The bilateral cochlear implant, a link between the world and people with deafness

The cochlear implant is a device whose technological development continues to connect the world with people who cannot hear. The electronic device performs the natural function of hearing: capturing the sound around us and converting the vibrations into electrical impulses that are sent to the brain.

Gonzalo Corvera Behar, director of the Mexican Institute of Otology and Neurotology, as well as president and founder of the Mexican Association for Hearing Help Us Hear (Amaoír), has been performing the operation to place implants for almost 40 years. Amazed at the knowledge that a very small computer could enable a profoundly deaf person to hear and follow a conversation, he developed his cochlear implant program, the oldest in Latin America. The results were already fantastic back then.he highlighted in an interview.

We listen with our brains, explained the otorhinolaryngologist, a graduate of the National Autonomous University of Mexico, specializing in ear and skull base surgery, in Toulouse, France.

This requires auditory stimulation, since the neural connections that will allow the baby to know what to do with the electrical signals it receives are formed in this organ. Without the stimulation, in a baby born with deafness, these synapses are not created, and therefore will not have the ability to speak or understand language. For this reason, it is very important to perform the neonatal screening test and detect the condition in time.he recommended.

The implant, he said, is also successful in a person who loses hearing at age 20 or older, because his or her brain already has the necessary brain connections. Things have changed a lot, he added, and it is now known that placing the device in both ears has better results.

Four decades ago, Corvera and his team implanted only one ear, With this, the patient could understand 40 percent of what he heard and the rest he understood from the context: lip reading, expressions with gestures. We considered that the benefit was sufficient. Now we do bilateral implants, with which the patient can hear 80-85 percent. People who hear from both sides understand much better in a noisy environment, which is still one of the difficult situations for someone with hearing impairment. So the advance is that he can distinguish the voice and understand what is said at a family meeting or when many people are talking at the same time..

He explained that the device consists of two parts: An internal one, the implant itself or receiver, which has electrodes that we insert into the cochlea so that they are in contact with the nerve; another external one, which captures the sounds and contains the batteries with which the prosthesis works..

He highlighted the importance of hair cells (sensory cells), which line the cochlea. Their function is to convert vibration into nerve impulses. We have about 2,500 rows of four or five of these units. Each row is tuned to a different frequency, a different pitch. The joke about hearing is that we can tell the difference between pitches (low and high). For example, an A and an E are distinguished by the pitches they are composed of..

The expert described: These cells are replaced with electrodes, which replaces the eardrum, which is then replaced with a microphone. It’s fantastic. We have patients with normal hearing in one ear and a cochlear implant in the other. One of the advantages is that in a work meeting you can hear what is being said on both sides of a table..

He said that between two and three children in every thousand are born with hearing loss. There are more than 200 genes that can cause it, although these are recessive and usually manifest when children inherit them from their parents. If only one of them has them, the children inherit them and pass them on to their offspring until they get together again and, suddenly, in a couple with five children, three were born deaf.

The condition, the specialist said, can also be caused by complications at birth, such as not breathing well or being premature babies, or having had sepsis. They may hear, but lose their hearing in the first hours of life.

Risk factors

Corvera Behar added: If the deafness is profound from birth, the sooner the implant is done the better. We have children operated on at 6 months. In the case of adults, the risk factors are working in noisy environments, smoking, obesity (together with diabetes), hypertension and high cholesterol..

Children love their implants and take great care of them because they know what it is like to not hear. There are accessories that protect the devices and allow children to play and even swim with them.

Regarding surgery, he stressed that much progress has been made. “Now smaller incisions are made and patients are discharged the same day, told to rest at home for four or five days. It is much less invasive and not painful. However, you do not leave the hospital hearing, because the device is not activated immediately, you have to let the area go down in inflammation. We have started to activate it a week after surgery, before we waited a month. Then you start to hear, the person gets used to the tones to understand. The brain accepts the device very well.”

The cases that are not so successful are due to the fact that the disease that causes hearing loss damages the nerve or also due to anatomical causes that prevent the electrodes from being placed in the optimal position. Even so, people hear 60 percent of the time.he said.

He said that Amaoír is a non-profit organization that helps people get the funds to pay for the implant, which is very expensive.

Regarding the intervention, the association has a program with the ABC hospital. A socioeconomic study is done, although many of our patients do not pay anything. The doctors perform the surgery for free..

The total price of a cochlear implant is around 900 thousand pesos: 700 thousand for the device and 200 thousand for the operation. Amaoír (amaoir.org) reduces that to just the cost of the implantconcluded Corvera Behar.