Neurosurgery notes/Infection/Spinal infection/Spinal subdural empyemas (SSE)

Spinal subdural empyemas (SSE)

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Spinal infection

Numbers

  • Are uncommon
  • 5th-7th decades.
  • Less common than
    • Cranial subdural empyema due to
      • Lack of air sinuses in the spine
    • And spinal epidural abscesses due to
      • The epidural space in the spine is an actual rather than potential space
      • Blood is directed centripetally in the spine, whereas it is directed centrifugally in the brain.

Location

  • Thoracolumbar spine

Spread

  • Hematogenous spread of primary infection,
  • Iatrogenic (lumbar puncture, spinal injections),
  • Direct extension into the subdural space (dysraphism, penetrating trauma, spinal infection),
    • The presence of discitis/osteomyelitis accompanies 2/3 of SEAs.
  • Cryptogenic.

Micro-organism

  • Most common organism is Staphylococcus aureus, other Staphylococcus species, Streptococcus, Escherichia coli, Pseudomonas aeruginosa, Streptococcus pneumoniae, and Peptococcus magnus.

Clinical presentation

  • Fever,
    • Common
  • Neck/back pain,
    • Common
    • Presence of spinal tenderness may favor epidural abscess rather than subdural empyema.
  • Symptoms of spinal cord/cauda equina compression.

Investigation

  • FBC, ESR, CRP;
  • Lumbar puncture is not performed due to risks of contaminating deeper meningeal layers.
  • MRI + C
    • Imaging of choice
    • Check spinal cord, vertebrae, disc spaces, extent of lesion, and extent of compression.
    • Limitation: inability to distinguish whether the lesion is intradural or extradural;

Management

  • Surgical decompression (laminectomy) with irrigation and drainage of the subdural space
    • Main way of treatment (see outcome below)
    • Indication
      • For microbiology diagnosis
        • Cultures should be obtained before using antibiotic irrigation.
      • Neurological deficit
      • Failure of antibiotics treatment alone
    • Technique
      • The exposure should encompass the extent of the abscess.
      • Copious irrigation
      • Primary closure of the dura.
      • The arachnoid should be preserved if possible.
  • Antibiotics
    • Empiric antibiotic coverage for these infections must cover gram-positive cocci.
    • Some advocate the additional use of corticosteroids (dexamethasone) during the perioperative period as a prophylaxis against the development of thrombophlebitis.

Outcome

  • Among the surgically treated group, 82.1% made a complete recovery or improved, whereas 17.9% died. In the conservatively treated group, 80% died (4 of 5 patients) and only 20% (1 of 5 patients) improved.