Cochlear implantation for sensorineural hearing loss

This disease is caused by hearing loss or loss caused by sensory dysfunction in the inner ear. Pure tone audiometry shows more high frequency hearing loss, and can be developed to medium and low frequency. The full frequency air conduction hearing threshold can be >70dB, bone conduction and air conduction curve. Close or coincide. It can be identified as a cochlear or post-cochlear lesion by suprathral auditory function measurement, acoustic impedance measurement, and electrical response audiometry. The following mainly introduces artificial (electron) cochlear implants. Cochlear implants are also known as electronic cochleas. In 1979, the animal experiment was started. In 1980, the leather socket type electronic cochlea was used in clinical practice. Because of the high incidence of postoperative infection, it could not be worn for a long time. In 1983, domestic inductive single-guide cochlear implants were used. A three-conductor cochlear has been developed in 1987. However, domestic cochlear implants have been temporarily eliminated due to quality problems such as craftsmanship. At present, the 24-inch cochlear implant of Cochlear in Australia is commonly used in China, and some products are used by Austrian Medel and American ABC (Clarion). The cochlear implant converts the acoustic energy into an electrical oscillation (amplitude-modulated wave) through an in-vibration speech sound processor, transmits it to the transmitter via a high-frequency cable, and induces it to the receiver in the body, which is reduced to a bio-audio current, and is implanted into the drum. The electrodes stimulate the auditory nerve so that the human hears the sound. As early as 1780, Volta inserted two metal rods into their ears, and the head was hit when the current was turned on, followed by a sound similar to the boiling of the glue liquid. At the end of the 19th century, the founder of the apex abscess syndrome, Gradenigo, found that the electrical stimulation of the ear caused a sense of sound. In 1930, the work of the cochlear microphonic potential discoverers Wever and Bray caused interest in the study of artificial hearing. In 1937, Stevens, Jones, and Flottorp placed a pair of electrodes on the skin of the auricle and external auditory canal. When the audio frequency current was used, the same sound as the stimulation frequency was heard. They called this phenomenon an electric sound. (electrophonic). This kind of hearing is actually caused by the capacitive whistling effect between the electrode and the skin surface. It is caused by the vibration of the gas bone conduction vibration to the cochlea. It is only found in the normal function of the cochlea, so it has no application value for the treatment of sputum. In 1957, the results of the study of the electrical stimulation of the VIII cranial nerve by the French ear surgeon Eyries and the engineer Djourno were published. They performed extensive surgery on a patient with cholesteatoma and then connected the working electrode to the remaining auditory nerve after surgery. The non-active electrode was placed in the diaphragm and the patient could hear the sound when applying current. This is the first time that artificial hearing has been used. The electrical stimulation of the device produced an auditory successful attempt, which opened the prelude to the application of electronic technology to simulate cochlear function. In the 1960s, Dogle, Simmons, and others applied different artificial devices and methods to deaf patients. The detailed research and large cases of Michelson, House, Bilger and others after the 1970s further promoted the development of this technology. In the late 1970s and early 1980s, the peak period of cochlear implants was formed. At present, cochlear implants have been carried out in many large cities in China. The implantation and postoperative results have reached the international advanced level. Cochlear implantation can cause extensive neurodegeneration, fibrous connective tissue hyperplasia and new bone formation, which has been confirmed by animal and postoperative patient's tibial tissue section results, but this does not affect the effect of cochlear implants. . There are many types, materials and techniques for cochlear implants abroad, including single-guide, 4-guide, 6-, 8-, 12-, or even 22-lead and 24-lead electrodes and external magnetic system. The latter applies to patients with residual hearing and the electrodes are implanted in the tympanic membrane and the adhesion of the drumstick. The cochlear implants that are widely used in the world and have a large impact are mainly produced by Cochlear of Australia, Clarion of the United States and MED EL of Austria. China's current use of more products is the Australian company Cochlear. Cochlear implant materials include polymers, metals, and bioceramics, but materials used as electrodes must have high electrical conductivity, no electrolyte and gasification. Currently, only platinum and platinum-rhodium alloys can meet these requirements. Cochlear implants currently use the posterior mastoid tympanic approach. Treating diseases: deafness Indication Sensorineural hearing loss cochlear implant for: 1. The binaural hearing loss or the hearing sensitivity of the hearing threshold above 90dB. 2. After the language, adult patients or children over 1.5 years old. 3. The microsonic potential of the cochlea disappears and there is no congenital malformation of the inner ear. 4. Emotional stability, normal intelligence, can cooperate with post-linguistic trainers. 5. The general health is good. Contraindications 1. Neurological spasm caused by post-cochlear lesions, such as postoperative acoustic neuroma. 2. Deafness with negative electrical stimulation test. 3. Those with a history of mental illness. 4. There are infectious lesions in the middle ear. 5. Wear a high-power hearing aid to hear the sound. 