Intraoperative assessment of cochlear nerve functionality in various vestibular schwannoma scenarios: Lessons learned.

The use of cochlear implants (CIs) is on the rise for patients with vestibular schwannoma (VS). Besides CI following tumor resection, new scenarios such as implantation in observed and/or irradiated tumors are becoming increasingly common. A significant emerging trend is the need of intraoperative evaluation of the functionality of the cochlear nerve in order to decide if a CI would be placed. The purpose of this paper is to explore the experience of a tertiary center with the application of the Auditory Nerve Test System (ANTS) in various scenarios regarding VS patients. The results are compared to that of the studies that have previously used the ANTS in this condition. Patients with unilateral or bilateral VS (NF2) who were evaluated with the ANTS prior to considering CI in a tertiary center between 2021 and 2023 were analyzed. The presence of a robust wave V was chosen to define a positive electrical auditory brainstem response (EABR). Two patients underwent promontory stimulation (PromStim) EABR previous to ANTS evaluation. Seven patients, 2 NF-2 and 5 with sporadic VS were included. The initial scenario was simultaneous translabyrinthine (TL) tumor resection and CI in 3 cases while a CI placement without tumor resection was planned in 4 cases. The ANTS was positive in 4 cases, negative in 2 cases, and uncertain in one case. Two patients underwent simultaneous TL and CI, 1 patient simultaneous TL and auditory brainstem implant, 3 patients posterior tympanotomy with CI, and 1 patient had no implant placement. In the 5 patients undergoing CI, sound detection was present. There was a good correlation between the PromStim and ANTS EABR. The literature research yielded 35 patients with complete information about EABR response. There was one false negative and one false positive case; that is, the 28 implanted cases with a present wave V following tumor resection had some degree of auditory perception in all but one case. The ANTS is a useful intraoperative tool to asses CI candidacy in VS patients undergoing observation, irradiation or surgery. A positive strongly predicts at least sound detection with the CI.

Comprehensive behavioral and physiologic assessment of peripheral and central auditory function in individuals with mild traumatic brain injury.

Auditory complaints are frequently reported by individuals with mild traumatic brain injury (mTBI) yet remain difficult to detect in the absence of clinically significant hearing loss. This highlights a growing need to identify sensitive indices of auditory-related mTBI pathophysiology beyond pure-tone thresholds for improved hearing healthcare diagnosis and treatment. Given the heterogeneity of mTBI etiology and the diverse peripheral and central processes required for normal auditory function, the present study sought to determine the audiologic assessments sensitive to mTBI pathophysiology at the group level using a well-rounded test battery of both peripheral and central auditory system function. This test battery included pure-tone detection thresholds, word understanding in quiet, sentence understanding in noise, distortion product otoacoustic emissions (DPOAEs), middle-ear muscle reflexes (MEMRs), and auditory evoked potentials (AEPs), including auditory brainstem responses (ABRs), middle latency responses (MLRs), and late latency responses (LLRs). Each participant also received magnetic resonance imaging (MRI). Compared to the control group, we found that individuals with mTBI had reduced DPOAE amplitudes that revealed a compound effect of age, elevated MEMR thresholds for an ipsilateral broadband noise elicitor, longer ABR Wave I latencies for click and 4 kHz tone burst elicitors, longer ABR Wave III latencies for 4 kHz tone bursts, larger MLR Na and Nb amplitudes, smaller MLR Pb amplitudes, longer MLR Pa latencies, and smaller LLR N1 amplitudes for older individuals with mTBI. Further, mTBI individuals with combined hearing difficulty and noise sensitivity had a greater number of deficits on thalamic and cortical AEP measures compared to those with only one/no self-reported auditory symptoms. This finding was corroborated with MRI, which revealed significant structural differences in the auditory cortical areas of mTBI participants who reported combined hearing difficulty and noise sensitivity, including an enlargement of left transverse temporal gyrus (TTG) and bilateral planum polare (PP). These findings highlight the need for continued investigations toward identifying individualized audiologic assessments and treatments that are sensitive to mTBI pathophysiology.

