Spinal Infection

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

1. See Also
   1. Osteomyelitis
   2. Vertebral Osteomyelitis
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)
   3. Gender predominance: Males by a ratio >2:1
3. 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. Disc space infection (Discitis)
   3. Vertebral infection
      1. Spondylitis
      2. Osteomyelitis
4. 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
5. 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)
6. Etiology
   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
7. 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)
8. Symptoms
   1. Back pain (70-90% of cases)
      1. Associated with secondary muscle spasm
      2. Pain not relieved with rest
      3. Pain provoked by standing and bearing weight
   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
9. Signs
   1. Focal tenderness at involved spinous process (60-70% of cases)
10. 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
11. 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
12. Imaging
    1. Gadolinium-enhanced Spine MRI (preferred)
       1. Test Sensitivity >90%
    2. CT with Myelography
13. 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. 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. Primary empiric antibiotics (MRSA)
          1. Vancomycin 1 gram IV q12 hours (dosing must be calculated based on weight)
       3. Alternative empiric antibiotics (MSSA coverage may be used if low MRSA risk in community)
          1. Nafcillin or Oxacillin 2 grams IV q4 hours or
          2. Cefazolin 2 grams IV q8 hours
       4. Additional Gram Negative Bacteria coverage indications
          1. Intravenous Drug Abuse
          2. Immunocompromised patients
          3. Concurrent Urinary Tract Infection
       5. Additional Pseudomonas coverage indications
          1. Intravenous Drug Abuse
       6. Other modified antibiotic coverage
          1. Mycobacterium tuberculosis suspected
14. 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%
15. 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%
16. References
    1. Della-Giustina (2014) Crit Dec Emerg Med 28(3): 2-9
    2. Chao (2002) Am Fam Physician 65(7):1341-6 [PubMed]
    3. Tompkins (2010) J Emerg Med 39(3): 384-90 [PubMed]