Brain abscess

Etiology

 Local spread (adjacent infection)

  • otitis media , mastoiditis, sinusitis
  • osteomyelitis
  • dental abscess

Hematogenous spread

  • adults: lung abscess, bronchiectasis, empyema
  • children: cyanotic heart disease with R to L shunt (blood is
  • shunted away from lungs preventing filtration of bacteria)
  • immunosuppression (AIDS - toxoplasmosis)
  • dural disruption
  • surgery, trauma
  • congenital defect, e.g. dermal sinus

Pathogens

  • Streptococci (most common), often anaerobic or microaerophillic
  • Staphylococci (penetrating injury)
  • Gram negatives, anaerobes

Other Causes of Pus...

  • subdural empyema (from sinusitis, mastoiditis - rare, 20% mortality)
  • meningitis, encephalitis, AIDS toxoplasmosis
  • osteomyelitis of skull (Pott’s puffy tumour), usually seen with sinusitis
  • granuloma (TB, sarcoid)

Diagnosis

  • Focal neurological signs and symptoms
  • Mass effect, increased ICP and sequelae
  • Seizures
  • +/– signs of systemic infection (mild fever, leukocytosis)
  • Blood cultures rarely helpful, LP not helpful and contraindicated
  • CT scan and MRI

Management

  • Supratentorial
  • Multiple aspirations of abscess, and send for C&S
  • Infratentorial

Excision

  • Antibiotics
  • Empirically: penicillin and metronidazole (cover Streptococci and anaerobes) +/– ceftriaxone (cover Gram negatives)
  • After sensitivity results return, revise antibiotics