Bone Conduction Auditory Brainstem Response Research Articles

Correlation of Grading and Number of Ear Subunits With Auditory Brainstem Response Findings in Children With Microtia.

The association between microtia severity and hearing function has been thoroughly investigated. This study examined the relationship between microtia grade, number of ear subunits (i.e., helix, antihelix, scapha, triangularis fossa, concha, lobule, tragus, and antitragus) with auditory brainstem response (ABR) findings in children with microtia. A retrospective chart review was employed in this study. We analyzed the ABR test results and photographs of 22 children with 30 microtia ears at Dr. Cipto Mangunkusumo National Hospital, Jakarta. The ABR test results were acquired using click (air conduction only) and 500-Hz tone burst stimuli (air- and bone-conduction). Ear photographs were overlaid with a template of a normal ear to determine the number of ear subunits present and the subsequent microtia grade. Number of ear subunits and ABR results were analyzed using the chi-square, Mann-Whitney U, and Spearman's correlation tests. ABR thresholds for click and 500-Hz tone bursts air-conduction were significantly poorer for ears with a subunit < 5 compared to ears with a subunit ≥ 5. No significant difference was observed in 500 Hz bone-conduction ABR thresholds between these groups. Correlation analysis showed a significant negative correlation between increased ear subunits and click ABR thresholds. No significant correlation was found between ear subunits and 500-Hz air- and bone-conduction ABR thresholds. A higher number of ear subunits are associated with a lower hearing threshold, as assessed using ABR with click stimuli. Therefore, the number of ear subunits and microtia grades can be used to examine the hearing level thresholds in infants and children with microtia. https://doi.org/10.23641/asha.25669440.

Hearing characteristics and otoradiological abnormalities in three patients with novel pathogenic variants of KMT2D-related Kabuki syndrome.

Kabuki syndrome 1 (KS1; OMIM:147920), which is characterized by distinctive dysmorphic facial features (such as arched eyebrows, long palpebral fissures with eversion of the lower lid, and large protuberant ears), intellectual disability, short stature, and dermatoglyphic and skeletal abnormalities, is brought on by pathogenic variants in KMT2D (OMIM:602113). In this work, three individuals with novel pathogenic KMT2D gene variants had their longitudinal audiological manifestations and ear structural characteristics outlined. The longitudinal audiological data from neonatal hearing screening and a battery of several hearing tests were evaluated. The battery of hearing tests included tympanometry, distortion product otoacoustic emission (DPOAE), click-evoked air-conduction auditory brain-stem response (AC-ABR), click-evoked bone-conduction auditory brain-stem response (BC-ABR), narrow band CE-chirp auditory steady-state response (NB CE-chirp ASSR), and pure-tone audiometry (PTA). Phenotype identification and whole exome sequencing (WES) were performed on recruited individuals. All three patients (two females and on male; last evaluations at 14 months, 11 months, and 5.7 years, respectively) failed the newborn hearing screening, and the audiological follow-up data revealed mild to profound fluctuating hearing loss, which was directly influenced by the incidence and severity of otitis media with effusion (OME). When OME occurred, the AC-ABR thresholds increased from 30-75 dBnHL to 45-90 dBnHL. The threshold for the BC-ABR and BC-PTA was between 25 and 50 dBnHL, indicating mild to moderate sensorineural hearing loss (SNHL). The high-resolution computed tomography (HRCT) pictures indicated that all three patients had middle and inner ear abnormalities. Middle ear anomalies showed as diminished mastoid gasification and ossicle dysplasia. Cochlear dysplasia, a dilated vestibule, fusion of the vestibule with the horizontal semicircular canals, and a short and thick horizontal semicircular canal were visible on images of the inner ear. This study recruited three individuals with three novel pathogenic variants (c.5104C>T, c.10205delA, and c.12840delC) of KMT2D who were identified at ages 27 days, 2 months, and 5.5 years. Hearing characteristics of three individuals with three novel pathogenic variants of KMT2D range from mild to profound fluctuating hearing loss with mild to moderate SNHL. HRCT scans showed that all three individuals had anatomical middle and inner ear abnormalities. KS 1 patients must get clinical therapy for OME, frequent auditory monitoring, and prompt intervention.

