A cochlear implant is a biomedically engineered device that can help restore hearing and speech communication to people who are deaf. Because cochlear implants are a new technology in the field of medicine and rehabilitation, there is a need for a reference standard for the selection of indications, pre- and post-operative evaluation, surgery, post-operative adjustment, and auditory speech rehabilitation. The purpose of this guideline is to provide guidance to clinicians, audiologists, and speech and language rehabilitation workers in this field, so that cochlear implantation in China can be standardized and standardized, thereby improving treatment outcomes and avoiding unnecessary risks.
Cochlear implantation involves many fields of medicine, audiology, biomedical engineering, education, psychology, and sociology, and requires the collaboration of otologists, audiologists, speech therapists, rehabilitation teachers, engineers, and parents to form a cochlear implant team.
Selection of Indications
I. Patient selection criteria
For patients with severe or profound deafness in both ears, cochlear implantation can be selected if the lesion is localized and diagnosed in the cochlea.
1. Selection criteria for patients with prelingual deafness:
(1) severe or profound sensorineural deafness in both ears; (2) the best age should be 12 months to 5 years; (3) the patient should be wearing appropriate hearing aids and have no significant improvement in auditory language ability after 3 to 6 months of hearing rehabilitation; (4) there is no contraindication to surgery; (5) the family and/or the implant recipient has correct knowledge and appropriate expectations of the cochlear implant; and (6) there are conditions for hearing and language rehabilitation education.
The younger the patient is at the time of surgical implantation, the better the outcome, as this maximizes the potential to avoid auditory sensory deprivation and expand speech and language skills before the critical period of brain plasticity. Children or adolescents older than 6 years of age need to have some basis in hearing and speech, a history of hearing aid wear and a history of hearing or speech training since childhood. Ineffective or poor hearing aids are defined as open phrase recognition ≤ 30% or two-word word recognition ≤ 70% in the best hearing aid listening environment.
The selection criteria for patients with postlingual deafness are: (1) patients of all ages with postlingual deafness; (2) patients with severe or profound sensorineural deafness in both ears; (3) patients with ineffective or poor hearing aids and open phrase recognition rate ≤ 30%; (4) patients without contraindications to surgery; (5) patients with good psychological quality and initiative, correct understanding of cochlear implants and appropriate expectations; and (6) patients with family support.
The age of onset and duration of deafness of post-speech deafness patients are closely related to the outcome after surgery. Generally speaking, patients with early onset of deafness and longer duration of deafness have poorer results after surgery. In addition, the listening environment in life and work after surgery can also affect the outcome of cochlear implantation.
3. Contraindications to surgery: (1) absolute contraindications, including severe malformations of the inner ear, such as Micheal malformation and cochlear malformation; auditory nerve deficiency; severe mental retardation; inability to cooperate with language training; severe mental illness; acute and chronic inflammation of the middle ear mastoid that has not been cleared; (2) relative contraindications, including poor general condition of the body; uncontrollable epilepsy; and lack of reliable rehabilitation training conditions.
Secretory otitis media and glue ear are not contraindications to surgery. In chronic otitis media with tympanic membrane perforation, if the inflammation is controlled, surgery can be performed in one phase or in stages. One-stage surgery refers to radical treatment of middle ear mastoid lesions, tympanic membrane repair (or mastoid cavity temporal muscle filling and closure of external ear canal) and cochlear implantation at the same time. Staged surgery means removing the lesion, repairing the tympanic membrane perforation or closing the external ear canal first, and then performing cochlear implantation 3-6 months later.
Pre-operative evaluation
1. History taking: Take a medical history and examine the cause of the disease. The emphasis of otologic history should be on the etiology and pathogenesis of deafness, including hearing history, history of tinnitus and vertigo, history of ototoxic drug exposure, history of noise exposure, history of systemic acute and chronic infections, past otologic history, developmental factors (systemic or local developmental abnormalities, intellectual development, etc.), family history of deafness, history of hearing aid wear, and other causes, such as epilepsy and psychiatric conditions. Children with deafness should also include: maternal pregnancy history, pediatric birth history, pediatric growth history, and speech development history.
It is also important to understand the patient’s language ability (e.g., articulation characteristics, clarity of sound composition) and language comprehension and communication ability (e.g., oral, lip reading, sign language, written, guessing, etc.).
