Brainstem Auditory Evoked Potentials Research Articles

Factors Related to the Progression of Clinically Isolated Syndrome to Multiple Sclerosis: A Retrospective Study in Lithuania.

Background and Objectives: Multiple sclerosis (MS) is a demyelinating disease which usually manifests as clinically isolated syndrome (CIS). Approximately 70% of patients with CIS progress to MS. Therefore, there is a pressing need to identify the most accurate predictive factors of CIS developing into MS, some of which could be a clear clinical phenotype of early MS as well as lesions in magnetic resonance imaging (MRI), pathological findings in cerebrospinal fluid (CSF) and evoked potentials (EP) tests. The problem is of outstanding importance since early MS diagnosis and treatment prevents long-term disability. The aim of our study is to analyze the factors that could influence the progression of CIS to MS. Materials and Methods: This study is a retrospective data analysis which included patients with their primary CIS diagnosis between 1st January 2015 and 1st January 2020. The prevalence and predictive value of clinical symptoms, MRI lesions, pathological CSF and EP findings were evaluated in accordance with the final diagnosis and compared between the sexes and age groups. Results: Out of 138 CIS patients, 49 (35.5%) patients progressed to MS. MS patients were more likely to have a diminished sense of vibration and proprioception (χ2 = 9.033, p = 0.003) as well as spinal cord MRI lesions (χ2 = 7.209, p = 0.007) in comparison with the non-MS group. Positive oligoclonal bands (OCBs) in CSF (χ2 = 34.859, p ≤ 0.001) and pathological brainstem auditory evoked potential (BAEP) test findings (χ2 = 10.924, p ≤ 0.001) were more prevalent in the MS group. Diminished sense of vibration and proprioception increased the risk for developing MS by 13 times (p = 0.028), whereas positive OCBs in CSF increased the risk by 100 times (p < 0.001). MS patients that were older than 50 years were more likely to exhibit positive Babinski’s reflex (χ2 = 6.993, p = 0.03), decreased muscle strength (χ2 = 13.481, p = 0.001), ataxia (χ2 = 8.135, p = 0.017), and diminished sense of vibration and proprioception (χ2 = 7.918, p = 0.019) in comparison with both younger age groups. Conclusions: Diminished sense of vibration and proprioception, spinal cord MRI lesions, positive OCBs and pathological BAEP test findings were more common among patients that developed MS. Diminished sense of vibration and proprioception along with positive CSF OCBs are predictors of CIS progressing to MS. Older patients that develop MS have more symptoms in general, such as positive Babinski’s reflex, decreased muscle strength, ataxia, and diminished sense of vibration and proprioception.

Clinical evaluation of acute necrotizing encephalopathy in children

ObjectiveAcute necrotizing encephalopathy (ANE) is a rare but severe encephalopathy and is associated with a high morbidity and mortality. We aimed to analyze and compare the clinical features and predictive indicators of pediatric ANE.Materials and methodsThis retrospective study included children with ANE diagnosed at Guangzhou Women and Children’s Medical Center between November 2018 and January 2020. Pediatric patients’ information, including clinical characteristics, laboratory tests, neuroelectrophysiology and brain magnetic resonance imaging (MRI) findings, MRI score, brainstem auditory evoked potential (BAEP) grades, ANE severity scores (ANE-SS), and modified Rankin scale (mRS), were collected.ResultsTwelve ANE patients were included. Among them, one patient (8.3%) died from brainstem dysfunction, one (8.3%) recovered and 10 (83.3%) experienced neurological sequelae. All patients had an initial viral infection and neurological symptoms such as acute disturbance of consciousness (ADOC) or seizure, and the interval from onset of the disease to neurological manifestations was 3 (1.25–3) days. MRI score-I ranged from 1 to 3 (1.8 ± 0.7), MRI score-II ranged from 1 to 4 (2.5 ± 1.1). ANE-SS varied from 1 to 6 (3.9 ± 1.3). The scores of mRS were from 0 to 6 (2.9 ± 1.7). Higher MRI score were associated with worse outcomes, while the BAEP grade and ANE-SS score were not significantly associated with mRS.ConclusionANE is a severe encephalopathy syndrome with rapid progression, resulting in serious neurological sequelae. Compared with BAEP grade and ANE-SS, brain MRI shows more comprehensive advantages in predicting the prognosis of ANE patients. More in-depth research and better indicators are still needed to support the evaluation and treatment of ANE.

