Researchers Reduce Shunt Maintenance for Hydrocephalus Patients

Shunts are the most common form of treatment for hydrocephalus, the excess fluid buildup in the ventricles of the brain. This shunt device — two catheters and a one-way valve system that drains excess fluid to another part of the body where it can be absorbed — has significantly improved the outcome of patients.

But shunt systems are imperfect devices. Problems occur often, including mechanical failure, infections, and obstructions; and the signs of a malfunctioning shunt are similar to those of common viral infections, including fever and headache.

“So the patient is rushed to the hospital, where doctors must perform a variety of diagnostic tests — X-rays, CT scans, MRIs, etcetera — to determine if the shunt is the problem and emergency surgery is required, or if the individual simply has a cold,” said George Coles, an engineer in the Research and Exploratory Development Department at the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel, Maryland.

Coles, along with a team of scientists at APL and physicians at Johns Hopkins Medicine, is working on a device that will help physicians quickly determine if a shunt is failing, without radiation or invasive procedures.

“The technology will incorporate the use of ultrasound to determine if there is damage to the shunt,” Coles explained. “With a simple and quick reading, doctors will be able to determine if a patient should be admitted for shunt revision surgery or sent home to rest.”

Coles and his co-principal investigators — Johns Hopkins pediatric hospitalist Sybil Klaus and Eric Jackson, a pediatric neurologist — came together after Coles delivered a presentation about the Implantable Pressure-Actuated Drug-Delivery Systems, APL’s 2010 Invention of the Year. These systems modify stents, the devices inserted to reopen and protect arteries suffering from atherosclerosis (“hardening of the arteries”). A microchip that contains a pressure sensor and a diaphragm filled with drugs is placed within the stent; when the sensor detects a predetermined change in blood pressure — such as during a heart attack — the microchip automatically delivers blood-thinning drugs intravenously.

The pressure sensor is a key component of this invention, and Klaus said it occurred to her that a similar pressure gauge might be developed for cerebral shunts.

Coles said the device could save lives, and save the medical system billions of dollars. “On average, CT scans are $212.80; shunt surveys cost about $300 each; MRIs are more than $400 each,” he explained. “Multiply that by the hundreds of pediatric patients that are seen in the emergency room each year with suspected shunt failures and you can get an idea of the money that can be saved.”

The technology could benefit warfighters as well, Coles said. “Traumatic Brain Injury (TBI) has become the signature wound of the Iraq and Afghanistan wars, and two-thirds of the soldiers returning with TBI suffer from hydrocephalus,” he said.

The research study is supported by an internal grant, with additional funding from JHU’s Neurology Department.

“If the concept proves to be promising, we will look into obtaining more significant funding so that more detailed testing and a complete prototype can be manufactured and tested,” Coles said.