Electrically Evoked Auditory Brainstem Responses Wave Research Articles

Elongated EABR wave latencies observed in patients with auditory neuropathy caused by OTOF mutation

ObjectivesWe sought to determine how the pathology altered electrically evoked auditory brainstem responses (EABRs) in patients with hearing loss by evaluating EABRs in auditory neuropathy patients with OTOF mutations comparing with various types of congenital deafness.MethodsWe included 15 patients with congenital hearing loss, grouped according to pathology: OTOF mutations (n = 4), GJB2 mutations (n = 4), SLC26A4 mutations (n = 4), or cytomegalovirus infections (n = 3). EABRs were recorded when patients underwent cochlear implantation surgery. We evaluated the latencies and amplitudes of the recorded EABRs and compared them statistically between four groups.ResultsThe EABR latencies of Wave III and Wave V, and of the interval between them, were significantly longer in the OTOF mutation group than in the GJB2 and SLC26A4 mutation groups (Wave III) and in all three other groups (Wave V and Wave III‐V latency); amplitudes were not significantly different between groups.ConclusionsOur results suggest OTOF mutations cause delayed (or slowed) postsynaptic neurotransmission, although the presumed mechanism involved reduced presynaptic transmission between hair cells and spiral ganglion neurons.Level of EvidenceMainly a case report

Electric auditory brainstem response (E-ABR) in cochlear implant children: Effect of age at implantation and duration of implant use

AimThe objective of this study is to obtain stable and accurate electrically evoked auditory brainstem responses (EABR) in cochlear implant children and to evaluate the effect of age at implantation and duration of implant use on these responses. Method30 Children were implanted with Nucleus 24 cochlear implant. EABR recording were performed to all subjects using a stimulus with pulse width of 25μs/phase. The EABR signals were recorded from two electrodes (electrode 5 and 20) and at different intensities. The latency of the EABR waves III and V, and the EABR threshold were measured and analyzed. ResultsEABR waves could be recorded in 93.3% of the studied subjects. This study indicated better EABR responses at electrode 20 (apical electrode) relative to the basal site (electrode 5). EABR responses in children did not differ from adult responses. Moreover, the age of implantation and duration of implant use were correlated with EABR wave latencies and thresholds. ConclusionA well-established EABR was obtained in cochlear implant children with proper parameters. The characterizations of the EABR waves including wave latencies and threshold were extracted at different electrodes. The EABR test proves to be an effective method to evaluate the functions of the auditory pathway in children after cochlear implantation.

The Relationship Between EABR and Auditory Performance and Speech Intelligibility Outcomes in Pediatric Cochlear Implant Recipients.

The primary purpose of the present study was to investigate the relationship between postimplant electrically evoked auditory brainstem response (EABR) measures (wave V threshold, wave V latency, input-output functions) and auditory performance and speech intelligibility outcomes measured using parental rating scales, such as Categories of Auditory Performance (CAP; Archbold, Lutman, & Marshall, 1995) and the Speech Intelligibility Rating scale (SIR; Allen, Nikolopoulos, Dyar, & O'Donoghue, 2001), respectively. The secondary purpose was to evaluate the relationship between age at implantation and ratings on the CAP and SIR. Forty children with congenital sensorineural hearing loss participated. Preimplant parental ratings on the CAP and SIR were obtained, and all the children underwent cochlear implantation. Intracochlear EABRs were recorded postimplantation. Postimplant parental ratings on the CAP and SIR were obtained. The relationships between EABR parameters and auditory performance and speech intelligibility outcomes were studied. The effect of age at implantation on auditory performance and speech intelligibility outcomes was also investigated. A significant negative correlation was found between EABR wave V thresholds and SIR growth (r = -.415, p = .016). Children with better CAP growths tended to have lower wave V thresholds than those with poorer CAP growths. Age at implantation had an effect on the auditory performance as measured using the CAP. The present study provides evidence for the relationship between wave V thresholds of the intracochlear EABR and auditory performance and speech intelligibility outcomes measured using parental rating scales in pediatric cochlear implant recipients. Data also indicate that early intervention has a positive impact on auditory performance outcomes.