[Clinical protocol: audiological assessment of infants in Russian Federation. Part I]. / Protokol audiologicheskogo obsledovaniya detei pervogo goda zhizni v Rossiiskoi Federatsii. Chast' I.

The clinical protocol of audiological assessment in infants was prepared by the workgroup of Russian pediatric audiologists from different regions. The goal of the protocol is unification approaches to audiological diagnosis of the infants. The protocol has been developed according the evidence based medicine principles, by reviewing current scientific publications on the topic and taking into account the order of providing medical services and other clinical practice guidelines. When direct evidence was not available, both indirect evidence and consensus practice were considered in making recommendations. This guideline is not intended to serve as a standard to dictate precisely how the child should be diagnosed. This guideline is meant to provide the evidence base from which the clinician can make individualized decisions for each patient. The first part of the protocol covers following sections: equipment, staff requirements, timing of the diagnostics, case history and risk factors, preparing the child for the appointment, sedation and general anesthesia, otoscopy, tympanometry and acoustic reflex, otoacoustic emissions, skin preparing, electrode montage, choosing the stimulators, auditory brainstem responses on broadband and narrow-band stimuli, on bone conducted stimuli, auditory steady-state responses, masking, combined correction factors.

Stroke in children and adolescents: Analysis of electrophysiological and behavioral assessment findings of auditory processing.

PURPOSE: This study aimed to analyze the auditory processing behavior of children and adolescents diagnosed with stroke and compare it with that of typically developing individuals. METHODS: This was an analytical cross-sectional study involving 48 participants aged between 7 and 17 years with adequate schooling for age and grade, allocated equally to two groups: Stroke (SG) and Control Groups (CG). For the SG, cases identified between 2003 and 2018 were considered. In the CG, school-aged participants with typical development were randomized. After screening for differential audiological assessment and confirmation of auditory pathway integrity at the brainstem level, binaural analyses of the auditory processing behavior were conducted using the Dichotic Digit Test (DDT), Frequency Pattern Test (FPT), and electrophysiological assessment (P300). The Shapiro-Wilk test for normality was conducted, followed by the T and Mann-Whitney tests, with a 95 % confidence level and significance offset at p < 0.05, using the SPSS software (IBM®, v. 22.) RESULTS: The CG performed better in terms of auditory processing. These differences were significant (p < 0.0001) for the binaural integration of DDT, FPT humming and Labeling, and P300 latency. The P300 results were similar; however, with a greater amplitude in the SG. CONCLUSION: This study showed that children and adolescents with stroke performed worse in electrophysiological and behavioral tests of auditory processing assessed using the auditory evoked potentials. These data reinforce the hypothesis that stroke-related lesions compromise the neural mechanisms underlying auditory processing.

Behavioral and functional assessment of mice inner ear after chronic exposure to an ultrahigh B0 field of 11.7 T or 17.2 T.

PURPOSE: Assess short-term and long-term effects of chronic exposure to an ultrahigh static magnetic (B0 ) field on mice inner ear in the context of MR safety of human scanning at 11.7 T. METHODS: Mice were chronically exposed to a B0 field of 11.7 T or 17.2 T during ten 2-h exposure sessions evenly distributed over a period of 5 weeks, resulting in a total of 20 h of exposure per mouse. During exposure sessions, mice were anesthetized and positioned either parallel or antiparallel to B0 . Before, during, and 2 weeks after the magnetic-field exposure period, mice performed behavioral tests (balance beam, rotarod, and swim tests) to evaluate their short-term and long-term motor coordination and balance. An auditory brainstem response (ABR) test was finally performed to assess the functional integrity of mice cochlea, 2 weeks after the last exposure. RESULTS: After awaking from anesthesia following B0 exposures at 11.7 Tor 17.2 T, mice displayed a transient (<5 min) rotating behavior. The behavioral tests did not show any difference between the exposed and the control mice at any time point. Determination of ABR thresholds did not reveal an impairment of cochlea hair cells resulting from chronic B0 exposure. CONCLUSION: Despite the transient disturbance of mice vestibular system observed immediately after B0 exposure, no short-term nor long-term alteration was detected with behavioral and ABR tests.

