What is a brain abscess?
A suppurative (pus-producing) collection of microbes (ie: bacterial/ fungal/ parasitic) within a gliotic capsule, in brain parenchyma. Lesions may be single/ multi-focal.
What is the pathophysiology of a brain abscess?
Most often originate in ischaemic white matter adjacent to cortex.
What are the 3 stages of brain abscess formation?
Early cerebritis, late cerebritis, frank abscess formation
Aetiology of a brain abscess?
Infection with bacterial/ fungal/ parasitic organisms.
- Bacterial: Streptococcus pyogenes, Staphylococcus aureus, Klebsiella pneumoniae,Neisseria meningitides, Mycobacterium tuberculosis, etc
- Fungal: Aspergillus fumigates,Candida albicans
Risk factors for a brain abscess?
Male, under 30 yo, sinusitis, otitis media, recent dental procedure/ infection/ recent neurosurgery, meningitis, congenital heart disease, endocarditis, immunocompromise, IVD abuse, premature birth
Signs and symptoms of a brain abscess?
Persistent headache (sometimes w meningism)
CN palsy, neurological deficits
Positive Kernig/ Brudzinski sign
Fever
What is a positive Kernig sign?
Position patient supine with hips flexed to 90°. The test is positive if there is pain on passive extension of knee.
What is a positive Brudzinski sign?
Position patient supine and passively flex their neck. The test is positive if this causes reflex flexion of the hip and knee.
What is a specific symptom of a brain abscess in an infant?
Increased head circumference
Ix: Investigations for a brain abscess?
- FBC: elevated WCC
- Serum ESR: elevated
- CRP: elevated (more likely to be abscess> tumour)
- Blood culture: may be positive
- MRI with contrast: ring enhancing lesion
Management for a presumed brain abscess?
- AB therapy: IV vancomycin + IV metronidazole/ clindamycin + IV ceftriaxone
- Consider: anticonvulsant, corticosteroid, urgent surgical decompression
Management for a confirmed brain abscess?
AB/ antifungal/ antiparasitic + anticonvulsant ( + maybe surgical excavation/ drainage)
