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Introduction
Brain abscesses are caused by bacterial, fungal and parasitic organisms. Infections in other body organs such as pneumonia, dental abscess or endocarditis, may spread through the blood stream and lodge in the brain, leading to one or more brain abscesses. Infections of the face or sinuses may spread directly to the brain. Occasionally, brain abscesses develop in patients following neurosurgical procedures, such as craniotomy for brain tumor.
Patients who are immunocompromised are at higher risk for brain abscesses. AIDS patients have a high predilection for developing toxoplasmosis infections of the brain (as well as other unusual organisms).
Symptoms
Patients may complain of headaches, low-grade fever, neck stiffness, and nausea or vomiting. Some will present with seizures or mental status changes. Focal neurological problems, such as speech problems, weakness or numbness can be noted if the abscess involves critical areas of the brain. If the brain abscess is secondary to another infectious process, there may be symptoms suggestive of the primary infection, for example pneumonia.
Diagnosis
 MRI scan showing several contrast enhancing lesions suspicious for brain abcess.
The diagnosis is usually made by a combination of the history, physical exam and brain imaging. MRI with and without contrast is the study of choice. Unlike other brain infections, a brain abscess is usually not diagnosed by CSF studies.
Lumbar puncture actually may be contraindicated in these patients secondary to the mass effect the abscess has on the brain. If CSF is removed, the swollen brain can shift into small openings in the dura and skull causing neurological deterioration.
Treatment
Patients are usually hospitalized and treated with IV fluids. Intubation may be necessary if the patient is significantly lethargic or has difficulty breathing. The treatment of the cerebral abscess depends on the organism identified. If abscesses are small or multiple, stereotactic aspriration may be performed to obtain a sample of tissue. Once the organism is identified, long term intravenous antibiotics area used to treat the infection.
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