Toward improved measurement of infant bone conduction auditory brainstem responses

Newborn hearing screening has led to improved detection and treatment of hearing loss (HL) in infants and young children, supporting improved communication outcomes in early childhood and beyond. However, current screening protocols are not equally sensitive to all forms of HL, limiting diagnostic accuracy and, ultimately, identification of appropriate treatment options. Correspondingly, treatment outcomes in children with HL remain quite variable. One fundamental and persistent challenge is the assessment of bone conduction hearing, which is essential to differentiate conductive versus sensorineural pathology. Whereas hearing via air conduction can be effectively assessed using the auditory brainstem response (ABR), a noninvasive electrophysiologic measure, bone conduction ABR measurements suffer from comparatively poor signal quality (including significant stimulus artifact), transducer acoustic output limitations, and generally lower test-retest reliability. Here we evaluated the prospective benefits of measuring infant bone conduction ABRs using a modified bone conduction transducer designed to reduce stimulus artifact and thereby improve measurement quality. Measurements obtained using a standard bone conduction transducer were compared on several dimensions to measurements obtained using the modified transducer. Improved bone conduction measurement tools are expected to support improved detection and classification of conductive and mixed HL, leading to improved treatment outcomes for this important patient population.

Effective Masking Levels for Bone Conduction Auditory Brainstem Response Stimuli in Infants and Adults with Normal Hearing.

The purpose of the present study was to investigate effective masking levels (EMLs) for bone conduction (BC) auditory brainstem response (ABR) testing in infants and adults. Early hearing detection and intervention programs aim to limit delays in identifying ear-specific type/degree of hearing loss in infants using the ABR. Ear-specific assessment poses challenges as sound delivered to one ear can travel across the skull and activate the contralateral cochlea. Wave V amplitude and latency measures ipsilateral and contralateral to the bone oscillator can be compared to isolate the test cochlea in some cases; however, when these findings are equivocal, clinical masking is required. This study aims to determine EMLs for ABRs elicited to 500- and 2000-Hz BC stimuli for normal-hearing infants (0 to 18 months) and adults. Participants were 21 adults (18 to 54 years) and 24 infants (5 to 47 weeks) with normal hearing. BC 500- and 2000-Hz brief tonal stimuli at intensities approximating normal levels were presented via a B-71 oscillator (infants: 20 dB nHL at 500 Hz and 30 dB nHL at 2000 Hz; adults: 500 and 2000 Hz at 20 and 30 dB nHL, respectively). White noise masking was presented binaurally via ER-3A earphones (22 to 82 dB SPL; 10-dB steps). The lowest level of masking to eliminate a BC response was deemed the EML. For stimuli presented at 20 dB nHL, adult mean (1 SD) EMLs for 500 and 2000 Hz were 65 (9) and 53 (6) dB SPL, respectively. Mean EMLs for infants were 80 (6) dB SPL for 500 Hz at 20 dB nHL and 64 (9) dB SPL for 2000 Hz at 30 dB nHL. Compared to adults, infants required approximately 13 dB more masking at 500 Hz but a similar amount of masking at 2000 Hz. Infants required 26 dB more masking at 500 versus 2000 Hz, whereas, adults required only 12 dB more masking. Maximum binaural EMLs for infant BC responses elicited to 500 Hz at 20 dB nHL are 82 dB SPL, and for 2000 Hz at 30 and 40 dB nHL, respectively, are 72 and 82 dB SPL. Monaural masking levels for the nontest ear (assuming 10 dB of interaural attenuation) recommended clinically are as follows: (1) 500 Hz: 72 and 82 dB SPL at 20 and 30 dB nHL, respectively; and (2) 2000 Hz: 62, 72, and 82 dB SPL at 30, 40, and 50 dB nHL, respectively. Unsafe levels of white noise would be needed to effectively mask at greater stimulus levels.

