CNS abscess

Brain abscess / subdural empyema

• Risk factors: immunocompromise, infective endocarditis, contiguous infection (sinus, ear, dental). Suspect in any patient with raised intracranial pressure.
• Clinical features:
  • Raised ICP — headache, nausea/vomiting, altered conscious state, papilloedema
  • Focal neurological signs — hemiplegia, dysphasia, ataxia
  • Seizures (~30%)
  • Fever (may be absent)
  • Signs of sepsis elsewhere (teeth, endocarditis)
• Investigations: MRI (or CT) brain; FBC, CRP, blood cultures; consider work-up for endocarditis. LP is contraindicated (risk of herniation).
• Management: urgent transfer for neurosurgical evaluation — aspiration or biopsy is essential to guide antimicrobial therapy. Subdural empyema requires urgent surgical drainage.

Spinal epidural abscess

Usual pathogen is Staphylococcus aureus.

• Context: adults and children; may be associated with osteomyelitis or discitis. Causes include contiguous infection (furuncle, ulcer, discitis), back trauma with haematoma, or post spinal/epidural anaesthetic block — about one-third are spontaneous.
• Clinical features (classic triad): increasing back pain ± radiculopathy, percussion tenderness over the spine, evolving neurological deficit (gradual leg weakness and sensory loss) ± fever (may be absent).
• Investigations: MRI (CT often misses an abscess); blood cultures.
• Management: refer to hospital for urgent neurosurgical assessment and IV antibiotics — flucloxacillin 2 g IV 6-hourly + ceftriaxone 2 g IV 12-hourly (vancomycin if MRSA risk).