Epidural Abcess

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Epidural Abcess
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Note Dura adheres to the skull above the foramen
magnum and anteriorly down to L1
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Mechanism of Damage

• Direct compression
• Thrombosis and thrombophlebitis of nearby veins
• Interruption of the arterial blood supply
• Focal vasculitis
• Bacterial toxins and mediators of inflammation

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Epidemiology

• Incidence- 25/100,000 hospital admissions
• 0.5-3 of patients with long term epidural
  catheters

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Microbiology

• Staphylococcus aureus 63 percent
• Gram negative bacilli 16 percent
• Streptococci 9 percent
• Coagulase-negative staphylococci 3 percent,
  mostly occurring in patients with prior spinal
  instrumentation
• Anaerobes 2 percent
• Others 1 percent
• Unknown 6 percent
• Mycobacteria- excluded in this list, but
  important in developing nations

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Sources of Infection

• No source IDd- 30
• Skin and soft tissue infxn- 22
• Spinal surgery- 12
• IVDU 10
• Other, including epidural catheters- 8
• Bone or Joint- 7
• UTI, URI, Sepsis, Abdomen, and other catheters
  each make up adtl lt 3

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Clinical Presentation

• Classic Triad
• Fever
• Back Pain
• Neurologic Deficit
• Progression Back pain? root pain?
  motor/sensory/bowel bladder? paralysis

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Delays in Diagnosis

• 63 SEA patients matched to 126 controls with
  spine pain
• Diagnostic delays in 75 of SEA patients.
• Residual motor weakness in 45 vs. only 13 of
  patients without diagnostic delays (p lt 0.05).
• Classic triad" in 13 of SEA patients and 1
  of controls during the initial visit (p lt 0.01)
• gt 1 RFs in 98 of SEA patients and 21 of
  controls (p lt 0.01)
• RFs-DM,IVDU, liver disease, renal failure,
  indwelling catheter, immunocompromised, recent
  invasive spinal procedure, vertebral fracture,
  and distant site of infection
• The clinical presentation and impact of
  diagnostic delays on emergency department
  patients with spinal epidural abscess. Davis DP
  Wold RM Patel RJ Tran AJ Tokhi RN Chan TC
  Vilke GM. J Emerg Med 2004 Apr26(3)285-91.

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Imaging
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Therapy

• Principles
• Reduction of the inflammatory mass
• Eradication of the causative organism
• Empiric Abx
• Nafcillin plus metronidazole plus either
  cefotaxime or ceftazidime
• Vancomycin (1 g every 12 hours) can be
  substituted for nafcillin
• Tx X 4-6 W or until improvement on MRI

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Therapy

•   A retrospective analysis of 57 cases txd over
  14 y in S.Dakota
• The lumbar region was most frequently involved,
  and 46 of patients were immunocompromised.
  Staphylococcus aureus was the most frequently
  encountered pathogen.
• For 60 treatment courses, management included
  medical only (25 patients), medical plus computed
  tomography-guided percutaneous needle aspiration
  (7 patients), or surgical drainage approaches (28
  patients).
• Prolonged use of antibiotics alone or combined
  with percutaneous needle drainage yielded
  clinical outcomes comparable with antibiotics
  plus surgical intervention, irrespective of
  patient age, presence of comorbid illness,
  disease onset, neurologic abnormality at time of
  presentation, or abscess size.
• Medical vs surgical management of spinal epidural
  abscess. Siddiq F Chowfin A Tight R Sahmoun
  AE Smeg RA Jr Arch Intern Med 2004 Dec
  13-27164(22)2409-12.

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References

• www.uptodate.com, unless otherwise noted