The Adult Cochlear Implant Program at Camino ENT
What is a cochlear implant?
A cochlear implant is different from a hearing aid. A hearing aid provides amplified sound to the ear canal, which is sent through the ear to the auditory nerve. The auditory nerve carries sound information to the brain. In individuals with significant hearing impairment, the sound that arrives in the ear is not fully processed due to damaged hair cells. Hair cells are tiny sensory cells that line the inner ear. If these hair cells are damaged, patients often describe sound as distorted or say that speech information is unclear. These patients will often say, “I can hear you but I cannot understand you.”
The cochlear implant device is placed in the inner ear (called the cochlea) and under the mastoid bone behind the ear. The internal device is placed or “implanted” during surgery. Surgery is completed with general anesthesia and the patient is usually released from the hospital the same day. As the incision is healing, the patient will not hear sound from the implant. The implant must be coupled with external equipment and activated in order for the patient to hear. The internal device is coupled to a microphone and speech processor worn externally. The external device is similar to a behind-the-ear hearing aid. The microphone picks up sound and changes the sound into a digital code. The digital code is sent along a small wire to a transmitter that is held in place by a small magnet in the internal receiver. The receiver inside the head alters the code into an electrical impulse, sending sound information to electrodes inside the cochlea. The electrical stimulation from the electrodes is sent along the hearing (auditory) nerve, which connects to the brain. Sound is then able to bypass the damaged portion of the ear.
A cochlear implant does not restore normal hearing and is not a cure for deafness. The device gives individuals access to sound that people with good hearing have access to everyday. Cochlear implants only deliver sound to the ear when the external equipment is powered on and connected with the internal device.
Cochlear Implant Audiologic Evaluation
Once hearing aids are optimized or maximized in some cases, the audiologist can evaluate the patient for a cochlear implant. The goal of a cochlear implant evaluation is to evaluate what degree of benefit the patient receives from the hearing aids. The patient’s hearing aids are initially tested on a special computer to determine the output (gain) of the hearing devices, to ensure they are appropriately set for the patient’s hearing loss. Once this has been confirmed, the patient is asked to sit in a sound treated room, in front of a speaker, with the hearing aids on. The patient is instructed to respond to sounds heard from the speaker by pressing a buzzer to find the threshold with the hearing aid (called an aided threshold). Aided thresholds are obtained for each hearing aid at a time, from 250 Hz to 6000 Hz. Aided speech testing is also completed. The patient is asked to repeat back sentences that are delivered through the speaker, for each hearing aid and then both hearing aids together (binaural).
The audiologist compares the aided results to those set by the Federal Drug Administration (FDA) in regard to cochlear implant candidates. Medicare also has standards set for cochlear implant candidates. If the patient is determined to be a cochlear implant candidate, audiologically, the audiologist will then explain how a cochlear implant works, how it is different than a hearing aid and what expectations the patient should have following surgery and rehabilitation. The audiologist will explain the three most common cochlear implant manufacturers and their devices, highlighting the differences between each device and the patient will try each device on externally. Also, educational materials will be given to the patient to read at home or access on the internet. If the patient decides to move forward based on this visit, the patient is referred back to the physician for medical follow-up and surgery consultation.
Cochlear Implant Medical Evaluation
Before a patient can schedule surgery for a cochlear implant, a full exam and discussion will need to be scheduled with the otolaryngologist (ear, nose and throat physician). The physician will take a thorough medical history and complete an exam of the head and neck. The physician may also ask the patient to obtain medical clearance from a primary care physician if any concerns exist regarding anesthesia.
Risks of Cochlear Implant Surgery
As with any surgery, Cochlear Implant Surgery does carry some risks. Our surgeon will explain these risks to you in detail and answer any questions you may have.
Part of the otolaryngologist’s medical evaluation will include a scan of the temporal bone. This scan will allow the physician to see whether the inner ear structure is intact, detect any abnormalities that may present a challenge for surgery and also help determine the cause of the hearing loss (if unknown).
Expectations for Cochlear Implant Recipients
Before a patient is implanted, the audiologist and physician must determine that the patient has realistic expectations for how they will do after surgery. These expectations will be explained once the audiologic and medical examinations are completed. Cochlear implant performance heavily depends on the duration of hearing loss, degree of hearing loss and the duration of hearing aid use. Also, the patient will be expected to complete rehabilitation exercises at home in order to learn how to hear through the implant more efficiently. Each cochlear implant manufacturer has rehabilitation resources to help patients reach these goals, some which can be purchased or found online.
Cochlear Implant Activation
Two to four weeks following implantation, after the surgical site has healed, the patient will be scheduled with the audiologist for the initial “activation” or “stimulation” of the implant. At this appointment, the audiologist will determine the most appropriate magnet strength to connect the transmitter coil to the internal device. The device will be connected to the computer and the patient will be instructed to listen for sound through the implant, as the audiologist sets the levels. Once levels are set through the computer, the implant is activated – all sound entering the microphone will be stimulating the implant. At first, many patients describe this sound as “noisy”. As the patient adapts to the implant over several weeks and months, the brain learns to hear and understand electrical sound. Depending on expectations set prior to surgery, the patient can learn to detect, discriminate, identify and comprehend speech in different listening environments over time.
Cochlear Implant Follow-Up Services
Once the cochlear implant has been activated, the audiologist will program the implant with several different “maps” containing increasing levels of sound. The patient will be instructed to progress through these maps to improve tolerance to electrical sound, so that speech can be heard through the implant. It is important that the patient have regular follow-up programming or “mapping” services, so that levels are set optimally. The audiologist will explain when follow-up appointments should occur so that the patient is seen at the appropriate intervals.
Cochlear Implant Manufacturers
Camino ENT works with the three most common cochlear implant manufacturers: Advanced Bionics, Cochlear Americas and Med-El. Each manufacturer markets their device differently and has a different device style and function. However, all three devices produce electrical sound that allows the patient to hear through the implant. Usually, the audiologist and surgeon do not have a preference for a device unless there is a medical or audiologic consideration that is shared with the patient. Since the decision is often left with the patient, it can be difficult for the patient to decide which device is right for them. The audiologist will explain the differences between all three devices and allow the patient to try them on externally. Also, educational materials will be given to the patient to read at home or access on the internet.
Cochlear Implant Troubleshooting
Although external equipment for cochlear implants are designed to be durable and last a long time, occasionally equipment can need repair. For cochlear implant patients, it is important to know how to contact the customer service department at their respective manufacturer for help troubleshooting their device. If the patient believes the equipment may be broken and in need of replacement, it is first recommended that the patient try troubleshooting with the backup speech processor. If hearing improves with the backup processor, the patient should contact the manufacturer to see about diagnosing the equipment problem. More information can be found in the user manual for the processor.
If hearing does not improve with the backup processor, the patient should contact the audiologist immediately to report the issue. Dr. Tucker, an audiologist at Camino ENT, can be conveniently contacted via email.