Clinical characteristics of the "Gap" between the prevalence and incidence of hearing loss using National Health Insurance Service data.

OBJECTIVES: Hearing loss is the inability to hear speech or sounds well, owing to a number of causes. This study aimed to simultaneously determine the prevalence, incidence, and the Gap between them in hearing loss in South Korean patients at the same point in time as well as to identify patients who have not recovered from hearing loss. METHODS: We examined the prevalence and incidence of patients diagnosed with hearing loss in the National Health Insurance Service database over an 11-year period from 2010 to 2020. The difference between the prevalence and the incidence was defined in this study as the term "Gap". Gap is the number of patients converted into the number of patients per 100,000 people by subtracting the incidence from the prevalence. Clinical characteristics such as sex and age per 100,000 individuals were examined. RESULTS: As of 2020, the domestic prevalence obtained in this study was 1.84%, increasing annually, and the prevalence increased with age to 4.10% among those over 60. The domestic incidence was 1.57%, increasing annually, and the incidence increased with age to 3.36% for those over 60s. The Gap was 0.27%, showing a steady increase from 2011 to 2020 with a corresponding increase in insurance benefit expenses. CONCLUSION: To fully understand the burden of hearing loss and develop effective prevention and treatment strategies, it is important to measure the Gap between its prevalence and incidence. This Gap means a lot because hearing loss is an irreversible disease. Gap represents patients who have already been diagnosed with hearing loss and are being diagnosed every year, indicating that the number of patients who do not recover is increasing. In other words, the increase in Gap meant that there were many patients who constantly visited the hospital for diagnosis of hearing loss.

Correlation Analysis and Comparison of Adult CE-Chirp ABR Response Threshold and Pure Tone Hearing Threshold.

OBJECTIVES: To study the application of CE-Chirp in the evaluation of hearing impairment in forensic medicine by testing the auditory brainstem response (ABR) in adults using CE-Chirp to analyze the relationship between the V-wave response threshold of CE-Chirp ABR test and the pure tone hearing threshold. METHODS: Subjects (aged 20-77 with a total of 100 ears) who underwent CE-Chirp ABR test in Changzhou De'an Hospital from January 2018 to June 2019 were selected to obtain the V-wave response threshold, and pure tone air conduction hearing threshold tests were conducted at 0.5, 1.0, 2.0 and 4.0 kHz, respectively, to obtain pure tone listening threshold. The differences and statistical differences between the average pure tone hearing threshold and V-wave response threshold were compared in different hearing levels and different age groups. The correlation, differences and statistical differences between the two tests at each frequency were analyzed for all subjects. The linear regression equation for estimating pure tone hearing threshold for all subjects CE-Chirp ABR V-wave response threshold was established, and the feasibility of the equation was tested. RESULTS: There was no statistical significance in the CE-Chirp ABR response threshold and pure tone hearing threshold difference between different hearing level groups and different age groups (P>0.05). There was a good correlation between adult CE-Chirp ABR V-wave response threshold and pure tone hearing threshold with statistical significance (P<0.05), and linear regression analysis showed a significant linear correlation between the two (P<0.05). CONCLUSIONS: The use of CE-Chirp ABR V-wave response threshold can be used to evaluate subjects' pure tone hearing threshold under certain conditions, and can be used as an audiological test method for forensic hearing impairment assessment.

Gaussian Processes for Hearing Threshold Estimation Using Auditory Brainstem Responses.

The Auditory Brainstem Response (ABR) plays an important role in diagnosing and managing hearing loss, but can be challenging and time-consuming to measure. Test times are especially long when multiple ABR measurements are needed, e.g., when estimating hearing threshold at a range of frequencies. While many detection methods have been developed to reduce ABR test times, the majority were designed to detect the ABR at a single stimulus level and do not consider correlations in ABR waveforms across levels. These correlations hold valuable information, and can be exploited for more efficient hearing threshold estimation. This was achieved in the current work using a Gaussian Process (GP), i.e., a Bayesian approach for non-linear regression. The function to estimate with the GP was the ABR's amplitude across stimulus levels, from which hearing threshold was ultimately inferred. Active learning rules were also designed to automatically adjust the stimulus level and efficiently locate hearing threshold. Simulation results show test time reductions of up to  âˆ¼ 50% for the GP compared to a sequentially applied Hotelling's T2 test, which does not consider correlations across ABR waveforms. A case study was also included to briefly assess the GP approach in ABR data from an adult volunteer.