2.Otological examination includes auricle, external auditory canal, tympanic membrane and eustachian tube, etc.
Audiological examination: ① subjective hearing threshold determination: children under 6 years old can use pediatric behavioral audiometry, including behavioral observation audiometry, visual reinforcement audiometry and play audiometry; ② acoustic conductance measurement: including tympanic chamber pressure curve and stapedius muscle reflex; ③ auditory brainstem response (auditorybrainstemresponse, ABR), 40Hz correlation potential (or multi-frequency Steady-state evoked potentials); ④ otoacoustic emissions (transient evoked otoacoustic emissions or aberrant product otoacoustic emissions); ⑤ speech audiometry: speech hearing threshold test for language perception threshold and language recognition threshold; speech recognition test including speech test word list and pediatric speech test word list; ⑥ hearing aid matching: professional audiologists are required to match hearing aids, generally need to wear both ears, after matching to do hearing aid hearing threshold test and speech recognition test, The hearing aid threshold test and speech recognition test should be done after the fitting, and the auditory language training should be conducted for 3-6 months; (7) vestibular function examination (for those with a history of vertigo); (8) electrical stimulation test of the drum head: the test includes threshold, dynamic range, frequency discrimination, interval discrimination and temporal discrimination and other psychophysical examinations.
Audiological evaluation criteria: ①Patients with postlingual deafness: Binaural pure tone air conduction hearing threshold measurement >80dBHL (average of 0.5, 1, 2, 4kHz, WHO standard). If the hearing loss is greater than or equal to 75 dB, a cochlear implant may be considered if the good ear is less than 30% for open phrase recognition [see the Food and Drug Administration (FDA) supplemental criteria]. The assessment includes: no auditory response to ABR examination of acoustic output (120 dBSPL); no response to 40 Hz correlation potential detection of the loudest output at frequencies above 2 kHz and frequencies below 1 kHz >100 dB; no response to multi-frequency steady-state audiometry at frequencies above 2 kHz at 105 dBHL; no response to aberration product otoacoustic emissions at all frequencies in both ears; no response to helpful acoustic field audiometry at frequencies above 2 kHz (3) For patients without any residual hearing, cochlear implantation can still be considered if there is a clear auditory response to electrical stimulation of the headphones. If there is no auditory response to electrical stimulation of the tympanic capsule, the patient or parents should be informed of the situation and they should assume the risk of surgery.
4. Imaging evaluation: Imaging is the most important test for patient selection. A thin layer CT scan of the temporal bone should be done routinely, and if necessary, cranial MRI, cochlea 3D reconstruction and inner ear canal cross-sectional scan should be done.
5. Language ability assessment: For patients with certain language experience or ability, speech ability assessment (language structure and function) should be done, including speech intelligibility, vocabulary, comprehension, grammar, expression and communication ability; for children younger than 3 years old who are uncooperative, the method of “parent-child game” video observation should be used for evaluation. For children younger than 3 years of age who were uncooperative, a “parent-child game” video observation was used to evaluate the patient’s language ability at this stage.
6.Psychological, intellectual and learning ability assessment: For children over 3 years old who lack language ability, the Schneider Learning Ability Test is optional; for those under 3 years old, the Greifers Mental Developmental Behavior Assessment Scale is optional. For those suspected of mental retardation (IQ < 68 on the Hinnai Learning Ability Assessment and mental developmental quotient < 70 on the Greiffels Test) or abnormal mental behavior, patients should be advised to go to an authoritative institution for further observation, diagnosis and identification. For patients with socio-cultural mental retardation, cochlear implantation may be considered; for patients with non-socio-cultural mental retardation, ADHD, autism and other mental retardation, parents should be informed of the great difficulties that these disorders may bring to the post-operative rehabilitation of the patient, and parents should be helped to establish objective psychological expectations.
7.Pediatrics or internal medicine evaluation: do a general physical examination and related auxiliary examinations.
8. Family conditions and rehabilitation conditions: Families who have received professional training or have regular guidance from a language training teacher can conduct auditory language training for the child at home; otherwise, the child should be sent to a rehabilitation school or institution for deaf children.