Diagnostic value of ABR wave and DPOAE test in 65 infants with secretory otitis media

Objective To study and analyze the diagnostic value of auditory brainstem response (ABR) and distortion product otoacoustic emission (DPOAE) in infants with secretory otitis media. Methods From June 2016 to June 2018, 65 infants (120 ears) with secretory otitis media who were treated at the First People's Hospital of Taizhou were selected.All the 120 ears were diagnosed by ABR wave test and DPOAE test machine.The results of different diagnostic methods were observed and compared. Results Among 65 cases (120 ears), 60 ears (50.00%) with mildly abnormality, 43 ears (35.83%) with moderate abnormality and 17 ears (14.17%) with normal ABR wave Ⅴ response threshold.There was no statistically significant difference in Ⅰ-Ⅴ wave interval between the mild abnormal group and the normal group (P>0.05), but Ⅰ-Ⅴ wave interval in the moderate abnormal group[(4.27±0.27)ms in moderate abnormal group] was significantly shorter than that in the normal group[(4.75±0.31)ms] and the mild abnormal group[(4.73±0.21)ms], the differences were statistically significant(t=5.949, 9.722, all P<0.05). The Ⅴ response threshold of bone-guided ABR wave was normal in 108 ears(90.00%, 108/120). The Ⅴ latency of bone guided wave was (8.16±0.22)ms, and abnormal in 12 ears (10.00%, 12/120). With the increase of the gas conduction reaction threshold, the bone conduction ABR reaction threshold also increased, but it was not as obvious as the air conduction.The wave Ⅴ latency in the normal BRT group was significantly lower than that in the abnormal group (compared with mild abnormal group, t=17.400, P<0.05; compared with moderate abnormal group, t=130.015, P<0.05). DPOAE test failed 86 ears (71.67%, 86/120), passed through 34 ears (28.33%, 34/120). Conclusion The latency of ABR wave I is sensitive to the diagnosis of secretory otitis media in infants.The combination of DPOAE and ABR is helpful to the early diagnosis of the disease.ABR and DPOAE tests have high value and are worthy of popularizing in clinic. Key words: Otitis media; Evoked potentials, auditory, brain stem; Distortion product otoacoustic emissions; Air-guided ABR waves; Bone-guided ABR waves; Wave I latency

571-P: Analysis of Hearing Loss Characteristics in Prediabetic Patients

Objective: The goal was to study auditory function in prediabetes. Pure Tone Audiometry (PTA), Distortion Product Otoacoustic Emission (DPOAE) and Auditory Brainstem Response (ABR) were used to detect whether there is early hearing deterioration in the prediabetes. Methods: 168 participants underwent the Oral Glucose Tolerance Test (OGTT). 58 prediabetes patients younger than 60 years old, and 50 controls, age and sex matched, were enrolled. All subjects underwent PTA, DPOAE and ABR examinations. All relevant parameters including air and bone conduction pure tone audiometry, DPOAE amplitude and ABR latencies were collected. Results: (1) There were 25 cases with hearing loss in prediabetes (43%), while 6 cases in the control group (12%) by PTA; the difference was statistically significant (P &amp;lt;0.001). The hearing thresholds at each frequency (0.25kHz, 0.5kHz, 1kHz, 2kHz, 4kHz and 8kHz) in the prediabetes were higher than those in controls but only statistically significant at 4kHz and 8kHz (P &amp;lt; 0. 001). Air- and bone-conduction pure-tone thresholds synchronization increased. The difference between air conduction and bone conduction checked by PTA was less than 10dB. (2) DPOAE amplitude at each frequency in the prediabetes group was lower than control group; there were statistically significant differences at 1, 1.5, 2, 3, 4, 6 kHz (P &amp;lt; 0. 001). (3) There were no significant differences of neuron response latencies in ABR measurements between prediabetes and the control group. Conclusions: (1) Loss of auditory function began in the prediabetes stage. Sub-clinical presentations were more pronounced in the prediabetes stage. (2) Bilateral symmetry sensorineural hearing loss, especially at high frequencies, is very characteristic in prediabetic patients. (3)The preliminary findings are that DPOAE is needed to detect the usually slight hearing loss in prediabetes whereas PTA was less sensitive and did not detect such losses. (4) The damage is mainly cochlear, not in the central nervous system. Disclosure Y. Meng: None. X. Zhuang: None. B. Lu: None. X. Wu: None. Funding Capital Health Research and Development of Special Fund (2016-2-7022, 2019-1-1091); Science and Technology Plan of Beijing Municipal Education Commission (KM201610025020)

Normalization of Bone Conduction Auditory Brainstem Evoked Responses in Normal Hearing Individuals.

