Changes in Cochlear Implant Candidacy and Technologies

Here's our report on the Advanced Bionics workshop at ALDAcon 2003 in Las Vegas. We presented the information from the Cochlear Corporation a couple of weeks ago, and we'll present the MedEl information next week.

The workshop was presented by Ann Marie Henson.

As cochlear implants (CIs) become better and better, the candidacy requirements are opened up to include more and more people. The requirements are based on an assessment of whether or not a person is likely to hear significantly better with a CI than she currently does with hearing aids. The current requirements for adults are:

- Healthy adult age 18 or older
- A hearing loss of 70 db or greater in both ears
- Lack of benefit from hearing aids, which normally means a HINT (Hearing in Noise Test) score of less than 50%. Those people who have trouble understanding strangers on the phone or those who score less than 30% on single word tests will probably qualify (score less than 50%) when given the HINT test.

Note that Medicare guidelines have not kept up with those established by the FDA. Medicare requires a HINT score of less than 30%, rather than the 50% required by the FDA.

A typical CI implantee can expect hearing thresholds of 20 db to 40 db at all test frequencies, which generally results in greatly improved hearing compared to the 70 db minimum for CI candidacy.

CI history shows a constant improvement in the hearing ability of recipients. Early recipients in 1981 scored an average of 12% correct on the Open Set Easy Sentence test. As unimpressive as that is by today's standards, it was still a considerable improvement for those people who scored 0% with their hearing aids. Increasing performance is reflected in scores of 30% in 1984, 58% in 1989, 77% in 1994, and 85% in 1999.

Advanced Bionics (AB) is committed to ensuring that previous recipients are able to take advantage of improving technology. One indication of that commitment is that all of their speech processors are backwards compatible with previous internal components.

In April 2001, Advanced Bionics changed their internal electronics to a system called CII. Then in the summer of 2003, they repackaged the CII into the HiRes 90K. It contains the same electronics, but is easier to implant.

Their HiRes system features a removable magnet, focusing electrodes and 90,000 samples per second. It includes 16 high-precision output circuits, which means that each of their 16 electrodes has its own power source. This allows all 16 electrodes to be stimulated at the same time. Other CIs have a single power source, which means that only one electrode can be stimulated at a time.

Advanced Bionics believes that their sound strategy provides the most accurate representation of real world sound. It starts with an increased input dynamic range compared to other CIs. Their input threshold is automatically adjusted to match the level of environmental sound. The range is from 25 dBs to 85 dBs. The effective Input Dynamic Range is 80db.

The signal is then processed through the 16 independent channels, which allows the HiRes system to deliver the full input spectrum. By comparison, other CIs using the CIS strategy are limited to 800 pulses per second, which is a low frequency signal.

Advanced Bionics testing indicates that the users do, in fact, perform better with the HiRes system than with the CIS strategy. Their studies indicate an average improvement of 14% on the HINT test, and those with the worst performance using CIS tend to show the most improvement. Advanced Bionics also thinks that the HiRes system performs better on music, because of its reproduction of high frequency components.

Advanced Bionics has recently introduced the Auria ear level processor, which is worn much like a behind-the-ear (BTE) hearing aid. It has a new, more comfortable shape, and the same processing capabilities as the body worn processor. It holds three programs.

One of the options with the Auria processor is the T-Mic, which is located in the ear canal. This placement allows the use of standard headphones and allows one to use any telephone (including cell phones) in a standard fashion.

Advanced Bionics has recently introduced several battery improvements for the Auria. Their standard rechargeable battery uses a new chemistry that provides an average of nine hours use on a charge. This battery is currently available for the Auria, and will be available for older processors in the spring of 2004. They are also developing new cells called Power Cell Plus, which are expected to provide an average of 17 hours use.

While some people prefer the ear level processor, those who prefer the body worn processor cite the following advantages:
- It doesn't fall off as easily as the ear-level processor
- It's easier to plug things in, because you can see the unit.
- The knobs are easier to manipulate.
- It's more comfortable, because there is nothing on the ear.

The CII has Neural Response Imagery, which allows an audiologist to test the function of the acoustic nerve without user input. This is especially useful for children.

The Auria has direct connection for connecting audio devices; the CI and CII have auxiliary earhooks with a connected cable that allow the attachment of audio devices.

The Phonak wireless system will be available for the Auria in the spring of 2003, and for the CI and CII in the summer.