Nov 2016  Labmate-Online

Cochlear implants are a wonderful achievement of modern medicine and have already helped many patients who are profoundly deaf or severely hard of hearing. The implant is surgically placed under the skin behind the ear. However, this technique requires highly trained surgeons and is not without risks. A surgical implant procedure may result in injury to the facial nerve, meningitis, tinnitus, infections, cerebrospinal fluid leakage and many other afflictions.

Internal View

 Swiss researchers have been looking into making cochlear implant surgery less invasive, working on an image-guided surgical robot system which is able to drill a small tunnel hole in the skull behind the ear through which the cochlear implant can be inserted.

The new procedure is much less invasive than conventional techniques and allows for rapid recovery and minimum hospital stay time. The surgery is preceded by a CT scan of the head, a thorough computer-based planning of the drilling trajectory and a semi-automatic segmentation of important anatomical features. For the actual surgery, the acquired information then needs to be synchronised with the patient. The surgical robot requires a drilling depth of approximately 25 mm.

Through innovative processes and a sophisticated security concept, the deviation from the planned end point can be kept below 0.2 mm, which reduces the risk of facial nerve damage significantly.“ It was very important for us to obtain a detailed thermal view of the bone structure, because we wanted to know exactly what happens during the drilling process in terms of temperature at any drilling depth,” said researcher Arne Feldmann. “The area we were interested in is only about 10mm in width and 30 mm in length. We were able to study this small window very accurately with the thermal camera. With its uncooled detector, high resolution, and all of the cutting-edge functionality scientists and researchers have come to expect from FLIR, the camera brings affordable research and science thermal imaging and measurement to a whole new level.

Combined with FLIR’s dedicated thermal analysis software, researchers have a powerful set of tools that allow them to achieve good results quickly. Thermal images acquired during the test set-up allowed researchers to compare standard drill bits with innovative, newly designed surgical drill bits. The patented new drill bit design clearly presented a significant temperature reduction during the drilling process. The FLIR camera was also used to compare the temperature impact of different cooling and irrigation strategies.

Furthermore, researchers discovered lower temperatures with a stepwise, interval based drilling procedure, as opposed to continuous drilling.