Which patients with sensorineural deafness are suitable for cochlear implantation? Cochlear implant surgery is indicated for patients of all ages with bilateral severe or profound sensorineural deafness. These include congenital deafness, drug-induced deafness, viral deafness, sudden deafness, noise-induced deafness and senile deafness. However, which patients are suitable for cochlear implants? When is the best time to get a cochlear implant? We summarize as follows: [Prelingual deafness] refers to patients with bilateral sensorineural deafness that is detected after birth or occurs in infancy. Because bilateral severe or very severe sensorineural deafness occurs before language acquisition, the child will be “deaf” and “mute”, so we call it prelingual deafness. 1. How to choose the timing of surgery for prelingual deafness according to the degree of sensorineural deafness? If the hearing aid is not effective for 3-6 months or the result is not satisfactory, cochlear implantation should be performed as soon as possible. 2. How to choose the timing of surgery for patients with prelingual deafness according to different ages? ①The younger the age of implantation, the better the effect of auditory and speech rehabilitation, therefore, if the surgical conditions are complete, a well-developed child aged 6-12 months can be implanted with a cochlear implant; ②The best age for cochlear implantation is generally considered to be 12 months to 5 years old; ③A child or adolescent with prespeech deafness aged 6 years or older must have a certain speech foundation or a history of hearing aid wear and auditory speech rehabilitation since childhood to be considered for cochlear implantation. The cochlear implant can only be considered for surgery if the child or adolescent has a history of hearing aid use and rehabilitation. Post-lingual deafness] Deafness that occurs after language acquisition is called post-lingual deafness. In general, cochlear implantation can be performed in patients with postlingual deafness who are in good health and have no contraindications to surgery, including: ①Patients of all ages with severe or profound sensorineural deafness in both ears; ②Patients of all ages with postlingual deafness who have ineffective or poor hearing aids and score ≤ 30% on the Open Speech Cognitive Test can undergo cochlear implantation.