Infections of the central nervous system

Bacterial meningitis is a medical emergency. Presentation commonly includes headache, fever and neck stiffness. Prompt treatment with high-dose parenteral antibiotics is essential. Prior or concurrent dexamethasone administration improves neurological outcome. Diagnosis is confirmed by analysis of cerebrospinal fluid. Lumbar puncture should be preceded by a computed tomography (CT) head scan when raised intracranial pressure is likely. Brain abscesses usually result from spread from a local infection such as otitis media or sinusitis. Patients present with a 2–3-week history of fever, convulsions and signs of an intracranial mass lesion and can be very ill. CT scan classically demonstrates a ring-enhancing lesion. Treatment includes surgical drainage and high-dose parenteral antibiotics for 6–8 weeks. Subdural empyema is a collection of pus between the dura and arachnoid mater. Presentation is more acute than for brain abscesses. The mortality rate is ∼34%. Epidural abscesses are commonly caused by Staphylococcus aureus and are associated with intravenous drug abuse and compromised immunity. Fever and backache are common signs. The diagnosis is confirmed by magnetic resonance imaging. Urgent surgical drainage is vital to preserve neurological function. Epidural abscesses following neuroaxial procedures occur in ∼1:1000 patients. Strict adherence to infection guidelines is essential to limit this risk.