Development of an audiological assessment and diagnostic model for high occupational noise exposure.

PURPOSE: To explore the diagnostic auditory indicators of high noise exposure and combine them into a diagnostic model of high noise exposure and possible development of hidden hearing loss (HHL). METHODS: We recruited 101 young adult subjects and divided them according to noise exposure history into high-risk and low-risk groups. All subjects completed demographic characteristic collection (including age, noise exposure, self-reported hearing status, and headset use) and related hearing examination. RESULTS: The 8 kHz (P = 0.039) and 10 kHz (P = 0.005) distortion product otoacoustic emission amplitudes (DPOAE) (DPs) in the high-risk group were lower than those in the low-risk group. The amplitudes of the summating potential (SP) (P = 0.017) and action potential (AP) (P = 0.012) of the electrocochleography (ECochG) in the high-risk group were smaller than those in the low-risk group. The auditory brainstem response (ABR) wave III amplitude in the high-risk group was higher than that in the low-risk group. When SNR = - 7.5 dB (P = 0.030) and - 5 dB (P = 0.000), the high-risk group had a lower speech discrimination score than that of the low-risk group. The 10 kHz DPOAE DP, ABR wave III amplitude and speech discrimination score under noise with SNR = - 5 dB were combined to construct a combination diagnostic indicator. The area under the ROC curve was 0.804 (95% CI 0.713-0.876), the sensitivity was 80.39%, and the specificity was 68.00%. CONCLUSIONS: We expect that high noise exposure can be detected early with this combined diagnostic indicator to prevent HHL or sensorineural hearing loss (SNHL). TRIAL REGISTRATION NUMBER/DATE OF REGISTRATION: ChiCTR2200057989, 2022/3/25.

Cost-effectiveness analysis on implementing newborn hearing screening programmes in a low- to middle-income country.

OBJECTIVE: To analyse the cost-effectiveness (CE) of implementing different newborn hearing screening protocols in a low- to middle-income country. DESIGN: A decision analytical model with a 78-year time horizon. STUDY SAMPLE: Direct medical, direct non-medical and indirect costs were collected from 126 subjects in southern Thailand. Various protocols involving universal newborn hearing screening (UNHS) and targeted newborn hearing screening (TNHS), using two technologies, namely automated otoacoustic emissions (aOAEs) and automated auditory brainstem responses (aABRs), were evaluated. Incremental cost-effectiveness ratios (ICERs) were calculated for all protocols in United States dollars (US$)/quality-adjusted life year (QALY) gained. Also, probabilistic sensitivity analyses with 1000 trials for each specific protocol were performed. RESULTS: The ICERs of UNHS with aOAE, UNHS with aABR, TNHS with aABR and UNHS with optimised baseline parameters were 3702, 3545, 1545 and 2483 US$/QALY gained, respectively. With the CE threshold of 5000 US$/QALY gained, the chances of ICERs to be cost-effective for UNHS with aOAE, UNHS with aABR, TNHS with aABR and UNHS with optimised baseline parameters were 72, 77, 93 and 94%, respectively. CONCLUSIONS: All screening protocols were considered as cost-effective, and a very high chance of being cost-effective for UNHS could be achieved when certain baseline parameters were optimised.