Relationship between hearing, cognitive function, and quality of life in aging companion dogs.

BackgroundElderly people with presbycusis are at higher risk for dementia and depression than the general population. There is no information regarding consequences of presbycusis in dogs.ObjectiveEvaluate the relationship between cognitive function, quality of life, and hearing loss in aging companion dogs.AnimalsThirty‐nine elderly companion dogs.MethodsProspective study. Hearing was evaluated using brainstem auditory evoked response (BAER) testing. Dogs were grouped by hearing ability. Owners completed the canine dementia scale (CADES) and canine owner‐reported quality of life (CORQ) questionnaire. Cognitive testing was performed, and cognitive testing outcomes, CADES and CORQ scores and age were compared between hearing groups.ResultsNineteen dogs could hear at 50 dB, 12 at 70 dB, and 8 at 90 dB with mean ages (months) of 141 ± 14, 160 ± 16, and 172 ± 15 for each group respectively (P = .0002). Vitality and companionship CORQ scores were significantly lower as hearing deteriorated (6.6‐5.4, 50‐90 dB group, P = .03 and 6.9‐6.2, 50‐90 dB group, P = .02, respectively). Cognitive classification by CADES was abnormal in all 90 dB group dogs and normal in 3/12 70 dB group and 11/19 50 dB group dogs (P = .0004). Performance on inhibitory control, detour and sustained gaze tasks decreased significantly with hearing loss (P = .001, P = .008, P = .002, respectively). In multivariate analysis, higher CADES score was associated with worse hearing (P = .01).Conclusions and Clinical ImportancePresbycusis negatively alters owner‐pet interactions and is associated with poor executive performance and owner‐assessed dementia severity.

Clinical efficacy of hyperbaric oxygen combined with different timings of right median-nerve electrical stimulation in patients with brain injury-induced disorders of consciousness.

ObjectiveThe objective of this study was to investigate the clinical efficacy of hyperbaric oxygen combined with right median‐nerve stimulation (RMNES) in patients with disorders of consciousness caused by brain injury.MethodsA total of 120 patients with consciousness disorders caused by brain injury were selected. They were randomly divided into three groups, a control group, test group 1 (treated with RMNES after hyperbaric oxygen therapy [HBOT]), and test group 2 (treated with RMNES at the same time as HBOT), with 40 patients in each group. Before and after treatment, the Glasgow coma scale (GCS), brainstem auditory‐evoked potential (BAEP), electroencephalogram (EEG), and upper‐limb sensory‐evoked potential (USEP) were evaluated for the three groups of patients.ResultsThe GCS score of patients in the three groups significantly improved compared with that before treatment (p < .05). There were significant differences in GCS scores among the three groups (p < .05), and the GCS score for the patients was test group 2>test group 1>control group. The EEG, BAEP, and USEP scores were significantly improved compared with those before treatment (p < .05), and the degree of improvement of patients in the three groups was test group 2>test group 1>control group (p < .05). The clinical efficacy of test group 2 was higher than that of test group 1, and the clinical efficacy of test group 1 was higher than that of the control group (p < .05).ConclusionHyperbaric oxygen combined with RMNES can improve the state of consciousness and promote the recovery of consciousness for patients with consciousness disorders caused by brain injury, and the effect of RMNES combined with HBOT in the chamber on improving the recovery of consciousness is better than after HBOT outside the chamber.

