Neurosurgery notes/Infection/Spinal infection/Intramedullary spinal cord abscesses (ISCAs)

Intramedullary spinal cord abscesses (ISCAs)

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Spinal infection

Numbers

  • Rare
  • Patients are young.

Location

  • Most frequently found in the thoracic region.

Pathogenesis

  • Spread
    • Most commonly no cause is found (cryptogenic).
    • Hematogenous spread
      • Via
        • Arterial supply (septic emboli),
        • Venous drainage (increased intrathoracic/abdominal pressure causing backflow in low pressure spinal venous system)
        • Lymphatics (draining mediastinum, abdomen connect with Virchow Robins paces in spinal cord via channels in spinal nerves).
      • Primary infection from
        • Pulmonary,
        • Endocarditis,
        • UTI
        • Peritonitis
        • Peripheral skin infections
    • Direct implantation
      • Via
        • Congenital midline neuroectodermal defect (e.g. dermal sinus tract),
          • Due to Staphylococcus epidermidis, S. aureus, Enterobacteriaceae, anaerobes, and Proteus mirabilis.
        • Postoperative
          • Due to S. epidermidis, S. aureus, Enterobacteriaceae, and Pseudomonas aeruginosa.
        • After penetrating trauma.

Microbiology

  • Staphylococcus and Streptococci,
    • Most common
  • Significant organisms Actinomyces, Proteus mirabilis, Pneumococcus, Listeria monocytogenes, Hemophilus, and Escherichia coli.

Clinical features

  • Motor deficits, sensory impairment, loss of sphincteric control, pain, and fever.
  • Temporal variation in presentation
    • Acute infections (< 2 weeks) partial transverse myelitis commonly associated with fever and leucocytosis,
    • Subacute (2-6 weeks) and chronic (> 6 weeks) present like intramedullary tumors.

Investigations

  • Blds
    • WCC, CRP, ESR, CSF analysis (usually negative unless meningitis).
  • MRI +C
    • May differentiate between early and late myelitis.
  • CT myelography
    • Widening of the cord at a focal segment
    • Obstruction to CSF flow.
  • X-rays are usually normal at presentation.
  • Associated features seen on imaging: osteomyelitis, spinal deformity, spinal stenosis, and spinal dysraphism, current recommendations are for immediate surgical treatment.

Management

  • Surgical
    • Technique
      • Laminectomies at the involved levels,
      • Intradural exploration,
      • Midline myelotomy,
      • Irrigation and drainage of the abscess cavity.
  • Antibiotics
    • The choice of antibiotics for empirical therapy should be based on the suspected source of infection and then adjusted on the basis of the operative culture results.
    • Minimum of 4-6 weeks of parenteral therapy.

Outcome

  • Patients presenting with acute symptoms have a worse prognosis in terms of neurologic recovery.
  • Overall, the death of a patient diagnosed with an ISCA is most frequently due to the presence of multiple CNS abscesses and, specifically, to brain or brainstem abscesses.