Auditory brainstem responses (ABR) are used to evaluate the peripheral and central functions of the auditory tract. Air and bone-conduction auditory stimuli are used to evaluate the type and degree of hearing loss. The wave latencies and interpeak latencies (IPLs) are the important diagnostic data in ABR tests. Gender and age of the patients are some of the factors affecting these latencies. This study investigated the effects of age and gender on the wave and IPLs of bone-conduction ABR. One hundred healthy individuals (50 women and 50 men) aged between 10 and 60 years were enrolled into this study, and both ears of all subjects (200 ears total) were included in the assessments. Based on their age, the subjects were equally divided into five groups, and each group consisted of 10 men and 10 women. The findings showed a significant difference in wave latencies and IPLs between the two genders (p<0.05). Depending on stimulus intensity, wave latencies also showed statistically significant differences between the age groups (p<0.05). However, no significant difference was noted between the age groups regarding IPLs. Normative values that covered wave latencies and IPLs evoked at stimulus intensities of 50, 30, and 10 dB nHL were established for the clinical use and use as a reference for the bone-conduction ABR testing procedure.

Measurements of bone conduction auditory brainstem response with the new audiometric bone conduction transducer Radioear B81

Objective: To compare recordings of bone conduction (BC) stimulated auditory brainstem response (ABR) obtained using the newer BC transducer Radioear B81 and the conventional BC transducer Radioear B71. Balanced electromagnetic separation transducer (BEST) design found in the B81 may influence the ABR magnitudes and latencies, as well as electrical artefacts.Design: ABRs to tone burst stimuli of 500 Hz, 2000 Hz, 4000 Hz, click stimulation, and broad-band chirp stimulation at 20 and 50 dB nHL were recorded. For each device, stimulus and intensity level, the ABR Jewett wave V amplitude and latency were obtained. The device-related electrical stimulus artefacts on the ABR recordings were also analysed by calculating the Hilbert envelope of the peri-stimulus recording segments.Study sample: Twenty-three healthy adults with normal hearing were included in the study.Results: The ABRs obtained by the B81 were similar to that of the B71 in terms of ABR wave V amplitude and latency. However, the B81 produced smaller electrical artefacts than B71 and this difference was statistically significant. Conclusions: The BC transducer Radioear B81 provides ABRs comparable to Radioear B71 while causing smaller artefacts.

Update on Bone-Conduction Auditory Brainstem Responses: A Review.

Auditory brainstem responses (ABR) have been used as a powerful and the most common objective tool to evaluate hearing sensitivity and to diagnose the types of hearing loss and neurological disorders, through the auditory peripheral pathway to a central level of the brainstem, since 1971. Although bone-conduction (BC) ABR could be an alternative to air-conduction (AC) ABR, as the former overcomes some limitations of the latter, the majority of clinicians rarely utilize it due to a lack of knowledge and no routine test administration. This review presents the weaknesses of AC ABR that apply to all clinical population, and discusses the development of BC ABR. The optimal placements of bone oscillators to obtain favorable clinical outcomes in infants, children, and adults, and the appropriate stimuli for BC ABR are examined. While providing absolute thresholds and latencies of BC ABR based on previous studies compared to AC ABR, this review includes clinical data of infants and young children with both normal hearing in terms of maturation, and with pathology such as congenital external auditory canal atresia. We recommend the future clinical application of BC ABR for candidacy as well as for patients with BC hearing implants.