Visual and Brainstem Auditory-evoked Potentials Correlate with Specific Motor and Non-motor Symptoms in Parkinson's Disease

Parkinson’s disease (PD) is a common and complex neurodegenerative disease characterized by progressive motor and non-motor symptoms. The current study investigated the dysfunction of brain hemispheres and brainstem of PD patients and its relation to motor and non-motor symptoms using brainstem auditory evoked potentials (BAEP) and pattern reversal visual evoked potentials (p-VEP). We hypothesized that some motor and non-motor symptoms of PD due to specific dysfunctions of brainstem and brain hemispheres could be related to changes in p-VEP and BAEP. Accordingly, the aim of this study was to explore the abnormalities of BAEPs and p-VEPs in patients with PD and its correlation to the motor and non-motor symptoms of PD. Seventy-six nondemented PD patients took part in the p-VEP evaluations and 66 nondemented PD patients were included in BAEP evaluation. In order to compare the p-VEP performance of PD group, we included a control group comprising 32 age-matched participants. A BAEP substudy involved 29 age-matched healthy controls. All patients underwent a comprehensive motor and non-motor neuropsychological assessment. We found significant changes in all tested parameters of p-VEPs in PD patients compared to control subjects. In addition, these lower scores in p-VEP correlate with the results of some tests for cognition related to frontal-striatal dysfunction and contralateral rigidity, but not with the results of overall motor evaluation or other non-motor symptoms studied. In BAEP, PD patients have a significant prolongation of III and V wave latencies compared to controls. In addition, when examining the possible associations of BAEP with other non-motor manifestations of the disease, such association was observed only by the apathy scale. In conclusion, the current study confirms the visual and auditory abnormalities among PD patients thatreflect brain hemispheres and brainstem pathological changes. It also correlates these abnormalities to some motor and non-motor features of the disease, providing a localizing tool for associated brain hemispheres and brainstem dysfunctions. Furthermore, abnormal visual evoked potentials are associated with motor and non-motor symptoms due to the basal ganglia dysfunction. In contrast, abnormal auditory evoked potentials are connected with apathy, which is considered to be related with brainstem raphe nuclei dysfunction.

소뇌교각부종양 수술 중 뇌줄기청각유발검사와 자유근전도를 활용한 전정신경 수술중신경계감시

Cerebellopontine angle tumors including schwannoma or meningioma are located around the vestibular nerve. In the case of surgical removal, intraoperative neurophysiologic monitoring (IONM) modality such as brainstem auditory evoked potential (BAEP) could detect its neurologic function. We demonstrate 2 cases of cerebellopontine angle surgery using BAEP as an IONM modality. And we also suggest how to deal with the case where BAEP is not measured, by using triggered electromyography.

Audiological Findings in Children with PLA2G6-Associated Neurodegeneration.

Audiological manifestations of patients with PLA2G6-associated neurodegeneration are limited. To analyze the audiological findings in a cohort of 13 children with infantile neuroaxonal dystrophy (INAD). Patients underwent a battery of audiological tests including tympanometry, distortion product otoacoustic emissions, impedance audiometry, and Brainstem Auditory Evoked Potentials (BAEPs). Audiological studies of 13 children indicated sensorineural hearing loss in six children and auditory neuropathy spectrum disorder in four children. This study may extend the auditory findings for INAD. Additional studies on quality of life and cognitive-brain degeneration related to this disease are required before making appropriate recommendations for aural rehabilitation.

미세혈관감압술에서 뇌줄기청각유발전위의 최신지견

Hemifacial spasm (HFS) is due to the vascular compression of the facial nerve at its root exit zone (REZ). Microvascular decompression (MVD) of the facial nerve near the REZ is an effective and curative treatment for HFS. Since the cochlear nerve lies directly adjacent to the facial nerve, postoperative hearing loss frequently occurs during MVD surgery for HFS. However, the rate of postoperative hearing loss has decreased since introducing the intraoperative neurophysiologic monitoring (IONM) of brainstem auditory evoked potentials (BAEPs). There have been many advances on this field in the recent decade. This article aimed to review and present advances in IONM of BAEPs.

