Last updated on:January 25th, 2022
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A cerebral abscess is a focal collection of pus surrounded by a capsule within the brain parenchyma. This occurs following the direct spread of pathogens as a complication of otitis, sinusitis, neurosurgery, or traumatic brain injury; or through hematogenous seeding.
The range of organisms is generally polymicrobial (i.e., aerobic and anaerobic pathogens). Streptococcus spp. and Staphylococcus spp. are the most common. This differs depending on the site of primary infection.
Opportunistic pathogens such as Toxoplasma gondii, Listeria monocytogenes, Nocardia, Aspergillus spp., and Cryptococcus are more common in immunocompromised hosts—e.g.: HIV patients. Depending on country, parasites such as Cysticercus, Schistosoma japonicum, Entamoeba histolytica, Naegleria fowleri, and Paragonimus may also need to be considered.
Many patients have predisposing factors. Examples include disruption of the natural protective barrier surrounding the brain following neurosurgery, cranial trauma, sinusitis, mastoiditis or dental infection; systemic sources of infection (e.g., endocarditis); shunting of the pulmonary circulation due to congenital heart disease, arteriovenous fistulas, or hereditary hemorrhagic telangiectasia; and immunosuppression.
The classical triad of fever, headache and focal neurological deficits is present in less than half of patients. The most common symptom is headache, followed by mental status changes, focal neurological deficits, fever, nausea, vomiting and seizures. The clinical manifestations depend on the location of the abscess.
Headache is the most common symptom. It is due to the mass effect and may be associated with pain localized to the site of abscess. Headaches typically last for days, vary with changes in position, and generally occur in the morning.
Nausea or vomiting
Nausea and vomiting is present in 40% of patients. This is due to the increased intracranial pressure.
Seizures may be the first manifestation of a cerebral abscess. This is due to irritation of the cortex; and may be focal or generalized.
Complications include meningitis, increased intracranial pressure, brain herniation, seizures, thrombosis of intracranial blood vessels and neurological deficits.