The preoperative evaluation of a patient for cochlear implantation is very important and is a necessary process for the physician to determine if the deaf patient is suitable for cochlear implantation intervention. To be eligible for cochlear implantation, the physician must first know the degree and nature of the deafness, whether the specific cause of the deafness can be identified, and what the patient’s general condition is. Can the patient tolerate anesthesia and the surgical procedure? Are there any contraindications to surgery? Are there any other concomitant diseases that may affect the recovery effect after cochlear implantation? The preoperative evaluation of cochlear implantation is very complex and extensive, so we will discuss each of the major items below. First of all, cochlear implantation is a method of auditory intervention for patients with more than severe sensorineural deafness, so the first thing is to conduct an audiological evaluation to understand the degree of deafness, its nature, and its impact on speech and language ability. . For children who cannot cooperate with pure tone audiometry, behavioral observation, visual reinforcement and play audiometry may be used, but these methods do not replace pure tone audiometry. Objective hearing tests: 1. Acoustic conductance (tympanogram and acoustic reflex): To understand the functional status of the middle ear. Patients who are suitable for cochlear implantation should have a type A or C tympanogram, which indicates that the middle ear function is normal or basically normal. Patients with cochlear implants should be unresponsive to acoustic reflexes because of the severe degree of deafness. 2. Auditory brainstem evoked potentials (ABR): For younger children who cannot cooperate with primary auditory observation, short sound ABR is the main method to understand the degree of their deafness. In addition, ABR combined with other tests can also help the physician identify specific deafness conditions and give some indication of the prognosis for cochlear implantation. 3. Otoacoustic emission (OAE): It mainly understands the functional status of the inner ear. Those who are suitable for cochlear implantation should have inner ear pathology; therefore, DPOAE or TEOAE cannot be elicited bilaterally for conventional cochlear implantation. 4. Multi-frequency steady-state evoked potentials (ASSR): To help understand the residual hearing of implant candidates, response thresholds in the 0.5kHz, 1kHz, 2kHz, and 4kHz speech frequency ranges are generally tested. This is a suprathreshold function test for pediatric patients with hearing aids to understand their hearing ability in the preoperative intervention state. 1. Lin’s six tones perception test: Lin’s six tones basically cover the normal speech frequency range, through this test, we can roughly know the speech frequency loss of the child after the hearing aid, and provide basic information for the doctor to judge whether the implantation surgery is needed. 2. Auditory Behavior Classification Questionnaire (CAP): CAP is a classification standard for assessing auditory perception, which is suitable for children of any age, especially for children between 0 and 6 years old, and reflects the child’s level of hearing in the daily environment. If the hearing aid is not effective, implantation surgery can be considered. 3. Auditory Integration Questionnaire (MAIS, IT-MAIS): It is used to assess the spontaneous response of the deaf child to sounds in daily life. The questionnaire covers three main aspects of hearing: acceptance of hearing aids, perception of sound, and understanding of the meaning of sound. A score of <20 on the Auditory Integration Questionnaire indicates that the original intervention was ineffective and that cochlear implantation may be considered. Auditory-speech ability test: 1. Speech recognition rate test (sometimes phrase recognition rate test may be added): Test the deaf patient's ability to acquire, recognize and understand speech information. 2. Speech Intelligibility Test: To understand the development of the deaf patient's own speech ability and the clarity of spoken language. 3. For children or younger deaf patients, the conventional speech test methods may be too difficult for them, so there are also special auditory-speech test methods for children: ① Rhyme recognition, vowel recognition, and bisyllabic word recognition: an average score of ≤ 70% in the three items is an auxiliary criterion for the need of cochlear implantation. ② Speech Intelligibility Rating Assessment Questionnaire (SIR): a questionnaire was used to assess speech intelligibility. Secondly, after the audiological examination meets the criteria for cochlear implantation, the deaf patient also needs an imaging evaluation, including high-resolution temporal bone CT and auditory nerve MRI. CT shows whether the bilateral cochlea and internal auditory canal structures are normal. MRI of the auditory nerve can show fluid filling of the cochlea and internal auditory canal and abnormalities in the development of the auditory nerve. If necessary, a cranial MRI is added to understand any organic/progressive lesions in the brain. Again, certain psychiatric, intellectual, and behavioral assessments are needed to understand the mental development of the pediatric population and the presence of psychological disorders and behavioral abnormalities. Specifically, these include: i. Hir-nai learning ability test score: suitable for people aged 3-17 years old to test, generally requiring a score >84. ii. Grayfells mental development test score: suitable for people under 3 years old or who cannot cooperate to complete the Hir-nai test, generally requiring a score >86. iii. Autism and autism tests: 1. Kirsch autism behavior scale score: suitable for subjects aged 2 years or older, requiring a score <10. 2. Rutter's Child Behavior Questionnaire score: suitable for subjects aged 7-16 years old, requiring a score of <9. All of the above examinations or tests are currently the main components of the preoperative evaluation required for cochlear implant candidates. Of course, as experience with cochlear implantation continues to accumulate and medical technology advances, the relevant examinations may change somewhat depending on the actual clinical situation. Some special tests may also be added for those who are ready for implantation with special circumstances. Finally, the interpretation and comprehensive evaluation of the results of all examinations is the key to determining whether a deaf patient can ultimately undergo cochlear implant intervention. For this reason, cochlear implant programs internationally are now multidisciplinary teams, especially for preoperative evaluation in the form of a Multi-Discipline Team (MDT).