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Brain abscess
Last reviewed: 04.07.2025
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A brain abscess is a collection of pus in the brain tissue. The disease is characterized by headache, lethargy, fever, and focal neurological deficit. The diagnosis is confirmed by CT with contrast or MRI and sometimes by bacteriological examination. Treatment involves antibacterial drugs and surgical drainage.
[ Causes brain abscess
Brain abscess may occur as a result of direct contact spread of infection (for example, osteomyelitis, mastoiditis, sinusitis, subdural empyema), penetrating head wounds (including neurosurgical interventions), and hematogenous transmission (bacterial endocarditis, congenital heart defects with right-to-left shunting, abuse of intravenous injections). Sometimes the entry point of infection remains undetermined.
The causative agents of infection are usually anaerobes, sometimes mixed microflora, including anaerobic streptococci or bacteroids. Staphylococcal infection often complicates the course of craniocerebral trauma, neurosurgical interventions or endocarditis.
Members of the Enterobacteriaceae family are isolated in otogenic infections. Abscesses may be caused by fungi (eg, Aspergillus) and protozoa (eg, Toxoplasma gondii, usually in HIV-infected individuals).
A brain abscess is formed as a result of necrosis of an area of inflamed brain tissue, around which glia and fibroblasts form a capsule. Perifocal edema may cause an increase in intracranial pressure.
Symptoms brain abscess
Symptoms of a brain abscess are caused by increased intracranial pressure and mass effect (compression of the brain tissue). Headache, nausea, vomiting, lethargy, epileptic seizures, mental changes, optic nerve congestion, and focal neurological symptoms develop over several days or weeks.
Fever, chills, and leukocytosis may subside once a capsule forms around the site of infection.
Diagnostics brain abscess
If a brain abscess is suspected, CT with contrast or MRI is performed. The abscess appears as an edematous mass surrounded by a ring-shaped formation that accumulates contrast, which can be difficult to differentiate from a tumor or brain infarction; culture and drainage may be required.
Lumbar puncture is contraindicated because it may cause transtentorial herniation, and CSF examination data have no diagnostic value.
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Treatment brain abscess
The duration of antibiotic therapy ranges from 1 to 2 months. Cefotaxime 2 g intravenously every 4 hours or ceftriaxone 2 g intravenously every 12 hours are prescribed empirically; both antibiotics are effective against streptococcal infections, representatives of the Enterobacteriaceae family, and most anaerobes, but not against the anaerobe Bacteroides fragilis, which requires metronidazole 7.5 mg/kg intravenously every 6 hours.
In case of staphylococcal infection (Staphylococcus aureus) brain abscess, the drug of choice is vancomycin 1 g every 12 hours until the results of determining the sensitivity of the pathogen to nafcillin (2 g every 4 hours).
The effectiveness of antibiotic therapy is monitored using serial CT or MRI.
Stereotactic or open drainage is the optimal intervention for single and surgically accessible abscesses, especially those larger than 2 cm in diameter. If intracranial pressure increases, the patient is prescribed a short course of high-dose glucocorticoids. Anticonvulsants are prescribed to prevent epileptic seizures.