Cochlear Implant Candidacy
Adults may be a cochlear implant candidate if they have:
- Moderate to profound sensorineural hearing loss
- Difficulty understanding people even with high power hearing aids
Cochlear Implant Device
A cochlear implant consists of two parts, an external portion and an internal portion. The speech processor and headpiece make up the external portion of the device. The speech processor is worn behind the ear and looks like a behind-the-ear hearing aid. The headpiece is worn on the scalp. Figure 1 shows a speech processor (1) and headpiece (2). The internal portion consists of the implant and electrode array. Figure 2 shows the implant (3) and the electrode array (4). The headpiece sticks to the implant via magnets on both pieces, and the electrode array is surgically placed in the inner ear (cochlea)
How a Cochlear Implant Works
Figure 3 shows how a cochlear implant works.
- The microphone on the speech processor captures sound and the processor converts the sound to a digital signal.
- The speech processor sends the digital signal across the skin to the internal implant.
- The internal implant changes the signal to electrical energy, sending it to the electrode array in the cochlea.
- The electrodes stimulate the hearing nerve and the brain interprets this stimulation as sound.
- The cochlear implant user can adjust the loudness of sound with controls on the speech processor. In addition, the user can choose from a number of different individualized listening programs stored in the speech processor. The processors are powered by either disposable or rechargeable batteries.
In the Adult Cochlear Implant Program at Washington University, we implant the Advanced Bionics, Cochlear Americas Nucleus, and Med El implant systems. Information about all implant systems will be provided during the initial visits.
Factors Affecting Benefit
- Length and degree of hearing loss: Adults who have had hearing loss for a short period of time may learn to understand speech with the cochlear implant more quickly and more easily than those who have had severe to profound hearing loss for a long time. Likewise, those still receiving some benefit from their hearing aid(s) at the time of cochlear implant surgery may transition to a cochlear implant more quickly and more completely than those patients who may no longer wear hearing aid(s). However, every patient is different and we cannot predict how much speech understanding a patient will receive from a cochlear implant. Based on each individual’s hearing history, we try to provide realistic expectations of the benefits that a cochlear implant will provide.
- Status of cochlea: The presence of cochlear ossification (bone growth in the cochlea) or the presence of unhealthy auditory neural tissue can affect a person’s ability to understand speech with a cochlear implant. Through pre-operative CT scanning we are able to gain some knowledge about the status of an individual’s inner ear or cochlea prior to surgery.
- Motivation and commitment: Success with a cochlear implant requires consistent use the device, proper care of the equipment, involvement in a rehabilitation program, and regular follow up appointments to the cochlear implant center for device programming and evaluation of device function.
Cochlear Implant Process
The cochlear implant process is an extensive one due to the fact that this is a procedure that requires surgery. The pre-implant and post-implant process is described below.
Medicare and many private insurance companies provide coverage for cochlear implantation. The cochlear implant team will assist each individual with submitting a letter to their insurance for predetermination of cochlear implant coverage. This is usually done following the initial evaluation once candidacy is established. It can take up to 8 weeks to determine whether or not the costs associated with the implant process are a covered benefit. If cochlear implantation is a covered benefit, the patient is responsible for any copayments, deductibles, out of pocket charges, etc. as outlined by their individual policy.
Pre-implant evaluation process
- An extensive hearing case history is obtained. A hearing evaluation is performed which includes unaided and aided hearing tests. Speech recognition testing is done to determine the individual’s ability to understand words and sentences with their hearing aid(s) and the contribution of each ear to word understanding.
- Otologic examination by one of the cochlear implant surgeons.
- CT scan of the cochlea.
- Consultation with cochlear implant team audiologist to review test results, discuss cochlear implant technology, discuss factors that affect performance and explain realistic expectations.
A decision to proceed with cochlear implant surgery is made IF:
- Audiological criteria are met
- The individual is a surgical candidate (i.e., healthy enough for surgery)
- The post-implant process and expectations are understood
- The individual is interested in proceeding with surgery
Surgery is scheduled following completion of the pre-implant evaluation. The surgery usually takes a few hours and is typically an outpatient procedure which involves an overnight hospital stay. A post-op check with the surgeon usually takes place 1 week after surgery. Two to four weeks following surgery the patient will receive the external equipment at the “hook-up”. This is the first time the patient will hear sound through the cochlear implant.
Patients attend a 12-16 week rehabilitation program with 2, 50-minute appointments per week. We work with patients as best we can to accommodate schedules. The rehabilitation appointments include:
- Programming of speech processor to determine ideal settings
- Instruction in use of the speech processor and accessories
- Communication strategies training
- Auditory training
- Counseling on assistive devices, music appreciation, and telephone use.
The goal of our rehabilitation program is to optimize the benefit that each individual patient receives from their cochlear implant.
At the completion of the rehabilitation program, recipients will continue to be followed to ensure proper device function through continued reprogramming of the speech processor and monitoring of the patient’s speech understanding with the device. Patients will be seen at the following intervals:
- 6 months post initial activation of the cochlear implant
- 1 year post initial activation
- 18 months post initial activation
- 2 years post initial activation
- Annually thereafter unless additional appointments are needed.
If it is determined that you are not a candidate for a cochlear implant, you may still be interested in our hearing rehabilitation program. Program highlights include:
- Communication strategies training
- Assistive devices consultation
- Music appreciation tips
- Telephone training
- Auditory training