Basics
Description
- A rare pyogenic infection of the spinal epidural space
- Most common in thoracic spine, followed by lumbar and cervical
Etiology
- Focus of infection is present followed by either hematogenous spread (~50%) or direct extension
- No focus identified in ~1/3
- Most common source is skin infection:
- Any pyogenic infection may be source
- Staphylococcus aureus accounts for >50% of cases:
- Many are MRSA
- Streptococcus is 2nd most common
- Haemophilus influenzae, gram-negative bacilli, mycobacteria, anaerobic, coagulase-negative Staphylococcus, fungal, and mixed infections also occur
- Complication of epidural catheter or spinal surgery
- Unusual complication of lumbar puncture (usually follows multiple attempts)
- Children present similar to adults with back pain, fever, and neurologic signs as well as nonspecific systemic symptoms
- Infants may exhibit only fever, irritability, and associated meningitis
- Sphincter disturbance is frequently seen
- Usually secondary to hematogenous spread
- Location and bacteriology similar to adults
Diagnosis
Signs and Symptoms
- Fever and severe back pain represent "red flag" for potentially serious condition:
- If pain is radicular or there is neurologic disturbance, likelihood of epidural abscess is increased
- Classic presentation:
- Severe, progressive back pain (often radicular)
- Fever
- Neurologic deficit:
- Weakness or paralysis
- Sensory level
- Sphincter disturbance
- May present with signs and symptoms of sepsis without prominent back pain
- Occurs at all ages including infants:
- Most patients have predisposing condition:
- IV drug abuse (IVDA)
- Diabetes
- Malignancy
- Chronic steroids
- Chronic alcoholism
- Instrumentation or spinal surgery
- Indwelling vascular catheter
- May occur in the absence of identifiable predisposing factors
History
- Back pain
- Fever
- Neurologic deficit:
- Weakness
- Paresthesias
- Incontinence
Physical Exam
- Fever
- Localized spinal tenderness and/or erythema
- Neurologic deficit
- Evidence of IV drug use or other predisposing factors
Essential Workup
- History should include predisposing conditions when this diagnosis is suspected
- Physical exam for source of infection, localized spinal tenderness, and neurologic findings:
- Decreased sphincter tone
- Saddle anesthesia
- Lower extremity weakness
- Postvoid residual or sonography
- Younger adults should have <50 mL postvoid residual urine:
- Older adults may have residual of 100 mL
- Erythrocyte sedimentation rate (ESR) as below
- MRI with and without gadolinium contrast is the diagnostic test of choice:
- CT with IV contrast or myelography if MR not available
- Suspected epidural abscess is an emergency and requires emergent imaging
Diagnosis Tests & Interpretation
Lab
- ESR is almost always elevated (~100%), but is nonspecific:
- Normal ESR makes diagnosis much less likely
- C-reactive protein nearly always elevated
- Blood cultures often positive (~60%)
- Leukocytosis with left shift is common (~70%)
- CSF often abnormal, but nondiagnostic; routine lumbar puncture should be avoided when epidural abscess is primarily suspected (may cause meningitis)
Imaging
- MRI is at least 90% sensitive:
- Shows high-intensity lesion on T2 imaging
- CT with IV contrast if MR or myelography not available
- Myelography and CT myelography are also sensitive, but risk dissemination
- Plain films are often abnormal but nonspecific
Differential Diagnosis
- Diagnosis is difficult owing to rarity of condition and nonspecific symptoms:
- Multiple physician encounters commonly precede diagnosis
- Most common initial diagnosis is benign musculoskeletal pathology: Muscular or ligamentous pain, degenerative arthritis, compression fracture, discogenic pain
- Back pain with fever, systemic signs, and symptoms:
- Vertebral osteomyelitis
- Spinal tumor (usually there is a known primary)