6. There are obvious infectious diseases in the nose and throat. Preoperative preparation 1. First, the patient should be made aware of the role of the operation and postoperative auditory condition, be willing to reluctantly accept the operation, and explain to the family members the relevant issues, especially the arduousness of postoperative language training, to obtain adequate patient and family members. Cooperate. 2. Carefully inspect the implant, including its sealing properties. 3. Detailed preoperative examination, including liver and kidney function, heart and lung status, etc., special examination including tibia X-ray photograph, CT scan, MRI, vestibular function test, drumstick electric stimulation test, complete audiology examination and nose, Physical examination of the pharynx and ear. 4. Operate the ear, shave the hair, or shave the side of the hair, give antibiotics in advance. 5. The anterior external auditory canal was given 3% boric acid ethanol for 3 days before surgery. 6. Prepare and administer according to general anesthesia requirements. Surgical procedure Incision Including the posterior incision and the incision of the ankle, the arc incision is made in the back of the ear. The incision is 2.0 to 2.5 cm from the posterior sulcus, down to the tip of the mastoid, and the upper edge of the upper auricle is attached to the fascia. The flap is separated forward and backward; the fascia, muscle and bone coat are then cut behind the skin incision, and the bone surface is deep, and the upper and lower sides of the flat line and the lower wall of the external auditory canal are respectively upper and lower. 2. Separation Use a stripper to separate the anterior and posterior bones, and expose the outer edge of the posterior wall of the external auditory canal and the posterior wall of the external auditory canal. The tip of the mastoid tip is exposed downward, and the sacral line is exposed upwards. The mastoid tip line and the posterior cranial surface of the humerus. 3. Contouring the mastoid Same as "radome radical surgery". As far as possible, the posterior wall of the external auditory canal is thinned, but it must not be worn to avoid exposure of the soft tissue of the external auditory canal to the surgical cavity. 4. Open the outer wall of the drum The bone wall is removed with a dense drill bit and a diamond drill bit in front of the initial section of the vertical section of the facial nerve, under the anvil socket and inside the tympanic nerve, and the outer side wall of the drum is opened to reveal the round window ridge, the cone bulge, the vestibular window sill and The trailing edge of the drumstick. Drill a hole in the front lower edge of the snail window with a 1mm diamond drill bit, open the bottom of the cochlear and the outer wall of the drum, and enter the drum step to insert the working electrode of the cochlear implant. In order to prevent accidental injury to the facial nerve, it is best to first grind out the contour of the vertical section of the facial nerve tube, and then remove the outer side wall of the front drum and the front side of the drum, revealing the round window sill, first remove the underside of the anvil bone, and the outer semicircular canal before the bulge The lateral wall of the lateral part of the vertical segment until the facial nerve canal is revealed. It is best not to open the bone tube to avoid facial paralysis. 5. Grind out the bone socket that houses the receiver and the tunnel through the electrode According to the size of the receiver, the bone socket is ground on the skull above the upper edge of the auricle to accommodate the receiver. It is preferable to keep the thin bone piece separated from the dura mater. Two holes are drilled on both sides of the bone socket to fix the receiver. A groove is formed under the bone socket to open into the mastoid cavity so that the electrode passes therethrough. 6. Place the receiver and electrode The two electrodes are inserted into the mastoid cavity from the groove, and the receiver is placed in the bone socket. The working electrode is placed from the rear tympanic cavity to the outer ostium of the tympanic anterior and posterior ventilator, and is introduced into the tympanic step. Feed in, until the required depth, close the pores around the electrode with muscle or fascia and fix the electrode. After the working electrode is placed in the drum step, it should be turned on to detect its functional status. If there is any abnormality, the working electrode should be adjusted to meet the requirements. The non-active electrode passes through the skull groove and then turns to the front and is placed between the periosteum of the tibia and the bone plate. 7. Stitching and dressing wounds The external auditory canal is filled with iodoform gauze, the wound is covered with sterile gauze, and the bandage is wrapped with a single ear. complication 1. Local bleeding: If there is a subcutaneous hematoma, it should be removed to prevent infection. 2. Dizziness: Some patients may have dizziness and tremors. 3. Facial nerve injury: When the outer wall of the drum is opened, the vertical section of the facial nerve is injured, causing facial paralysis, or due to poor electrode insulation, contact with the facial nerve, causing facial spasm when starting up. 4. Otitis media, mastoiditis: mostly due to the damage of the posterior wall of the external auditory canal, the electrode is also damaged by the soft tissue of the external auditory canal, also seen in the eustachian tube dysfunction. 5. Meningitis: secondary infection can be caused by labyrinthitis or accidental injury to the meninges. 6. Cochlear dysfunction: There are mainly electrode dislocation; electrode insulation layer is damaged, body fluid infiltration; receiver circuit failure. 7. Cochlear implant bulge: The receiver is jacked up mainly due to the development of the skull, and the receiver is re-operated if necessary.