Intracranial abscess

Brain abscess is a focal collection of pus within the brain parenchyma. Abscesses can develop as a result of:

• direct spread of an infection from an adjacent site. e.g - meningitis, sinusitis, mastoiditis
• hematogenous spread from a distant location

It accounts for:

• 1-2% of all intracranial space occupying lesions in developed countries
• 8% of all intracranial space occupying lesions in developing countries (1)

Brain abscesses may occur within the cerebral hemispheres or within the cerebellum.

Solitary abscesses are most often located in the temporal lobe or cerebellum; multiple abscesses occur most often in the cerebrum at the junction of the white and grey matter

• most often results from a direct spread from adjacent foci (paranasal sinus)

Multiple abscesses occur

• mainly in the grey/white boundary
• in the region supplied by the middle cerebral artery (2)

Rarely, brain abscess arise rapidly; more commonly, their development is gradual with three phases recognisable:

• invasion - headache, nausea, slight CSF changes
• latent - transient attacks of headache, malaise, etc.
• manifest - localising signs, CSF pressure effects

Diagnosis is from the history, and is confirmed by CT scan.

Regard suspiciously any person with minimal symptoms and signs who have received antibiotics.

Mortality may be high.

References:

• 1. Garg M. et al. Brain Abscesses: Etiologic Categorization with in Vivo Proton MR Spectroscopy. Radiology 2004; 230:519-527
• 2. Robinson S, Stewart W. Inflammatory diseases of the CNS II: Meningitis and cerebral abscess. ACNR 2004; 4(4)