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Sinusitis and Subdural Empyema: T2-weighted axial MRI scans. Note the prominent bright signal in the frontal sinuses, and spread of the process to the subdural space. Aspiration of the subdural collection demonstrated frankly purulent material, in this case resulting from direct spread from the frontal sinuses. This is a subdural empyema.

Intracranial abscesses can occur in the epidural and subdural space as well as in the brain parenchyma. Infection most often occurs from spread through the blood system, or from direct invasion of an infection from an adjacent structure (e.g., sinusitis, otitis, mastoiditis, etc). Patients most often present subacutely over days to a few weeks with fever, headache, and/or focal neurological signs, including seizures.