Here is everything you want to know about deafness and cochlear implants!

The sound of traffic on the street, the sound of birds singing in the sky, the caring voices of family members in the room... These are commonplace for most people, but for some people, they are particularly precious. They don't know what a horn sounds like, what tune a song is... The emergence of "cochlear implants" may help them make up for these regrets and enjoy a normal life.

At present, for patients with severe and profound hearing loss, cochlear implants are the only effective treatment to restore hearing. Unfortunately, the rate of cochlear implants for hearing-impaired people in my country is less than 1%, due to various reasons, such as the public's low level of awareness of cochlear implants, inadequate grassroots training, and economic constraints. Today, let's learn about cochlear implants with Pangke~

What is deafness?

In the auditory system, lesions occur in the auditory nerves and centers at all levels in the sound transmission, sound perception and auditory conduction pathways, causing auditory dysfunction and varying degrees of hearing loss, collectively known as deafness.

Deafness can be classified differently from different perspectives. If divided according to the part of the lesion, it can be roughly divided into three categories: conductive deafness, lesions occur in the outer ear and middle ear; sensorineural deafness, lesions occur in the cochlea of ​​the inner ear, the auditory nerve, and the auditory center of the brain; mixed deafness, lesions occur in both the sound transmission part and the sound sensing part of the ear.

How do cochlear implants work?

So why is it said that "cochlear implant is the only effective treatment for restoring hearing"? How does a "cochlear implant" help people hear sounds? Before solving these problems, let's first look at how a normal person's cochlea works.

The human ear consists of three main parts: the outer ear, the middle ear, and the inner ear. The cochlea we are talking about is the inner ear. It is shaped like a snail shell and is a spiral bone tube, so it is called the "cochlea". The tube is filled with lymph fluid that is incompressible like water. The vibration transmitted from the middle ear causes the lymph fluid to vibrate, and then other structures in the ear convert the mechanical vibration into electrical signals, stimulating the auditory nerve in the cochlea, and the excited neurons are transmitted to the language center of the brain.

As a replacement for the normal cochlea, the "cochlear implant" converts sound signals in the environment into electrical signals and provides electrical pulse stimulation to the auditory nerve fibers in the cochlea, ultimately allowing the patient to regain hearing.

The cochlear implant consists of an implant in the body, an electrode array, and an external sound processor, headpiece, microphone, and wires. The core part is the sound processor, which is responsible for processing speech signals, extracting useful parameter information for speech encoding, and transmitting it to the stimulation chip implanted in the ear to determine which electrode to stimulate and the size of the stimulation current. The size of the sound we can hear depends on it.

Since the cochlear implant consists of two parts, the internal part and the external part, its working principle can also be divided into two parts:

Working principle of the external part: The microphone in the headpiece is used to collect sounds from the external environment, and convert the sound signals into digital signals through the sound processor, which are then wirelessly transmitted to the internal implant through the magnetic induction coil in the headpiece.

Working principle of the internal part: The microprocessor decodes the received digital signal and restores it into electrical signals. The electronic signals are sent to specific positions in the electrode series, stimulating the nerve fibers in the cochlea, and finally transmitted to the auditory center of the computer. The brain recognizes these electrical signals as sounds.

Can all deaf people get cochlear implants?

It can be seen that "cochlear implants" are undoubtedly a great blessing for people with hearing impairments. However, not all patients can choose cochlear implant surgery, and the surgery itself has certain limitations and requirements:

Physical condition

Cochlear implantation is an open surgery, and the contraindications of conventional general anesthesia surgery are applicable to it. Patients with epilepsy cannot undergo cochlear implantation during the acute phase of the disease, but can undergo surgery during the stable phase. In addition, cochlear implantation is not recommended for patients with severe psychological problems or intolerance to general anesthesia.

In addition, age is also an important factor affecting the effect of cochlear implantation. For patients with severe or profound hearing loss, especially children, cochlear implantation should be performed as early as possible to achieve better rehabilitation results.

Degree of hearing loss

If the hearing loss is mild or moderate, it is recommended to wear a hearing aid to improve hearing. If the hearing loss is severe or extremely severe, a cochlear implant can be considered. Generally speaking, when the patient's hearing threshold is below 70dB, it is recommended to wear a hearing aid. If the hearing threshold reaches 70dB or above, a cochlear implant is required.

Fee Requirements

The cost of cochlear implant surgery is high, sometimes even up to hundreds of thousands of dollars, which is also a considerable expense for many families.

Even if all the above requirements are met, cochlear implant surgery may not necessarily be performed. For patients who are eligible for surgery, relevant medical history collection is required so that the cause of the disease can be better understood, such as the patient's hearing history, tinnitus and vertigo history, history of exposure to ototoxic drugs, previous history of ear diseases, developmental factors, family history of deafness, history of hearing aid wearing, etc. These factors will affect whether the implant surgery can be successful.

What is the difference between a hearing aid and a cochlear implant?

In life, we often see some hearing-impaired people wearing hearing aids. So under what circumstances should they wear hearing aids? Under what circumstances is cochlear implant surgery necessary?

This is related to the classification of deafness we mentioned above. Conductive deafness is caused by the blockage of the outer ear or middle ear, which prevents sound from reaching the inner ear, greatly reducing hearing. This type of deafness can be greatly enhanced by using hearing aids. We can simply think of hearing aids as a bridge that can smoothly transport sound to the inner ear, thereby restoring the auditory system. The entire working process is a physical method, and no signal conversion is performed.

Sensorineural hearing loss is different. It is caused by the necrosis of the part of the inner ear responsible for converting sound vibrations into electronic signals, which prevents our brain from receiving the sound signals transmitted by the auditory nerve. In this case, hearing aids cannot work and only cochlear implant surgery can be performed. The cochlear implant is an electronic device and the overall operation is more sophisticated.

In fact, the difference between hearing aids and cochlear implants can be mainly attributed to two aspects: one is that hearing aids still output sound signals after amplifying the input sound signals, while cochlear implants ultimately output electrical signals; another difference is that the gain effect of hearing aids is not as obvious as that of cochlear implants. For mild to moderate or moderate to severe hearing loss, hearing aids can meet the requirements, but for severe or extremely severe hearing loss, only cochlear implants can compensate for it.

Cochlear implants are of great significance to deaf patients. With continuous research and exploration, its related technologies and surgical techniques have made great progress. The age limit for implantation has been lowered and the concept of minimally invasive surgery has been constantly updated. I believe that this field will bring more hope to more severely deaf patients in the future.

Creative team: China Science and Technology Museum New Media Team

Review expert: Yuan Xiandao, deputy chief physician of the Department of Otolaryngology, Beijing Anzhen Hospital, Capital Medical University

This article comes from: China Digital Science and Technology Museum