Cerebral abscess

Question 1

Aetiology of cerebral abscesses

Answer 1

Bacteria: contiguous spread from a parameningeal site e.g. sinus, middle ear / haematogenous e.g. endocarditis
- Strep. Pyogenes
- Staph. Aureus
- Bacteroides fragilis
- Enterobacter
- Klebsiella
- Neisseria meningitides
Fungal:
- Aspergillus fumigates
- Candida albicans
- Cryptococcus neoformans
Parasitic:
- Toxoplasmosa gondii
- Trypanosoma
- Echinococcus granulosus

Question 2

Risk factors for cerebral abscesses

Answer 2

Previous infection: sinusitis, otitis media, dental infection, meningitis
Recent head and neck surgery
Recent neurosurgery
Recent dental work
Congenital heart disease
Infective endocarditis
Diabetes mellitus
HIV/immunocompromise
IVDU
Chronic granulomatous disease
Male

Question 3

Symptoms and signs of cerebral abscesses

Answer 3

Fever
Headache (raised ICP)

Seizures
Meningism: + Kernig or Budzinski sign
Neuro:
- Localising signs e.g. third/sixth nerve palsy
- Bacterial abscesses = peripheral
- Toxoplasma abscesses = deeper; basal ganglia
Fundoscopy:
- Papilloedema

Question 4

Investigations for cerebral abscesses

Answer 4

FBC: raised WCC
ESR: elevated
CRP: raised
Clotting
Cross match
G&S
Blood cultures

MRI head with contrast: ring enhancing lesion
CT head with contrast: ring enhancing lesion

Question 5

Management for cerebral abscess

Answer 5

Urgent neurosurgical referral: decompression

1. Sepsis 6
   a. IV Abx: vancomycin 15mg/kg + Metronidazole 500mg IV + ceftriaxone 2g IV
2. Supportive
   a. Decompensating → dexamethasone 10mg IV single dose (treatment in infection/sepsis controversial)
   b. Seizures/abscess near motor cortex → levetiracetam
3. Source of infection found
   a. Bacterial → continue abx
   b. Fungal → amphotericin B ± flucytosine
   Parasitic → pyrimethamine + sulfadiazine

Question 6

Complications for cerebral abscesses

Answer 6

Abscess rupture → ventriculitis
SIADH → hyponatraemia
Cognitive dysfunction (esp. in children)
Seizures
Hydrocephalus
Death

Question 7

Prognosis for cerebral abscesses

Answer 7

Overall mortality <13%
Permanent hemiparesis and long-term seizures under 50%
Early diagnosis and prompt treatment correlates with improved outcome