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epidural abscess

Localized collection of pus between the dura mater & the overlying skull or adjacent vertebral column. Information here in general refers to spinal epidural abscess. Etiology: 1) hematogenous dissemination from infectious foci elsewhere in the body 2) continguous extension of an adjacent infection - infected intervertebral discs 3) may be associated with transient bacteremia 4) organisms a) Staphylococcus aureus, including MRSA (50%) b) gram negative bacilli (12-17%) 1] Escherichia coli 2] Pseudomonas aeruginosa c) Streptococci (8-17%) 5) primary source of infection not identified in 20-40% 6) risk factors - prolonged use of epidural catheter - epidural injections - diabetes mellitus - HIV1 infection - trauma - injection drug use - tattoos - alcoholism - acupuncture [1] Clinical manifestations: 1) clinical manifestations due to a) compression on adjacent structures b) ischemia due to thrombophlebitis 2) spinal pain followed by nerve root pain 3) neurologic manifestations occur late a) long spinal tract signs b) complete paralysis may occur Red flags suggesting spinal epidural abscess - unexplained fever - focal neurologic deficit with progressive/disabling symptoms - active infection - immunosuppression - intravenous drug use - prolonged glucocorticoid use - unexplained weight loss - enduring back pain - history of cancer Laboratory: 1) complete blood count (CBC) 2) blood cultures prior to antibiotic therapy 3) inflammatory markers - ESR, serum CRP Special laboratory: - CT-guided fine-needle aspiration [1] - not initial diagnostic test [6] Radiology: 1) magnetic resonance imaging (MRI) with gadolinium enhancement a) diagnostic procedure of choice b) preferred over computed tomography (CT) because of better visualization of the spinal cord & epidural space c) identification of associated pathology 1] osteomyelitis 2] intramedullary spinal cord lesions 2) myelogram 3) X-ray may add to diagnostic confirmation Differential diagnosis: - vertebral osteomyelitis Management: 1) surgical decompression, drainage of the abscess & antibiotics [2] a) empiric coverage for Staphylococcus aureus & gram-negative bacilli - coverage should include MRSA - vancomycin & 3rd or 4th generation cephalosporin (cefepime) b) culture of surgical tissue c) decompressive laminectomy 1] not indicated for paralysis > 24-36 hours 2] may be useful in treating epidural infection 2) antibiotics alone for patients a) with high operative risk b) paralysis > 24 hours c) panspinal infection d) lack of consent for surgery 3) antibiotic alone may be considered for patients without long spinal tract signs - frequent follow-up neurologic exams & serial MRIs to demonstrate epidural abscess resolution [1] 4) independent predictors of failure for non-operative management a) presenting motor deficit b) pathologic or compression fracture in affected levels c) active malignancy d) diabetes mellitus e) sensory changes f) dorsal location of abscess [4] Notes: - diagnosis initially missed in 75-84% of patients [3]

Related

brain abscess subdural empyema; subdural abscess

General

abscess

References

  1. Medical Knowledge Self Assessment Program (MKSAP) 11, 15, 16, 18, 19. 17, 18. American College of Physicians, Philadelphia 1998, 2009, 2018, 2021. 2012, 2015, 2018.
  2. Darouiche RO Spinal epidural abscess N Engl J Med 2006, 355:2012 PMID: 17093252
  3. Bhise V, Meyer AND, Singh H et al. Errors in diagnosis of spinal epidural abscesses in the era of electronic health records. Am J Med 2017 Aug; 130:975 PMID: 28366427 http://www.amjmed.com/article/S0002-9343(17)30323-6/fulltext
  4. Shah AA, Ogink PT, Nelson SB, Harris MB, Schwab JH. Nonoperative management of spinal epidural abscess: Development of a predictive algorithm for failure. J Bone Joint Surg Am 2018 Apr 4; 100:546 PMID: 29613923 https://insights.ovid.com/crossref?an=00004623-201804040-00002
  5. Chow F Brain and Spinal Epidural Abscess Continuum (Minneap Minn). 2018 Oct;24(5, Neuroinfectious Disease):1327-1348. PMID: 30273242 Review.
  6. NEJM Knowledge+