Cochlear implants are very advanced electronic devices used in the hearing rehabilitation of patients with hearing loss who do not benefit enough from the hearing aid. These devices convert the sound energy into electrical energy, thereby stimulating the auditory nerve directly in the inner ear and thus enabling the person to hear again. Cochlear implants consist of two main parts. It consists of an inner part that is surgically placed in the ear and an outer part that is attached behind the ear just like a hearing aid. The outer part and the inner part come into contact with a magnet system.
The cochlear implant takes over the function of the hearing organ in the inner ear. For this reason, in order to perform cochlear implant surgery, the patient must have an inner ear to which the implant can be placed and a sound auditory nerve.
Hearing is very important for language and language development. Normal hearing is necessary for a person to understand speech and learn to speak. Therefore, rapid rehabilitation of hearing in children with hearing loss is very important.
WHO IS INSTALLED COCHLEAR IMPLANT?
Those with congenital severe hearing loss: Early diagnosis of hearing loss is very important in children with congenital hearing loss. Because there is a critical period for language and language development in children. At this time, he is around 2 years old. For this reason, the ideal operation time for babies with severe hearing loss is around 1 year old. The probability of obtaining near-normal hearing and language development in children with cochlear implant surgery at the age of 1 is over 95%. The results of the surgeries performed between the ages of 1-2 are also very pleasing. After the age of 2, the success rate starts to decrease. If it is around 4 years of age, it is considered the critical age. Because it is not possible to achieve success when a cochlear implant is applied after the age of 4 in children with congenital hearing loss and no language development. There is only one exception to this situation. If the child is older than 4 years and has some language development, then there may be a chance to benefit from a cochlear implant.
Hearing loss that occurs later: Cochlear implant surgeries are also performed in severe hearing loss in adults and children who have completed language development. In fact, this group is the group that benefits most from the cochlear implant. If surgery is performed shortly after hearing loss occurs, these people regain their hearing from the first use of the device and generally understand what is being said. However, many years pass will reduce the success of the implant. If it has been more than 10 years since the hearing loss occurred, the chance of benefiting from the implant is very low in these people. Therefore, surgeries should be performed as soon as possible.
HOW IS THE COCHLEAR IMPLANTATION PROCESS IN AN BABY WITH HEARING LOSS?
In our country, national newborn hearing screening is carried out by the Ministry of Health. All newborn babies undergo hearing screening within the first month. During this screening, babies with suspected hearing loss are sent to appropriate centers for further investigations to confirm the diagnosis of hearing loss. After detailed examinations in these centers, the diagnosis of hearing loss is confirmed. After this, the baby is immediately started on the use of hearing aids and the training program. The baby is taken into the cochlear implantation program and followed up. If it is understood that the baby does not benefit enough from the hearing aid around the age of 1, the baby is operated and a cochlear implant is placed. Approximately 1 month after the operation, the external part is attached and the device is activated and its settings are made. These children need special education for language and language development.
WHO CANNOT HAVE COCHLEAR IMPLANT SURGERY?
It is not applied to people who have enough benefit from hearing aids despite having hearing loss.
It is not applied to people with severe inner ear structure and/or hearing nerve (brain stem implant is applied to these patients).
It is not applied to children with congenital hearing loss who are older than 5-6 years old and have no language development.
It is not applied to people who develop hearing loss in adulthood and who have passed more than 10-15 years.
IS THERE A RISK OF COCHLEAR IMPLANT SURGERY?
All surgical procedures have certain risks. Of course, there are some risks in cochlear implant surgery. These:
Anesthesia-related risks: These are very rare conditions and are at the same rate as any surgery.
Risk of facial paralysis: Facial paralysis may develop very rarely due to the passage of the facial nerve through the surgical area. This rate is less than 1%
Brain fluid leakage: Since the inner ear is opened during the surgery, patients may rarely have a postoperative brain fluid leak. This problem is more common in patients with disorders in the inner ear structure.
development of meningitis. In these patients, there is a very rare risk of post-operative meningitis due to the opening of the inner ear. Therefore, all cochlear implant patients are vaccinated for meningitis protection prior to surgery.
Risk of deterioration of the device: Since these devices are electronic devices, the device may malfunction over the years in some patients. This rate is around 1-3%. However, the damaged device can be replaced with a new one without any problems by surgery.
COCHLEAR IMPLANTATION IN CHILDREN WITH ADDITIONAL PROBLEMS
Today, the audiological criteria for the selection of cochlear implantation candidates have been determined in a way that everyone agrees on. However, in some candidates, various organic or psychological disorders accompany hearing loss and can sometimes be a contraindication for cochlear implantation. We call such situations an additional handicap. Gallaudet university defines the term additional handicap as: “any physical, mental, emotional or behavioral impairment that complicates the education of a child with hearing loss”. The World Health Organization, on the other hand, mentions 3 categories in this field in 1980: 1- impairment—any loss or abnormality in the psychological or anatomical structure, 2- disability—limitation or limitation in performing activities that are considered normal for humans. inability to perform, 3- handicap—the disadvantage arising from the inability to perform something that should be normal for that person due to a deficiency or disability (1).