Study in air-conducted and bone-conducted auditory brainstem responses in children with congenital external auditory canal atresia

Objective To study the clinical value of air- and bone-conduction auditory brainstem responses(ABRs) in children with congenital aural atresia. Methods Air- and bone-conduction click-evoked ABRs in 38 children with congenital external auditory canal atresia were compared to those in 34 normal-hearing children. Results ABR threshold were (65.0±8.7) dBnHL for air conduction and (10.6±7.0) dBnHL for bone conduction in children with congenital external auditory canal atresia; and (25.6±1.7) dBnHL and (9.7±6.7) dBnHL respectively in normal hearing children.There was statistically difference between the two groups in air-conduction ABR threshold(t'=21.59, P 0.05). While the air-bone ABR threshold gap was greater in children with external auditory canal atresia than in normal hearing children(t'=13.78, P 0.05). Conclusion Bone conduction ABR is valuable in assessing function of cochlea, auditory nerve and brainstem in individuals with congenital external auditory canal atresia.It has important clinical value in objective differential diagnosis of conductive deafness with combined application of air- and bone-conduction ABRs. Key words: Ear, external; Congenital abnormalities; Auditory brainstem response

Intrauterine Lipopolysaccharide-Induced Chorioamnionitis in a Sheep: Does It Affect the Auditory System?

Fetal exposure to in utero inflammation such as chorioamnionitis is related to central nervous system injury. We hypothesized that chorioamnionitis can provoke inflammatory changes in the perilymph and alter hearing outcome. Pregnant ewes were randomized into 2 groups: intrauterine injection with lipopolysaccharide (LPS; n = 19) or saline (n = 21). In the first experiment, fetal perilymph samples were taken for cytokine analysis. In the second experiment, consecutive bone-conducted auditory brain stem responses were obtained from 1 to 7 months after birth. Perilymph samples showed a significant elevation in interleukin 8 in the LPS group. Auditory brain stem response analysis demonstrated higher response thresholds and a prolongation of absolute peak V and interpeak intervals I to V and III to V in the LPS group compared to sham treatment. Our study confirms the hypothesis that an intrauterine inflammation by LPS can result in a fetal perilymphatic inflammatory response and functional impaired hearing outcomes after birth in a sheep model.

Air-And Bone-Conduction Auditory Brainstem Response in Children with Congenital External Auditory Canal Atresia

Objective: This study aimed to determine the clinical value of air- and bone-conduction auditory brainstem responses (ABRs) in children with congenital external auditory canal atresia (EACA).

Air and Bone Conduction Click and Tone-Burst Auditory Brainstem Thresholds Using Kalman Adaptive Processing in Nonsedated Normal-Hearing Infants.

To study normative thresholds and latencies for click and tone-burst auditory brainstem response (TB-ABR) for air and bone conduction in normal infants and those discharged from neonatal intensive care units, who passed newborn hearing screening and follow-up distortion product otoacoustic emission. An evoked potential system (Vivosonic Integrity) that incorporates Bluetooth electrical isolation and Kalman-weighted adaptive processing to improve signal to noise ratios was employed for this study. Results were compared with other published data. One hundred forty-five infants who passed two-stage hearing screening with transient-evoked otoacoustic emission or automated auditory brainstem response were assessed with clicks at 70 dB nHL and threshold TB-ABR. Tone bursts at frequencies between 500 and 4000 Hz were used for air and bone conduction auditory brainstem response testing using a specified staircase threshold search to establish threshold levels and wave V peak latencies. Median air conduction hearing thresholds using TB-ABR ranged from 0 to 20 dB nHL, depending on stimulus frequency. Median bone conduction thresholds were 10 dB nHL across all frequencies, and median air-bone gaps were 0 dB across all frequencies. There was no significant threshold difference between left and right ears and no significant relationship between thresholds and hearing loss risk factors, ethnicity, or gender. Older age was related to decreased latency for air conduction. Compared with previous studies, mean air conduction thresholds were found at slightly lower (better) levels, while bone conduction levels were better at 2000 Hz and higher at 500 Hz. Latency values were longer at 500 Hz than previous studies using other instrumentation. Sleep state did not affect air or bone conduction thresholds. This study demonstrated slightly better wave V thresholds for air conduction than previous infant studies. The differences found in the present study, while statistically significant, were within the test step size of 10 dB. This suggests that threshold responses obtained using the Kalman weighting software were within the range of other published studies using traditional signal averaging, given step-size limitations. Thresholds were not adversely affected by variable sleep states.

