Etiologies of hearing impairment among infants and toddlers: 1986-1987 versus 2001.

OBJECTIVE: This study compares etiological factors for hearing loss, relevant neuro-sensory impairments and demographics between two groups of children referred for early hearing habilitation in Israel. Group I was referred in the years 1986-1987 (n=73) and group II was referred during 2001 (n=73). METHODS: Family history, pregnancy, risk factors, developmental milestones, medical history, auditory brainstem response, tympanometry, otoacoustic emissions and behavioral audiometric results were retrospectively retrieved in 2003 from medical records at the MICHA Society for Deaf Children in Israel. RESULTS: New referrals per year have doubled themselves over the 15 years that elapsed between 1986-1987 and 2001. No changes in gender and age at time of admission were found. The prevalence of mild-to-moderate hearing loss was higher in Group II while severe and profound hearing loss was more prevalent in Group I. Assisted reproductive technologies were involved only in Group II. There were more twin births and post-natal hypoxia in Group II. Rh incompatibility was reported only in Group I. Severe hearing loss was associated with younger age at admission. No significant associations were found between age at admission and etiology with the exception of the fact that children with genetic background were admitted at an earlier age. Since no significant association between genetic background and severity of hearing loss was found, it is conclude that the association between severity of hearing loss and age at admission did not account for changes in etiology in our sample. CONCLUSIONS: Classic risk factors for hearing loss among infants and toddlers have not changed much over time, and the few changes that have been noticed are probably due to expanded medical knowledge and improved technologies.

Objective measurements of auditory nerve recovery function in nucleus CI 24 implantees in relation to subjective preference of stimulation rate.

OBJECTIVE: Setting the optimal rate of stimulation for individual cochlear implant recipients is critical to the successful functional outcome of cochlear implantation. In the absence of an objective methodology, cochlear implants are currently fitted by means of a time-consuming (and therefore expensive) trial-and-error process of limited accuracy. The aim of this study was to evaluate a possible relationship between the patient's subjectively preferred stimulation rate and an objective measurement of auditory nerve recovery time. MATERIAL AND METHODS: Eleven recipients of Nucleus CI 24 implants initially fitted with a speech processor using the ACE speech-coding strategy at a rate of 900 Hz were introduced to 2 other stimulation rate options, 1200 and 1800 Hz, at 2 different fitting sessions and asked to choose their preferred rate. Preferences were compared with objective measurements of auditory nerve recovery time obtained using the refractory recovery function of neural response telemetry. RESULTS: The auditory nerve recovery time for individuals with a subjective preference for a slow stimulation rate was longer than that for individuals who preferred a fast stimulation rate, with significant differences between the 2 groups for 3 tested electrodes (7, 11 and 15): p = 0.024, 0.009 and 0.03, respectively (Mann-Whitney test). CONCLUSION: The association observed between the subjective stimulation rate preference and measurements of auditory nerve recovery time indicates that the measured auditory nerve recovery time can be used as a reliable predictor for setting up a basic stimulation rate of a particular individual's map, thus reducing the cost of the technology and significantly increasing its effectiveness.

NRT-based versus behavioral-based MAP: a comparison of parameters and speech perception in young children.

The present study was designed to evaluate the effect of neural response telemetry (NRT)-based cochlear implant (CI) programming versus behavioral-based programming on electrical stimulation parameters (MAP) threshold (T) and comfortable (C) levels and speech perception abilities in young children, during the first year of implant use. Ten congenitally deaf children at the age of 12-39 months (mean age: 25.2 months) implanted with the Nucleus 24R(CS) CI participated in the study. The group was randomly divided into two: (1) NRT-based MAP group (n = 5) consisted of children who were programmed using intra-operative NRT measurements; (2) behavioral-based MAP group (n = 5) consisted of children who were programmed using the behavioral responses of the patients. MAP parameters as well as sound-field aided thresholds and speech perception abilities were compared between the two groups at consecutive programming sessions: 1, 3, 6, and 12 months post initial stimulation. Results indicated no significant differences among NRT-based MAPs and behavioral-based MAPs. Although MAP profiles at initial stimulation differed in the apical region, these differences decreased with time. In addition, a gradual increase of T and C levels of NRT-based MAPs as well as those of behavioral-based MAPs was evident until the 1-month time point, thereafter stabilization occurred. Sound-field aided thresholds improved with time for both groups; however, they were found to be significantly better for the NRT-based MAP group. Despite these differences, speech perception abilities were comparable among groups at 12 months post initial stimulation. NRT-based programming was found to be significantly shorter than behavioral-based programming. In conclusion, for this small group of children, our findings support the use of NRT for programming of young children during the initial period after implantation.

Objective measurements of auditory nerve recovery function in nucleus CI 24 implantees in relation to subjective preference of stimulation rate.

OBJECTIVE: Setting the optimal rate of stimulation for individual cochlear implant recipients is critical to the successful functional outcome of cochlear implantation. In the absence of an objective methodology, cochlear implants are currently fitted by means of a time-consuming (and therefore expensive) trial-and-error process of limited accuracy. The aim of this study was to evaluate a possible relationship between the patient's subjectively preferred stimulation rate and an objective measurement of auditory nerve recovery time. MATERIAL AND METHODS: Eleven recipients of Nucleus CI 24 implants initially fitted with a speech processor using the advanced combination encoders speech-coding strategy at a rate of 900 Hz were introduced to 2 other stimulation rate options, 1200 and 1800 Hz, at 2 different fitting sessions and were asked to choose their preferred rate. Preferences were compared with objective measurements of auditory nerve recovery time obtained with the refractory recovery function of neural response telemetry. RESULTS: The auditory nerve recovery time for individuals with a subjective preference for a slow stimulation rate was longer than that for individuals who preferred a fast stimulation rate, with significant differences between the 2 groups for 3 of the tested electrodes (Nos. 7, 11 and 15): p = 0.024, 0.009 and 0.03, respectively (Mann-Whitney test). CONCLUSIONS: The association observed between subjective stimulation rate preference and measurements of auditory nerve recovery time indicates that the measured auditory nerve recovery time can be used as a reliable predictor for setting up a basic stimulation rate of a particular individual's map, thus reducing the cost of the technology and significantly increasing its effectiveness.