Dr. Benjamin Warf thought the prospects were poor that Ugandan children with hydrocephalus, an excess of water on the brain, could be successfully treated by implanting a drainage tube. Families he cared for at a Mbale hospital had limited access to health care. A blockage in the tube, called a shunt, could be disastrous.

In the early 2000s, Warf devised an alternative that reduced the number of infants who needed brain shunts by about two-thirds. It became the standard of care at Boston Children’s Hospital, where he ­directs the Neonatal and Congenital Anomaly Neurosurgery Program. Now Warf is unraveling the causes of hydrocephalus, work he hopes could lead to prevention.