Approach and solutions to congenital hearing impairment in Cameroon: perspective of hearing professionals

ObjectivesTo bring out the diagnostic attitude of hearing professionals in Cameroon towards congenital hearing impairment (CHI), assess availability of tests, neonatal screening, and create a national map of availability of treatment opportunities.MethodsWe conducted a cross-sectional online-based survey from June to December 2021, concerning ear–nose–throat (ENT) specialists, hearing care professionals, speech therapists and ENT nurses. A Google Forms online questionnaire was used to collect data, filled by eligible professionals involved in hearing care in Cameroon.ResultsA total of 93 professionals working in 31 different health facilities participated. A cumulative percentage of 79.9% of ENTs were found in just two out of 10 regions. Specialists sought by ENTs for assessment of patients with CHI included neurologists/neuro-pediatricians (96.8%), pediatricians (47.6%), other ENTs (34.9%), and psychologists (3.2%). Investigations requested included auditory-evoked brainstem response (ABR; 87.3%), otoacoustic emissions recording (OAE; 71.4%), and tympanometry (66.7%). There were eight OAE and nine ABR machines in the country. Twenty-five (88.6%) out of 31 facilities with otolaryngologists did not carry out systematic neonatal screening. Reasons included unavailability of equipment (21; 84%), and administrative delays (14; 56%). Sixteen (51.6%) facilities had ENTs with additional training in otologic surgery and 11 (35.5%) were equipped to perform ear surgery. Three centers (9.7%) specialized in hearing aid provision and maintenance services. Three hospitals (9.7%) had performed cochlear implantation.ConclusionOur results show scarcity and overt unevenness in distribution of specialists, equipment and solutions to CHI in Cameroon. A serious negative health care consequence of this shortage is the unavailability of universal newborn hearing screening and implementation programs.

Neurophysiological Aspects in SARS-CoV-2-Induced Acute Respiratory Distress Syndrome.

Patients with coronavirus disease 2019 (COVID-19) often develop acute respiratory failure and acute respiratory distress syndrome (ARDS) that requires intensive care unit (ICU) hospitalization and invasive mechanical ventilation, associated with a high mortality rate. In addition, many patients fail early weaning attempts, further increasing ICU length of stay and mortality. COVID-19 related ARDS can be complicated by neurological involvement with mechanisms of direct central nervous system (CNS) infection and with overlapping para-infective mechanisms of the peripheral nervous system (PNS). We aimed to evaluate the possible involvement of the brainstem and PNS in patients with COVID-19 related ARDS and difficulty in weaning from mechanical ventilation. We evaluated electroencephalogram (EEG), brainstem auditory evoked potentials (BAEPs), electroneurography of the four limbs and the phrenic nerve in 10 patients with respiratory insufficiency due to SARS-CoV-2. All were admitted to intensive care unit and were facing prolonged weaning from mechanical ventilation. All ten patients showed a mild diffuse non-specific slowing of brain electrical activity on the EEG. Four patients had an acute motor axonal neuropathy with absent or reduced amplitude phrenic nerve CMAP while four patients showed impairment of the BAEPs. A patient with peripheral nerve impairment suggestive of Guillain-Barré syndrome (GBS) underwent an intravenous immunoglobulin (IVIg) cycle that led to an improvement in the weaning process and progressive motor improvement. The inclusion of a comprehensive neurological evaluation in COVID-19 patients in ICU facilitated the early identification and effective management of Nervous System involvement.