Evaluation of Objective Test Techniques in Cochlear Implant Users With Inner Ear Malformations

The aim of the study was to compare results of objective test techniques in cochlear implant users with inner ear malformations and incomplete partition anomalies with types I and II and to show which techniques should be used in the evaluation and fitting of cochlear implant users with inner ear malformations. Retrospective clinical study. The subjects in the control group were selected randomly from cochlear implant users with normal cochlea. Inclusion criteria for patients group were having inner ear malformation for the study group and at least 1 year cochlear implants use for both groups. For each individual subject, electrically evoked compound action potentials (ECAPs), electrically evoked stapedius reflex threshold (ESRT), and electrically evoked auditory brainstem response (EABR) thresholds were determined. These tests were applied after a normal cochlear implant fitting session. There were 20 subjects in inner ear malformation group and 15 subjects in the control group. For each subject, 6 intracochlear electrodes, representing apical, middle, and basal array of intracochlear electrode, were used. In the cochlear malformation group, percentage of acquired ECAP thresholds was 25%. However, in the control group, percentage of ECAP was 74%. Similarly with ECAP, percentage of ESRT in the cochlear malformation group was 17.5%, and that in the control group was 90%. The difference between these percentages was statistically significant. Both current levels and latencies of EABR wave V were significantly different from each other for the inner ear malformation group and the control group. For statistical analysis, Mann-Whitney U test for 2 independent samples, Kruskal-Wallis analysis and Dunn's Z test were used. For the inner ear malformation group, EABR is a more applicable objective test technique when compared with ECAP and ESRT.

Electrically Evoked Auditory Brainstem Responses in Adults and Children

Previous electrophysiologic studies of electrode placement within the scala tympani in both animals and humans have shown effects on neural responses to electrical stimulation. The specific effects, however, may be dependent on electrode design, the location of an electrode along the array, and the method of perimodiolar positioning. The present study compares the effects of lateral and medial positioning of the Nucleus Contour electrode array on electrophysiologic responses in adult and pediatric subjects. Prospective clinical study. Comprehensive Cochlear Implant Program/Tertiary Referral Center. Subjects were adults (n = 15) and children (n = 20) who were consecutively implanted at our center with the Nucleus 24 Contour device. Rehabilitative. Intraoperative electrically evoked auditory brainstem responses (EABRs) were recorded within subjects for lateral and medial placement of the electrode array. Effects of electrode placement on EABR Wave V threshold and suprathreshold amplitude were measured. Group analyses showed significant decreases in EABR threshold and significant increases in EABR amplitude across all electrodes with medial electrode placement. The effects differed across electrode locations for the adult and pediatric subjects. No significant changes in Wave V input/output function slope were found. Medial electrode placement from stylet removal with the Nucleus 24 Contour array results in an increased neural response compared with the lateral condition as demonstrated by lower threshold and larger suprathreshold amplitude of the EABR. Possible clinical implications of these findings are lower psychophysical threshold and comfortable levels with medial cochlear electrode position.

The pattern of auditory brainstem response wave V maturation in cochlear-implanted children

Objective Maturation of acoustically evoked brainstem responses (ABR) in hearing children is not complete at birth but rather continues over the first two years of life. In particular, it has been established that the decrease in ABR wave V latency can be modeled as the sum of two decaying exponential functions with respective time-constants of 4 and 50 weeks [Eggermont, J.J., Salamy, A., 1988a. Maturational time-course for the ABR in preterm and full term infants. Hear Res 33, 35–47; Eggermont, J.J., Salamy, A., 1988b. Development of ABR parameters in a preterm and a term born population. Ear Hear 9, 283–9]. Here, we investigated the maturation of electrically evoked auditory brainstem responses (EABR) in 55 deaf children who recovered hearing after cochlear implantation, and proposed a predictive model of EABR maturation depending on the onset of deafness. The pattern of EABR maturation over the first 2 years of cochlear implant use was compared with the normal pattern of ABR maturation in hearing children. Methods Changes in EABR wave V latency over the 2 years following cochlear implant connection were analyzed in two groups of children. The first group ( n = 41) consisted of children with early-onset of deafness (mostly congenital), and the second ( n = 14) of children who had become profoundly deaf after 1 year of age. The modeling of changes in EABR wave V latency with time was based on the mean values from each of the two groups, allowing comparison of the rates of EABR maturation between groups. Differences between EABRs elicited at the basal and apical ends of the implant electrode array were also tested. Results There was no influence of age at implantation on the rate of wave V latency change. The main factor for EABR changes was the time in sound. Indeed, significant maturation was observed over the first 2 years of implant use only in the group with early-onset deafness. In this group maturation of wave V progressed as in the ABR model of [Eggermont, J.J., Salamy, A., 1988a. Maturational time-course for the ABR in preterm and full term infants. Hear Res 33, 35–47; Eggermont, J.J., Salamy, A., 1988b. Development of ABR parameters in a preterm and a term born population. Ear Hear 9, 283–9] of normal hearing children: a sum of two decaying exponential functions, one showing an early rapid decrease in latency and the other a slower decrease. Remarkably, the time-constants fell well within the ranges described by Eggermont and Salamy (i.e., 3.9 and 68 weeks), consistent with the time-course of the neurophysiological mechanisms presumably involved in auditory pathway maturation during the first 2 years of life: i.e., myelination and increased synaptic efficacy. In contrast, relatively little change in wave V was evident in children with late-onset deafness. In agreement with the notion that EABR maturation follows an apex-to-base gradient as described for ABR, we observed that wave V latencies were longer for the basal than the apical end of the implant electrode array and remained so throughout the study period, whatever the time of onset of deafness. Conclusions The findings in the early-onset of deafness group support the theory that auditory pathways remain “frozen” during the period of sensory deprivation until cochlear implant rehabilitation restores the normal chronology of maturational processes. In children with late-onset deafness, however, some maturational processes may occur before the onset of deafness, and thus less additional maturation is required during the first two years of implant use resulting in no significant EABR latency changes being observed in this period. The results suggest that the rehabilitation-induced plasticity of the auditory pathways is, in case of late auditory deprivation, unlikely to result in neurophysiological outcomes similar to those observed in children with early auditory deprivation. Significance Changes in EABR wave V latency over the first 2 years of cochlear implant use were found to be well fitted by the sum of two decaying exponential functions in children with early-onset deafness. This is in line with the maturation of ABR wave V latency in normal-hearing children over the first two years of life. Further studies are needed to assess whether the differences observed in terms of auditory pathways maturation are associated with consistent differences in terms of language development.