Does Hearing Impairment Impact Spatial Orientation, Navigation, and Rotation Abilities?

OBJECTIVES: Spatial cognition is a perceptual-motor function that pertains to the comprehension and processing of two-dimensional and three-dimensional space. The impairment of any sensory system can have adverse effects on cognitive functioning. The objective of this study is to examine spatial cognition in adults with hearing impairments. METHODS: There were a total of 61 individuals in this study: thirty-six with hearing loss and 25 with normal hearing. The Spatial Orientation Test (SOT), the Mental Rotation test (MR), and the Money's Road Map Test (RMT) were administered to assess participants' spatial learning-orientation, mental imagery-rotation, and spatial navigation abilities. A high number of errors in RMT, high angle difference in SOT and a low score in MR suggest poor spatial abilities. RESULTS: Participants with hearing loss had a greater number of RMT errors and SOT angle difference, but lower MR scores than those with normal hearing (P < .001). Hearing impairment negatively impacted all 3 spatial cognitive assessments. Hearing loss was associated with a 6.9 increase in the number of RMT errors (95% Confidence Interval (CI): 4.8, 9), a 23.6 increase in the SOT angle difference (95% CI: 16, 31.2), and an 8.5 decrease in the MR score (95% CI: -10.8, -6.2). CONCLUSIONS: The study found that individuals with hearing loss exhibited lower performance in various cognitive tasks related to spatial orientation, navigation, spatial learning, mental imagery, and rotation abilities when compared to an age and sex matched control group. In future study, it is imperative to place greater emphasis on hearing loss as a potential detrimental factor in the prediction of spatial cognition impairment.

Reliability and Accuracy of Chirp Based Multiple Auditory Steady State Response (MSSR) and Auditory Brainstem Response (ABR) in Children.

OBJECTIVE: The purpose of this study was to compare the reliability and accuracy of chirp-based Multiple Auditory Steady State Response (MSSR) and Auditory Brainstem Response (ABR) in children. METHODS: The prospective clinical study was conducted at Selayang Hospital (SH) and Hospital Canselor Tuanku Muhriz (HCTM) within one year. A total of 38 children ranging from 3 to 18 years old underwent hearing evaluation using ABR tests and MSSR under sedation. The duration of both tests were then compared. RESULTS: The estimated hearing threshold of frequency specific chirp MSSR showed good correlation with ABR especially in higher frequencies such as 2000 Hz and 4000Hz with the value of cronbach alpha of 0.890, 0.933, 0.970 and 0.969 on 500Hz, 1000Hz, 2000Hz and 4000Hz. The sensitivity of MSSR is 0.786, 0.75, 0.957 and 0.889 and specificity is 0.85, 0.882, 0.979 and 0.966 over 500Hz, 1000Hz, 2000Hz and 4000Hz. The duration of MSSR tests were shorter than ABR tests in normal hearing children with an average of 35.3 minutes for MSSR tests and 46.4 minutes for ABR tests. This can also be seen in children with hearing loss where the average duration for MSSR tests is 40.0 minutes and 52.0 minutes for ABR tests. CONCLUSION: MSSR showed good correlation and reliability in comparison with ABR especially on higher frequencies. Hence, MSSR is a good clinical test to diagnose children with hearing loss.

Investigating the optimal stimulus to evoke the binaural interaction component of the auditory brainstem response.