Exploring auditory thresholds for Reindeer, Rangifer tarandus

Current and proposed human development throughout high northern latitudes must assess and try to mitigate impacts on caribou and reindeer ( Rangifer tarandus ) herds. Sound created by development can be far-reaching, and determining the potential impacts of noise on wildlife can inform landscape use. To advance our understanding of Rangifer ’s potential response to anthropogenic noise, we must first understand what they can hear. Using domestic reindeer from the Large Animal Research Station at the University of Alaska Fairbanks, we performed a Brainstem Auditory Evoked Response to estimate auditory thresholds of the species. We assessed the central auditory response and tested the sensitivity in 6 female reindeer of various ages. Prior to our work, the lowest audible frequency for the species was reported to be 63 Hz in previous studies. We identified an auditory threshold lower limit of 30 Hz in our study subjects and quantified reindeer sensitivity thresholds (dB peSPL) to frequencies ranging from 30 to 16,000 Hz. Our results indicate that anthropogenic sounds previously thought to be beyond the hearing range of Rangifer —such as seismic exploration—are likely to be audible to the species, and therefore have the potential to affect their soundscape. We compared our findings on Rangifer hearing with new measurements of anthropogenic sounds recorded on passive acoustic monitors distributed throughout northern Alaska, as well as biological sounds produced by the Rangifer themselves (e.g., vocalizations and sesamoid clicks produced by the ankles). All classes of anthropogenic sound fall within the threshold range that we identified for Rangifer . Our findings have important implications for the assessment of environmental impacts within Rangifer range and will inform future soundscape ecology research.

Intraoperative Neuromonitoring for Skull Base Surgery

Intraoperative neuromonitoring techniques can be used to evaluate neural functions during surgical procedures. For removal of tumors in the skull base region, we perform them for both structural mapping of the compressed cranial nerves and continuous monitoring of their preservation. The goal is to eliminate the critical irreversible damage to the neurological structures and prevent postoperative neurologic deficits. Recording techniques have been developed and neuromonitoring equipment used in the operation room with the intravenous anesthesia technique. For skull base surgery, in particular, the neuromonitoring contains motor evoked potential(MEP), brainstem auditory evoked potential(BAEP), visual evoked potential(VEP), and others. We believe that the appropriate recording and interpretation of these data can greatly improve the surgical outcomes of tumor removal and prevent postoperative neurologic deficits.

Effect of Low Frequency Repetitive Transcranial Magnetic Stimulation (rTMS) Combined with Hyperbaric Oxygen (HBO) on Awakening of Coma Patients with Traumatic Brain Injury.

Coma caused by craniocerebral injury is a common condition of neurosurgical acute injury. There is no specific method to promote awakening in a clinic. Early comprehensive treatment may be helpful to patients. The common methods are hyperbaric oxygen (HBO) and low-frequency repetitive transcranial magnetic stimulation (rTMS). However, the application effect and mechanism of rTMS combined with HBO on coma patients with traumatic brain injury need to be further studied. The brain stem auditory evoked potential (BAEP) is examined by the Kennedy coma recovery scale (CRS-R), the recovery of brain function and the state of consciousness are evaluated, and the therapeutic effect is evaluated by the Glasgow Coma Scale (GCS). Cerebrospinal fluid NE level, MCA blood flow velocity, and left brainstem and right brainstem auditory evoked potential are used to evaluate brain rehabilitation. RTMS combined with HBO could shorten the wake-up time, improve the wake-up rate, improve the GCS score and CRS-R score, shorten the brain wave latency time of the left and right brainstem, increase the NE level of cerebrospinal fluid, and decrease the blood flow velocity of MCA. RTMS combines with HBO can improve the nerve excitability of brain cells, reduce the disturbance of consciousness, promote the functional recovery of brain injury, and has a certain role in promoting the awakening of patients with traumatic brain injury coma.

Brainstem auditory evoked potential in cognitive impairment in patients with type 2 diabetes mellitus.

