I. Patient selection criteria Cochlear implantation is mainly used to treat severe or profound sensorineural deafness in both ears. (1) The age of implantation is usually 12 months to 6 years old. The younger the age of implantation, the better the results, but special precautions should be taken to prevent complications such as anesthesia accidents, excessive blood loss, and damage to the facial nerve inside and outside the temporal bone. It is not recommended to implant cochlear implants in children under 6 months of age, but in cases of deafness caused by meningitis, due to the risk of cochlear ossification, it is recommended to operate as early as possible when the surgical conditions are complete. children or adolescents over 6 years of age need to have a certain degree of basic hearing and speech, and have a history of wearing hearing aids and a history of auditory-verbal rehabilitation training since childhood. (2) Severe or profound sensorineural deafness in both ears. After comprehensive audiological evaluation, children with severe deafness should have cochlear implantation if wearing hearing aids for 3-6 months is ineffective or the result is unsatisfactory; children with profound deafness can be considered for direct cochlear implantation. (3) There is no contraindication to surgery. (4) The guardian and/or the implantee has a correct understanding of cochlear implantation and appropriate expectations. (5) The conditions for auditory-verbal rehabilitation education are available. (2) Selection criteria for post-speech deaf patients: (1) Post-speech deaf patients of all ages. (2) Severe or very severe sensorineural deafness in both ears, unable to communicate with normal auditory speech by relying on hearing aids. (3) No contraindications to surgery. (4) The implantee himself/herself and/or his/her guardian has correct understanding and appropriate expectation of cochlear implantation. Contraindications to surgery 1. Absolute contraindications: severe malformations of the inner ear, such as Michel’s malformation, absence or interruption of the auditory nerve, acute suppurative inflammation of the middle ear mastoid. Relative contraindications: frequent seizures that cannot be controlled, severe mental, intellectual, behavioral and psychological disorders, inability to cooperate with auditory-verbal training. Guiding recommendations for special cases 1. Cerebral white matter lesions: also known as cerebral white matter dystrophy, is a group of lesions mainly involving the white matter of the central nervous system, which is characterized by abnormal development of the myelin sheath of the central white matter or diffuse damage. If MRI reveals a cerebral white matter lesion, intellectual and neurologic signs and MRI review are required. If there is no regression in intellectual and motor development, the function of other systems except hearing and speech is basically normal, there is no positive pyramidal sign or no change in signs on neurological examination, and there is no high signal in the area of white matter lesion on MRI (DWI image). If there is no enlargement of the lesion under dynamic observation (interval > 6 months), cochlear implantation can be considered. 2.Auditory neuropathy (auditory neuropathy spectrum disorder): It is a special kind of neurological deafness, which is a hearing impairment caused by the malfunction of inner hair cells, auditory nerve synapses and/or the auditory nerve itself. Audiological testing is typically characterized by normal otoacoustic emissions (OAE) and/or cochlear microphonic potentials (CM) and absent or severely abnormal auditory brainstem responses (ABR). Currently, cochlear implantation is effective in improving hearing in most patients with auditory neuropathy, but it may be ineffective or ineffective in some patients, so the patient and/or guardian must be informed of the risks before surgery. Bilateral cochlear implantation: Bilateral implantation can improve sound source localization, speech comprehension in quiet and background noise, help to obtain a more natural sound perception, and promote the development of auditory speech and music appreciation. Bilateral implantation or sequential implantation can be chosen. The shorter the interval between two surgeries for sequential implantation, the more favorable it is for postoperative speech rehabilitation. 4. Cochlear implantation for people with residual hearing: People with residual hearing, especially those with high-frequency steeply falling hearing loss are suitable for electrode implantation with residual hearing preservation, and can choose acoustic-electrical co-stimulation mode after the operation, but the patient and/or guardian must be informed of the risk of residual hearing decline or loss after the operation. 5. Cochlear implantation in patients with structural abnormalities of the inner ear: structural abnormalities of the inner ear related to cochlear implantation include common cavity malformation, cochlear dysplasia, cochlear ossification, and stenosis of the internal auditory canal, etc. Most of the patients can be implanted with cochlear implants, but a case discussion should be organized before the operation, and the patient should be handled with caution during the operation, and the use of facial nerve monitoring is recommended. The postoperative effect varies greatly among individuals. 6, chronic otitis media with tympanic membrane perforation cochlear implantation: chronic otitis media with tympanic membrane perforation if the inflammatory reaction has been controlled, you can choose to one-stage or staged surgery. One-stage surgery refers to the cochlear implantation at the same time of radical treatment of middle ear mastoid lesion, tympanic membrane repair (or mastoid cavity autologous tissue filling and external ear canal closure); staged surgery refers to the removal of the lesion, repair of the tympanic membrane perforation or closure of the external auditory canal, and then cochlear implantation after 3-6 months.