Spinal Infection

Aka: Spinal Infection, Spinal Cord Infection, Spinal Osteomyelitis, Spinal Epidural Abscess, Epidural Abscess, Discitis, Diskitis

1. See Also
   1. Osteomyelitis
   2. Vertebral Osteomyelitis
   3. Acute Spinal Cord Compression (includes Spinal Cord Syndrome)
2. 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
3. Precautions
   1. Spinal Epidural Abscess is frequently misdiagnosed on initial presentation
   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
4. 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
5. 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
6. 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)
7. 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
8. 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. AIDS
      2. Chronic Renal Failure (esp. Dialysis)
      3. Diabetes Mellitus
      4. Alcoholism
      5. Malignancy
   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)
9. 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 (70% of cases, but often subtle)
      1. Bowel or Bladder dysfunction
      2. Extremity weakness
10. Signs
    1. Focal tenderness at involved spinous process (60-70% of cases)
11. 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
12. Labs
    1. Complete Blood Count
       1. Leukocytosis (30% 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
13. Imaging
    1. Gadolinium-enhanced Spine MRI (preferred)
       1. Test Sensitivity >90%
       2. Enhancing Lesion seen in T2-Weighted Images
       3. Differentiates Diskitis from Vertebral Osteomyelitis
    2. CT with Myelography
14. Management
    1. Emergent Neurosurgery Consultation
    2. Surgical decompression (first-line, preferred management)
       1. Open decompression (preferred)
          1. May be performed with endoscopy-assisted surgery
       2. Percutaneous drainage
          1. Aspiration under CT guidance is performed in some cases
    3. Empiric Antibiotics
       1. Start early empiric therapy and modify based on culture results
          1. Discuss with neurosurgery (in some cases, 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 Coverage, 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 Coverage 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. Other modified antibiotic coverage
          1. Mycobacterium tuberculosis suspected
15. Prognosis: Positive prognostic indicators
    1. Intact or only mild neurologic symptoms prior to intervention
       1. Most accurate prognostic indicator
    2. Age under 60 years
    3. Cord symptoms (e.g. Bladder dysfunction) <24 hours
    4. No comorbid conditions
    5. Thecal sac compression <50%
16. 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: 5-23%
17. 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. Chao (2002) Am Fam Physician 65(7):1341-6 [PubMed]
    4. Tompkins (2010) J Emerg Med 39(3): 384-90 [PubMed]