Approximately 30-40% of children with hearing loss have various additional handicaps besides hearing impairment. The most common additional handicaps are: Mental retardation, learning disorders, attention deficit and hyperactivity disorders, visual disorders, cerebral palsy, orthopedic disorders and other physical disabilities (2). While the presence of additional handicaps was considered a contraindication for cochlear implantation in the first years, cochlear implantation is now performed in children with additional handicap in many centers as a result of the developments in implant technology and increasing surgical and educational experience (2–4). However, there is still no consensus in the literature regarding cochlear implantation of children with additional handicap. In individuals with hearing loss as the only disability, the decision of implantation should be determined by the benefit to be obtained. However, the benefit to be provided for the additional handicapped is controversial. Should the benefit be considered only as success in language and language development, or should the increase in psychosocial development and quality of life be taken into account? In fact, children with additional handicap have lower scores in language and language development than children without additional problems other than hearing loss, and only a limited number of them can show language and language development (2). Hamzawi et al (3) published the results of the EARS test battery in 10 children with cochlear implants with additional handicap and stated that most of the children were regular implant users. As a result of the study, they stated that the cochlear implant provides certain benefits for both the child and the family in multi-handicap children. Recently, Berretini et al. (5) published the results of 23 additional handicapped children who underwent cochlear implantation and stated that all patients benefited from the implant to a certain extent.
The presence of additional handicaps brings with it special problems related to pre-surgical evaluation, post-surgical rehabilitation and follow-up. A multidisciplinary approach should be applied, especially neurological and neuropsychiatric evaluation should be done with care. However, it may be difficult to diagnose diseases such as learning disability, mental retardation, and autism in very young children, or they may not show any symptoms yet. Considering that the age of the implant is getting smaller and smaller, the importance of pre-surgical evaluation and informing the family about this issue will be better understood. It should be stated to the family that approximately one third of children with hearing loss have additional handicaps and this may not show symptoms until the child reaches a certain age. In addition, it should be noted that the presence of additional handicaps may affect the success of the cochlear implant(5).
Additional handicaps related to cognitive retardation and learning difficulties:
The general opinion in the literature is that children with mild to moderate mental retardation will benefit from cochlear implants. In a study conducted by Daneshi and Hassanzadeh (2), the auditory perception scores of the patients before and after the implant were compared and the auditory perception score of 8 patients with mild mental retardation increased from 2.75 before the implant to 45 after the implant. The auditory perception score, which was 2.8 before the implant, increased to 37.2 after the implant.
Recently, Holt and Kirk (6) published their study on 69 cochlear implanted children with prelingual hearing loss. 19 of the children in this study consisted of children with cognitive delay and the others without any additional handicap. During the entire follow-up period, significant improvement in language and language development was detected in children in both groups. However, a significant difference was observed between the cognitively delayed group and the other healthy children in terms of both receptive language development and expressive language development. The scores of the group with cognitive delay were lower. As a result of this study, the researchers stated that children with mild cognitive delay benefited from the cochlear implant, but this benefit was lower than healthy children and concluded that it would be appropriate to implant these children. Similarly, Berrettini et al. (5) reported that the results were satisfactory in the evaluation of 10 children with mental retardation with cochlear implants. They stated that all children use the implant continuously and that half of the patients develop open-ended perception ability. They found that although only 2 patients were able to communicate by speaking, all patients benefited from their communication skills.
Motor Developmental Retardation:
Edward et al. (7) reported that children’s general development and cognitive development levels are the most important determinants of post-implant language and language development. While the results are very poor in patients with significant growth retardation, the results are satisfactory in patients with mild retardation. In their study published in 2011, Amirsalari et al. (8) compared the language and language development of 28 children with prelingual hearing loss with mild to moderate motor developmental delay and 234 children with prelingual hearing loss without developmental delay after cochlear implantation. There was no difference between the two groups in terms of CAP (categories of auditory perception scales) and SIR (Speech Intelligibility Rating) scores. Therefore, the researchers concluded that cochlear implantation can be performed in children with mild to moderate motor developmental delay and the results are similar to healthy children.
Cerebral palsy is a permanent group of diseases that includes movement and posture disorders and is usually accompanied by problems such as mental retardation, speech and feeding problems, vision and hearing disorders. The incidence of hearing loss in patients with cerebral palsy is 4-15%. Bacciu et al (9) recently published the results of 5 cochlear implantation cases with cerebral palsy. All of the cases were diagnosed early and used hearing aids in the pre-implantation period and used verbal communication. After implantation, a significant increase in language and language development was observed in all cases. The researchers concluded that cerebral palsy alone would not constitute a contraindication for cochlear implantation.
Autistic Spectrum Diseases:
Even children with normal hearing who have diseases in the autistic spectrum have various degrees of communication disorders and speech difficulties. Therefore, autistic patients are generally considered contraindicated for cochlear implantation. Another issue to be considered in this disease group is that there are patients who may receive this diagnosis after implantation due to the earlier implantation age. When we look at the current literature, we see that cochlear implantation is applied to a limited number of patients. However, the benefit rate of these patients was very limited (1,2).
It is necessary to examine the patients in this group in 3 categories: 1- Patients with congenital vision loss who develop hearing loss in later years. 2- patients with congenital hearing loss who develop vision loss in later years (usually patients with Usher syndrome are in this group). 3- patients with congenital hearing and vision loss. Cochlear implantation results for the first 2 groups are quite successful (10). The third group is a very problematic group. The post-implantation education of these children is more challenging than other children. Recently, Dammeyer (11) published the results of cochlear implantation of 5 patients with congenital deafness and vision. The implantation age of the patients is between 2.2 and 4.2. None of the post-implantation patients showed significant speech language development. However, the cochlear implant has greatly benefited the communication skills of all patients and the same opinion has been expressed by the families.
As a result, there is no clear consensus on the implantation of children with additional handicap. However, the current literature shows that children with additional handicap show a significant improvement after cochlear implantation, but this development is slower and at a lower level than children without additional handicap. Some of these children never show open-ended perception skills and cannot reach the level of communicating by speaking. However, even in these patients, the cochlear implant has a significant benefit in the maintenance of daily living activities and quality of life (5).