1. Age of implantation The younger the patient is at the time of surgical implantation for prespeech deafness, the better the outcome, which maximizes the potential for avoiding auditory deprivation and expanding speech and language skills before the critical period of brain plasticity. The minimum age previously adopted by the FDA was 18 months. Currently, there is a growing body of literature showing that children with cochlear implants at 12 months of age experience greater improvement in hearing and speech, and that children are more likely to reach their full potential without having to “catch up” or learn at a rate that exceeds the normal rate to reach the goal. Therefore, the optimal age is 12 months to 6 years. Currently, observations have shown that the low incidence of anesthesia, surgery, and long-term complications for cochlear implants in children younger than 12 months demonstrates that the risks of this practice are minimal, and the advantages for language acquisition and development are clear. 2. Uncertainty of outcome and noise sensitivity The literature shows that despite the high success rate of cochlear implant surgery, about 1 in 5 implantees still suffer from low postoperative speech recognition, as shown in the figure. Why is this? The explanation is still unclear. In addition, low speech recognition in noisy environments is a problem that has long plagued many cochlear implant recipients and physicians. Studies have shown that in steady state noise and intermittent noise environments, the speech recognition thresholds of normal hearing people are about 15 dB and 35 dB lower than those of implanted people, respectively. Preoperative evaluation of cerebral white matter lesions Cerebral white matter abnormalities are mainly divided into two categories: one is cerebral leukoencephalopathy, commonly known as cerebral white matter dystrophy, which is characterized by widespread, diffuse lesions on imaging, and which poses a difficulty in preoperative evaluation because its diagnosis and treatment are still in the exploratory stage. This type of abnormality is a demyelinating or myelin dysplasia disease with a genetic predisposition, resulting in impaired conduction of neuroelectrical signals due to diffuse, multifocal demyelinating damage to the cerebral white matter. Such patients mainly present with cognitive and speech impairments, mental retardation, and behavioral changes. In children, it is an important neurological disorder that affects growth and development. The second category is cerebral white matter changes caused by hypoxia, infection, trauma, jaundice, etc. The imaging manifestation is scattered patchy shadows, which is not the real sense of cerebral white matter disease, and because its damage can be compensated during brain development, the effect of cochlear implantation is mostly better. Hong et al. observed 10 cases of cochlear implantation in which preoperative MRI showed abnormalities in the white matter of the brain, of which 2 cases had delayed speech development and communication difficulties after surgery, and the other 8 cases recovered well after surgery. This study suggests that abnormal white matter imaging does not mean that cochlear implantation is ineffective, and that it is important to distinguish true white matter disease from limited white matter imaging abnormalities. A preoperative MRI of the head can show the size, extent, morphology, and location of white matter lesions. If MRI reveals a 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 the sign in neurological examination, there is no high signal in the white matter lesion area of MRI (DWI image), and there is no enlargement of the lesion in the dynamic observation for more than 6 months, then cochlear implantation can be considered, but it is necessary to communicate the condition with the family of the patient to make the patient build up a reasonable expectation value. Auditory neuropathy is a disease characterized by progressive or intermittent moderate to severe sensorineural hearing loss, which is mainly manifested by normal EOAE and severely abnormal ABR. Patients with auditory neuropathy have the option of undergoing cochlear implantation, but the results are unpredictable. If the site of injury is in the cochlea, electrical stimulation bypassing the inner hair cells and directly stimulating the VIIIth cranial nerve can produce a better response; however, if the lesion is located in the auditory nerve or auditory center, such as a demyelinating lesion of the VIIIth cranial nerve, the electrical stimulation may experience the same results as acoustic stimulation. Given this second possibility, cochlear implantation in patients with auditory neuropathy should be performed with extreme caution, and the risks should be thoroughly communicated prior to surgery. 5. / Bilateral implantation vs. binaural bimodality Our auditory environment is filled with sounds of complex origin, which can be challenging for the auditory system. Binaural hearing provides clues for separating target signals from distracting sounds and identifying the source of the sound, which can improve speech recognition. For the vast majority of children with unilateral cochlear implants, there are still difficulties with speech understanding in noise, sound source localization, tone recognition, and music perception. The significant improvement in speech comprehension and sound source localization associated with bilateral cochlear implantation results in better hearing outcomes for children and adults with bilateral cochlear implants than with unilateral cochlear implants. Simultaneous bilateral cochlear implantation avoids the trauma of two surgeries and general anesthesia and reduces medical costs. In addition to bilateral cochlear implantation, another avenue of assistance is bimodality. There are two types of bimodality, one for hearing aids on the opposite side (binaural bimodality); the other for hearing aids on the same side (monaural bimodality), which is suitable for implanted ears that are left with partial (especially low-frequency) residual hearing after surgery. Steep-drop hearing loss is used in the latter case. For many children with unilateral cochlear implants and residual hearing in the non-implanted ear, the binaural bimodal approach with a cochlear implant in one ear and a hearing aid in the other can improve speech understanding, sound source localization, tone recognition, and music perception in the presence of noise in a way that a unilateral cochlear implant cannot. It is difficult to draw conclusions about the superiority of bilateral cochlear implants and binaural bimodality (one cochlear implant on one side and a hearing aid on the other side). Some scholars believe that matched binaural input signals (bilateral cochlear implants) provide better hearing than unmatched (binaural bimodal). Others believe that more advantage may be gained from complementary frequency bands (binaural bimodal) than from overlapping bands (bilateral cochlear implants). Although the pros and cons of binaural bimodality and bilateral cochlear implantation are not conclusive, binaural bimodality may be a safer choice for economic reasons and for preservation of residual hearing, as long as there is usable residual hearing in the non-implanted ear. However, it is important to note that during binaural bimodal fitting, it is best to fine tune the two devices to balance the sound intensity between the two ears, which requires a higher level of skill on the part of the fitter who also knows how to adjust the hearing aid and the cochlear implant.