Objective assessment of spatial and binaural hearing deficits remains a major clinical challenge. The binaural interaction component (BIC) of the auditory brainstem response (ABR) holds promise as a non-invasive biomarker for diagnosing such deficits. However, while comparative studies have reported robust BIC in animal models, BIC in humans can sometimes be unreliably evoked even in subjects with normal hearing. Here we explore the hypothesis that the standard methodology for collecting monaural ABRs may not be ideal for electrophysiological assessment of binaural hearing. This study aims to improve ABR BIC measurements by determining more optimal stimuli to evoke it. Building on previous methodology demonstrated to enhance peak amplitude of monaural ABRs, we constructed a series of level-dependent chirp stimuli based on empirically derived latencies of monaural-evoked ABR waves I, IV and the binaural-evoked BIC DN1, the most prominent BIC peak, in a cohort of ten chinchillas. We hypothesized that chirps designed based on BIC DN1 latency would specifically enhance across-frequency temporal synchrony in the afferent inputs leading to the binaural circuits that produce the BIC and would thus produce a larger DN1 than either traditional clicks or chirps designed to optimize monaural ABRs. Compared to clicks, we found that level-specific chirp stimuli evoked significantly greater BIC DN1 amplitudes, and that this effect persisted across all stimulation levels tested. However, we found no significant differences between BICs resulting from chirps created using binaural-evoked BIC DN1 latencies and those using monaural-evoked ABR waves I or IV. These data indicate that existing level-specific, monaural-based chirp stimuli may improve BIC detectability and reduce variability in human BIC measurements.

A multi-channel EEG mini-cap can improve reliability for recording auditory brainstem responses in chinchillas.

BACKGROUND: Disabling hearing loss affects nearly 466 million people worldwide (World Health Organization). The auditory brainstem response (ABR) is the most common non-invasive clinical measure of evoked potentials, e.g., as an objective measure for universal newborn hearing screening. In research, the ABR is widely used for estimating hearing thresholds and cochlear synaptopathy in animal models of hearing loss. The ABR contains multiple waves representing neural activity across different peripheral auditory pathway stages, which arise within the first 10 ms after stimulus onset. Multi-channel (e.g., 32 or higher) caps provide robust measures for a wide variety of EEG applications for the study of human hearing. However, translational studies using preclinical animal models typically rely on only a few subdermal electrodes. NEW METHOD: We evaluated the feasibility of a 32-channel rodent EEG mini-cap for improving the reliability of ABR measures in chinchillas, a common model of human hearing. RESULTS: After confirming initial feasibility, a systematic experimental design tested five potential sources of variability inherent to the mini-cap methodology. We found each source of variance minimally affected mini-cap ABR waveform morphology, thresholds, and wave-1 amplitudes. COMPARISON WITH EXISTING METHOD: The mini-cap methodology was statistically more robust and less variable than the conventional subdermal-needle methodology, most notably when analyzing ABR thresholds. Additionally, fewer repetitions were required to produce a robust ABR response when using the mini-cap. CONCLUSIONS: These results suggest the EEG mini-cap can improve translational studies of peripheral auditory evoked responses. Future work will evaluate the potential of the mini-cap to improve the reliability of more centrally evoked (e.g., cortical) EEG responses.

Auditory brainstem response: Key parameters for good-quality recording.

Auditory brainstem response (ABR) is widely used in ENT to investigate hearing loss. This test evaluates the response of the ascending auditory pathway, from cochlea to mesencephalon, following auditory stimulation. It provides precise analysis of waves numbered I to V according to location on the auditory pathway, in terms of amplitude, latency and inter-wave interval. Good-quality assessment requires familiarity with the parameters to be used and the factors likely to modify response. We describe the procedure for ABR examination and the recorded responses, with particular attention to factors influencing response to which the examiner must be vigilant. These factors are related to the individual (age, gender, hearing loss, body temperature, drug treatments), transducer (air or bone conduction), stimulation parameters (type, polarity, intensity, calibration, duration, cadence, number of clicks, background noise) and acquisition parameters (analysis window, scale, electrodes). We also briefly describe the clinical applications of this examination.

Acoustic change complex for assessing speech discrimination in normal-hearing and hearing-impaired infants.

OBJECTIVE: This study examined (1) the utility of a clinical system to record acoustic change complex (ACC, an event-related potential recorded by electroencephalography) for assessing speech discrimination in infants, and (2) the relationship between ACC and functional performance in real life. METHODS: Participants included 115 infants (43 normal-hearing, 72 hearing-impaired), aged 3-12 months. ACCs were recorded using [szs], [uiu], and a spectral rippled noise high-pass filtered at 2 kHz as stimuli. Assessments were conducted at age 3-6 months and at 7-12 months. Functional performance was evaluated using a parent-report questionnaire, and correlations with ACC were examined. RESULTS: The rates of onset and ACC responses of normal-hearing infants were not significantly different from those of aided infants with mild or moderate hearing loss but were significantly higher than those with severe loss. On average, response rates measured at 3-6 months were not significantly different from those at 7-12 months. Higher rates of ACC responses were significantly associated with better functional performance. CONCLUSIONS: ACCs demonstrated auditory capacity for discrimination in infants by 3-6 months. This capacity was positively related to real-life functional performance. SIGNIFICANCE: ACCs can be used to evaluate the effectiveness of amplification and monitor development in aided hearing-impaired infants.