Electrophysiologic effects of placing cochlear implant electrodes in a perimodiolar position in young children.

The purpose of this study was to intraoperatively record the electrically evoked auditory brainstem response (EABR) before and after placement of the electrode positioning system (EPS) (CII Bionic Ear with HiFocus I cochlear implant electrode array) as well as before and after stylet removal (Nucleus Contour cochlear implant electrode array). It was hypothesized that physiologic changes would occur after perimodiolar positioning of the electrode array and these changes would be evident from the EABR recordings. Consecutive young (11-36 month old) pediatric cochlear implant recipients (n = 17) had intraoperative EABRs recorded from three intracochlear electrodes that represented apical, medial, and basal locations. Wave V amplitudes and thresholds were studied relative to electrode location and pre- versus postperimodiolar positioning. These evoked potential measures were analyzed for statistical significance. Tertiary referral children's hospital/medical college. Wave V thresholds of the EABR were lower, and amplitudes were larger after perimodiolar positioning, although the changes were dependent on electrode location and implant design. Statistically significant decreases in EABR wave V threshold and increases in suprathreshold wave V amplitude were found for the basal electrode for the CII Bionic Ear HiFocus I and for the apical electrode for the Nucleus Contour. Placement of either the CII Bionic Ear HiFocus I or Nucleus Contour cochlear implant electrode array in the perimodiolar position in young children resulted in less electrical current necessary to stimulate the auditory system. Changes in electrophysiologic thresholds and amplitudes, measured with EABR, indicate that the electrode array is placed closer to the modiolus with both electrode designs.

Electrically evoked auditory brain stem responses for lateral and medial placement of the Clarion HiFocus electrode.

The purpose of this study was to compare the electrically evoked auditory brain stem response (EABR) for lateral and medial placement of the Clarion HiFocus cochlear implant electrode array via the electrode positioning system (EPS). Twenty-five adult and pediatric cochlear implant recipients participated in the study. Intraoperatively recorded EABRs were evoked by stimuli via three intracochlear electrodes representing apical, medial, and basal locations, and responses were elicited before and after positioner insertion. Evoked potential measures of wave V amplitude and threshold were examined for statistical significance using ANOVA for repeated measures and Chi-Square methods. For a given supra-threshold stimulus level, the increase in EABR wave V amplitude was significantly larger after EPS placement compared to before EPS placement for electrodes 1 (apical) and 13 (basal). Likewise, when the stimulus was decreased to obtain a minimal amplitude, the wave V threshold was significantly lower after EPS placement for electrodes 7 (medial) and 13. The number of measurements that showed decreased wave V threshold after EPS insertion was significantly dependent on intracochlear electrode location. Placement of the Clarion Electrode Positioning System following HiFocus electrode insertion resulted in a reduction in the electrical current required to activate the auditory system. The effect of the EPS was greatest for the basal location, demonstrated by lower wave V thresholds and a larger percentage increase in wave V amplitude. The EABR reflected electrophysiologic changes relative to lateral-to-medial changes in intracochlear electrode position due to the EPS.