Usefulness of 1000-Hz probe tone in tympanometry according to age in Korean infants

ObjectiveNumerous studies have shown the superiority of a 1000-Hz frequency probe tone for evaluating the middle ear status of infants. However, most of these studies examined Caucasian populations. This study validated the 1000-Hz probe tone and evaluated the age at which it should be used in Korean infants. MethodsData from 83 infants (43 males, 40 females; mean age 9.2±6.2 (range 1–30) months, 165 ears) were analyzed. Tympanograms were classified according to Baldwin's modification of the method of Marchant et al. and correlated with results based on combined diagnostic tests, including an endoscopic examination of the tympanic membrane, myringotomy findings, and the air and bone conduction auditory brainstem response (ABR) thresholds. Data were analyzed in five age groups, each covering a 3-month range. The traces were measured for both 226- and 1000-Hz probe tones. The sensitivity and specificity for the different age groups were also determined. ResultsFor the 226-Hz probe tone, the tympanograms showed normal traces for most ears with otitis media effusions in infants younger than 12 months. By contrast, the tympanograms using the 1000-Hz probe tone showed abnormal traces in most of the infants with otitis media effusions in all age groups. In infants with no otitis media effusion, the tympanograms using both 226- and 1000-Hz probe tones were interpreted as normal in most cases in all age groups. In infants younger than 12 months, the sensitivity of the 226-Hz probe tone was very low (0–6.6%), whereas that of the 1000-Hz probe tone was very high (90–100%). In infants older than 13 months, however, the sensitivities of the 226- and 1000-Hz probe tones were 76.2% and 85.7%, respectively. Regarding specificity, the difference between the two probe tones was not significant for any age group. ConclusionsThis study confirmed the superiority of the 1000-Hz probe tone for evaluating the middle ear in infants. We recommend using a 1000-Hz probe tone at least up to the age of 12 months for Korean infants.

Provisional stimulus level corrections for low frequency bone-conduction ABR in babies under three months corrected age

Objective: To estimate bone-conduction stimulus level corrections by testing the auditory brainstem response (ABR) of normally-hearing newborns. The stimuli used were low frequency tone pips calibrated to reference levels derived from ISO 389 values. Design: Tone pips were presented via supra-aural earphones and a B71 Radioear bone vibrator at 0.5 or 1 kHz. ABR thresholds from both transducers were compared at each frequency. Study sample: twenty-seven newborn hearing screening referrals (33 ears) who passed an ABR discharge criterion at 4 kHz. Results: Median air- and bone-conduction ABR threshold differences were 30 dB at 0.5 kHz and 20 dB at 1 kHz. Conclusion: The 0.5 kHz data from this study and previous studies were compared. Previous studies suggested lower figures for the bone-conduction stimulus level correction. Likely sources of this discrepancy are discussed. The average 0.5 kHz bone-conduction correction value for infants < 3 months old is about 28 dB. The correction for 1 kHz is 20 dB. We recommend that calibration reference levels used in this study be adopted and that appropriate corrections be applied to bone conduction ABR thresholds in infants < 3 months old before calculation of any air-bone gap and subsequent clinical interpretation.