Diagnóstico audiológico de lactentes após falha na triagem auditiva neonatal universal / Hearing assessment after referral in universal newborn hearing screening

RESUMO Objetivo Estudar o processo de diagnóstico audiológico de lactentes que falharam na Triagem Auditiva Neonatal Universal (TANU). Métodos Análise dos prontuários de 51 lactentes que falharam na TANU nas maternidades do munícipio e que foram encaminhados a um centro de referência em saúde auditiva para diagnóstico audiológico, entre janeiro e junho de 2021. Foram identificados os lactentes que finalizaram o diagnóstico, aqueles que não compareceram ao agendamento para exames ou evadiram durante o processo. Tentativas de contato foram realizadas com os responsáveis pelos lactentes que evadiram, para identificar o motivo da evasão. Resultados O comparecimento ao diagnóstico ficou em 75%, com evasões entre o encaminhamento da maternidade para o centro de referência, bem como durante o processo de diagnóstico. Cinquenta por cento dos sujeitos concluíram as avaliações audiológicas até os 3 meses de vida. A tentativa de contato foi bem-sucedida com os responsáveis pelos lactentes que evadiram, sendo os motivos mais frequentes: adoecimento do lactente, distância entre a moradia e o centro de referência, horário de trabalho dos pais. Conclusão Na etapa de diagnóstico, o índice de comparecimento e o tempo de conclusão até o terceiro mês de vida da criança ficaram abaixo dos índices recomendados, diminuindo a efetividade do Programa de Triagem Auditiva Neonatal Universal (PTANU). A busca ativa por contato telefônico e uso de aplicativo de mensagem telefônico foi importante para reduzir a evasão em 76%. Outras ferramentas que aprimorem o processo para um diagnóstico não prolongado, evitando evasões, necessitam ser estudadas.

ABSTRACT Purpose To study the process of hearing assessment in infants who were referred by professionals responsible for Universal Newborn Hearing Screening (UNHS). Methods Analysis of the medical records of 51 infants referred by maternity hospitals where UNHS was performed and were referred to a Hearing Health Center, between January and June 2021. Infants who completed hearing assessment, who never attended the appointments, or were lost during the diagnostic process were identified. Attempts were made to contact infants' guardians in order to understand the reason for missing the appointments. Results The attendance to the diagnosis was 75%. Fifty percent of the infants completed hearing assessment as recommended, up to 3 months of life. The attempt to contact parents who missed the appointments was successful, and the most frequent reasons are: the infant was ill on the day of scheduled appointment, distance from home to the hearing health center, parents' working hours. Conclusion For the diagnostic stage, the attendance rate and the age for completing hearing assessment were below the recommended. The active search for telephone contact and use of phone messaging application was important to reduce evasion by seventy-six percent. Tools that optimize the diagnostic process with less infants missing still must be studied.

Assessment of auditory functions in patients with hepatic glycogen storage diseases.

BACKGROUND: Hepatic glycogen storage diseases are a group of diseases manifesting mainly with hypoglycemia and hepatomegaly. The patients require frequent daytime and nocturnal feedings. Hypoglycemia may cause sensorineural hearing loss and nocturnal feeding is a risk factor for the development of gastroesophageal reflux that may cause chronic otitis media and hearing loss consequently. We aimed to determine the prevalence and characteristics of hearing loss in hepatic glycogen storage diseases. METHODS: A total of 24 patients with hepatic glycogen storage disease (15 glycogen storage disease type I and 9 non type I) and 24 age/sex matched healthy controls were enrolled in the study. Pure tone audiometer, immitansmetry, acoustic reflex measurement, otoacoustic emission test (OAE) and auditory brainstem response (ABR) tests were applied to all participants. RESULTS: Hearing loss was determined in 17/24 patients (12 glycogen storage disease type I and 5 non type I) with pure tone audiometer. Interpretation of all the findings revealed a total of 8 patients had conductive and 9 had mixed hearing loss. All parameters were significantly different than the control group. CONCLUSIONS: This is the first study to comprehensively assess the auditory functions of patients with hepatic glycogen storage disease. Audiological findings determined a significantly increased prevalence of conductive/ mixed type hearing loss in the patient group which is a new finding in the literature. Further studies with extended patient numbers are required to enlighten the underlying pathophysiology.

