Brain Abscess



  • 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

Geriatric Considerations
Age does not affect outcome as much as the abscess size and state of neurologic dysfunction at presentation.

Pediatric Considerations

  • ~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]

Risk Factors

  • Immunocompromised state (e.g., organ transplantation)
  • IV drug abuse
  • Penetrating skull trauma
  • Prior craniotomy
  • Cyanotic congenital heart disease
  • Dental or lung infections
  • Cerebrovascular accidents

General Prevention

  • 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

  • AIDS
  • Congenital heart disease
  • Cardiac vegetations
  • Diabetes
  • Cirrhosis
  • Organ transplantation (solid organ and hematopoietic stem cell)
  • Vitamin K deficiency
  • Hereditary hemorrhagic telangiectasia

There's more to see -- the rest of this topic is available only to subscribers.