Pediatric Applications of Wideband Acoustic Immittance Measures

Wideband acoustic immittance (WAI) measures have potential capability to improve newborn hearing screening outcomes and middle ear diagnosis for infants and children. To fully capitalize on these immittance measures for pediatric hearing care, developmental and pathologic effects need to be fully understood. Published literature on wideband immittance (reflectance, absorbance, tympanometry, and acoustic reflexes) is reviewed in this article to determine pathologic effects in newborns, infants, and children relative to standard audiologic tests such as otoacoustic emissions (OAEs), standard tympanometry, air and bone conduction auditory brainstem response, and otoscopy. Infants and children with surgically confirmed otitis media with effusion have lower absorbance in the mid-frequency range (1 to 3 kHz) for the affected ear(s). Newborns that do not pass OAE screening at birth also have lower absorbance for frequencies from 1 to 3 kHz, suggesting that nonpass results are frequently associated with middle ear issues at birth. In Newborn Hearing Screening Programs, WAI may help to interpret hearing screening results. Conclusions are limited by the fact that the true status of the middle ear and cochlea are not known for newborns and infants in studies that use OAE or tympanometry as the reference standard. Likelihood ratios for reflectance against surgery gold standards range from diagnostically suggestive to informative. Although some of the results are promising, limited evidence and methodological considerations restrict the conclusions that can be drawn regarding the diagnostic accuracy of WAI technologies in infants and children. Additional investigations using stronger gold standard comparisons are needed to determine which tools can most accurately predict middle ear status in the pediatric population.

The Effect of CO2and KTP laser on the cat saccule and utricle

To assess the potential carbon dioxide (CO(2)) and potassium-titanyl-phosphate (KTP) laser-related trauma to the saccule and utricle in a cat model. Basic science experiment utilizing cat model. Twelve adult male cats were divided into two groups-CO(2) and KTP-to assess the potential saccule and/or utricle trauma with direct discharge of laser energy into the vestibule after the stapes was removed. Both groups were subdivided to assess the effects with acute sacrifice and three-month survival. Bone conduction auditory brain-stem response thresholds were used to monitor auditory function. Clinical observation was used to monitor vestibular function. The temporal bones were harvested, processed, and stained with hematoxylin and eosin (H&E) in all animals with the uninvolved side serving as the control. None of the animals demonstrated changes in bone conduction auditory brain-stem responses. None of the animals in the survival group demonstrated clinical vestibular dysfunction. Saccular and utricular wall rupture was observed in all animals sacrificed acutely. None of the saccular and utricular wall ruptures were of a size and location that could be attributed to laser trauma, and none of the saccular and utricular wall ruptures were associated with neuroepithelial trauma. There is no evidence of a difference between the CO(2) and KTP laser in potential laser-related trauma. Using bone-conducting auditory brain-stem response threshold and clinical monitoring of vestibular function, there was no evidence of clinical auditory or vestibular dysfunction. The histologic evidence of saccular and utricular wall rupture is more consistent with stapes extraction trauma than laser-related trauma.

Normal Ipsilateral/Contralateral Asymmetries in Infant Multiple Auditory Steady-State Responses to Air- and Bone-Conduction Stimuli

