0.4 per 100,000/year: Brain abscesses occur infrequently, with a yearly incidence of 4 cases per million (51).
25% in children: Overall, about 25% of brain abscesses occur in children (12).
Incidence increasing: With increased numbers of surviving immunocompromised patients (AIDS, transplant survivors, and chemotherapy patients), the development of resistant bacteria, and the widespread availability of improved imaging techniques, the numbers of patients diagnosed with brain abscesses is increasing (51, 55).
Contiguous spread less common: The incidence of contiguous spread of infection into the cerebral parenchyma is falling in most parts of the world owing to prompt treatment of the initial source of infection (30, 119).
4–7 years: Brain abscesses occur most often in children between 4 and 7 years of age (51, 82). The location tends to vary with the child’s age; cerebellar abscesses are more common in younger children and temporal lobe abscesses in older children (31).
Etiology varies with age: There appears to be a clear difference between infants and the general pediatric group in the main predisposing factors. The main cause of brain abscesses in infants is reported as meningitis in all published series (30, 130).
1.5 to 3.1 male preponderance: A male preponderance has been found in most series (55). In general series covering all age groups, the male:female ratio ranges between 1.5 and 3.1 (60). Brain abscesses that occur in the first two decades of life are reported to have an unexplained male predilection (118).
Wide variation in incidence but higher in emerging world: Reported series demonstrate that there is a wide geographic variation in the incidence of brain abscess, with a much higher incidence in underdeveloped countries (55). Brain abscesses are reported to account for 8% of all intracranial mass lesions in Third World countries (55).
Living in underdeveloped communities: In emerging countries, where living standards are relatively lower, brain abscess constitutes a disproportionate percentage of space-occupying intracranial lesions compared with their presence in developed nations.
Differ from those of adults: In children the predisposing risk factors and their prevalence differ from those in adults. These risk factors include congenital heart disease, dermal sinus tract, and foreign bodies in the lungs.
Relationships to Other Disease States and Syndromes
Sources: Congenital heart disease, immunodeficiency, folliculitis of facial skin, chronic pulmonary disease, AVMs of pulmonary vascular bed, foreign bodies in lungs, bronchiectasis, osteomyelitis, and bacteremia from other sources have been reported to be associated with brain abscesses (17, 23, 28, 30, 43, 51, 62, 65, 74, 103, 109).
Foreign material introduced through a penetrating traumatic injury
Sources: Penetrating head injuries make children susceptible to intracerebral abscess formation, because retained debris and/or bone fragments can serve as a nidus of infection. Many children sustain penetrating ocular injuries as a result of experimenting with sharp objects such as pencils and sticks, and intracranial extension may lead to an abscess (7, 50, 71).
Complication of neurosurgical procedure
Sources: Post-intracranial procedures, shunt infections, halo or tong application.