You Want This Robot to Drill Into Your Ear, Trust Us

A robot is now capable of performing the trickiest part of cochlear implant surgery on a live human.

It sounds violent and dangerous, but you’d definitely want a precise robot drilling a 1.8-millimeter hole through your skull — working in just 2.5 millimeters of space — for the procedure that’s so difficult and dangerous that human doctors continue to struggle with it.

In July 2016, a 51-year-old woman participating in a clinical trial became the first patient to successfully undergo cochlear implant surgery, partially completed by a robot. As of two weeks ago, that robot is up to four. The research was published Wednesday in the journal Science Robotics.

This surgery is the sort where the slightest hand tremor could cause permanent damage. And indeed, about a third of patients who opt for it (as performed by human doctors) still end up with hearing loss from damage incurred during the procedure. Robots could change that.

The critical task where the robot takes over here is called a keyhole surgery. A human doctor needs to access the inner ear — the cochlea — from outside the skull. They open up a large section behind the ear and move slowly down, trying to identify bony canals of sensitive facial nerve as they go. Once they’ve found the right place, they need to drill a hole.

“So we said, ‘what if we can drill a vectorized approach from outside the skill, between the nerves, directly toward the cochlea?’” co-author Stefan Weber tells Inverse. “The challenge though is that you can find the angle you want, but when you need the robot to drill it, the surgeon has no idea whether the robot is actually in the right orientation.”

There’s no way to tell just by looking at the robot whether it’s safe to proceed with the drilling. Weber and his colleagues instituted a number of safeguards for this issue, including three separate sensors to monitor the robot’s progress. It’s been successful so far, but we’re still just talking about four people. Will it be able to improve on the percent of patients who suffer hearing loss from the surgery?

“This is exactly what we’re working on now, to see whether we can get this number down,” Weber says. “We have no estimates, no guesstimates, but this is what motivates the research.”

For now, at least, the robot still only performs part of the surgery — even if it is the most notoriously difficult part — so they won’t be putting human doctors out of work anytime soon. The researchers are working with a cochlear manufacturer to create commercial versions and are in the process of getting the regulatory approvals they need to conduct clinical trials in the future. But the emphasis at the moment is on singular event of the milestone itself (well, technically there are now four), not scaling it up or collecting statistically significant data.

“It’s a tech story right now,” Weber says.

Abstract

Surgical robot systems can work beyond the limits of human perception, dexterity and scale making them inherently suitable for use in microsurgical procedures. However, despite extensive research, image-guided robotics application for microsurgery have seen limited introduction into clinical care to date. Among others, challenges are geometric scale and haptic resolution at which the surgeon cannot sufficiently control a device outside the range of human faculties. Mechanisms are required to ascertain redundant control on process variables that ensure safety of the device, much like instrument-flight in avionics. Cochlear Implantation surgery (CI) is a microsurgical procedure, in which specific tasks are at sub-millimetric scale and exceed reliable visuo-tactile feedback. CI is subject to intra- and inter-operative variations, leading to potentially inconsistent clinical and audiological outcomes for patients. The concept of robotic CI aims to increase consistency of surgical outcomes such as preservation of residual hearing and reduce invasiveness of the procedure. We report the first successful image-guided, robotic CI in man. The robotic treatment model encompasses: computer-assisted surgery planning, precision stereotactic image-guidance, in-situ assessment of tissue properties and multipolar neuromonitoring, based on in vitro, in vivo and pilot data. The clinical assessment sets-out the surgical workflow: planning, robotic access-drilling, computer-assisted electrode selection and keyhole electrode-placement. The model is expandable to integrate additional robotic functionalities such as cochlear access and electrode insertion. Our results demonstrate the feasibility and possibilities of using robotic technology for microsurgery on the lateral skull base. It has the potential for significant benefit in other microsurgical domains for which there is no task-oriented, robotic technology available at present.