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April 2008 Issue

Ravi Samy, MD, uses a hard foam skull to demonstrate how a robot can drill a perfectly circular cochlear implant well.
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Docs Research the Use of Robotics to Treat Skull-Base Tumors

By Cindy Starr
Published April 2008

In the surgical treatment of skull-base tumors, such as acoustic neuromas (a benign but worrisome brain tumor), getting there is half the battle.

Tucked beneath the skull, behind the ear and close to the facial nerve and other important structures, an acoustic neuroma is like a feisty warrior wedged and barricaded behind a stone wall. In short, it’s in a spot that can be difficult for surgeons to reach.

One of the ways is through the inner ear, says Ravi Samy, MD, assistant professor of otolaryngology at UC and physician at the Neuroscience Institute at UC and University Hospital.

“Quite a bit of skull behind the ear must be removed,” says Samy, who is also on staff at Cincinnati Children’s Hospital Medical Center. “It involves a lot of work, and it takes the surgeon about two to four hours just to do the approach.

“This is before we even get to the tumor work—which is the delicate portion of the procedure.”


Cross-Campus Collaboration

How to spare the surgeon’s energy, while reducing the potential for error and injury to the facial nerve during the delicate procedure, is a problem that a new kind robot may help solve.

Samy is working closely with Albert Bosse, PhD, associate professor in UC’s aerospace engineering department, on a robotic arm that may one day perform the heavy drilling.

The researchers are studying this option in UC’s Skull-Base Robotics Laboratory with a Mitsubishi robotic arm, which has a one-meter reach and seven degrees of freedom, or seven joints.

“Essentially this robot is very similar to a human arm,” Bosse explains. “It can do what your own arm can do.”

But unlike a human arm, the robotic arm doesn’t get tired.

“Instead of drilling for four hours and then doing the delicate work of tumor removal, we make it so that the early part of bone removal can be done by the robotic arm,” Samy says. “So we’re fresher for
the tumor removal.”

Using a joystick to maneuver the arm and a foot pedal to operate the drill, Samy and Bosse tested the device on cadaveric temporal bone samples and accumulated sufficient data to acquire grant funding for further study.

The researchers’ diverse skills make them an ideal team on the frontier of robotics surgery of the skull base, the area at the bottom of the skull, beneath the brain.  

Bosse came to UC in 2005 from the Naval Research Laboratory, where he was a civilian employee working for the Naval Center for Space Technology. In his previous job, he says, he essentially performed surgery on satellites.

“The first step is to capture the satellite,” he explains. “Once you capture it, it’s very similar to surgery. You have to figure out how to go in. You might replace electronics or repair some damage or something like that. It’s a delicate operation that requires accurate positioning.”

Samy was intrigued by Bosse’s background and attended a lecture about spacecraft capture that he was giving.

“I realized a lot of the stuff he has dealt with in space is very similar to what we do, except that it’s not hundreds of miles away,” Samy says.

“Both endeavors have risk, whether you’re dealing with a satellite worth hundreds of millions of dollars or human life. So a lot of what he said in his lecture made me think, wow, we could adapt what he’s doing to what I’m doing.”


Space-Age Robotics in Medicine

There is ample precedent for the use of robotics in medicine. The da Vinci Surgical System has applications for cardiothoracic, urologic and gynecological surgery. 

“Robotics has revolutionized prostate surgery,” Samy says. “It can do things that our hands cannot or may not be able to do. What we learned from our own experimentations—even though we’re using a single arm—is that not only can we do skull-base applications, orthopedic and spinal, but we can eventually start working on soft tissue as well.

“And not just with one arm, but maybe two or more different arms working together. The da Vinci has a total of four arms that can be used. One is typically a camera-holder; the other three work in the cavity during procedures.”

The robotic arm, Bosse says, is 10 times more accurate than a surgeon. A major benefit is the reduction of tremor.

“No matter how still you keep your hand, we surgeons all have a pulse-related tremor,” Samy says. “If you’re in a stressful situation, the tremor will be greater. And for residents who are still developing their skills, the tremor is likely to be greater still.”

Another factor is scale of motion. Even skilled microsurgeons have a tendency to go a little faster than they would wish around delicate structures and to make human-sized movements.

“If you want to move a millimeter or two,” Samy says, “you can get the robot to move at one-tenth that distance.”

Samy and Bosse have been using the robot to test its ability, when programmed, to drill a cochlear implant well into a hard foam board. A cochlear implant well, the site behind the ear where a cochlear implant receiver is placed, today is drilled by hand. The robot-produced well is, not surprisingly, perfectly circular.

“This is better and faster than we could ever do,” Samy says. “Plus, it takes only two minutes for the robot to do this. For me, it takes maybe five minutes; for a resident, 15 to 20 minutes. Our ultimate goal is to have the robotic arm put this cochlear implant well right onto the skull.”

Samy and Bosse hope to integrate other advanced technologies with robotics, including simulation training and image guidance. They envision a time when imaging data can be loaded into a computer prior to a surgical case, enabling physicians to plan and practice the surgical path they will take.

“You could practice ahead of time, as opposed to going into the operating room and practicing,” Samy says. “It’s already being done in aviation. There is simulation training for flying 747s and other planes.”

The duo also sees a day when a neurotologist here in Cincinnati controls a robotic arm during an operation in another part of the world.

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