Toxoplasma gondii infections in pediatric neurosurgery

Toxoplasma gondii is a parasite that is estimated to infect one-third of the world’s population. It is acquired by ingesting contaminated water and food specially undercooked meat, contact with domestic or wild feline feces, and during pregnancy by transplacental transmission. Immunocompetent hosts are usually asymptomatic, and infection will be self-limited, while those patients whose immune system is debilitated by HIV infection, immunosuppressive therapy, long-term steroid treatment, and fetuses infected during gestation will show evidence of systemic activity which is more severe in the central nervous system and eyes due to insufficient immune response caused by their respective blood barriers. Congenital toxoplasmosis has an estimated incidence of 8% in mothers who were seronegative at the beginning of their pregnancy. Infection in the first trimester may result in spontaneous abortion or stillbirth; however, it is estimated that the highest risk for vertical transmission is during the second and third trimesters when blood flow and placenta thickness favor parasitic transmission. Congenital toxoplasmosis can be detected with periodic surveillance in endemic areas, and with appropriate treatment, the risk of vertical transmission can be reduced, and the severity of the disease can be reversed in infected fetuses. While most infected newborns will show no evidence of the disease, those who suffer active intrauterine complications will present with cerebral calcifications in 8–12% of cases, hydrocephalus in 4–30%, and chorioretinitis in 12–15%. Also, seizure disorders, spasticity, and varying degrees of neurocognitive deficits can be found in 12%. Four distinct patterns of hydrocephalus have been described: aqueductal stenosis with lateral and third ventricle dilatation, periforaminal calcifications leading to foramen of Monro stenosis with associated asymmetrical ventricle dilatation, a mix of aqueductal and foramen of Monro stenosis, and overt hydrocephalus without clear evidence of obstruction with predominant dilatation of occipital horns (colpocephaly). While all patients diagnosed with congenital toxoplasmosis should undergo pharmacological treatment, those presenting with hydrocephalus have traditionally been managed with CSF shunting; however, there are reports of at least 50% success when selected cases are treated with endoscopic third ventriculostomy. Successful hydrocephalus management with appropriate treatment leads to better intellectual outcomes.