Distortion Product Otoacoustic Emission Test is Not the Test to Use in Nonclinical Safety Assessment.

Ototoxicity and ocular toxicity screening are but two examples of specialty product lines that are often employed as Tier II or III nonclinical safety/hazard screening assessments. Compared to the regulatory guidelines that govern over standard toxicology or neurotoxicology programs, there is a paucity of regulatory strategies to address these specialized product lines. With respect to ototoxicity testing, we argue for the inclusion of the "least burdensome principles" adopted by the US FDA in providing the most pragmatic, efficient, and directed identification of potential harm to auditory function in the nonclinical safety arena. We argue for the exclusive use of the auditory brainstem response and the exclusion of the distortion product otoacoustic emissions (DPOAEs) in these Tiered II safety assessment programs. The inclusion of both are a burden on operational staff and, due to the extended episodes of anesthesia required to conduct both assays, this strategy poses a health and welfare concern for the selected animal species to be used. The DPOAE does not provide any sufficiently valid or reliable data above and beyond the gold standard ABR data, followed by complete oto-histopathology and cytocochleogram combination designs.

Prevalence, behavioural, and management outcomes of infants with auditory neuropathy spectrum disorder.

AIM: To provide an overview of electrophysiological and behavioural outcomes from a large UK centres data set on children diagnosed with auditory neuropathy (ANSD) between 2002 and March 2018. METHOD: A systematic audit was undertaken, collating the electrophysiological data from auditory brainstem response (ABR) follow-up, risk factors, and later behavioural results/management. These were then compared to look for trends between groups. The study sample consisted of 118 925 infants born, with 46 (0.039%, 0.39 per 1000 births) being diagnosed with congenital ANSD (39 bilateral, seven unilateral). RESULTS: Twenty-nine per cent of ears with ANSD had short latency components on ABR testing. Forty-four per cent of ears with present cochlear microphonics but absent transient-evoked otoacoustic emissions (TE-OAE) and no ABR went on to have profound behavioural hearing threshold levels. All but one child went on to show a hearing loss on behavioural testing. ANSD was not confined to the population from neonatal intensive care units: there were three bilateral and five unilateral cases in the typically developing infant population. INTERPRETATION: The incidence of ANSD is higher in this sample than that reported previously in the literature. Children who had cochlear microphonics with absent ABR and absent TE-OAE had significantly worse later behavioural outcomes than other patterns of electrophysiological results.

Auditory brainstem response prior to MRI compared to standalone MRI in the detection of vestibular schwannoma: A modelling study.

OBJECTIVES: To determine the cost-effectiveness of auditory brainstem response prior to MRI (ABR-MRI) compared to standalone MRI to diagnose vestibular schwannoma. DESIGN: A state transition model was developed to simulate costs and effects (quality-adjusted life years [QALY]) for both diagnostic strategies for patients suspected of a vestibular schwannoma. Model input was derived from literature, hospital databases and expert opinions. Scenario and sensitivity analyses addressed model uncertainty. RESULTS: Over a lifetime horizon, ABR-MRI resulted in a limited cost-saving of €68 or €98 per patient (dependent on MRI sequence) and a health loss of 0.005 QALYs over standalone MRI. ABR-MRI, however, did miss patients with other important pathology (2% of the population) that would have been detected when using standalone MRI. In total, €14 203 or €19 550 could be saved per lost QALY if ABR-MRI was used instead of standalone MRI. The results were sensitive to the detection rate of vestibular schwannoma and health-related quality of life of missed patients. CONCLUSION: The cost-saving with ABR-MRI does not seem to outweigh the number of missed patients with VS and other important pathologies that would have been detected when using standalone MRI.

On prediction of aided behavioural measures using speech auditory brainstem responses and decision trees.