Type 2 diabetes mellitus (T2DM) can cause mild cognitive impairment (MCI) which threatens the health of patients. So the diagnosis of MCI is particularly important. It is reported that brainstem auditory evoked potential (BAEP) is a sensitive tool to detect the brainstem function in patients with T2DM. This study aimed to investigate the relationship between BAEP and MCI in patients with T2DM. A total of 244 T2DM patients with normal hearing, including 117 normal cognition patients and 127 MCI patients, were recruited in this cross-sectional study. Each subject underwent the BAEP examination. The diagnosis of MCI was based on the diagnostic guideline developed by the National Institute on Aging-Alzheimer's Association workgroups. The Montreal Cognitive Assessment (MoCA) was used to assess the cognitive function of the subjects. Compared with the normal cognition group, the patients in the MCI group had longer latencies of waves III and V and interpeak latencies (IPL) I-V in both ears (P<0.05). The significant negative correlations were found between the latencies of waves III, V, IPL I-V, and MoCA score in both ears (P<0.05). Logistic regression showed that the prolongations of latunits of waves III and V and IPL I-V in both ears were still associated with MCI after adjustment for mixed factors (P<0.05). These results indicate abnormal auditory pathway in brainstem of T2DM patients with MCI. BAEP may contribute to the clinical diagnosis of MCI in patients with T2DM.

Effect of Connexin on Cochlear Blood-Labyrinth Barrier in a Mouse Model of Endolymphatic Hydrops

To examine the expression of tight-junction connexin ZO-1 in the stria vascularis tissue of the cochlea by using spontaneous endolymphatic hydrops animal model constructed with PHEX gene mutant mice, and to analyze the dynamic changes of the gene mutant mice in pathology, imaging, and hearing function. Male Hyp-Duk/Y mice with PHEX gene mutation were selected as the experimental group at three time points, 21 days post birth (P21), 90 days post birth (P90) and 120 days post birth (P120), and wild-type male mice of the same ages were selected as the control groups. The cochlear sections were HE-stained in order to observe whether endolymphatic hydrops was present or absent and to assess its severity. The expression of connexin ZO-1 in both groups was evaluated through immunohistochemical staining of cochlear sections. Auditory-evoked brainstem response (ABR) was induced in both groups at P90 and gadolinium-enhanced MRI was conducted in vivo to observe the middle-order endolymphatic dilatation of cochlea in experimental and control mice aged P21, P90 and P120. HE staining of pathological sections of PHEX Hyp-Duk/Y mice aged P90 and P120 showed increased endolymphatic hydronephrosis. The level of striae ZO-1 in PHEX Hyp-Duk/Y mice aged P90 and P120 was significantly lower than that of the controls of the same age (P<0.05). The expression level of ZO-1 was significantly negatively correlated with the degree of endolymphatic hydronephrosis (r=-0.939, P<0.01). The bilateral ABR threshold of PHEX Hyp-Duk/Y mice aged P90 was higher than that of the wild-type mice of the same age, and the mutant mice showed asymmetric hearing loss on both sides. Severe endolymphatic hydronephrosis was observed in PHEX Hyp-Duk/Y mice aged P90 and P120 through in vivo MRI gadolinium imaging. PHEX Hyp-Duk/Y can be used as a sound model for basic research of Ménière's disease. Compared with wild-type mice, PHEX Hyp-Duk/Y mice showed decreased expression of connexin protein ZO-1, which damaged the function of the blood-labyrinth barrier in stria vascularis, and was involved in the formation of endolymphatic hydrops. 7.0 T MRI gadolinium imaging can be used to observe the changes of severe endolymphatic hydrops in mice in vivo, providing imaging basis for the diagnosis of Ménière's disease.

