Spinal Infection

Aka: Spinal Infection, Spinal Cord Infection, Discitis, Diskitis

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II. Epidemiology

  1. Incidence: 0.2 to 2.8 cases per 10,000 per year
  2. Most common in ages 31 to 70 years old (peak Incidence ages 60-70 years old)
    1. Also occurs in children <5 years old
  3. Gender predominance: Males by a ratio >2:1

III. Precautions

  1. Spinal Epidural Abscess is frequently misdiagnosed on initial presentation
    1. Triad of back pain, fever and neurologic deficit is present in <15% of cases
    2. Fever is present in <50% of cases
  2. Be alert for red flag presentations (esp. with back pain)
    1. Unexplained fever (present in 86% of cases)
    2. Focal neurologic deficits with progressive or disabling symptoms (present in 82% of cases)
  3. References
    1. Bhise (2017) Am J Med 130(8): 975-81 +PMID: 28366427

IV. Types: Spinal Infection

  1. Spinal Epidural Abscess (SEA) - typically the primary infection site
    1. Infection in the space between the Dura Mater and the adjacent Vertebral Column
    2. Of the Spinal Infections, SEA is the most acute of presentations with fever, neurologic deficits and spinal pain
  2. Disc space infection (Discitis)
  3. Vertebral infection
    1. Spondylitis
    2. Osteomyelitis

V. Pathophysiology: Spinal Cord Injury Mechanisms

  1. Direct compression from Epidural Abscess
  2. Venous thrombosis or Thrombophlebitis of nearby veins
  3. Arterial perfusion disrupted
  4. Bacterial toxin induced injury
  5. Inflammatory mediator related injury

VI. Pathophysiology: Sources of Spinal Infection

  1. Hematogenous spread (50%)
  2. Contiguous spread (33%)
    1. Retropharyngeal Abscess
    2. Psoas Abscess
  3. Direct introduction of infection
    1. Spinal injection
    2. Spinal surgery

VII. Pathophysiology: Sites of Spinal Infection

  1. Most cases involve thoracolumbar spine
  2. Anterior Epidural Abscess (20%)
    1. Associated infections
      1. Disk space infection (Discitis)
      2. Vertebral Osteomyelitis
    2. Blunt Trauma and associated Hematoma infection
    3. Direct extension from adjacent infection
      1. Retropharyngeal Abscess
      2. Retroperitoneal abscess
  3. Posterior Epidural Abscess (80%)
    1. Distant source (Cellulitis, dental, Pharyngitis)

VIII. Causes

  1. Acute Infection (within 5-10 days)
    1. Staphylococcus aureus (most common)
    2. Actinomycosis (rare)
  2. Chronic Infection (within 3-6 months)
    1. Other indolent infections
    2. Fungus
    3. Tuberculosis (Pott's Disease)
      1. Vertebral collapse
      2. Sharply angulated spinal deformity

IX. Risk Factors

  1. Idiopathic without risk factors in 20% of cases
  2. Intravenous Drug Abuse
    1. Back pain in IVDA is a Spinal Infection until proven otherwise
  3. Immunodeficiency
    1. HIV Infection or AIDS
    2. Chronic Renal Failure (esp. Dialysis)
    3. Advanced Liver Disease
    4. Diabetes Mellitus
    5. Alcoholism
    6. Malignancy
    7. Immunosuppressants (e.g. Chemotherapy, Corticosteroids)
    8. Advanced Age
  4. Recent spinal procedure
    1. Spinal surgery
    2. Epidural Anesthesia
  5. Recent back Trauma
  6. Concurrent infectious sources
    1. Genitourinary infection
    2. Skin Infection
    3. Poor Dentition (Associated with Actinomyces)

X. Symptoms

  1. Back pain (70-90% of cases)
    1. Associated with secondary Muscle spasm
    2. Severe localized back pain not relieved with rest
    3. Pain provoked by standing and bearing weight
      1. Children may limp or refuse to crawl or walk
  2. Systemic symptoms
    1. Fever (30-60% of cases)
    2. Rigors
    3. Malaise
  3. Neurologic compromise (33% to 70% of cases, indicates spinal compression)
    1. Findings are often subtle, especially early in course
    2. Bowel or Bladder dysfunction
    3. Extremity weakness

XI. Signs

  1. Focal tenderness at involved spinous process (60-70% of cases)

XII. Precautions

  1. Keep a high index of suspicion
    1. Classic triad of back pain, fever and neurologic symptoms occurs in <37% of patients
  2. Avoid Lumbar Puncture
    1. Not diagnostic
    2. Risk of contiguous seeding of subarachnoid space (and secondary Meningitis)
  3. Disposition to rapid intervention at time of diagnosis
    1. Delays result in greater risk for neurologic injury
    2. Abscess results in direct mechanical compression of the spinal cord
    3. Local infection may result in ischemic injury to the cord via thrombosis of vessel Occlusion

XIII. Labs

  1. Complete Blood Count
    1. Leukocytosis (30 to 66% of cases)
  2. Acute phase reactants (increased in 95% of cases)
    1. Erythrocyte Sedimentation Rate (ESR) increased
    2. C-Reactive Protein (C-RP) increased
  3. Blood Cultures
    1. Identify responsible organism in 60% of cases