Auditory late cortical response and speech recognition in Digisonic cochlear implant users.

The purpose of the study was to test for differences in late electrically evoked auditory potentials between subjects exhibiting "good" versus "poor" speech recognition performances with their cochlear implants. Late auditory evoked responses were measured in 30 subjects equipped with the Digisonic (MXM, Antibes, France) cochlear implant, 15 of whom had "good" speech recognition scores (i.e., more than 89% correct phoneme identification without lip reading). The 15 other subjects had poorer speech recognition scores (i.e., less than 85%). Differences in N1P2 amplitude, as well as P1, N1, and P2 latencies, and N1-P1 and N1-P2 latency intervals were tested. Wave P2 latency was found to be significantly different between the two groups (P =.016), being shorter in "good" than in "poor" performers. The strength of the statistical relationship between electrophysiological and speech recognition variables (r2 = 17%) was substantially smaller than that observed using electrically evoked auditory brainstem response (EABR) for the same implanted device (r2 = 49% for the EABR wave III-V latency interval). Some characteristics of late electrically evoked auditory potentials differ significantly among cochlear implant users depending on their speech recognition performance. However, the relationship between electrophysiological and speech recognition variables is more pronounced when early (brainstem) rather than late (cortical) evoked responses are considered.

Sensorineural hearing loss during development: morphological and physiological response of the cochlea and auditory brainstem

We have investigated the effects of sensorineural hearing loss on the cochlea and central auditory system of profoundly deafened cats. Seventeen adult cats were used: four had normal hearing; 12 were deafened neonatally for periods of <2.5 years (five bilaterally, seven unilaterally); and one animal had a long-term (∼8 years) profound bilateral hearing loss. Bipolar scala tympani stimulating electrodes were bilaterally implanted in each animal, and electrically evoked auditory brainstem responses (EABRs) were recorded in an acute study to evaluate the basic physiologic response properties of the deafened auditory pathway. The cochleae and cochlear nuclei (CN) of each animal were examined with light microscopy. Spiral ganglion cell density in neonatally deafened cochleae was 17% of normal, and only 1.5% of normal in the long-term deaf animal. There was a 46% reduction in total CN volume in neonatally deafened animals compared to normal, and a 60% reduction in the long-term deaf animal. Neural density in the anteroventral CN of bilaterally deafened animals was 37% higher than normal; 44% higher in the long-term deaf animal. Significantly, however, we saw no evidence of a loss of neurones within the anteroventral CN in any deafened animal. There was a significant increase in EABR threshold and wave IV latency in the deafened animals, and a significant decrease in response amplitude and input/output function gradient. Again, these changes were more extensive in the long-term deaf animal. These data show that a sensorineural hearing loss can evoke significant morphological and physiological changes within the cochlea and auditory brainstem, and these changes become greater with duration of deafness. It remains to be seen whether these changes can be reversed following the introduction of afferent activity via chronic electrical stimulation of the auditory nerve.

Loudness Growth Functions and EABR Characteristics in Digisonic Cochlear Implantees

Electrically evoked auditory brainstem responses (EABRs) and loudness functions were measured in 14 subjects equipped with an MXM Digisonic cochlear implant. EABRs were evoked by 75-Hz pulse trains presented on the apical electrode. Loudness functions at the same rate and at a rate more conventional for psychoacoustic measurements (300 Hz) were measured using a categorical loudness-scaling procedure. The results revealed a significant difference in the loudness functions measured at 75 and 300 Hz, loudness increasing more steeply with stimulus intensity for the latter rate. Significant correlations between EABR wave V thresholds and perceptual thresholds measured at both 75 and 300 Hz were observed. Furthermore, in 8 out of the 14 patients, EABR wave V saturated at a stimulus level corresponding precisely to the loudest bearable, i.e. ?Too loud? level for the 300-Hz stimulation rate; this same level corresponded to the ?Comfortable? loudness level for the 75-Hz stimulation rate. On average, an almost linear relationship was observed over the first half of the loudness range between the stimulus intensity, expressed as a pulse duration in log units, and wave V amplitude in dB. Although further investigation is required before maximum comfort levels can be predicted reliably from EABR measures in individual subjects, these results indicate new directions regarding the estimation of perceptual dynamic range limits on the basis of EABR measures in cochlear implantees.