United Kingdom national paediatric bilateral project: Results of professional rating scales and parent questionnaires

OBJECTIVES

This fourteen-centre project used professional rating scales and parent questionnaires to assess longitudinal outcomes in a large non-selected population of children receiving simultaneous and sequential bilateral cochlear implants.

METHODS

This was an observational non-randomized service evaluation. Data were collected at four time points: before bilateral cochlear implants or before the sequential implant, one year, two years, and three years after. The measures reported are Categories of Auditory Performance II (CAPII), Speech Intelligibility Rating (SIR), Bilateral Listening Skills Profile (BLSP) and Parent Outcome Profile (POP).

RESULTS

Thousand and one children aged from 8 months to almost 18 years were involved, although there were many missing data. In children receiving simultaneous implants after one, two, and three years respectively, median CAP scores were 4, 5, and 6; median SIR were 1, 2, and 3. Three years after receiving simultaneous bilateral cochlear implants, 61% of children were reported to understand conversation without lip-reading and 66% had intelligible speech if the listener concentrated hard. Auditory performance and speech intelligibility were significantly better in female children than males. Parents of children using sequential implants were generally positive about their child's well-being and behaviour since receiving the second device; those who were less positive about well-being changes also generally reported their children less willing to wear the second device.

CONCLUSION

Data from 78% of paediatric cochlear implant centres in the United Kingdom provide a real-world picture of outcomes of children with bilateral implants in the UK. This large reference data set can be used to identify children in the lower quartile for targeted intervention.

United Kingdom national paediatric bilateral project: Demographics and results of localization and speech perception testing

OBJECTIVES

To assess longitudinal outcomes in a large and varied population of children receiving bilateral cochlear implants both simultaneously and sequentially.

METHODS

This observational non-randomized service evaluation collected localization and speech recognition in noise data from simultaneously and sequentially implanted children at four time points: before bilateral cochlear implants or before the sequential implant, 1 year, 2 years, and 3 years after bilateral implants. No inclusion criteria were applied, so children with additional difficulties, cochleovestibular anomalies, varying educational placements, 23 different home languages, a full range of outcomes and varying device use were included.

RESULTS

1001 children were included: 465 implanted simultaneously and 536 sequentially, representing just over 50% of children receiving bilateral implants in the UK in this period. In simultaneously implanted children the median age at implant was 2.1 years; 7% were implanted at less than 1 year of age. In sequentially implanted children the interval between implants ranged from 0.1 to 14.5 years. Children with simultaneous bilateral implants localized better than those with one implant. On average children receiving a second (sequential) cochlear implant showed improvement in localization and listening in background noise after 1 year of bilateral listening. The interval between sequential implants had no effect on localization improvement although a smaller interval gave more improvement in speech recognition in noise. Children with sequential implants on average were able to use their second device to obtain spatial release from masking after 2 years of bilateral listening. Although ranges were large, bilateral cochlear implants on average offered an improvement in localization and speech perception in noise over unilateral implants.

CONCLUSION

These data represent the diverse population of children with bilateral cochlear implants in the UK from 2010 to 2012. Predictions of outcomes for individual patients are not possible from these data. However, there are no indications to preclude children with long inter-implant interval having the chance of a second cochlear implant.

Cochlear implantation of a deaf blind patient with mitochondrial cytopathy

Genetic defects of the mitochondrial DNA often cause sensorineural hearing impairment, accompaniment by disorders of organs within the body. This case report describes cochlear implantation of a 33-year-old deaf blind female with mitochondrial cytopathy. The outcome was very successful, and vastly improved quality of life for this patient. Many cases of mitochondrial cytopathy cause progressive deafness; it is, therefore, likely that other patients with this unusual disorder will present for cochlear implant assessment.

Bilateral otoacoustic emissions pass in a baby with Mondini deformity and subsequently confirmed profound bilateral hearing loss

Evoked otoacoustic emissions are well established as a hearing screening technique and are used extensively in paediatric audiology. They are believed to originate from the outer hair cells and can be detected in almost 100% of normally hearing ears; even a mild hearing loss has been shown to abolish otoacoustic emissions. Results are presented of a baby boy born at 29 weeks' gestation requiring 77 days of neonatal care, but experiencing no complications following discharge from the neonatal unit. This child had clear bilateral evoked otoacoustic emissions at almost four months of age, but was subsequently found to have a profound bilateral hearing impairment and absent otoacoustic emissions. Radiological investigations revealed bilateral Mondini dysplasia, and this child has now been implanted with a multi-channel MXM Digisonic cochlear implant. He is progressing well and shows awareness of sound. Approximately 10 previous cases of otoacoustic emissions occurring in profoundly deaf ears have been reported in the literature. Although it is likely that this child's hearing loss was progressive in nature, the authors believe that this is the first reported case of otoacoustic emissions being recorded in the presence of Mondini dysplasia. This raises concerns about the use of neonatal screening in isolation without adequate mechanisms for later identification of hearing impairment, although it is acknowledged that it represents a rare situation.

Feasibility of otoacoustic emissions as a hearing screen following grommet insertion

Following grommet insertion, it is important to establish that there is no underlying sensorineural hearing impairment. In this hospital, approximately 1000 grommet insertions are performed each year, thus generating a heavy workload of review appointments for ENT and audiology. The present study investigates the efficacy of performing evoked otoacoustic emissions screening on 108 children when they were ready to leave the hospital following grommet insertion. Bilateral normal otoacoustic emissions were recorded in 32% (35 children), although 99% (105) of the 106 children attending the outpatient review appointment had normal hearing sensitivity. If normal hearing thresholds were established immediately following surgery, it can be argued that this obviates the need for an outpatient review appointment; however, in this study only one-third of children could be discharged after surgery. Otoacoustic emissions therefore does not represent an effective screen at this stage.

Integrity testing of cochlear implants in the awake child

Cochlear implantation is becoming a routine rehabilitation process for profoundly deaf adults and children. Often children are implanted at just two or three years of age and therefore the subsequent tuning of the device is challenging. Although some children demonstrate quick and reliable responses to electrical stimulation, there are others who do not respond consistently thus causing concern about the functioning of the device. It is therefore desirable to have an objective test of the integrity of the implanted electrodes. The principle of the integrity test is the measurement of voltages generated by the biphasic current pulses at the electrode array; this is accomplished using surface electrodes placed around the implanted ear, in conjunction with recording and averaging equipment typically used for evoked response testing. Traditional integrity testing usually requires a general anaesthetic in young children, however this study demonstrated a simple, quick and reliable method of obtaining results in the normally active child using ear-clip electrodes. Results are presented from 12 children tested in this way, and compared with results from 20 children who were tested in theatre using a different electrode configuration. The tests were performed in common ground stimulation mode, but some measurements were also made in bipolar + 1 and pseudo-monopolar modes. The three stimulation modes were compared, with the conclusion that common ground mode provides an efficient check of implant function in the awake child, while pseudo-monopolar mode may be preferable for anaesthetized patients. In addition, measurements were made in vitro using a functioning cochlear implant in a saline tank in order to investigate the current flow during stimulation. The standard procedure in this department is to perform a full intra-operative integrity test on all implanted children. The simplified technique is used to repeat the measurement post-operatively if required.