Hybrid Cochlear Implant

Most hearing loss occurs in the high pitch (frequency) region of the inner ear. High-frequency sounds include consonants in words, such as the “f”, “s”, “th” sounds. Without them, words can sound similarly, making what you hear jumbled and sometimes difficult to understand. High-frequency sounds also include birds chirping or melody in music, so you may find that you can no longer enjoy these sounds.

If you can hear low-frequency sounds (male voices) but are missing high-frequency sounds, a Hybrid cochlear implant may be a solution. Hybrid cochlear implants use any residual low-frequency hearing you have while providing access to the high-frequency sounds you are missing, for a richer hearing experience.

The external processor of the hybrid cochlear implant picks up incoming sounds and transmits the low frequency information to a hearing aid. The hearing aid then amplifies the sound based on the patient’s low frequency hearing. The high frequency sound information is transmitted to the cochlear implant component of the device, which is then converted into electrical signals which stimulate the high frequency regions of the hearing nerve.

A hybrid cochlear implant is for those with a severe to profound high frequency hearing loss with intact or moderately lost low frequency hearing. Age-related hearing loss and noise-induced hearing loss are the most common causes of sensorineural hearing loss, and almost always result in a high frequency hearing loss.

The hearing loss is caused by damage to the inner hair cells in the cochlea. The high frequency inner hair cells are more susceptible to aging and noise effects, resulting in that common high frequency hearing loss configuration. People who have done a lot of shooting or served in the military, at an older age will lose more cells in the inner ear from aging and are the most common hybrid cochlear implant candidate.

The high frequency hearing loss causes difficulty with understanding speech, especially in noisy environments. It can severely affect an individual’s social and work environments. The high frequency sounds create clarity of speech. When you are unable to hearing those high frequency consonant sounds, words can be difficult to distinguish and sound muffled.

There are currently two cochlear implant manufacturers that are now offering a hybrid implant system, Cochlear and Med-El. Those with high frequency hearing loss who do not benefit from traditional hearing aids may be a candidate for a hybrid implant.

Dr. Djalilian uses the same gentle technique of implant placement in all patients undergoing cochlear implantation. However, the insertion of the hybrid electrode is performed more slowly with a 10-15 second gap between each electrode vs. 5-10 second in the traditional electrode. A slower insertion has a higher chance of hearing preservation. A few technical points are below:

• All soft tissue and bony work are completed prior to opening the cochlea. Usually a round window approach is taken to reduce blood and bone dust from entering the cochlea which can cause inflammation and hearing loss. Steroids are placed locally to reduce the likelihood of inflammation. Patients are also treated with steroids before and after surgery.
• A very minimally-traumatic opening is made into the cochlea. No suctioning of the inner ear fluid (perilymph) is performed. Prior to opening the cochlea, hyaluronic acid gel is placed to prevent blood from going in and the fluid from leaking out. The opening in the cochlea is done very gently.
• A minimally-traumatic insertion is performed. The electrode is placed after the opening is made with a very short time lapse. The electrode is inserted very slowly.

Dr. Djalilian has been performing the soft technique for cochlear implantation for many years since it was first described in Europe. We have been fortunate to have one of the highest hearing preservation rates in cochlear implant surgery and strive to continue to refine the techniques we have developed in over 500 surgeries to improve our outcomes even further.