Two-channel recordings of infants' air- and bone-conduction auditory brainstem responses to brief tones show ipsilateral and contralateral (to the stimulated ear) asymmetries which may be used to isolate which cochlea is the primary contributor to the response. The objective of this study was to determine whether similar ipsilateral/contralateral asymmetries are also present in the air- and bone-conduction "brainstem" (77 to 101 Hz) auditory steady-state responses (ASSRs) of infants. Two-channel ASSRs were recorded in infants (2 to 11 mo) and adults (18 to 40 yr) with normal hearing. Multiple stimuli (carrier frequencies: 500 to 4000 Hz; amplitude/frequency modulated) were presented using a B-71 oscillator on the temporal bone or an ER3-A insert earphone. Bone-conduction ASSR amplitudes, phase delays, and thresholds were obtained for the electroencephalographic (EEG) channels ipsilateral and contralateral to the oscillator temporal-bone placement. Bone-conduction ASSRs were also obtained to the stimulus presented to the opposite temporal bone (at 40 dB HL only). Air-conduction ASSR amplitudes and phase delays were obtained at 60 dB HL in each ear for the EEG channels ipsilateral and contralateral to the transducer. Infants showed more ipsilateral/contralateral asymmetries in both air- and bone-conduction ASSRs compared with adults. Mean bone-conduction ASSR thresholds in infants were 13 to 15 dB higher (i.e., poorer) in the contralateral EEG channel compared with the ipsilateral EEG channel for 500 to 4000 Hz. In adults, there were no large differences (i.e., within 1 dB) between ipsilateral and contralateral ASSR thresholds. Based on ipsilateral/ contralateral threshold differences in infants, interaural attenuation for bone-conducted stimuli was estimated to be at least 10 to 30 dB for most infants. In contrast, most adults showed little interaural attenuation for bone-conducted stimuli. ASSR amplitudes are larger and phase delays are shorter in the ipsilateral EEG channel. For infants, the difference in air-conduction ASSR amplitude between EEG channels was twice that observed for adults. Infants also had greater ASSR amplitude differences between EEG channels for bone-conduction stimuli compared with adults, but the difference was less than that seen for air-conduction stimuli. For air-conduction stimuli, infants had significantly longer phase delays in the contralateral EEG channel compared with the ipsilateral EEG channel. Adults showed no significant differences in air-conduction ASSR phase delay between EEG channels. For bone-conduction stimuli, both infants and adults had significantly longer phase delays in the contralateral EEG channel compared with the ipsilateral EEG channel; the differences in ASSR phase delays between EEG channels were much smaller in infants compared with adults and fewer adults had absent responses in the contralateral EEG channels compared with infants (12% versus 34%). When the transducers were switched to the opposite ear/mastoid, the infant and adult ipsilateral/contralateral asymmetries also switched. Ipsilateral/contralateral asymmetries in air- and bone-conduction ASSRs are clearly present more often and are larger in infants compared with adults. Our findings also suggest that most infants have at least 10 to 30 dB of interaural attenuation to bone-conducted stimuli. These asymmetries in the bone-conduction ASSR have potential as a clinical tool for isolating the cochlea that is contributing to the response in infants.

Electrophysiologic threshold study in air and bone conduction in children with 2 months or less age

The differential diagnosis of hearing loss with air and bone Auditory Brainstem Response in small children has not been enough studied in Brazil. To compare air and bone Auditory Brainstem Response results in children under 2 months of age with normal hearing. clinical with transversal cohort. 12 children who passed the hearing screening were evaluated using air and bone Auditory Brainstem Response. No contralateral masking was used in the bone conduction test. The responses were compared and analyzed by the McNemar test and repetitive measurements of the variance test. There were no statistic differences between air and bone conduction Auditory Brainstem Response thresholds (p>0.05). The bone conduction latency for wave V was statistically higher than air conduction latency (p=0.000). There was agreement on the results recorded for air and bone conduction Auditory Brainstem Response for threshold intensities; latency for bone conduction wave V was statistically higher than the air conduction latency.

Potenciais evocados auditivos do tronco encefálico por condução óssea em indivíduos normais

bone conduction auditory brainstem responses (ABR) in normal hearing individuals. to evaluate the clinical applicability of bone conduction ABR, characterizing normality and determining an assessment protocol. participants of this study were 22 individuals with normal hearing (20dB NA), with ages between 20 and 30 years, 14 female and 8 male. All individuals were assessed using air and bone (vibrator positioned on the forehead and mastoid) conduction ABR. EP25 equipment, Interacoustic; 3A insertion phone; B-71 bone vibrator; click stimulus. it was possible to evaluate the bone conduction ABR in all individuals. The results demonstrate that the electrophysiological threshold obtained when the vibrator was positioned on the forehead (32.69+/-5.63 and 32.5+/-7.07dB nHL) was higher than that obtained when the vibrator was positioned on the mastoid (25.00+/-7.33 and 30.00+/-5.34dB nHL) for both genders respectively. For this reason the vibrator was positioned on the mastoid. The electrophysiological threshold obtained by bone conduction was higher than that obtained by air conduction for both genders and also when all individuals were grouped together. Thus it is necessary to use a correction factor, according to the results, of 10dB nHL. The latency-intensity values of the V wave in the ipsilateral and contralateral recordings differed statistically according to gender, and should be considered separately. The value of 26.81+/-6.99dB nHL was adopted as being the normal threshold for bone conduction ABR. it is possible to evaluate bone conduction ABR in the clinical environment. These results, when considered along with the air conduction ABR, increase the chances of a more precise diagnosis regarding the type of hearing loss.