Modified T2 Statistics for Improved Detection of Aided Cortical Auditory Evoked Potentials in Hearing-Impaired Infants.

The cortical auditory evoked potential (CAEP) is a change in neural activity in response to sound, and is of interest for audiological assessment of infants, especially those who use hearing aids. Within this population, CAEP waveforms are known to vary substantially across individuals, which makes detecting the CAEP through visual inspection a challenging task. It also means that some of the best automated CAEP detection methods used in adults are probably not suitable for this population. This study therefore evaluates and optimizes the performance of new and existing methods for aided (i.e., the stimuli are presented through subjects' hearing aid(s)) CAEP detection in infants with hearing loss. Methods include the conventional Hotellings T2 test, various modified q-sample statistics, and two novel variants of T2 statistics, which were designed to exploit the correlation structure underlying the data. Various additional methods from the literature were also evaluated, including the previously best-performing methods for adult CAEP detection. Data for the assessment consisted of aided CAEPs recorded from 59 infant hearing aid users with mild to profound bilateral hearing loss, and simulated signals. The highest test sensitivities were observed for the modified T2 statistics, followed by the modified q-sample statistics, and lastly by the conventional Hotelling's T2 test, which showed low detection rates for ensemble sizes <80 epochs. The high test sensitivities at small ensemble sizes observed for the modified T2 and q-sample statistics are especially relevant for infant testing, as the time available for data collection tends to be limited in this population.

New horizons in holistic, person-centred health promotion for hearing healthcare.

Over the course of a lifetime, the risk of experiencing multiple chronic conditions (multimorbidity) increases, necessitating complex healthcare regimens. Healthcare that manages these requirements in an integrated way has been shown to be more effective than services that address specific diseases individually. One such chronic condition that often accompanies ageing is hearing loss and related symptoms, such as tinnitus. Hearing loss is not only highly prevalent in older adults but is also a leading cause of disability. Accumulating evidence demonstrates an interplay between auditory function and other aspects of health. For example, poorer cardiometabolic health profiles have been shown to increase the risk of hearing loss, which has been attributed to microvascular disruptions and neural degeneration. Additionally, hearing loss itself is associated with significantly increased odds of falling and is a potentially modifiable risk factor for cognitive decline and dementia. Such evidence warrants consideration of new possibilities-a new horizon-for hearing care to develop a holistic, person-centred approach that promotes the overall health and wellbeing of the individual, as well as for audiology to be part of an interdisciplinary healthcare service. To achieve this holistic goal, audiologists and other hearing healthcare professionals should be aware of the range of conditions associated with hearing loss and be ready to make health promoting recommendations and referrals to the appropriate health practitioners. Likewise, healthcare professionals not trained in audiology should be mindful of their patients' hearing status, screening for hearing loss or referring them to a hearing specialist as required.

Amplitude-modulation forward masking for listeners with and without hearing loss.

Amplitude-modulation (AM) forward masking was measured for listeners with normal hearing and sensorineural hearing loss at 4000 and 1000 Hz, using continuous and noncontinuous masker and signal carriers, respectively. A low-fluctuation noise (LFN) carrier was used for the "continuous carrier" conditions. An unmodulated low-fluctuation noise (U-LFN), an unmodulated Gaussian noise (U-GN), and an amplitude-modulation low-fluctuation noise (AM-LFN) were maskers for the "noncontinuous carrier" conditions. As predicted, U-GN yielded more masking than U-LFN and similar masking to AM-LFN, suggesting that U-GN resulted in AM forward masking. Contrary to predictions, no differences in masked thresholds were observed between listener groups.

Effects of text supplementation on speech intelligibility for listeners with normal and impaired hearing: a systematic review with implications for telecommunication.