HP01: Usefulness of auditory brainstem evoked response in the assessment of bilirubin-induced auditory toxicity in infants with jaundice: A case-control study

To assess ABR alterations due to hyperbilirubinemia in jaundiced infants compared to a control group. Background: Bilirubin-induced neurotoxicity has predilection to specific areas of the brain including the auditory pathway structures. These latter are assessed by auditory brainstem evoked response (ABR). Methods: This was a retrospective study including two groups: jaundiced infants (G1) and age-matched (p>0.05) infants without jaundice (G2). All infants underwent ABR on each ear to screen deafness. Responses obtained at 90 dB were studied. Responses of G2 were normal. The Mann-Whitney U test was used to compare the responses between the two groups. Results: Twenty infants (40 ears) were included with a mean age of 33.5±13 months. G1 and G2 included 18 and 20 ears, respectively. Wave-I latency was significantly more prolonged in G1 (1.71±0.2 ms) compared to G2 (1.56±0.1 ms) with p=0.02. There was no difference in I-III interpeak interval (IPL). The III-V IPL was significantly increased in G1 (2.04±0.1 ms) compared to G2 (1.92±0.1 ms) with p=0.04. I-V IPL was more prolonged in G1. Discussion: Both peripheral and central auditory pathways may be altered in infants with jaundice. Bilirubin-induced toxicity may affect the inner part of the ear. The central dysfunction may occur at the brainstem level between the bulbo-protuberant junction and the inferior colliculus. This may be due to the hyperbilirubinemia-induced changes in the central synaptic transmission. Conclusion: Hyperbilirubinemia-induced auditory toxicity can occur at different levels of the auditory pathway. Therefore, there is a need for an early ABR assessment in jaundiced infants.

Gom1 Mutant Mice as a Model of Otitis Media.

Otitis media (OM) disease is a common cause of hearing loss that is primarily the result of middle ear infection. At present, our understanding of the mechanisms leading to OM is limited due to the lack of animal models of OM with effusion (OME). Here, we report that the mice with genetic otitis media one (gom1) mutants are prone to OM. gom1 Mice were produced by the N-ethyl-N-nitrosourea (ENU) mutagenesis program as an animal model to study OM. These mice demonstrate many common features of OM, such as middle ear effusion and hearing impairment. We revealed that gom1 mice display various signs of middle ear and inner ear dysfunctions, including elevated thresholds of auditory-evoked brainstem response (ABR) and lack of cochlear microphonic responses. Decreased compliance intympanometrymeasurements indicates tympanic membrane and ossicular chain malfunction. We confirmed through histological examinations of middle ear structures that 34/34 (100 %) of the mutant mice suffered from severe OME. While individual ears had different levels of effusion and inflammatory cells in the middle ear cavity, all had thickened middle ear mucosa and submucosa compared to control mice (B6). Moreover, the mutant mice displayed cochlear hair cell loss. These observations also suggested the craniofacial abnormalities in the gom1 mouse model. Together, these results indicate that gom1 mice could be valuable for investigating the genetic contribution to the development of middle ear disease.

Active Middle Ear Implant Evoked Auditory Brainstem Response Intensity-Latency Characteristics.