XIV. Imaging

  1. Precautions
    1. Image the entire spine (skip lesions are common in Spinal Infections)
  2. Gadolinium-enhanced Spine MRI (preferred)
    1. Test Sensitivity >90%
    2. Enhancing Lesion seen in T2-Weighted Images
    3. Differentiates Diskitis from Vertebral Osteomyelitis
    4. Skip lesions are present in 15% of cases and have several associated risk factors
      1. Older age
      2. Very high Erythrocyte Sedimentation Rate (ESR)
      3. Concurrent area of infection outside the spine
      4. Longer symptom duration
  3. CT with Myelography
    1. Indicated when MRI is contraindicated or unavailable
    2. Underestimates Spinal Epidural Abscess size

XV. Evaluation

  1. Have a high index of suspicion (see precautions above)
  2. Low risk patients (significant risk factors, reassuring history and exam)
    1. No imaging needed
  3. Moderate risk patients (risk factors present, but no motor deficits)
    1. Obtain CRP and ESR and if elevated obtain MRI
  4. High risk patients (motor deficits identified)
    1. Obtain MRI

XVI. Differential Diagnosis

  1. See Cauda Equina Syndrome
  2. Flu-like Symptoms with Spine Pain and Acute Neurologic Symptoms (e.g. cord syndrome, Peripheral Neuropathy)
    1. Spinal Epidural Abscess or Discitis
    2. Menigitis or Encephalitis
    3. Transverse Myelitis
    4. Endocarditis
    5. Myocarditis
    6. Toxic Shock Syndrome
    7. Psoas Abscess
    8. Carbon Monoxide Poisoning
    9. Swaminathan, Shoenberger and Long in Swadron (2023) EM:Rap 23(3): 19-21

XVII. Management

  1. Emergent Neurosurgery or Spine SurgeryConsultation
  2. Surgical decompression of Epidural Abscess (first-line, preferred management)
    1. Indications
      1. Developing or worsening neurologic deficits
        1. However, pre-surgical paralysis may not benefit from surgery
      2. Cervical or Thoracic Spine involvement
        1. Higher risk for neurologic complications than Lumbar Spine (except Cauda Equina Syndrome)
      3. Phlegmon
    2. Open decompression (preferred)
      1. May be performed with endoscopy-assisted surgery
    3. Percutaneous drainage (aspiration under CT guidance)
      1. Consider in posterior Spinal Epidural Abscess AND
      2. Lack of neurologic deficit OR high surgical risk patient
    4. References
      1. Epstein (2015) Surg Neurol Int 6(suppl 19): S476-86 [PubMed]
  3. Empiric Antibiotics
    1. Start early empiric therapy and modify based on culture results
      1. Discuss with neurosurgery (may ask to withhold Antibiotics until surgical culture obtained)
      2. Typical IV Antibiotic duration: 6 weeks
    2. Drug 1: MRSA Coverage (Staphylococcus aureus is most common cause, used with drug 2 below)
      1. Vancomycin 15-20 mg/kg IV every 8-12 hours (dosing must be calculated based on weight, levels)
      2. Alternatives: Linezolid, Daptomycin
    3. Drug 2: Gram Negative, esp. IVDA, Immunosuppression, UTI (used in combination with MRSA Drug 1 coverage)
      1. Gram Negative Coverage without Pseudomonas coverage
        1. Ceftriaxone 2 g IV every 24 hours
        2. Cefepime 2 g IV every 8 hours
        3. Levofloxacin 750 mg IV every 24 hours
      2. Gram Negative With Pseudomonas coverage as indicated (e.g. IV Drug Abuse, recent hospitalization)
        1. Ceftazidime 1-2 g IV every 8-12 hours
        2. Ciprofloxacin 400 mg IV every 12 hours
        3. Piperacillin-Tazobactam 4.5 g IV every 6 to 8 hours
        4. Meropenem 1 g IV every 8 hours
    4. Drug 3: Anaerobe Coverage
      1. Metronidazole 500 mg IV every 6 hours
    5. Candida Coverage Indications
      1. Immunocompromised State
      2. Recent Spine Surgery
    6. Other modified Antibiotic coverage
      1. Mycobacterium tuberculosis suspected

XVIII. Prognosis: Positive prognostic indicators

  1. Intact or only mild neurologic symptoms prior to intervention
    1. Most accurate prognostic indicator
    2. Neurologic symptoms progress with delayed diagnosis
    3. Residual deficits persist after surgery in 50% of cases (paralysis is often irreversible)
  2. Age under 60 years
  3. Cord symptoms (e.g. Bladder dysfunction) <24 hours
  4. No comorbid conditions
  5. Thecal sac compression <50%

XIX. Complications

  1. Cauda Equina Syndrome
    1. Results from direct mechanical compression of cord
  2. Meningitis (or overwhelming Sepsis)
    1. Results from spread into subarachnoid space
  3. Mortality
    1. Mortality rate: 5%

XX. References

  1. Dasburg (2020) Crit Dec Emerg Med 34(6): 28-9
  2. Della-Giustina (2014) Crit Dec Emerg Med 28(3): 2-9
  3. Long and Carlson in Swadron (2022) EM:Rap 22(7): 7-9
  4. Bond (2016) Biomed Res Int 2016:1614328 +PMID: 28044125 [PubMed]
  5. Chao (2002) Am Fam Physician 65(7):1341-6 [PubMed]
  6. Tompkins (2010) J Emerg Med 39(3): 384-90 [PubMed]

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