Current clinical strategies to assess benefits from hearing aids (HAs) are based on self-reported questionnaires and speech-in-noise (SIN) tests; which require behavioural cooperation. Instead, objective measures based on Auditory Brainstem Responses (ABRs) to speech stimuli would not require the individuals' cooperation. Here, we re-analysed an existing dataset to predict behavioural measures with speech-ABRs using regression trees. Ninety-two HA users completed a self-reported questionnaire (SSQ-Speech) and performed two aided SIN tests: sentences in noise (BKB-SIN) and vowel-consonant-vowels (VCV) in noise. Speech-ABRs were evoked by a 40 ms [da] and recorded in 2x2 conditions: aided vs. unaided and quiet vs. background noise. For each recording condition, two sets of features were extracted: 1) amplitudes and latencies of speech-ABR peaks, 2) amplitudes and latencies of speech-ABR F0 encoding. Two regression trees were fitted for each of the three behavioural measures with either feature set and age, digit-span forward and backward, and pure tone average (PTA) as possible predictors. The PTA was the only predictor in the SSQ-Speech trees. In the BKB-SIN trees, performance was predicted by the aided latency of peak F in quiet for participants with PTAs between 43 and 61 dB HL. In the VCV trees, performance was predicted by the aided F0 encoding latency and the aided amplitude of peak VA in quiet for participants with PTAs ≤ 47 dB HL. These findings indicate that PTA was more informative than any speech-ABR measure, as these were relevant only for a subset of the participants. Therefore, speech-ABRs evoked by a 40 ms [da] are not a clinical predictor of behavioural measures in HA users.

Assessment of cochlear electrophysiology in typically developing children and children with auditory processing disorder.

OBJECTIVE: Children with auditory processing disorder (APD) are reported to have abnormal auditory brainstem responses (ABR) but little is understood about their cochlear integrity. Poor cochlear integrity can affect neural responses. In this study, cochlear and auditory brainstem integrity was investigated in children with APD. METHOD: Twenty children with APD, sixteen typically developing children and twenty adults participated in this study. Click evoked electrocochleography (ECochG) and ABRs were recorded from all the participants. Cochlear responses were analyzed using a) latency and amplitude of summating potential; action potential, b) transmission time between summating potential and action potential, c) summating potential/action potential amplitude ratio and d) action potential latency difference to condensation and rarefaction polarity. Amplitude in the ABR components was examined. RESULTS: Children with APD showed similar cochlear function to the typically developing children. There were no significant differences in wave I amplitude between children with APD and typically developing children. However, wave V amplitude was significantly reduced in children with APD compared to typically developing children. CONCLUSION: In the absence of any functional differences in the cochlea, children with APD can show poor amplitude in the later components of the ABR. The ABR anomalies observed in children with APD arise due to poor neural processing, possibly after the first auditory synapse.

Assessment of Hearing in Children with Cerebral Palsy.

The objective of this study is to identify the prevalence and nature of auditory analyzer pathology in children with different forms of infant cerebral palsy by recording otoacoustic emission and recording short latency brainstem auditory evoked potentials. The subject group consisted of 75 children, 40 (53%) males and 35 (47%) were females, ranging from 3 to 14 years of age with a confirmed diagnosis of cerebral palsy on the basis of a psycho-neurological hospital in Tashkent. (Uzbekistan). The examination of children was carried out by the following methods: clinical examination of patients (general and otorhinolaryngological) and functional research methods of the auditory analyzer. All children underwent acoustic impedancemetry, including tympanometry with determination of the type of tympanogram and acoustic reflex. The data obtained revealed a bilateral lesion of the peripheral part of the auditory analyzer. Beilateral sensorineural hearing loss was detected in 21 - I - II degree, in 12 - III degree and in 15 - IV degree. Marked changes in the main parameters of BAEP were detected in the study of the stem structures of the auditory analyzer in children with cerebral palsy. Thus, disorganization, configuration disturbances of the component composition (I, III, V) were noted. Thus, the study revealed a disorder of auditory function by sound-detecting type and justified the need for hearing correction in these children. Evaluation of auditory function made it possible to determine the level of auditory analyzer injury and localization of the process from the results of a complex, objective examination.

