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Cochlear Implants and other implantable hearing devices

Timothy C. Hain, MD. Page last modified: February 17, 2017

An exciting recent development is an ability to provide hearing to some bilaterally deafened individuals through implantation of a device which directly stimulates the hearing nerve (actually the spiral ganglion). Although this device is not generally considered as a "hearing aid", it performs the same purpose for individuals with severe hearing impairment involving both ears. At the time of writing of this section, there are three companies that make implants -- Advanced Bionics, Med-El, and Cochlear Ltd. Generally an electrode is threaded into the cochlea, often via the round window.

Cochlear Implant -- CT scan
Cochlear implant from a patient of Dr. Hain's practice in Chicago. Axial CT scan of a cochlear implant electrode

Cochlear implants do not completely substitute for a normally hearing ear,and at very best, may allow someone who was previously totally deaf to understand conversation on a telephone. Cochlear implant packages, including the device, surgery, and rehabilitation are much more expensive than hearing aids (roughly $45,000), but when one is indicated, they are sometimes covered by insurance, unlike the usual situation with hearing aids.

With respect to cost-effectiveness of cochlear implants,  Lammers et al (2011) reported that it varies widely, and more data is needed to come to a firm conclusion.  This doesn't speak very well for the cost effectiveness of implants -- if they were very effective, there would be no quibbling. Our observations is that cochlear implants in the US are generally found in persons with special financial resources -- they may be very wealthy, they may very well insured, or they are indigent, perhaps on Medicaid, and the cost is paid by government programs. Obviously, the great majority of people in the middle are left out. 

A patient-contributed history is found here. Remarkable improvements in performance have been accomplished since 1980.

Indications for Cochlear Implants

Unless one is independently wealthy, one wants one's cochlear implant to be "indicated" so that insurance will cover the extremely high cost.  At the present writing (2017), this means that one should be "unaidable" -- meaning that hearing aids do not provide reasonable hearing. Roughly speaking, "unaidable" is assessed by the 50-50 rule -- more than 50db down, and less than 50% word recognition. Most people are worse than this -- they are 70 dB down in each ear. What is considered as "unaidable" is determined by individual insurance carriers:

Medicare criteria are set at a 40% word recognition. From the online document, (accessed 2/17/2017)

"The Centers for Medicare and Medicaid Services (CMS) has determined the following: The evidence is adequate to conclude that cochlear implantation is reasonable and necessary for treatment of bilateral pre-or-postlinguistic, sensorineural, moderate-to-profound hearing loss in individuals who demonstrate limited benefit from amplification. Limited benefit from amplification is defined by test scores of ≤ 40% correct in the best-aided listening condition on tape recorded tests of open-set sentence cognition."

We think Medicare made a typographical error here - -the word "cognition" should be something else -- perhaps completion, as we don't think that one can measure "cognition".

The very high initial cost of these devices (similar to the very high cost for some types of cancer chemotherapy), combined with the limited benefit of these devices (i.e. it is wonderful to hear again, but no lives are saved here), makes for some interesting ethical issues, as well as interesting insurance situations. One might wonder -- if there is a fixed amount of monetary resources for health care, should a given $50,000 be spent on a cochlear implant, or on HIV medication ? Again, no lives are saved by cochlear implants. There could certainly be huge differences of opinions, in a world where health care benefits are rationed.

Again, suppose that an individual who could not afford an insurance that would pay for a CI, were "helped out" through a charitable program, or perhaps even a health care facility, that bought them insurance, which could then be used to purchase an implant. The patient, health care facility and device providers all benefit, but the insurance company might be unenthused with this tactic.

There has been a trend towards implants being used in people who are not "unaidable".  For example, persons who have one implant already seeking a second implant. In Germany, implants have been used for single-sided deafness -- i.e. people with good hearing on one ear (Jacob et al, 2011). Our take on this is that in general, the costs of implants are very high, and the benefits are low, and thus medical/social resources would be better spent elsewhere. In other words, we don't think that government funding should be paying for these devices. Of course, the independently wealthy are in another category and they can do whatever they want as long as they are paying for it themselves.

We also think that the BAHA device or the CROS hearing aid for unilateral deafness is a far better choice than a cochlear implant as it is not nearly as invasive.

Further information about cochlear implants can be found at the following sites:

  1. Alexander Graham Bell Association for the deaf
  2. Auditory-Verbal International
  3. Clarion corporation home page

Complications of Cochlear Implants:

Cochlear implants sometimes have complications. Dodson reported a 9.3% overall complication rate, with 59% being due to device failure (Dodson et al, 2007).

Vertigo post cochlear implant is common.

We have a separate discussion of this problem here.

Other implantable hearing devices

The BAHA (bone attached hearing aid) is an excellent implantable device for persons who have either primarily a conductive hearing loss or good hearing on the opposite ear.

There is also a device that is implanted into the middle ear, in essence, implanting the speaker part of the hearing aid. This device, the Symphonix Vibrant Soundbridge, is mainly used for individuals who are unable to tolerate conventional hearing aids. It avoids the "occlusion" effect and feedback. These devices often have mechanical problems. The Vibrant Soundbridge is now available in the US through MED-EL Corporation.

The auditory brainstem implant (ABI) is mainly used for people with "nerve" deafness, such as persons with neurofibromatosis. It provides sound quality similar to a single-channel cochlear implant (i.e. sound awareness, but not speech comprehension).

MRI safety of cochlear implants:

REFERENCES

 

Copyright February 17, 2017 , Timothy C. Hain, M.D. All rights reserved. Last saved on February 17, 2017