Preparation for auditory language rehabilitation
Patients, parents and teachers should be made aware of the importance of post-operative auditory language rehabilitation, especially how to prepare the child with pre-speech deafness for post-operative rehabilitation and the choice of rehabilitation site. Pre-operative rehabilitation should be tailored to the age and level of hearing and speech of the child, and should focus on the establishment of auditory awareness and the understanding of the definition of concepts, so as to prepare the patient for post-operative start-up and rehabilitation.
Cochlear implant surgery
Cochlear implantation is a delicate microscopic otologic surgery that requires the surgeon to implant the electrodes in the best position in the cochlea without damaging the electrodes or damaging the important tissues of the middle and inner ear. Deformities of the middle or inner ear are often encountered during surgery. Therefore, the surgeon should have extensive experience in middle ear mastoid surgery and some specialized training in cochlear surgery. Before completing cochlear implant surgery independently, the surgeon should have completed three to five cases of cochlear implant surgery under the guidance of an experienced physician.
The operating room and basic equipment requirements should have good sterile surgical conditions, a clear field of view and adequate illumination for the operating microscope, a stable operating drill, and a full complement of drill bits. If possible, hospitals can use facial nerve monitor, which is more necessary in case of congenital temporal bone malformation, re-operation and implantation that may damage the facial nerve.
Pre-operative preparation
Pre-operative conversation: For patients and families who are suitable for cochlear implant surgery, the surgeon and audiologist should have a pre-operative conversation with them to make them fully understand the possible risks and complications of the surgery, the benefits, shortcomings and drawbacks of the cochlear implant, especially the possibility of long-term maintenance of the external device and failure of the internal device, and sign the informed consent form for the surgery.
2. The informed consent form for surgery is attached to this document.
3.Surgical preparation, general anesthesia preparation and preoperative medication are the same as other surgeries.
The surgical procedures and methods should be performed in accordance with the operation manuals provided by the cochlear implant companies.
V. Intraoperative testing of the electrodes after implantation is performed according to the cochlear implant used, and electrode impedance testing and electrically evoked nerve response testing are performed to understand the integrity of the electrodes and the response of the auditory nerve to electrical stimulation.
Post-operative treatment is the same as that of general otologic surgery.
Common complications of cochlear implantation include: perforation of the tympanic membrane or external auditory canal, bulbar nerve palsy, thick scalp affecting signal transmission, vertigo, facial muscle twitching or pain during electrical stimulation, severe infection of the incision, injury to the mastoid vessels or sigmoid sinus leading to hemorrhage, cerebrospinal fluid leakage, facial nerve palsy, meningitis and so on. A small amount of subcutaneous hematoma can be absorbed by itself without special treatment. Larger hematomas can be aspirated by hematopuncture and bandaged with pressure. Infections in the middle ear usually do not affect the implanted device and can be controlled with conventional methods. Mild vertigo usually resolves on its own within a few days, while anti-vertigo medication may be used if the vertigo is severe. Severe complications require reoperation, such as facial nerve decompression, cerebrospinal fluid repair, cochlear implant replacement, etc. Facial muscle twitching and pain caused by unipolar electrical stimulation can be solved by adjusting the machine.
In special cases, such as enlarged vestibular canal, congenital abnormalities of the cochlear canal, Mondini and commoncavity inner ear malformations, and cochlear ossification, cochlear implantation can be performed in most special cases, but should be handled carefully during surgery. In cases where an intraoperative blowout may occur, technical preparations should be made to repair and fill the leak before surgery. In cases with bony defects in the inner ear canal, electrode insertion into the inner ear canal should be avoided to avoid facial nerve paralysis or poor postoperative results. The clinical diagnosis of auditory neuropathy is difficult, but as long as the patient has residual hearing, a better result can be achieved after surgery; patients without residual hearing should undergo electrical stimulation test of the ear head and should consider carefully whether to operate or not. In special cases, preoperative case discussion should be organized.
IX. Post-operative imaging evaluation
Before starting the machine after the operation, the electrode implantation should be understood by imaging method.
Start-up and commissioning
The cochlear implant can be turned on two to four weeks after surgery. Turning on the cochlear implant refers to the process of fitting and turning on the external device, the speech processor, for the patient. During the use of the cochlear implant, the implantee’s electrode impedance, auditory pathway and auditory center will change with time and experience, so the patient’s program will need to be adjusted every once in a while to make the sound heard more clearly and comfortably. Generally, the tuning is done once a week for the first month after the machine is turned on, then once every half month or once a month, and the interval of tuning will be extended after the hearing is stabilized, and finally once a year.