Assessment of auditory and vestibular damage in a mouse model after single and triple blast exposures.

The use of explosive devices in war and terrorism has increased exposure to concussive blasts among both military personnel and civilians, which can cause permanent hearing and balance deficits that adversely affect survivors' quality of life. Significant knowledge gaps on the underlying etiology of blast-induced hearing loss and balance disorders remain, especially with regard to the effect of blast exposure on the vestibular system, the impact of multiple blast exposures, and long-term recovery. To address this, we investigated the effects of blast exposure on the inner ear using a mouse model in conjunction with a high-fidelity blast simulator. Anesthetized animals were subjected to single or triple blast exposures, and physiological measurements and tissue were collected over the course of recovery for up to 180 days. Auditory brainstem responses (ABRs) indicated significantly elevated thresholds across multiple frequencies. Limited recovery was observed at low frequencies in single-blasted mice. Distortion Product Otoacoustic Emissions (DPOAEs) were initially absent in all blast-exposed mice, but low-amplitude DPOAEs could be detected at low frequencies in some single-blast mice by 30 days post-blast, and in some triple-blast mice at 180 days post-blast. All blast-exposed mice showed signs of Tympanic Membrane (TM) rupture immediately following exposure and loss of outer hair cells (OHCs) in the basal cochlear turn. In contrast, the number of Inner Hair Cells (IHCs) and spiral ganglion neurons was unchanged following blast-exposure. A significant reduction in IHC pre-synaptic puncta was observed in the upper turns of blast-exposed cochleae. Finally, we found no significant loss of utricular hair cells or changes in vestibular function as assessed by vestibular evoked potentials. Our results suggest that (1) blast exposure can cause severe, long-term hearing loss which may be partially due to slow TM healing or altered mechanical properties of healed TMs, (2) traumatic levels of sound can still reach the inner ear and cause basal OHC loss despite middle ear dysfunction caused by TM rupture, (3) blast exposure may result in synaptopathy in humans, and (4) balance deficits after blast exposure may be primarily due to traumatic brain injury, rather than damage to the peripheral vestibular system.

Assessment of Visual and Brainstem Auditory Evoked Potentials in Patients with Hashimoto's Thyroiditis.

BACKGROUND: The present study was aimed to evaluate parameters of visual and brainstem auditory evoked potentials (VEP, BAEP) in euthyreotic Hashimoto's thyroiditis (HT) patients without central nervous system involvement. METHODS: 100 HT patients (92 women, 8 men), mean age 46.9 years, and 50 healthy controls. They underwent a neurological examination, thyroid hormone levels, thyroid autoantibody titers, and brain imaging. Latencies and amplitudes of the N75, P100, and N145 component of VEP and the I-V components of BAEP were analyzed. RESULTS: The neurological examination revealed in 31 patients signs of increased neurovegetative excitability. Brain resonance imaging showed no abnormalities in HT patients. The mean P100, relative P100, and N145 VEP latencies were significantly longer, and P100 amplitude significantly higher in HT patients than the controls. HT patients also had a longer mean wave BAEP V latency and mean wave III-V and I-V interpeak latencies, and significantly lower mean wave I and V amplitudes. Abnormal VEP and BAEP were recorded in 34% of the patients. There were no statistically significant correlations between the mean VEP parameters and thyroid profile and the applied dose of L-thyroxine. There was a relationship between the level of TSH and the wave BAEP III-V interpeak latency. CONCLUSIONS: There were changes in the brain's bioelectrical activity in one-third of the patients with HT without nervous system involvement. The increased amplitude of the VEP may indicate increased cerebral cortex activity. Disorders of the brain's bioelectrical activity in the course of HT may be associated with an autoimmune process.

Brainstem auditory evoked responses and bone conduction assessment in alpacas.

