Hearing Loss and Cochlear Implants

Hearing loss can be a very troublesome problem and is more prevalent than some may think. According to the National Institute of Health (NIH), about 2 to 3 out of every 1,000 children in the United States are born with a detectable level of hearing loss in one or both ears, and 15% of adults over age 18 complain of hearing loss. About 2 percent of adults aged 45 to 54 have disabling hearing loss. The rate increases to 8.5 percent for adults aged 55 to 64. Nearly 25 percent of those aged 65 to 74 and 50 percent of those who are 75 and older have disabling hearing loss (https://www.nidcd.nih.gov/health/statistics/quick-statistics-hearing).

There are numerous studies showing a strong link between hearing loss and dementia; specifically early-onset dementia (Wolfgang, Kelly Hearing Loss and Dementia: Breakthrough Research Seeks Causal Link, The Hearing Journal: September 2019 - Volume 72 - Issue 9 - p 22,23,26 doi: 10.1097/01.HJ.0000582420.42570.de ). The problem arises when hearing loss interferes with one's ability to function in social settings (e.g. noisy restaurants, parties, and family gatherings). Hearing loss will cause an inability to keep up with the conversation, leading to social isolation and a decrease in mental stimulation. This is what leads to early-onset dementia. For these reasons, I recommend to all my patients who are having these problems to get a hearing test and consider hearing aids depending on the severity of their loss.

Some patients are beyond the help of hearing aids. Either they have tried them for years and they no longer work, their loss is so bad that hearing aids were never beneficial, or they were born without any functional hearing in the first place. In these patients, a cochlear implant may be a good option. A cochlear implant is an electrode array that is inserted into the cochlea (the hearing organ of the inner ear). These electrodes then stimulate the hearing nerve directly, bypassing the areas most commonly affected by hearing loss.

The implants are placed with outpatient surgery, usually, one at a time but can be done on both sides simultaneously in certain cases. It does take several weeks of healing before the implant can be activated, and then several sessions over the course of weeks to months after surgery before the device is fully functional. This is done slowly to prevent over-stimulation of the brain from this new mode of hearing.

The hearing a patient will get from a cochlear implant is not akin to natural hearing. It does not perceive normal sounds, which will be more noticeable to a patient who has a history of normal hearing. Some patients describe it as "tinny" or "mechanical", and it can be difficult to appreciate the nuances of noise which are important in the appreciation of things like music. However, if a patient's hearing is already beyond the help of hearing aids, then they likely were not able to appreciate the subtleties of music prior to surgery. And the functional benefits of the implant will likely outweigh these limitations.

The surgery and implant come with risks; as all surgeries do. These include pain, bleeding, infection, scarring, dizziness, injury to the nerve which controls movement of the face (Facial nerve), Injury to the nerve which provides taste to the tongue (Chorda tympani nerve), loss of some or all residual normal hearing, and spinal fluid leak. Each of these risks should be considered carefully before agreeing to surgery.

• Postoperative pain is usually mild and manageable with minimal medications.
• Bleeding is usually minimal during surgery, but bleeding occurring after surgery can put the implant at risk.
• Infections are always a risk when foreign material is implanted in the body. The most common infection with cochlear implant surgery is a mild skin wound infection which is managed easily with antibiotics. However, more serious infections (like meningitis) are possible, which is why all patients should receive a pneumococcal (pneumonia) vaccine prior to surgery which significantly reduces the risk of meningitis.
• The scar would be placed behind the ear extending slightly up onto the scalp, usually hidden by hair.
• Dizziness is usually temporary, lasting minutes to hours after surgery, but rarely can last for several weeks if severe.
• The facial nerve passes through the ear on its way out to the facial muscles and can potentially be injured during any ear surgery that requires drilling of bone. Nerve monitors are utilized to ensure that the position of the nerve is known at all times during surgery and this has helped to prevent injuries to the nerve. Facial nerve injury during cochlear implant surgery is exceptionally rare.
• The Chorda Tympani nerve, which supplies taste to the tongue, can be stretched or injured during surgery, causing an alteration of taste postoperatively. This is usually temporary but can rarely be permanent.
• Although every effort is made to preserve any remaining natural hearing ability, the insertion of the implant into the cochlea can damage the hearing mechanism, resulting in partial or complete loss of residual hearing. This does not affect the function of the implant itself but would make the patient completely dependent on the implant for any hearing function. Although this is not always the case, patients should expect to lose most if not all residual natural hearing from the surgery so they are mentally prepared for that outcome.
• The brain is bathed in spinal fluid and there is thin bone separating the ear from the brain. The bony drilling required during surgery can damage this barrier and cause a leak of spinal fluid into the ear. If this is recognized at the time of surgery it would be repaired immediately with no adverse effects. However, if it is not recognized until after surgery then additional surgery may be required for repair.

Overall cochlear implant surgery is very safe and well-tolerated. The restoration of hearing can have a profound impact on a person's quality of life and interactions with loved ones. If you or someone you know has very poor hearing that has not responded well to hearing aids, consider a visit to your local ENT surgeon to discuss the possibility of cochlear implant surgery.

Helpful info can be found at one of the manufacturer's websites here: https://www.cochlear.com/us/ci-landing-page?utm_campaign=lg-m_all_adu_bau_bau_brand&utm_source=google&utm_medium=cpc&utm_term=cochlear%20americas&utm_content=dtc_cochlear-brand-highvolume-exact&gclid=CjwKCAjw7rWKBhAtEiwAJ3CWLCZ0XABV3KFJIrhzSuLsSDJUupaGo-KcD9nk30BRv1h3ZfmaQ24JGBoCniMQAvD_BwE