Hematogenous Inoculation Causing Brain Abscesses in Children

Cyanotic Congenital Heart Disease

• 6–51% abscesses: The prevalence of brain abscesses in children with cyanotic congenital heart disease is 6–51% (51). Of patients diagnosed with a brain abscess, 30–34% have underlying heart defects (23, 51, 109).
• Right-to-left shunting: Pronounced right-to-left shunting secondary to cardiac defects increases the risk of brain abscesses via paradoxical emboli (62). Tetralogy of Fallot, transposition of the great vessels, atrial septal defects, ventricular septal defects, and the Eisenmenger complex are examples of cardiac anomalies with potential right-to-left shunting known to predispose children to brain abscesses (30, 74, 103).
• Persistent left superior vena cava: Although rare, a persistent left superior vena cava may also lead to a brain abscess because in patients with this abnormality, venous blood from the left arm and left side of the head drains directly into the left atrium, resulting in a right-to-left shunt (43).

Endocarditis

• 9–10% abscesses: Available data indicate that endocarditis is the underlying cause of brain abscesses in 9–10% of patients (51).

Bacteremia

• 8% abscesses: Bacteremia of unknown source is the underlying cause of brain abscesses in 8% of patients (51).

Skin Folliculitis

• 1–3% abscesses: The underlying cause of brain abscesses is skin folliculitis in 1–3% of patients (51),

Chronic Pulmonary Infections

• 1–10% abscesses: The underlying cause of brain abscesses is pulmonary infection in 1-10% of patients (51). Pulmonary foreign bodies aspirated by children can lead to hematogenous seeding of the brain with bacteria and the subsequent development of abscesses (51).

Pulmonary Arteriovenous Malformations

• Right-to-left shunting: Patients with pulmonary AVM (often associated with Osler’s disease—hereditary hemorrhagic telangiectasia) are at increased risk of developing brain abscesses due to a right-to-left pulmonary vascular shunt (17, 65).

Bronchiectasis

Brain abscesses are described as a rare complication of bronchiectasis (1). Multiple brain abscesses are a rare complication that may occur in patients with infected bronchiectasis and intrathoracic sepsis (131, 135).

Osteomyelitis

Osteomyelitis of the skull is an important but rare predisposing condition for brain abscesses in neonates and children (136).

• Secondarily infected sites of trauma: Infected cephalhematoma, placement of a scalp electrode, scalp-vein line insertion, or trauma to scalp by instruments are thought to be common routes of introducing infection in cases of pediatric osteomyelitis (136, 137).
• Pott’s puffy tumor: The Pott’s puffy tumor (a subperiosteal abscess of the frontal bone associated with osteomyelitis) has been reported to be a cause for frontal lobe abscesses (138).