OBJECTIVE: Telecommunication can be difficult in the presence of noise or hearing loss. The purpose of this study was to systematically review evidence regarding the effects of text supplementation (e.g. captions, subtitles) of auditory or auditory-visual signals on speech intelligibility for listeners with normal or impaired hearing. DESIGN: Three databases were searched. Articles were evaluated for inclusion based on the Population Intervention Comparison Outcome framework. The Effective Public Health Practice Project instrument was used to evaluate the quality of the identified articles. STUDY SAMPLE: After duplicates were removed, the titles and abstracts of 2019 articles were screened. Forty-six full texts were reviewed; ten met inclusion criteria. RESULTS: The quality of all ten articles was moderate or strong. The articles demonstrated that text added to auditory (or auditory-visual) signals improved speech intelligibility and that the benefits were largest when auditory signal integrity was low, accuracy of the text was high, and the auditory signal and text were synchronous. Age and hearing loss did not affect benefits from the addition of text. CONCLUSIONS: Although only based on ten studies, these data support the use of text as a supplement during telecommunication, such as while watching television or during telehealth appointments.

Comparison of ABR and ASSR using narrow-band-chirp-stimuli in children with cochlear malformation and/or cochlear nerve hypoplasia suffering from severe/profound hearing loss.

OBJECTIVES: In pediatric audiology, objective techniques for hearing threshold estimation in infants and children with profound or severe hearing loss play a key role. Auditory brainstem responses (ABR) and auditory steady-state responses (ASSR) are available for frequency-dependent hearing threshold estimations and both techniques show strong correlations but sometimes with considerable differences. The aim of the study was to compare hearing threshold estimations in children with and without cochlear and cochlear nerve malformations. METHODS: Two groups with profound or severe hearing loss were retrospectively compared. In 20 ears (15 children) with malformation of the inner ear and/or cochlear nerve hypoplasia and a control group of 20 ears (11 children) without malformation, ABR were measured with the Interacoustics Eclipse EP25 ABR system® (Denmark) with narrow-band CE-chirps® at 500, 1000, 2000 and 4000 Hz and compared to ASSR at the same center frequencies under similar conditions. RESULTS: ABR and ASSR correlated significantly in both groups (r = 0.413 in malformation group, r = 0.82 in control group). The malformation group showed a significantly lower percentage of "equal" hearing threshold estimations than the control group. In detail, patients with isolated cochlear malformation did not differ significantly from the control group, whereas patients with cochlear nerve hypoplasia showed significantly greater differences. CONCLUSION: ABR and ASSR should be used jointly in the diagnostic approach in children with suspected profound or severe hearing loss. A great difference in hearing threshold estimation between these techniques could hint at the involvement of cochlear nerve or cochlear nerve hypoplasia itself.

Optimizing Parameters for Using the Parallel Auditory Brainstem Response to Quickly Estimate Hearing Thresholds.

OBJECTIVES: Timely assessments are critical to providing early intervention and better hearing and spoken language outcomes for children with hearing loss. To facilitate faster diagnostic hearing assessments in infants, the authors developed the parallel auditory brainstem response (pABR), which presents randomly timed trains of tone pips at five frequencies to each ear simultaneously. The pABR yields high-quality waveforms that are similar to the standard, single-frequency serial ABR but in a fraction of the recording time. While well-documented for standard ABRs, it is yet unknown how presentation rate and level interact to affect responses collected in parallel. Furthermore, the stimuli are yet to be calibrated to perceptual thresholds. Therefore, this study aimed to determine the optimal range of parameters for the pABR and to establish the normative stimulus level correction values for the ABR stimuli. DESIGN: Two experiments were completed, each with a group of 20 adults (18-35 years old) with normal-hearing thresholds (≤20 dB HL) from 250 to 8000 Hz. First, pABR electroencephalographic (EEG) responses were recorded for six stimulation rates and two intensities. The changes in component wave V amplitude and latency were analyzed, as well as the time required for all responses to reach a criterion signal-to-noise ratio of 0 dB. Second, behavioral thresholds were measured for pure tones and for the pABR stimuli at each rate to determine the correction factors that relate the stimulus level in dB peSPL to perceptual thresholds in dB nHL. RESULTS: The pABR showed some adaptation with increased stimulation rate. A wide range of rates yielded robust responses in under 15 minutes, but 40 Hz was the optimal singular presentation rate. Extending the analysis window to include later components of the response offered further time-saving advantages for the temporally broader responses to low-frequency tone pips. The perceptual thresholds to pABR stimuli changed subtly with rate, giving a relatively similar set of correction factors to convert the level of the pABR stimuli from dB peSPL to dB nHL. CONCLUSIONS: The optimal stimulation rate for the pABR is 40 Hz but using multiple rates may prove useful. Perceptual thresholds that subtly change across rate allow for a testing paradigm that easily transitions between rates, which may be useful for quickly estimating thresholds for different configurations of hearing loss. These optimized parameters facilitate expediency and effectiveness of the pABR to estimate hearing thresholds in a clinical setting.

