Brain Abscess

Basics

DESCRIPTION

  • Suppurative infection involving the brain parenchyma
  • May be a single or multiple lesions

EPIDEMIOLOGY

  • Males more commonly affected (2:1 male-to-female predominance)
  • Typical age of presentation is 4 to 7 years but varies according to predisposing factor.
  • 85% of cases have a predisposing risk factor.

INCIDENCE

~1,500 to 2,500 cases (adults and pediatric combined) occur per year with up to 25% being children.

RISK-FACTORS

  • Cyanotic congenital heart disease (tetralogy of Fallot is most common)
  • Otorhinolaryngologic infections such as sinusitis, mastoiditis, and chronic otitis media
  • Meningitis (especially in neonates)
  • Penetrating head trauma
  • Surgical manipulation of the brain (ventriculoperitoneal shunts, tumor removal)
  • Congenital lesions of the head and neck
  • Cystic fibrosis
  • Dental infections
  • Lung infections
  • Patients who have traveled to endemic areas where neurocysticercosis (Latin America, parts of Africa, Asia, and the Indian subcontinent) is endemic
  • Immunocompromised patients (congenital or acquired)

GENERAL-PREVENTION

  • During recreational activities, wearing helmets may prevent penetrating head trauma.
  • Appropriate management of acute otitis media and acute sinusitis as well as timely recognition of treatment failure

PATHOPHYSIOLOGY

  • Microorganisms enter the brain parenchyma by contiguous or hematogenous extension.
  • Location of brain abscesses:
    • Cyanotic congenital heart disease patients tend to have abscesses within the middle meningeal artery distribution: frontal, parietal, and temporal lobes.
    • Frontal abscesses are commonly seen with sinus and dental infections.
    • Temporal, parietal, or cerebellar abscesses tend to occur with mastoiditis or otitis media.
    • Brain abscesses can occur anywhere in the brain parenchyma, regardless of a predisposing risk factor, secondary to hematogenous metastasis.

ETIOLOGY

  • Bacteria are the most common causes.
  • Streptococcus milleri (anginosus) group and Staphylococcus spp. are the most commonly cultured microorganisms.
  • Neonates may develop brain abscesses as a complication of gram-negative meningitis (Proteus, Citrobacter, Enterobacter, and Cronobacter species).
  • Polymicrobial infections occur in 30–50% of cases.
  • Anaerobic organisms are found with increasing incidence with improved laboratory and culture techniques. Common pathogens include Bacteroides, Peptostreptococcus, Fusobacterium, Propionibacterium, Actinomyces, Veillonella, and Prevotella.
  • Neurocysticercosis is caused by the parasite, Taenia solium. Fungi and protozoa can cause brain abscess in immunocompromised patients.

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