- Meningitis (cervical epidural abscess may mimic, but bacterial meningitis usually associated with abnormal mental status)
- Discitis (usually postinstrumentation)
- Pyelonephritis
- Back pain with neurologic signs and symptoms:
- Cord compression
- Cord ischemia
- Disc herniation
Fever and back pain should be urgently investigated with MRI when epidural abscess is suspected
Treatment
Pre-Hospital
Spinal immobilization if trauma suspected or other cause of fracture suspected
Initial Stabilization/Therapy
Broad-spectrum parenteral antibiotics early
- Must include coverage for S. aureus, Streptococci, and gram-negative rods
- Vancomycin (for possible MRSA) and a 3rd-generation cephalosporin (for gram-negative coverage) are appropriate initial antibiotics
- Cover Pseudomonas if IVDA
- 1 suggested regimen includes vancomycin, ceftazidime, and metronidazole (for anaerobes)
Ed Treatment/Procedures
- Urgent imaging essential when diagnosis is considered
- Delay in treatment is associated with poorer outcome
- If unable to localize lesion on physical exam, consider imaging entire spine
- Urgent neurosurgical consultation or transfer for definitive therapy (surgical decompression) after diagnosis and antibiotic administration:
- Conservative treatment (prolonged [6 wk] antibiotic therapy) may be successful
Medication
- Ceftazidime: 2 g (peds: 50 mg/kg)
- Vancomycin: 15 mg/kg IV loading dose (peds: 10-15 mg/kg q6-8h) q12h
- Metronidazole: 500 mg IV
First Line
- Ceftazidime
- Vancomycin
- Metronidazole if anaerobes suspected
Follow-Up
Disposition
Admission Criteria
Patients with epidural abscess should be admitted; MRI is needed emergently; transfer patient if necessary
Discharge Criteria
Patients with definite or strongly suspected epidural abscess should not be discharged
Issues for Referral
Patients with spinal epidural abscess require admission to facility with neurosurgical capability:
- Transfer usually indicated if a neurosurgeon or MRI is unavailable:
- Administer antibiotics and obtain blood cultures (positive in ~60%) prior to antibiotics unless this results in a delay
Pearls and Pitfalls
- Successfully treated epidural abscess may reoccur, especially in the setting of decreased immunity
- Patients with Staphylococcal bacteremia and back pain or neurologic signs/symptoms should be investigated for epidural abscess
- Failure to order images that include the involved area:
- Careful physical exam for areas of spinal tenderness and level of neurologic deficit may help avoid this pitfall:
- Consider both thoracic and lumbar imaging for a problem suspected in the mid back and cervical and thoracic imaging for upper back and neck pathology
- If unable to localize lesion on physical exam, consider imaging entire spine
Additional Reading
- Darouiche RO. Spinal epidural abscess. New Engl J Med. 2006;355:2012-2020.
- Davis DP, Salazar A, Chan TC, et al. Prospective evaluation of a clinical decision guideline to diagnose spinal epidural abscess in patients who present to the emergency department with spine pain. J Neurosurg Spine. 2011;14:765-770.
- 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;26:285-291.
- Karikari IO, Powers CJ, Reynolds RM, et al. Management of a spontaneous spinal epidural abscess: A single-center 10-year experience. Neurosurgery. 2009;65:919-923.
- Siddiq F, Chowfin A, Tight R, et al. Medical vs surgical management of spinal epidural abscess. Arch Intern Med. 2004;164:2409-2412.
- Soehle M, Wallenfang T. Spinal epidural abscesses: Clinical manifestations, prognostic factors, and outcomes. Neurosurgery. 2002;51:79-87.
Codes
ICD9
324.1 Intraspinal abscess
ICD10
G06.1 Intraspinal abscess and granuloma
SNOMED
- 61974008 epidural abscess (disorder)
- 427916006 Abscess in epidural space of thoracic spine (disorder)
- 429437003 Abscess in epidural space of lumbar spine (disorder)
- 427787004 Abscess in epidural space of cervical spine (disorder)