR) before administering antibiotics
  • If unstable: obtain blood cultures and give broad-spectrum antibiotics
    • Vancomycin 20 mg/kg IV, metronidazole 500 mg IV, and a third generation cephalosporin (cefotaxime 2 g IV, ceftriaxone 2 g IV, or ceftazidime 2 g IV)

References:

1. Long B, Carlson J, Montrief T, Koyfman A. High risk and low prevalence diseases: Spinal epidural abscess. Am J Emerg Med. 2022 Mar;53:168-172.
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6. Adogwa O, Karikari IO, Carr KR, et al. Spontaneous spinal epidural abscess in patients 50 years of age and older: a 15-year institutional perspective and review of the literature: clinical article. J Neurosurg Spine. 2014;20(3):344-349.
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8. Lener S, Hartmann S, Barbagallo GMV, Certo F, Thomé C, Tschugg A. Management of spinal infection: a review of the literature. Acta Neurochir (Wien). 2018;160(3):487-496.
9. Patel AR, Alton TB, Bransford RJ, Lee MJ, Bellabarba CB, Chapman JR. Spinal epidural abscesses: risk factors, medical versus surgical management, a retrospective review of 128 cases. The Spine Journal. 2014;14(2):326-330.
10. Alerhand S, Wood S, Long B, Koyfman A. The time-sensitive challenge of diagnosing spinal epidural abscess in the emergency department. Intern Emerg Med. 2017;12(8):1179-1183.
11. Davis DP, Salazar A, Chan TC, Vilke GM. Prospective evaluation of a clinical decision guideline to diagnose spinal epidural abscess in patients who present to the emergency department with spine pain. 2011;14(6):765.
12. Davis DP, Wold RM, Patel RJ, et al. The clinical presentation and impact of diagnostic delays on emergency department patients with spinal epidural abscess. J Emerg Med. 2004;26(3):285-291.
13. Bond A, Manian FA. Spinal Epidural Abscess: A Review with Special Emphasis on Earlier Diagnosis. Biomed Res Int. 2016;2016:1614328