Shunts often are surgically placed in the brains of infants with hydrocephalus to drain excess cerebrospinal fluid. Unfortunately, these devices eventually fail, and the problem is hard to detect until the child shows neurologic symptoms. CT and MRI scans may then be performed to check for a blockage of flow—followed by urgent neurosurgery if the shunt has failed.
Early detection of shunt failure was the problem pitched last fall at Hacking Pediatrics in Boston. Two bioengineers, Christopher Lee, a PhD student at Harvard-MIT Health Sciences and Technology program, and Babak Movassaghi, PhD, an MBA candidate at MIT Sloan, took the bait.
“We heard that parents would not take vacations in areas without an experienced neurosurgeon around,” says Movassaghi, a former Philips Healthcare engineer with 32 patents in cardiology and electrophysiology. “We were intrigued to solve that.”
Their initial idea was a smart device to measure how much fluid was draining from the shunt day to day, establishing a “norm” that could be used to determine whether, and to what extent, a shunt was malfunctioning.
But many device developers like Medtronic, they learned, were seeking to do the same thing. “About halfway through, we thought, ‘I don’t think there’s anything we can do here; the landscape is dominated by these big players,’” recounts Lee.
They considered cutting their losses. “But at home, I started looking at pictures of kids with hydrocephalus and got a little emotional,” says Movassaghi. “Then I came across Dr. Warf.”
That led them to redefine the problem entirely—with hours left to spare.
A solution in Africa
Benjamin Warf, MD, a Boston Children’s neurosurgeon, could be considered a “hacker” in his own right. Over the past decade and a half, as a medical missionary in Uganda, he developed a minimally invasive procedure that avoids the need for surgical shunt implantation altogether.
In the developed world, children with hydrocephalus have, on average, two to three shunt operations and sometimes many more; in Africa, most children with hydrocephalus have no access to emergency care should a shunt fail.
Warf’s procedure, called ETV-CPC, has two steps: first, an endoscopic third ventriculostomy (ETV), in which a small hole is made in the brain’s third ventricle—a fluid-filled cavity—allowing the trapped cerebrospinal fluid to escape; second, choroid plexus cauterization (CPC), an endoscopic procedure in which surgeons burn the pulsating tissue in the ventricles that produces much of the fluid.
Warf brought the procedure to Boston Children’s Hospital from Africa five years ago, and it proved to be successful in more than half of infants with hydrocephalus who formerly would have received shunts. That’s a huge savings, since shunts cost more than $1,000 for the initial hardware alone. To date, Warf has trained 20 neurosurgeons in 18 countries in ETV-CPC, along with five neurosurgery fellows at Boston Children’s and more than half a dozen pediatric neurosurgeons from around the United States.
But he’s faced barriers in disseminating the technique in the U.S. more widely. One has to do with ETV. Making an opening requires going perilously close to the basilar artery, a major artery going into the brain. If that’s punctured, a child could die. While this is rare in experienced hands, it can be scary for surgeons learning the procedure.
“We semi-blindly poke a hole through the ventricle floor,” explains Warf. “To make the technique safer and to be able to train more people, it would be very helpful to make that hole in a way that’s less anxiety-provoking. Also, sometimes the edges of the opening flap up and down and can heal back together, causing the ETV to fail.”
A course correction
Back at home, Movassaghi read up on Warf and ETV-CPC until 4 a.m. He fired off an email to Lee, suggesting they look at this procedure.Lee agreed. “Once we delved into the shunting industry, we found that it makes its business mainly off the fact that shunts fail.”
As they emailed with Warf, who was in San Francisco at the time, the engineers’ main focus became finding alternative, safer ways of forming the drainage hole in ETV. For perspective, they interviewed a senior neurosurgery resident and a neurosurgery fellow at Boston Children’s.
“At MIT, we’ve learned to go to the people who will adopt the device or not,” explains Movassaghi.
The young neurosurgeons confirmed that puncturing the ventricle floor with a blunt probe, so close to the basilar artery, was the scariest part of the procedure.
“It’s like taking a fist to punch through paper,” says Lee. “It leaves behind areas of floppiness, tissue flaps that can come into contact with each other and seal over the hole. We envisioned a device that would prevent this and make the opening in a more controlled fashion.”
Vanessa Nahon, an MBA student at Sloan, joined the team. She had worked on an esophageal suctioning device at Boston Scientific and brought expertise in regulatory considerations and device commercialization.
The project won third place at Hacking Pediatrics. In collaboration with Warf, the team hopes to get more funding and explore other improvements, such as speeding up the CPC portion of the procedure. Shrinking the tissue faster would reduce children’s exposure to anesthesia, Warf says.
“Right now, we have this 1-mm wire that goes down the working channel of the scope,” he explains. “It touches the tissue at different points, and the tissue gradually shrinks. It can take about 45 minutes to do this in both ventricles.”
“We have two objectives now,” says Movassaghi, “to help make more people adopt the procedure and to make it faster and safer.”