Ear is consists of three major parts – the external ear, middle ear and inner part that plays a vital role in hearing. When a person has any disease or obstruction in ear canal, ear drum or middle ear, then his/her conductive hearing may be impaired. This can be corrected with medical or surgical treatment or in some cases; a hearing aid may also be used. Sensorineural impairment or nerve deafness can occur due to inner ear problem and it cannot be corrected with medicines but only can be treated with cochlear implant. It is different from hearing aid as cochlear implant can help person with little or no hearing.
People who have moderate to severe hearing loss in both ears, doesn’t receive any or little benefit from hearing aid, and have poor hearing in both ears, not able to understand speech without lip reading etc should consider the cochlear implant procedure.
A cochlear implant is a small electronic device that stimulates the cochlear nerve electrically and replaces the function of damaged inner ear. This is implanted in the inner ear through surgery and activated by a device worn outside the ear. This device bypasses the damaged parts of the auditory system and stimulates the nerve of hearing directly. The cochlear implant has two main parts:
· The external part – the external part of this implant sits behind the ear and consists of speech processor, microphone, and battery.
· The internal part – the internal part of the device is surgically implanted under the skin behind the ear. This part consists of receiver and electrodes.
Many people have cochlear devices implanted in both ears which can improve the ability if listening and to identify the direction from where the sound is coming from. There are various benefits of this implant that may include:
· Better hearing ability
· Better focus even in noisy environment
· Can enjoy music
· Can watch TV without captions
· Can have conversations with people easily
· Reconnect with missed sounds
· Can talk and hear on phone
A cochlear implant may not be right for every person with hearing disease. The implant team that consists of otolaryngologist, audfiologist, medical nurse etc will determine whether a person is suitable for cochlear implant or not. This can be done by performing several tests that may include:
· Otologic (ear) evaluation – in this test, the ear canal and middle ear is examined properly to ensure that no active infection or other abnormality should hinder the implant surgery
· Physical examination – is performed to check any potential problems with the use of general anesthesia required for the procedure.
· Audiologic (hearing) evaluation- the extensive hearing tests are performed to find out how much a person can hear with or without the help of hearing aid.
· X-ray (radiographic) evaluation – computerized tomography (CT scan) or magnetic resonance imaging (MRI) scans are done to evaluate inner ear anatomy of a person.
· Psychological examination - to see if patient will be able to cope with the implant.
During the surgery, patient will be given general anesthesia through intravenous lines and surgeon will make an incision behind the ear to open mastoid bone to expose the middle ear space. Once it is done, an opening is made in cochlea and surgeon will insert implant electrodes. An electronic device called receiver will be placed under the skin behind the ear. Incisions will be closed and patient will be shifted to the recovery room to be under observation at least for two hours. This whole procedure can take 2-4 hours and is done as outpatient procedure.
Post discharge, patient will be given instructions on how to care for the incisions and stitches. The external part of the cochlear implant will be added after about 4 to 6 weeks which will include a microphone and speech processor. Patient will learn how to use and manage the implant gradually. Regular follow-ups are required for readjustment of the speech processor as needed. Visiting speech-language pathologists, audiologists, counselors may be required
There are some risks and complications involved in the cochlear implant procedure that may include:
· Unexpected bleeding
· Infection at the implant site
· Tinnitus (ringing in the ears)
· Dizziness or vertigo
· Taste disturbances
· Leakage of the fluid in the cochlea
· Spinal fluid leakage
· Facial nerve injury
· Inflammation around the implant