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- A purulent collection within the brain most commonly arising from hematogenous sources of infection (pulmonary, cardiac, renal), contiguous spread (sinusitis, dental, and mastoiditis), or direct trauma (postoperative, gunshot) (1)[C]
- Symptoms can mimic brain tumors but can progress rapidly (days to weeks)—mean duration of symptoms around 8.3 days.
- Treatment includes IV antibiotics, stereotactic aspiration, and/or surgical excision.
- Synonym(s): cerebral abscess
Age does not affect outcome as much as the abscess size and state of neurologic dysfunction at presentation.
- ~1/3 of total cases occur in the pediatric age group.
- Newborns or infants may present with cranial enlargement.
- Frequently associated with cyanotic congenital heart disease (risk of abscess 4–7%)
- Predominant age: median age 30 to 40 years, although brain abscess occurs at all ages
- Predominant sex: male > female (2:1)
Reported range from 0.3 to 1.3 per 100,000 (2); however, rates are increased in immunocompromised patients and in developing countries; approximately 2,000 cases a year in the United States
Etiology and Pathophysiology
- Abscess formation can result from contiguous spread, hematogenous spread, or direct trauma.
- Hematogenous spread most often occurs from bacteremia related to lung abscesses, pneumonia, or endocarditis.
- Hematogenous spread usually occurs in the middle cerebral artery (MCA) territory at the junction of the gray-white matter (3)[C].
- Direct extension occurs from otitis, mastoiditis, sinusitis, or dental infections.
- Fungal infection of the nasopharynx
- Contiguous spread from odontogenic and sinus infections frequently present with frontal lobe abscesses
- Contiguous spread from mastoiditis typically present with temporal lobe or cerebellar abscesses, although widespread use of antibiotics for otitis has decreased the incidence of this presentation.
- Four stages of abscess formation include early and late cerebritis followed by early and late capsule formation (1).
- Most common organisms: streptococci, staphylococci (especially after neurosurgery), enteric gram-negative bacilli, anaerobes (usually same as source of infection), Nocardia, fungi, or polymicrobial
- Toxoplasma gondii (HIV/AIDS patients)
- Most common fungal sources include Aspergillus sp., Candida sp., and Zygomycetes.
- Risk factors for fungal infection include immunocompromised, penetrating CNS trauma, and immunocompetent hosts in fungal endemic areas.
- Amebic brain abscess, amebiasis, amebic dysentery
Associated with single nucleotide polymorphisms in the ICAM-1 and MCP-1 genes (4)[C]
- Immunocompromised state (e.g., organ transplantation)
- IV drug abuse
- Penetrating skull trauma
- Prior craniotomy
- Cyanotic congenital heart disease
- Dental or lung infections
- Cerebrovascular accidents
- Treat potential sources of infection: otitis media, mastoiditis, sinusitis, dental abscess, other ear/nose/throat (ENT) infections.
- Prophylactic antibiotics after compound skull fracture or penetrating head wounds
Commonly Associated Conditions
- Congenital heart disease
- Cardiac vegetations
- Organ transplantation (solid organ and hematopoietic stem cell)
- Vitamin K deficiency
- Hereditary hemorrhagic telangiectasia
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