Assessing Agreement between Frequency-Specific Chirp Auditory Steady-State Response and Pure Tone Audiometry in Adults by Intraclass Correlation Coefficient.

INTRODUCTION: Chirp auditory steady-state response (ASSR) can be used to assess frequency-specific hearing thresholds. However, its reliability has not been confirmed yet. The purpose of this proposed study is to analyze the agreement of thresholds measured by chirp-ASSR and pure tone audiometry (PTA) to investigate the value of chirp-ASSR in hearing threshold evaluation. METHODS: Participants with normal hearing (age: 18-66, 108 ears) and patients with sensorineural hearing loss (age: 22-82, 75 ears) were tested using PTA and chirp-ASSR at 0.5, 1, 2, and 4 kHz, respectively. Intraclass correlation coefficient (ICC) and Bland-Altman plot were introduced to analyze the agreement between the 2 methods. RESULTS: One-hundred eight participants underwent both chirp-ASSR and PTA to estimate their thresholds. The ICCs yielded by these 2 methods are 0.757, 0.893, 0.883, and 0.921 (p < 0.001) at 0.5, 1, 2, and 4 kHz carrier frequency, respectively. However, there is a significant difference between the 2 methods at 2 kHz: the mean value of the ASSR thresholds is 5.27 dB HL higher than the value of PTA thresholds. Additionally, the 95% limits of agreement range from -27.48 to 26.66 dB HL at 0.5 kHz, from -18.19 to 17.87 dB HL at 1 kHz, from -12.01 to 22.55 dB HL at 2 kHz, and from -21.29 to 19.17 dB HL at 4 kHz, which are large enough to affect clinical decision-making. CONCLUSION: In this study, we have confirmed good to excellent correlation between chirp-ASSR and PTA in threshold estimation for adults with and without hearing loss. The degree of correlations is higher for participants with hearing loss and for measurements at high frequencies. However, significant systematic difference and large limits of agreement between the 2 methods have been found. These findings show that chirp-ASSR can be treated as a supplementary method to PTA when evaluating the hearing level, but the 2 methods are not interchangeable due to their systematic difference and large limits of agreement.

Neural attentional-filter mechanisms of listening success in middle-aged and older individuals.

Successful listening crucially depends on intact attentional filters that separate relevant from irrelevant information. Research into their neurobiological implementation has focused on two potential auditory filter strategies: the lateralization of alpha power and selective neural speech tracking. However, the functional interplay of the two neural filter strategies and their potency to index listening success in an ageing population remains unclear. Using electroencephalography and a dual-talker task in a representative sample of listeners (N = 155; age=39-80 years), we here demonstrate an often-missed link from single-trial behavioural outcomes back to trial-by-trial changes in neural attentional filtering. First, we observe preserved attentional-cue-driven modulation of both neural filters across chronological age and hearing levels. Second, neural filter states vary independently of one another, demonstrating complementary neurobiological solutions of spatial selective attention. Stronger neural speech tracking but not alpha lateralization boosts trial-to-trial behavioural performance. Our results highlight the translational potential of neural speech tracking as an individualized neural marker of adaptive listening behaviour.

Susceptibility to Residual Inhibition Is Associated With Hearing Loss and Tinnitus Chronicity.

