Robot Brain Surgery: Robot uses steerable needles to treat brain clots

Surgery to relieve the damaging pressure caused by hemorrhaging in the brain is a perfect job for a robot.

That is the basic premise of a new image-guided surgical system under development at Vanderbilt University. It employs steerable needles about the size of those used for biopsies to penetrate the brain with minimal damage and suction away the blood clot that has formed.

The system is described in an article accepted for publication in the journal IEEE Transactions on Biomedical Engineering. It is the product of an ongoing collaboration between a team of engineers and physicians headed by Assistant Professor Robert J. Webster III and Assistant Professor of Neurological Surgery Kyle Weaver.

Brain clots are leading cause of death, disability

The odds of a person getting an intracerebral hemorrhage are one in 50 over his or her lifetime. When it does occur, 40 percent of the individuals die within a month. Many of the survivors have serious brain damage.

“When I was in college, my dad had a brain hemorrhage,” said Webster. “Fortunately, he was one of the lucky few who survived and recovered fully. I’m glad I didn’t know how high his odds of death or severe brain damage were at the time, or else I would have been even more scared than I already was.”

Steerable needle could prevent “collateral damage” during surgery

Operations to “debulk” intracerebral hemorrhages are not popular among neurosurgeons: They know their efforts are not likely to make a difference, except when the clots are small and lie on the brain’s surface where they are easy to reach. Surgeons generally agree that there is a clinical benefit from removing 25-50 percent of a clot but that benefit can be offset by the damage that is done to the surrounding tissue when the clot is removed. Therefore, when a serious clot is detected in the brain, doctors take a “watchful waiting” approach – administering drugs that decrease the swelling around the clot in hopes that this will be enough to make the patient improve without surgery.

For the last four years, Webster’s team has been developing a steerable needle system for “transnasal” surgery: operations to remove tumors in the pituitary gland and at the skull base that traditionally involve cutting large openings in a patient’s skull and/or face. Studies have shown that using an endoscope to go through the nasal cavity is less traumatic, but the procedure is so difficult that only a handful of surgeons have mastered it.

Last summer, Webster attended a conference in Italy where one of the speakers, Marc Simard, a neurosurgeon at the University of Maryland School of Medicine, ran through his wish list of useful imaginary neurosurgical devices, hoping that some engineer in the audience might one day be able to build one of them. When he described his wish to have a needle-sized robot arm to reach deep into the brain to remove clots, Webster couldn’t help smiling because the steerable needle system he had been developing was perfect for the job.

Webster’s design, which he calls an active cannula, consists of a series of thin, nested tubes. Each tube has a different intrinsic curvature. By precisely rotating, extending and retracting these tubes, an operator can steer the tip in different directions, allowing it to follow a curving path through the body. The single needle system required for removing brain clots was actually much simpler than the multi-needle transnasal system.

I think this can save a lot of lives.When Webster returned, he told Weaver about the potential new application. The neurosurgeon was quite supportive: “I think this can save a lot of lives.There are a tremendous number of intracerebral hemorrhages and the number is certain to increase as the population ages.”

Graduate student Philip Swaney, who is working on the system, likes the fact it is closest to commercialization of all the projects in Webster’s Medical and Electromechanical Design Laboratory. “I like the idea of working on something that will begin saving lives in the very near future,” he said.

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