A cochlear implant (कर्णावत प्रत्यारोपण) is a surgically implanted neuroprosthesis that provides a person who has moderate-to-profound sensorineural hearing loss with sound perception. With the help of therapy, cochlear implants may allow for improved speech understanding in both quiet and noisy environments. A CI bypasses acoustic hearing by direct electrical stimulation of the auditory nerve. Through everyday listening and auditory training, cochlear implants allow both children and adults to learn to interpret those signals as speech and sound. The surgical procedure is performed under general anesthesia. Surgical risks are minimal and most individuals will undergo outpatient surgery and go home the same day. However, some individuals will experience dizziness, and on rare occasions, tinnitus or facial nerve bruising.
What is Cochlea?
It is the spiral cavity of the inner ear containing the organ of Corti, which produces nerve impulses in response to sound vibrations.
What is Cochlear?
It is an electronic device that stimulates the auditory nerve through electrodes placed in the cochlea of the inner ear, allowing some severely deaf people to perceive sounds: “for those with severe to profound hearing loss, implantable hearing devices like cochlear implants can be an effective solution”.
Cochlear implant Meaning
A cochlear implant is a medical device designed to provide hearing sensation to individuals with severe to profound hearing loss who do not benefit significantly from traditional hearing aids. It’s a complex electronic device that helps restore a sense of sound by directly stimulating the auditory nerve.
How Cochlear implant work?
How Cochlear implant is better than traditional hearing aids?
What are the Risk factors of a Cochlear implant Surgery?
Parts for Cochlear implant
Cochlear implants bypass most of the peripheral auditory system which receives sound and converts that sound into movements of hair cells in the cochlea; the deflection of stereocilia causes an influx of potassium ions into the hair cells, and the depolarisation in turn stimulates calcium influx, which increases release of the neurotransmitter, glutamate. Excitation of the cochlear nerve by the neurotransmitter sends signals to the brain, which creates the experience of sound. Instead, the devices pick up sound and digitize it with an implant, convert that digitized sound into electrical signals, and transmit those signals to electrodes embedded in the cochlea. The electrodes electrically stimulate the cochlear nerve, causing it to send signals to the brain.
There are several systems available, but generally, they have the following components:
- One or more microphones that pick up sound from the environment
- A speech processor that selectively filters sound to prioritize audible speech
- A transmitter that sends power and the processed sound signals across the skin to the internal device by radio frequency transmission
- A receiver/stimulator, which receives signals from the speech processor and converts them into electric impulses
- An electrode array embedded in the cochlea
A totally implantable cochlear implant (TICI) is currently in development. This new type of cochlear implant incorporates all the current external components of an audio processor into the internal implant. The lack of external components makes the implant invisible from the outside and also means it is less likely to be damaged or broken.
Assistive listening devices
Most modern cochlear implants can be used with a range of assistive listening devices (ALDs), which help people to hear better in challenging listening situations. These situations could include talking on the phone, watching TV, or listening to a speaker or teacher. With an ALD, the sound from devices including mobile phones or from an external microphone is sent to the audio processor directly, rather than being picked up by the audio processor’s microphone. This direct transmission improves the sound quality for the user, making it easier to talk on the phone or stream music.
ALDs come in many forms, such as neck loops, pens, and specialist battery pack covers. Modern ALDs are usually able to receive sound from any Bluetooth device, including phones and computers, before transmitting it wirelessly to the audio processor. Most cochlear implants are also compatible with older ALD technology, such as a telecoil.
Surgical procedure for Cochlear implant
Alternative surgical technique for Cochlear implant
Other approaches, such as going through the supramental triangle, are used. A systematic literature review published in 2016 found that studies comparing the two approaches were generally small, not randomized, and retrospective so were not useful for making generalizations; it is not known which approach is safer or more effective.
Endoscopic cochlear implantation
With the increased utilization of endoscopic ear surgery as popularized by Professor Tarabichi, there have been multiple published reports on the use of endoscopic techniques in cochlear implant surgery. However, this has been motivated by marketing and there is a clear indication of increased morbidity associated with this technique as reported by the pioneer of endoscopic ear surgery.
Complications of cochlear implant surgery
As cochlear implant surgical techniques have advanced over the last four decades, the global complication rate for CI surgery in both children and adults has decreased from >35% in 1991 to less than 10% at present. The risk of postoperative facial nerve injury has also decreased over the last several decades to less than 1%, most of which demonstrated a complete return of function within six months. The rate of permanent paralysis is approximately 1 per 1,000 surgeries and likely less than that of inexperienced CI centers.
The majority of complications following CI surgery are minor requiring only conservative medical management or prolongation of hospital stay. Less than 5% of all complications are major resulting in surgical intervention or readmission to the hospital. Reported rates of revision cochlear implant surgery vary in adults and children from 3.8% to 8% with the most common indications being device failure, infection, and migration of the implant or electrode. Disequilibrium and vertigo after CI surgery can occur but the symptoms tend to be mild and short-lived. CI rarely results in significant or persistent adverse effects on the vestibular system when hearing conservation surgical techniques are practiced. Moreover, gait and postural stability may actually improve post-implantation.
What is the efficacy of a Cochlear implant?
In conclusion, cochlear implants have revolutionized the lives of individuals with severe to profound hearing loss, offering a remarkable solution when traditional hearing aids provide limited benefit. Through direct stimulation of the auditory nerve, these devices enable improved speech understanding, communication, and quality of life. While outcomes can vary based on factors such as age at implantation, auditory rehabilitation, and individual variability, cochlear implants have demonstrated their efficacy in enhancing hearing abilities and fostering greater participation in various aspects of society. As technology continues to advance, the potential for even more refined and personalized outcomes from cochlear implants remains promising, reinforcing their status as a transformative intervention for those facing significant hearing challenges.
Frequently Asked Questions