Residual inhibition, that is, the temporary suppression of tinnitus loudness after acoustic stimulation, is a frequently observed phenomenon that may have prognostic value for clinical applications. However, it is unclear in which subjects residual inhibition is more likely and how stable the effect of inhibition is over multiple repetitions. The primary aim of this work was to evaluate the effect of hearing loss and tinnitus chronicity on residual inhibition susceptibility. The secondary aim was to investigate the short-term repeatability of residual inhibition. Residual inhibition was assessed in 74 tinnitus subjects with 60-second narrow-band noise stimuli in 10 consecutive trials. The subjects were assigned to groups according to their depth of suppression (substantial residual inhibition vs. comparator group). In addition, a categorization in normal hearing and hearing loss groups, related to the degree of hearing loss at the frequency corresponding to the tinnitus pitch, was made. Logistic regression was used to identify factors associated with susceptibility to residual inhibition. Repeatability of residual inhibition was assessed using mixed-effects ordinal regression including poststimulus time and repetitions as factors. Tinnitus chronicity was not associated with residual inhibition for subjects with hearing loss, while a statistically significant negative association between tinnitus chronicity and residual inhibition susceptibility was observed in normal hearing subjects (odds ratio: 0.63; p = .0076). Moreover, repeated states of suppression can be stably induced, reinforcing the use of residual inhibition for within-subject comparison studies.

Cortical potentials evoked by tone frequency changes compared to frequency discrimination and speech perception: Thresholds in normal-hearing and hearing-impaired subjects.

Frequency discrimination ability varies within the normal hearing population, partially explained by factors such as musical training and age, and it deteriorates with hearing loss. Frequency discrimination, while essential for several auditory tasks, is not routinely measured in clinical setting. This study investigates cortical auditory evoked potentials in response to frequency changes, known as acoustic change complexes (ACCs), and explores their value as a clinically applicable objective measurement of frequency discrimination. In 12 normal-hearing and 13 age-matched hearing-impaired subjects, ACC thresholds were recorded at 4 base frequencies (0.5, 1, 2, 4 kHz) and compared to psychophysically assessed frequency discrimination thresholds. ACC thresholds had a moderate to strong correlation to psychophysical frequency discrimination thresholds. In addition, ACC thresholds increased with hearing loss and higher ACC thresholds were associated with poorer speech perception in noise. The ACC threshold in response to a frequency change therefore holds promise as an objective clinical measurement in hearing impairment, indicative of frequency discrimination ability and related to speech perception. However, recordings as conducted in the current study are relatively time consuming. The current clinical application would be most relevant in cases where behavioral testing is unreliable.

Resolved External Ophthalmoplegia and Hearing Loss in Wernicke's Encephalopathy With Thiamine Replacement.

BACKGROUND: Wernicke encephalopathy (WE) is classically described by a clinical triad consisting of confusion, ataxia, and ophthalmoplegia, but recent reports emphasize a history of malnutrition along with 2 elements of the WE triad (Caine's criteria) to enhance diagnostic sensitivity. The ophthalmoplegia, vestibular, and auditory expeditious improvement with intravenous thiamine usually confirms the diagnosis; serum levels generally provide additional diagnostic certainty. METHODS: Here, we discuss the case of a woman with a distant history of gastric sleeve, poor nutrition and protracted vomiting, who developed acute confusion, imbalance, near-total external ophthalmoplegia (EO), and hearing loss. The baseline thiamine level was 28 πmol/L (Normal: 70-180 πmol/L). We performed serial neurological, vestibular, and audiological examination to document over 5 days, the effect of intravenous (IV) thiamine, and again at 3 months with continued oral supplementation. We provide serial documentation with photographs and video recording of oculomotor abnormalities, audiometric testing, and a video of horizontal head impulse testing, and imaging findings. RESULTS: Over the course of 5 days of IV thiamine supplementation, we demonstrate our patient's resolution of near complete EO. We assessed vestibular paresis with horizontal head impulse testing, after complete resolution of the EO. The initially positive bilateral h-HIT showed decreased gain and overt corrective saccades, it clinically resolved by day 5, but video h-HIT testing demonstrated persistent decreased horizontal vestibulo-ocular reflex (VOR) gain and covert horizontal saccades, which persisted at the 3-month examination. By contrast, the vertical VOR gain was normal without corrective saccades. Bedside audiometry completed during the acute phase demonstrated severely restricted auditory speech comprehension, which normalized 3 months later. Severe truncal ataxia improved as well. CONCLUSIONS: This case is an example of how awareness of the variations in the clinical presentation of WE can be crucial in achieving an early diagnosis and obtaining better outcomes. A history of the poor nutritional status can be an important clue to aid in this early diagnosis.