Maxum Implant: Interview with Michael E. Glasscock III, MD
Douglas L. Beck, AuD, spoke with Dr. Glasscock, otologist and neurotologist, about the Maxum Implant as a hearing restoration option.
Academy: Hi, Mike. It's a pleasure to chat with you and thanks so much for your time! By way of disclosure, I'd like to mention you and I have been friends for some 15 years (or so). Further, I believe you're among the most, well-respected neurotologists in the world and I very much respect and appreciate your thoughts and opinions on neurotology and related matters.
Glasscock:: Thanks, Doug. It's a pleasure speaking with you, too.
Academy: For readers not familiar with you, let me mention you went to the University of Tennessee for medical school and the University of Tennessee, Department of Otolaryngology, for your ENT residency and then you completed your otology and neurotology fellowship in 1966, with Dr. Bill House at the Otologic Medical Group (House Ear Institute) in Los Angeles.
From 1969 to 1997, you practiced in Nashville, and at this point (2013) you've restricted your practice to the Maxum implant by Ototronix, at The Glasscock Hearing Implant Center in Woodlands (just outside of Houston), Texas.
Glasscock:: That sounds about right.
Implant in situ on ossicular chain
Academy: It's rather extraordinary to find a neurotologist who practices in such a finite area, which begs the question, what makes the Maxum by Ototronix so different from other implanted and more traditional hearing restoration options?
Glasscock:: Well, there are quite a few impressive features the Maxum offers. The first thing to note is traditional hearing aids have receivers/speakers, through which the processed sound is delivered to the ear canal and the tympanic membrane. The Maxum doesn't have a receiver/speaker—it's speakerless.
In fact, the Maxum uses an electromagnetic transfer of energy to transmit the sound from the custom-made, in-the-canal instrument (located about 4 or 5 mm from the tympanic membrane) to the implanted magnet located on the head of the stapes. So then, to get the processor in the canal and the implanted magnet to be aligned to optimally transmit and receive information, we use a very deep complete ear canal impression, and we teach an audiology course to reveal the ear impression protocol and to make sure the audiologist has the techniques and tools to safely accomplish this.
Academy: Yes, I know the deep impression technique is unique and the materials used in the technique are quite different from the familiar silicone impression material, and the end result is an impression all the way to the tympanic membrane, resulting in an impression of the umbo, itself?
Glasscock:: Yes, the impression is obviously critically important and we've re-engineered the protocol and the materials to allow a safe and excellent quality deep ear impression.
Academy: And, with regard to the energy transfer, the essential idea is you a rare-earth magnet sealed in a titanium canister that is sort of laser-crimped onto the head of the stapes, and an electromagnetic coil located in the medial end of the deep in-the-canal processor and the coil sends electromagnetic energy across the tympanic membrane which vibrates the implanted magnet, is that correct?
Glasscock:: Yes, that's the essential idea. And I should note that to implant the internal magnet, it's a "minimally invasive surgery." We create a flap in the external auditory canal and lift the tympanic membrane (similar to a stapes approach)—we don't go through the mastoid at all, there's no need to disarticulate the ossicles—and the surgery is entirely within the ear canal. The whole procedure takes about 30 to 45 minutes under local anesthesia and the patient goes home the same day.
Academy: That's very cool. And, by the way, what's the spectral response of the magnet?
Glasscock:: We can deliver a full spectrum of sound out to about 7000 Hz, where we then roll off. Because we don't have a speaker, acoustic feedback is simply not an issue so we can give significant gain, and, deliver more spectral content than standard hearing aids.
Implant and BTE in situ
Academy: That's a very interesting concept. What do the patients report and do you have data you can share with us?
Glasscock:: I absolutely knew you were going to ask that! The patient reports have been extremely positive. They often say the sound delivered through the Maxum is very natural, and because the sound is so clear, they do really well in noisy backgrounds. As you know Doug, that's the number one complaint of hearing aid patients, and qualitatively, we believe we've got a great solution. As far as data, we've got data collection underway and as soon as we have that published, we'll be happy to share it with you.
Academy: Okay, fair enough. What is the audiometric profile of the ideal candidate?
Glasscock:: Yes, good questions….we've had excellent results with patients with moderately-severe to severe high-frequency sensorineural loss, particularly high-frequency ski-slope hearing loss patients.
Academy: And, as far as the amount of gain measured in typical patients, what are you looking at as far as a functional gain, measured threshold benefit?
Glasscock:: Generally, we expect 50 to 60 dB of functional gain improvement from about 1000 to 7000 Hz. So the goal is increased audibility of the speech signal and to provide a very natural, high quality spectral response.
Academy: And, Mike, as best I recall, you wore the Maxum for six months. What was your experience like?
Glasscock:: Well, as you know, I had an Esteem implanted in one of my ears during the clinical study years ago, and then while the Esteem was awaiting FDA approval, I had the Maxum implanted in the contralateral ear. So all I can offer subjectively is that the Maxum delivers a very high quality sound and frankly, it's hard to remember that I'm wearing any sort of hearing prosthetic as the sound is a very high quality and very natural and there wasn't occlusion.
Academy: Okay, well I'm very interested to learn more and I'll look forward to your group-based audiometric data when that's ready. In the meantime, if you'll attach some illustrations and Web site information, we'll be in good shape. Thanks very much for your time and your willingness to participate.
Glasscock:: Thanks for your interest, Doug.
Michael Glasscock, MD, is an otologist/neurotologist, an adjunct professor of otolaryngology—Head and Neck Surgery, Vanderbilt Medical Center, and chair of the Medical Advisory Board, Ototronix and Maxum Implant Surgeon, at Glasscock Hearing Implant Center, The Woodlands, Texas.
Douglas L. Beck, AuD, Board Certified in Audiology, is the Web content editor for the American Academy of Audiology.