HEARO cochlear implantation – microsurgery via robot

Until now, robots have assisted surgeons in the operating room to enhance their capabilities. CASCINATION is a Swiss medical device company who has teamed up with MED-EL – the Innsbruck-based hearing implant company – to develop a system that can perform an autonomous cochlear implantation. Since then, HEARO has been successfully used – including at the Medical University of Vienna (MedUniWien).

In this MEDICA-tradefair.com interview, Professor Wolfgang Gstöttner, the Head of the University Hospital for ENT Diseases, explains how the system works and details the advantages it has over conventional cochlear implant surgery.

Professor Gstöttner, your University Hospital performed the first HEARO robotic cochlear implantation procedure successfully at the end of 2021. Who or what is HEARO?

Gstöttner: HEARO is an autonomous robotic surgical system. It is not comparable to other robotic surgical systems, which translate the surgeon’s hand movements to provide better accuracy and manual control. That’s because HEARO is a fully autonomous milling robot equipped with a drill that can drill a very precise channel measuring over 30 millimeters in length into the skull.

What are the advantages of a fully automated system like HEARO compared to the conventional methodology?

Gstöttner: Conventional cochlear implant surgery requires surgeons to create a large opening in the mastoid bone (the part of your skull located behind your ear) to get a better view and gain access to the cochlea. This leaves a cavity that’s two-by-two centimeters in size. While you can use a bone pate (a mixture of bone dust and fibrin glue) to close and cover the area, you still end up with a cavity when you perform conventional surgery in this setting.

This is not the case when you use the robot. It drills a 1.8 mm wide access channel and removes as little bone as possible. Its drilling accuracy is in the tenth of a millimeter range, which is based on data from a previously obtained computer tomography (CT) scan.

It’s a safe minimally invasive surgical method that involves less bone removal.

Surgical robots are like self-driving cars: While they can self-drive, they still require human oversight to be allowed on roadways. Does HEARO have safeguards?

Gstöttner: HEARO uses multiple safety features and measures.

One safety measure includes continuous neuromonitoring. Cochlear implantation is a complex microsurgical procedure because surgeons mill at an average distance of half a millimeter – sometimes even less – distance from the Nervus facialis (facial nerve). The robot performs continuous nerve stimulation to track nerve function. We also measure the electrical current needed to stimulate the nerve. Indirectly, we can also measure the bone density via the drilling resistance. The drill head shuts off automatically if it gets too close to the facial nerve. The surgeon can also track the drill head movement via a monitor. Thanks to this visual and real-time measurement data, surgeons have accurate information about the most critical point of the intervention.

After the start of the process, we recheck whether the drilled channel calculated at the beginning is correct. The only drawback is that you need to perform another CT scan at this point. A metal sleeve is inserted into the drilled channel, while the final CT scan confirms the correct positioning of the template.

Did you have any reservations about the process and how it works?

Gstöttner: My biggest concern was that the inserted cochlea electrode could somehow become entangled or that we would be unable to maintain control over the process. After all, you must navigate the electrode through the channel and the cochlea – that’s an insertion depth of about six centimeters (2,4 inches).

During the first surgery, we therefore used a tiny microscope to monitor through the eardrum whether the electrode is guided properly and is in the correct position. I haven’t done this in recent times because the drilled channel is so precise and consistent, which makes the electrode insertion a very safe process. I am fully satisfied and completely confident about it.

How many surgeries have been performed at your hospital with HEARO?

Gstöttner: Unfortunately, we have only performed three implantations to date. The preselection of patients is a very intricate and elaborate process. Not all persons who might be suited can be candidates because you must ensure a particular angle to approach from the surface of the skull to the inner ear to allow the drill to bypass the facial nerve by at least 50 micrometers. We cannot use the robot if this is not the case.

Patient education is also quite difficult as not all patients are excited about the idea of being the first person that undergoes surgery with the equipment.

Hence for now, the overall surgery time is much longer than the conventional cochlear implantation. We are still in a learning phase. Right now, the precise preparation before the surgery pertaining to the navigation is the most complex part. The robot’s mere drilling task doesn’t take long at all, but the navigation must be adjusted with screws, and you must also perform another CT scan.

That being said, we have planned more surgeries.

What will the future of the surgical robot look like?

Gstöttner: We can perform the conventional surgical procedure very well. However, from a global perspective, I am sure that robots will soon handle these conventional interventions exclusively.

Our goal is to use the robot for procedures that we can no longer perform with the same accuracy and precision. After all, cochlear implantations go along with a variety of complicated situations. These may include facial nerve abnormalities or anatomic variations, ossification, or other issues.

We are presently looking for solutions to problems that only a robot can solve. And this is an area where we expect to see exciting changes in our field this year.