Cochlear Implant Surgery Procedure Techniques & Complications

[Gopi Shah MD]
Can you tell us a little bit about the surgery itself and the insertion approaches?

[Jacob Hunter MD]
The surgical procedure for cochlear implants consists of a bread and butter procedure that every ENT goes through for training. First is a mastoidectomy. Then, we drill a small tunnel, a window into the middle ear. That provides us a door into the cochlea. So there's a small window there called the round window. I strongly believe in placing the electrode into the round window because we like to place it in a specific compartment called the scala tympani.

Sometimes, that round window is difficult to see because it’s angled, or there's pathology. In these cases, surgeons will do what we call an extended round window. They'll partially insert the electrode through the round window and use the drill to open the bone right next to it so that they extend the round window. Then, there are some surgeons who prefer to do a cochleostomy. They drill a hole on the outside of the cochlea to place the electrode. Again, there's no right answer. Some people believe strongly in their way, but those are the three approaches.

[Jacob Hunter MD]
When we're drilling on the cochlea [during the cochleostomy], I turn the drill speed down to 10,000 with the understanding that I could still cause acoustic trauma if I drill at a high speed. My advice is to drill slowly and then slowly insert the electrode into the cochlea. I will literally have the resident count out every 5 or 10 seconds with the goal of inserting it somewhere between 1 minute and a 1.5 minutes. We call this a soft surgery approach. There is an argument that everybody should be doing that approach whenever possible. The idea is to try to preserve the natural structure of the cochlea as best as possible.

[Ashley Agan MD]
When you and I had talked earlier, you mentioned that in the future, we'll most likely use robotics to help insert electrodes perfectly. This could minimize the trauma.

[Jacob Hunter MD]
Yes, when you're slowly inserting that electrode, it might look smooth and steady to your eye. However, I remember being a trial participant in a study during my fellowship. They measured the forced insertion trauma, and when some people jackhammer it in there, it’s not good for the cochlea. There are a couple of people in the US that are working with robots to insert the electrode. As far as I'm aware, they will have everything set up, and then they use a computer/robot to insert the electrode.

[Jacob Hunter MD]
For those patients with residual hearing, patients that we would be able to acoustically aid after surgery, I don't use any special products. I like administering IV steroids during the case. Most patients get this through anesthesia, but I will actually bathe the middle ear in steroids. This allows absorption of the steroid through the round window and/or the oval window, with the goal of getting steroids into the cochlea to minimize postoperative inflammation. One of my colleagues in California actually injects the middle ear with steroids at the beginning of the case, about 30 minutes before, so maybe it has a little more time to get in there.

[Gopi Shah MD]
What kind of steroids do you use when you bathe the middle ear?

[Jacob Hunter MD]
I always ask for a preservative-free dexamethasone, but I don't know if that makes much of a difference. The hope is that it enters the cochlea through passive diffusion and minimizes fibrosis or scarring afterwards. I also send the patient home with a short steroid course. Administering steroids at the time of surgery increases the chance of maintaining the residual hearing in the long-term. We can still preserve the residual hearing at the time of surgery, but then there's a risk that they could either naturally lose it due to scarring or lose it at a faster rate due to the presence of a foreign object. The data suggests that administering steroids might minimize the chance of hearing loss in the long-run.

[Gopi Shah MD]
Let’s talk about the older population. Let’s say you have a patient that started having hearing trouble at 65, got hearing aids at 73, and now they're 80. What perioperative factors are unique to this population?

[Jacob Hunter MD]
That's a fair question. Obviously, as we get older, more of our patients have other medical problems. I ask about blood thinners if we're going to surgery, and I remind the patient and their family, "Continue them. Don't stop them. The risks are too great." My mentor, David Haynes and a colleague up at Mayo, Colin Driscoll, had done a study of patients who stopped their blood thinners, and there were significant consequences for stopping them.

I would love to be able to do the procedure under local anesthesia [to avoid the higher risk caused by general anesthesia], but our anesthesiologists don't feel comfortable doing it for our patients because it would be difficult to get access to the airway.

Another big postoperative factor is dealing with a small little device that has small buttons and a lot of little pieces. As we get older, our dexterity might not be as good, and this is an issue for some patients. Our audiologists help persuade them to choose a manufacturer’s device that requires less fiddling.

Those are the three big issues for this group, from a perioperative perspective.

[Gopi Shah MD]
Are there concerns about wound healing at the incision site in this age group or pressure ulcers from the external processor that they wear?

[Jacob Hunter MD]
I have not really been worried about the wound healing. Obviously, I ask about any other medical problems or past surgeries, and they might mention some previous complication that can play a role in this surgery.

For some older patients, the skin can be thin, so we do see occasionally that the skin demonstrates redness, erythema and sometimes erosion. We do pay attention to that in older patients. I saw a patient that came in right when we reopened after COVID, and his entire implant was exposed. It's rare, but we do see it occasionally. Since it is a magnet that allows the external device to connect to the internal device, we can reduce the magnet strength or put a pad on there to protect the skin.

[Ashley Agan MD]
Yeah. I feel like a lot of my older patients are nervous about the implications of having surgery when they’re 85.

[Jacob Hunter MD]
We actually have a paper coming out that looks at the barriers to implantation on a number of levels. We administered a survey to patients about why they did or did not elect to go through surgery. To break the numbers down, for every 4 patients that come to see us for an evaluation, 3 of them qualify for surgery, within those who qualify, only 2 of them end up proceeding with surgery. We wanted to explore why some patients did not proceed with surgery. Anesthesia and surgery are concerns, but those were surprisingly not the number one issue. The number one issue was that patients were worried about being worse off.

Another big issue is their concern about the possibility of better technology coming out later on. Researchers are actively looking into stem cell regeneration, and hopefully that will become a reality soon. Patients are thinking: Do I wait for something better, or do I go for something now?

I think the more we talk about it and the more we implant, the more we can increase awareness. Hearing healthcare is a big issue and we need to get the word out.