Brain Abscess

Question 1

Definition of brain abscess

Answer 1

Is a pus collection of microbes (most often bacterial, fungal or parasitic) within a gliotic capsule occurring within the brain parenchyma

Question 2

Aetiology of brain abscess

Answer 2

• Brain abscesses can arise from infection with bacterial, fungal or parasitic organisms

• Bacterial:
‣ Streptococcus pyogenes (more common)
‣ Staph aureus

• Fungal:
‣ Aspergillosis fumigates

• Parasitic:
‣ Toxoplasma gondii

• Brain abscess can follow from:
• Ear, sinus, dental or periodontal infection (most often due to sinusitis or otitis)
• Skull fracture
• Congenital heart disease
• Endocarditis
• Bronchiectasis

Question 3

Pathophysiology of brain abscess

Answer 3

There would be inflammation of the cerebrum which would then lead to the formation of an abscess
• Entry into the brain can be through direct extension or haematogenous spread (more likely)

• There is increased permeability of the blood brain barrier through the stages of abscess development

Question 4

History and examination of brain abscess

Answer 4

• Fever: Common finding, but can be absent
• Seizures
• Signs of increasing ICP: HEADACHE, NEUROLOGICAL DEFICIT
• Coma

Question 5

Risk factors of brain abscess

Answer 5

• Sinusitis, otitis media, dental procedure, meningitis etc
• Male sex
• Age <30

Question 6

Investigations for brain abscess

Answer 6

• FBC: Elevated WBC count in most patients. This would favour brain abscess over tumour
• ESR: elevated in the majority of patients, favours abscess over tumour
• Blood culture: may be positive
• MRI WITH CONTRAST:
‣ Initial test ordered in suspected brain abscess, unless a CT head already ordered
‣ One or more ring-enhancing’ lesions

Question 7

Treatment of brain abscess

Answer 7

Presumed brain abscess:
1) Empiric antibiotic therapy: First line treatment and started immediately. Vancomycin AND metronidazole or clindamycin

+ Anticonvulsant: Cerebral abscess patients are treated prophylactically with anticonvulsants (Phenytoin)

+ treat ICP

Antifungals or Antiparasitics for other causes

Question 8

Complications and prognosis of brain abscess

Answer 8

• Seizures: very frequent complication. Prophylaxis with anticonvulsants needed
• Death

Outcome has improve
Major prognostic factor is patient’s neurological status upon presentation
Effective treatment can reduce the risk of mortality and risk of permanent hemiparesis and long term seizures