The age at cochlear implant surgery for children with congenital hearing loss has tended to become lower and lower, in Japan as well as around the world. This could be attributable to the introduction of neonatal hearing screening having made it possible to diagnose hearing loss at an early age, and to early cochlear implantation having become established as being of superior benefit for spoken language acquisition. The Japanese pediatric cochlear implant adaptation standard, which used to be 2 years old or older, was revised to 1 and a half years old in 2006, and then to “the adaptation age should be 1 year old or older (weight 8 kg or more) in principle” in 2014. In addition, there are reports from overseas showing the significant effectiveness of cochlear implant surgery performed under the age of one year, and some countries have even removed the age limit from the indication criteria. On the other hand, the period from the discovery of hearing loss in newborn hearing screening to cochlear implant surgery has become shorter, and it seems that the anxiety and burden on parents and nursing institutions are increasing. I think it is meaningful to summarize what should be done from the viewpoint of auditory rehabilitation before cochlear implant surgery.
Herein, we provide an outline of habilitation, including mapping and auditory verbal habilitation, and discuss issues and managements of psychological and social adaptation in pediatric patients undergoing cochlear implantation. Since the auditory input from a cochlear implant is complementary for the development of the language and speech, the appropriateness of mapping has an influence on auditory language learning and articulatory development in children undergoing cochlear implantation. During cochlear implant mapping in children, it is essential to avoid stimulation with a strong amount of charge in the charge amount setting, and to enable the cochlear implant to be worn stably and continuously with an appropriate charge amount map.
We consider that it is important to select the most adequate communication mode and method of habilitation for language development according to the cause of hearing impairment and other complications in individual children with cochlear implants.
It is necessary to anticipate psychological and social adaptation problems due to hearing limitations of cochlear implants at all stages of life, from childhood to adulthood, and to utilize cochlear implant hearing aid systems. We consider that it is important for continuous rehabilitation and support to be provided over the long term by a multidisciplinary team composed of doctors, speech therapists, and teachers of special hearing support schools to children with cochlear implants.
We assessed the mapping characteristics and speech perception in 32 pediatric patients with inner ear anomalies, including 9 children with a common cavity (CC group), 12 with incomplete partition type I anomaly (IP-I group), and 11 with incomplete partition type II anomaly (IP-II group); 19 patients with GJB2-related deafness without inner ear anomalies served as the control group. All patients underwent cochlear implantation between 2004 and 2020, and were followed up for more than two years.
The IP-II group had no programming difficulties and there were no significant differences from the control group in regard to the electric charge requirements for loudness in the cochlear implant and the clarity of speech perception. Therefore, the IP-II group required no special considerations while devising a programming map.
We had to inactivate some electrodes due to a lack of auditory sensation in 8 patients of the CC group and 1 patient of the IP-I group. The electric charge requirement was larger by up to 5 times in the CC group and by up to 2.5 times in the IP-I group as compared to the control group. Speech perception in the CC and IP-I groups was variable, but word perception was 60% or better in all the children of the CC and IP-I groups.
The results of newborn hearing screening (NHS) in 1549 children who underwent hearing tests at our hospital between 2016 and 2018 were investigated from the patient referral documents and records of the Maternal and Child Health Handbook (MCH Handbook). The format of the MCH Handbook was changed in 2012 and 2017, so it was also confirmed (before 2012: Type A, 2012-2016: type B, after 2017: Type C). A total of 1402 children were screened, and 147 were had not been screened, corresponding to an examination rate of 91%. The results of NHS were “bilateral refer” for 34%,“unilateral refer” for 21%, and “bilateral pass” for 45%. Recording in the MCH Handbook could be confirmed for 718 cases. The inspection date could be confirmed in 92%, the evaluation method could be confirmed in 55%, and the test results could be confirmed in 64%. Information about the NHS was described in 97% of Type B and 95% of Type C. While the current Type C provides a variety of information about NHS, the percent coverage of the entire information about NHS was only 62%; in other words, 38% had missing records. Although an information sharing system using the MCH Handbook is available, it is necessary to improve the NHS system to reduce missing records of NHS in the MCH Handbook.
With the implementation of newborn hearing screening (NHS), children with unilateral hearing loss also began to be identified at birth, and it began to be realized that these children also require early intervention services. This questionnaire survey covered 18 schools, including two schools for the deaf in Niigata prefecture, that have individual classes or/and resource rooms for students with hearing loss. The teachers in these individual classes and resource rooms were asked to respond to the questionnaire about their students with unilateral hearing loss. Sixteen schools that responded to our survey had 21 students with unilateral hearing loss. The parents and guardians of 8 out of the 21 students agreed to provide us with further information. The teachers and guardians of these eight students with unilateral hearing loss thought that they had some problems in these four aspects, “learning,” “behavior,” “listening,” and “articulation.” One of the eight students was diagnosed as having hearing loss from the result of NHS, but this student began to receive educational support from the fifth grade. Our findings imply that the students with unilateral hearing loss may not seek support until they realize that they have problems at school.
To investigate the wearing situations of sound processors and the sound environments of children with cochlear implants, the distribution of 5 selected parameters were analyzed based on the data logging results of 100 children under 18 years of age with cochlear implants. The results of three groups, namely, preschool children, elementary school pupils, and junior high/high school students, were compared.
As for the cochlear implant wearing time, the higher the age, the longer the wearing time, and the more stable the wearing of the transmission coil in the junior and senior high school students. As for the sound environments, speaking voices in noise accounted for a higher percentage than those in silence, suggesting the importance of environmental adjustments for information security.
Cochlear implant data logging is expected to enable rehabilitation tailored to individual children by allowing the medical staff to grasp the accumulated values from a certain number of results, and also the changes over time, and share such information with the parents and related organizations.
We assessed the outcomes in terms of speech perception, CAP (categories of auditory performance), and SIR (speech rating intelligence) in 36 pediatric patients with inner ear anomalies, including 10 patients with a common cavity (CC group), 13 with incomplete partition type I (IP-I group), and 12 with incomplete partition type II (IP-II group); in addition, 36 patients with GJB2-related deafness without inner ear anomalies served as the control group. All children underwent cochlear implantation (CI) between 2004 and 2020, and were followed up for more than three years. The results in the IP-II group were good, but not significantly different from those in the control group. The results in the 13 cases of the IP-I group were not as good as those in the control group, but there were little variations among these cases, and good results were obtained in which auditory verbal communication was possible. Of the 10 patients in the CC group, the monosyllable perception in 8 patients without CND was 60% or more, except 1 patient, in whom only 8 electrodes were used for CI mapping. The monosyllable perception in the remaining 2 cases without CND in the IP-I group and 6 cases of the IP-II group who underwent a second CI were similar to those after the initial surgery, and the effect of bilateral CI was confirmed in cases with of inner ear malformations.