The method and procedure of start-up and tuning can be performed according to the requirements of each cochlear implant company.
Audiologist requirements: The audiologist should have good basic theoretical knowledge of audiology and cochlear implants and be trained and approved by the cochlear implant company. For infants and young children, an experienced audiologist should perform the tuning.
Evaluation of surgical outcomes
Successful surgery should include the following:
1. Good healing of the incision after surgery.
2.After X-ray examination, the electrodes are correctly positioned and the number of implanted electrodes meets the requirements of the company providing the product.
3.Patients have subjective or objective auditory response after a period of adjustment and rehabilitation (usually 3-6 months).
Auditory speech rehabilitation
Auditory language rehabilitation after implantation differs for patients with prelingual deafness and postlingual deafness. Post-implantation deafness focuses on auditory rehabilitation, while prelingual deaf children require a complete auditory language rehabilitation program.
I. Rehabilitation goals
1. The establishment of rehabilitation goals should be based on the postoperative evaluation. The main goal is to develop the auditory language ability at the developmental level, but also to take into account the laws of physical and mental development, with the characteristics of stage, sequence, continuity and observability, and to achieve the goal of being able to hear and speak.
2. The content of rehabilitation should include auditory, language, cognitive, social behavior, emotional development, etc., to improve the use of language and communication skills and to promote their overall development.
II. Rehabilitation Model
1. The rehabilitation model of “rehabilitation institution as the guide and family rehabilitation as the center” should be established.
2. To establish a normal auditory language learning environment, preschool deaf children with certain auditory language ability can enter normal kindergartens, and school-age children can enter ordinary schools.
3.Special attention is paid to the role of parents, kindergarten and general school teachers in the rehabilitation guidance.
4. Rehabilitation institutions always play the role of technical resources in the whole process of hearing and speech rehabilitation for deaf children.
III. Rehabilitation Principles
1. Emphasis on “hearing-oriented”, and the reasonable application of visual and tactile aids.
2.Optimize the listening environment, pay attention to provide rich and appropriate sound, especially the experience of music, to develop listening habits, and establish auditory advantage.
3, language learning should begin with the understanding of language, pay attention to the practicality of language. Adhere to the principle of encouragement, pay attention to the gradual progress, in the use of language and interaction in the development of language skills.
3.In the process of language learning, attention should be paid to the problems of breathing, pronunciation and phonology in the language production process and corrected to improve language clarity.
4. Based on the results of the stage assessment, we follow the 8 stages of auditory development, including auditory perception, attention, localization, discrimination, memory, selection, feedback, and concept, to develop individual education plans and strengthen one-on-one individual guidance.
IV. Rehabilitation assessment
1. Auditory ability assessment: The auditory ability of cochlear implant recipients is evaluated through speech and language recognition. Auditory assessment with speech sounds can achieve the purpose of understanding the whole process of auditory pathways. The tests of Chinese tone recognition, vowel recognition, rhyme recognition, and bisyllabic word recognition can be used to quantify the perception and speech intelligibility of the cochlear implant recipients at the fundamental, mid, and high frequencies of speech. The results of the evaluation are important for optimizing speech coding strategies, setting T and C values, and guiding auditory training. The test apparatus and method can be used according to the purpose of the test, and the “Children’s Chinese Language Speech Auditory Vocabulary” of the Chinese Deaf Children Rehabilitation System can be used for the assessment.
2. Language ability assessment: This test is an assessment of the language ability of deaf children. It is based on the language development indicators of normal children at all ages, i.e., language age. It does not address all elements of language, but only some of the distinctive developmental features. For example, cochlear implants are evaluated for articulation, speech comprehension, speech expression, speech use, and speech grammar. It is also possible to measure the balance of the deaf child’s language development and to select materials that are appropriate for the child’s language age in rehabilitation training, which is important for one-on-one instruction. The test instrument and method can be used to assess the language ability of deaf children according to the purpose of the test, which is part of the deaf children’s rehabilitation assessment questions used in the China Deaf Children Rehabilitation System.