ObjectiveTo analyze intensity-latency functions of intraoperative auditory evoked brainstem responses (ABRs) to stimulation by the Vibrant Soundbridge (VSB) active middle ear implant with respect to coupling efficiency, VSB evoked ABR thresholds, and coupling modality [oval window (OW) placement vs. Incus placement and vs. round window (RW) placement].Study DesignExploratory study.SettingBi-centric study at tertiary referral centers.PatientsTwenty-four patients (10 female, 14 male, mean age: 58 years) who received a VSB.Outcome MeasuresWave-V intensity-latency functions of intraoperative VSB evoked ABRs using a modified audio processor programmed to preoperative bone conduction thresholds for stimulation. Threshold level correction to coupling efficiency and ABR thresholds. Individual plots and exponential function fits.ResultsAfter ABR threshold level correction, the latency functions could be aligned. A large variance of latencies was observed at individual threshold level. Wave-V latency was longest in the Incus placement subgroup (9.73 ms, SD: 1.04) as compared to OW placement subgroup (9.47 ms, SD: 1.05), with the shortest latency in the RW placement subgroup (8.99 ms, SD: 0.68). For increasing stimulation levels, the variance decreased with intensity-latency function slopes converging toward a steady-state (saturation) latency caused by saturation of audio processor (stimulation) gain. Latency saturation was reached at a stimulation level of 50 dB nHL for the OW placement subgroup, 35 dB nHL for the Incus placement subgroup, and 30 dB nHL for the RW placement subgroup. The latency and saturation results indicated decreased dynamic range for RW placement, i.e., reverse stimulation.ConclusionsVSB evoked ABR wave-V intensity-latency function slopes were similar to acoustic stimulation at high stimulation levels with a shift toward longer latencies caused by audio processor signal delay. Saturation of latencies occurred for higher stimulation levels due to saturation of audio processor gain. Thus, the analysis of VSB evoked intensity-latency functions appears to allow for the objective assessment of a patient's individual dynamic range. This can further improve diagnostics as well as intraoperative and postoperative quality control.

The Auditory Afferent Pathway as a Clinical Marker of Alzheimer's Disease.

Brain stem neural tracts and nuclei may be disturbed prior to observable neuronal atrophy in AD. In this perspective, we discuss the notion of functional deficits presenting prior to structural abnormalities in Alzheimer's disease (AD). Imaging of inferior colliculi using magnetic resonance spectroscopy (MRS) shows significant decrease in the neuronal markers, N acetyl aspartate/creatine ratio and increase in the glial marker myo-Inositol, in subjects with Mini-Mental State Examination scores greater than 24 and with no signs of atrophy in their MRI of the medial temporal lobe. Abnormalities in components of the auditory event-related potentials (ERPs) are described in cognitive impairment including AD. We observed a significant decrease in amplitude and increase in latency during the first 10 ms of auditory evoked potentials measured on electroencephalography (EEG) indicating slow auditory response of the brainstem. EEG spectral power recorded at the cortex is also associated with neural activity at the level of the inferior colliculi. We postulate that a functional examination of auditory afferent pathways, using non-invasive techniques, such as MRS, brain stem auditory evoked potentials (BAEPs) and ERPs may improve diagnostic accuracy of AD. Functional changes precede structural changes and it is important to further understand the relationship between biochemical and electrophysiological measures such as MRS, BAEPs and EEG.

Normative data for brainstem auditory evoked potential responses in North Indian menopausal females

Background: Ovarian hormones are known to influence central neuronal functioning. Many studies have established the brainstem auditory evoked potential (BAEP) pattern vis-à -vis the cyclical fluctuations of these hormones in young females; however, there is a paucity of research involving BAEP patterns among menopausal females. Aim: This study was conducted to provide normative values for various BAEP parameters in menopausal females from North India. Materials and Methods: A cross-sectional study was done on 100 females aged 46–70 years. BAEP recording was done using a standardized protocol. The data were analyzed using SPSS software. It consisted of mean wave latencies I, II, III, IV, and V and interpeak latencies (IPL) I-V, I-III, and III-V. Student's unpaired t-test was used for statistical analysis. Results: The average value of means of wave latencies and IPL from both the ears was obtained. The latencies of waves I, II, III, IV, and V were 1.82 ± 0.27 ms, 2.81 ± 0.27 ms, 4.09 ± 0.35 ms, 4.87 ± 0.33 ms, and 6.19 ± 0.31 ms, respectively. The mean values of IPL I-V, I-III, and III-V were 4.37 ± 0.38 ms, 2.26 ± 0.33 ms, and 2.1 ± 0.32 ms, respectively. Conclusion: The study findings compared favorably with already existing data from similar studies conducted elsewhere. The data from the present study would prove useful to the clinicians to detect subtle neurodegenerative changes at an early stage within the central auditory pathways, even in the absence of any perceptible hearing loss, in this subset of population.