Prompt treatment of hydrocephalus in congenital toxoplasmosis linked to better cognitive outcomes

Babies born with toxoplasmosis, which is caused by a congenital parasitic infection, can develop hydrocephalus, a condition where excess fluid creates damaging pressure in the brain. Prompt treatment of hydrocephalus in congenital toxoplasmosis is linked to better cognitive outcomes, find researchers.

A new study led by University of Chicago Medicine researchers, collaborating with a group of physician-scientists in Chicago, suggests that the faster a baby with congenital toxoplasmosis can be given a fluid-draining shunt to treat their hydrocephalus – even in cases of severe hydrocephalus – the better their cognitive outcome. The study has appeared in the Journal of Neurosurgery Pediatrics.

Based on a longitudinal study of 65 patients born with Toxoplasma gondii infections who developed hydrocephalus during a 38 year period, the research found that prompt treatment led to substantially improved outcomes for children with debilitating conditions. The patients were all part of a larger ongoing research project, the National Collaborative Chicago-Based Congenital Toxoplasmosis Study.

“This is another step forward for children who benefit from early shunting,” said David Frim, MD, PhD, Chief of the Section of Neurosurgery at UChicago Medicine. “It also gives those who study toxoplasmosis a little more of a window into the brain of an infected child, because we still don’t fully understand what toxoplasmosis does to the brain.”

A widespread, common infection

Toxoplasma gondii is a parasite found throughout the world that has infected roughly 2 billion people, more than 40 million of whom live in the United States. Individuals become infected when they eat undercooked, contaminated meat or are exposed to material contaminated by feces from an acutely infected cat. Most healthy people who are infected have no recognizable symptoms, but people with weakened immune systems are more likely to develop toxoplasmosis, a disease that can damage the brain, eyes and even cause death. Toxoplasma can also pass from a mother infected for the first time to her unborn baby.

“Left untreated, this infection causes problems, even in babies who at first seem normal,” said Rima McLeod, MD, lead author of the study and a professor of ophthalmology and visual sciences and pediatric infectious diseases who directs the Toxoplasmosis Center at UChicago. “An infection early in pregnancy can lead to severe disease in the baby, and even with milder involvement at birth, virtually all of these untreated children end up having eye disease by the time they are teenagers and some may experience a fall-off in cognition as well.”

Babies born with toxoplasmosis can develop hydrocephalus when the cerebrospinal fluid that normally circulates through the brain’s ventricles backs up and damages the brain. To treat this, surgeons place a tube called a shunt in these children so that the excess fluid in the ventricles can drain to the abdomen.

Little has been known about the effectiveness of this treatment on the long-term neurological function of these patients, however. Furthermore, shunt surgery for children with severe presumed irreparable brain damage from toxoplasmosis-linked hydrocephalus at birth was in the past deemed unlikely to be beneficial.

Of the 46 patients who underwent shunt placement, almost all showed improvement following placement. Four patients showed no improvement, one patient died and one was lost to follow up. Dramatic increases in thickness of the cortical mantle, the outer gray matter of the brain, were not uncommon. Importantly, there were patients who presented with severe hydrocephalus and cortical mantle thinning who, after shunt placement, experienced an impressive cortical re-expansion and ultimately normal cognitive function.