Auditory loss has been reported in camelids using brainstem auditory evoked responses (BAER). Differentiation between conductive versus sensorineural dysfunction has not been investigated. Therefore, the objective of the study was to investigate auditory function using BAER and bone conduction (BC). Twenty-four alpacas: 15 females, 9 intact males (2-16 years of age) were included in a randomized clinical trial. BAER and BC were recorded using two derivations (vertex to mastoid and vertex to cranial aspect of second cervical vertebra). All alpacas underwent complete physical examinations and were sedated with xylazine hydrochloride at 0.6 mg/kg IM. Peaks, when present, were identified and latencies, amplitudes, and amplitude ratios were determined. Eleven alpacas had normal responses and 13 had auditory loss based on BAER. The latter consisted of complete absence of peaks bilaterally (n = 3), absence of peaks unilaterally (n = 1), delayed latencies bilaterally (n = 4), and delayed latencies unilaterally (n = 5). Distinct peaks on BC supported conductive auditory loss in 6 alpacas, difficult to interpret due to stimulus artifact and additional undefined peaks in 4, and absent peaks in 3 alpacas. The cause of auditory loss was presumed to be due to otitis in 6, aging in 4 (10-16 years old), and congenital sensorineural (absent peaks on BAER and BC) in 3 alpacas with unpigmented fiber and irises. BAER and BC are useful and non-invasive to perform techniques for the investigation of auditory loss in alpacas, and further characterization as conductive or sensorineural.

Assessment of hearing screening programmes across 47 countries or regions II: coverage, referral, follow-up and detection rates from newborn hearing screening.

OBJECTIVES: To assess the performance of newborn hearing screening (NHS) programmes, through selected quality measures and their relationship to protocol design. DESIGN: NHS coverage, referral, follow-up and detection rates were aggregated. Referral rates were compared to age at screening step 1, number of steps, and test method: OAE or aABR. STUDY SAMPLE: A questionnaire on existing hearing screening was completed by experts from countries in Europe, plus Russia, Malawi, Rwanda, India and China. RESULTS: Out of 47 countries or regions, NHS coverage rates were reported from 26, referral rates from 23, follow up from 12 and detection rates from 13. Median coverage rate for step 1 was 96%. Referral rate from step 1 was 6-22% where screening may be performed <24 h from birth, 2-15% for >24 h, and 4% for >72 h. Referral rates to diagnostic assessment averaged 2.1% after one to two steps using OAE only, 1.7% after two steps including aABR, and 0.8% after three to four steps including aABR. Median detection rate for bilateral permanent hearing impairment ≥40dB was 1 per 1000 infants. CONCLUSION: Referral rates were related to age, test method and number of screening steps. Quality measures were not available for many NHS programmes.

Assessment of hearing screening programmes across 47 countries or regions I: provision of newborn hearing screening.

OBJECTIVES: Newborn hearing screening (NHS) varies regarding number and type of tests, location, age, professionals and funding. We compared the provision of existing screening programmes. DESIGN: A questionnaire containing nine domains: demography, administration, existing screening, coverage, tests, diagnosis, treatment, cost and adverse effects, was presented to hearing screening experts. Responses were verified. Clusters were identified based on number of screening steps and use of OAE or aABR, either for all infants or for well and high-risk infants (dual-protocol). STUDY SAMPLE: Fifty-two experts completed the questionnaire sufficiently: 40 European countries, Russia, Malawi, Rwanda, India and China. RESULTS: It took considerable effort to find experts for all countries with sufficient time and knowledge. Data essential for evaluation are often not collected. Infants are first screened in maternity wards in most countries. Human development index and health expenditure were high among countries with dual protocols, three screening steps, including aABR, and low among countries without NHS and countries using OAE for all infants. Nationwide implementation of NHS took 6 years, on average. CONCLUSION: The extent and complexity of NHS programmes are primarily related to health expenditure and HDI. Data collection should be improved to facilitate comparison of NHS programmes across borders.