Contralateral Ear Research Articles

Multicomponent tympanometry in ears with cochlear implant

Abstract Introduction: Multifrequency and multicomponent tympanometry procedures enable the evaluation of minute changes in the middle ear system and the estimation of resonant frequency. Changes in the resonant frequency beyond normative values indicate the presence of pathology or change in the natural characteristics of the middle ear. The present study aimed to investigate if there is a difference in the admittance of the middle ear on the side of cochlear implantation and the contralateral ear for different probe tones. The study also investigated if there was a difference in the type of multicomponent tympanogram obtained in ears that have undergone cochlear implantation when compared to the contralateral ear. Methods: Twenty children in the age range of 4–14 years with bilateral severe to profound sensorineural hearing loss, having undergone unilateral cochlear implantation, were included in the study. Tympanometry using four probe-tone frequencies (226 Hz, 678 Hz, 800 Hz, and 1000 Hz) was carried out in each ear. Total compliance (Y) and type of tympanogram were compared across the ear with cochlear implantation and the contralateral ear. Results: It was found that the implanted ears had lower mean admittance values as compared to the contralateral side at all four probe-tone frequencies. Wilcoxon signed-rank test indicated that the difference was statistically significant for 226 Hz, 678 Hz, and 800 Hz probe tones, suggesting increased stiffness in the ear with cochlear implantation. There was a significant difference in the type of tympanograms obtained in the two ears for 800 Hz and 1000 Hz probe-tone frequencies. Conclusions: These results warrant the testing of the contralateral ear for obtaining electrically evoked stapedial reflex thresholds (eSRT).

The Effect of Electromagnetic Interference Produced by Smartphones Using 5G Network on Patients With Permanent Pacemakers (EMS5G‐PPM Study)

Background: The safety of new‐generation mobile phones using 5G networks in patients with modern‐generation pacemakers has not been studied.Objectives: This study aimed to compare the risk of electromagnetic interference (EMI) generated by a new‐generation mobile phone with 5G networks when positioned at the pacemaker pocket or the contralateral ear and assess the incidence of EMI with telemetry interrogation in patients with permanent pacemakers.Methods: We enrolled 489 patients with pacemakers from three different manufacturers. The pacemaker mode was programmed for overdrive pacing and sensing mode if an intrinsic rhythm was present. A smartphone (Samsung S21 + 5G) was placed directly over the pulse generator and right ear. The phone was tested under standby mode, 5G internet connection, and incoming and outgoing calls for each location. Real‐time electrocardiography (ECG) monitoring and patient symptoms were recorded to determine the occurrence of EMI. The possibility of EMI with interrogation telemetry was also investigated.Results: A total of 4824 tests were performed on 489 patients. Most pacemakers were dual‐chamber (82%) or magnetic resonance imaging (MRI)‐compatible systems (83%). EMI was not detected with both mobile phone positions. Interference with telemetry was demonstrated in 11.5% of patients. Almost all incidences of interference (98.2%) occurred during incoming calls. Single‐chamber pacemakers, non‐MRI‐compatible systems, older pulse generators, older leads, and unipolar settings were significantly related to a higher incidence of interference with interrogation telemetry.Conclusions: The risk of EMI between modern smartphones with 5G networks and pacemakers is low. Nevertheless, interference with the interrogation telemetry may still occur.

Effects of Drilling in Mastoid Cavity over Hearing in the Contralateral Ear

Effects of Drilling in Mastoid Cavity over Hearing in the Contralateral Ear

Bilateral and symmetric glycinergic and glutamatergic projections from the LSO to the IC in the CBA/CaH mouse.

Auditory space has been conceptualized as a matrix of systematically arranged combinations of binaural disparity cues that arise in the superior olivary complex (SOC). The computational code for interaural time and intensity differences utilizes excitatory and inhibitory projections that converge in the inferior colliculus (IC). The challenge is to determine the neural circuits underlying this convergence and to model how the binaural cues encode location. It has been shown that midbrain neurons are largely excited by sound from the contralateral ear and inhibited by sound leading at the ipsilateral ear. In this context, ascending projections from the lateral superior olive (LSO) to the IC have been reported to be ipsilaterally glycinergic and contralaterally glutamatergic. This study used CBA/CaH mice (3-6 months old) and applied unilateral retrograde tracing techniques into the IC in conjunction with immunocytochemical methods with glycine and glutamate transporters (GlyT2 and vGLUT2, respectively) to analyze the projection patterns from the LSO to the IC. Glycinergic and glutamatergic neurons were spatially intermixed within the LSO, and both types projected to the IC. For GlyT2 and vGLUT2 neurons, the average percentage of ipsilaterally and contralaterally projecting cells was similar (ANOVA, p = 0.48). A roughly equal number of GlyT2 and vGLUT2 neurons did not project to the IC. The somatic size and shape of these neurons match the descriptions of LSO principal cells. A minor but distinct population of small (< 40 μm2) neurons that labeled for GlyT2 did not project to the IC; these cells emerge as candidates for inhibitory local circuit neurons. Our findings indicate a symmetric and bilateral projection of glycine and glutamate neurons from the LSO to the IC. The differences between our results and those from previous studies suggest that species and habitat differences have a significant role in mechanisms of binaural processing and highlight the importance of research methods and comparative neuroscience. These data will be important for modeling how excitatory and inhibitory systems converge to create auditory space in the CBA/CaH mouse.

The Effect of Simultaneous Contralateral White Noise Masking on Cortical Auditory Evoked Potentials Elicited by Speech Stimuli.

Introduction Noise obscures speech signal, causing auditory masking. The effects of this masking can be observed through the cortical auditory evoked potentials (CAEPs). White noise, in turn, has an effect on the auditory cortex, interfering, for example, with lexical decision making. Objective To analyze the effect of simultaneous masking by contralateral white noise on CAEPs elicited by speech stimuli. Methods Cross-sectional observational analytical study carried out with 15 participants of both sexes, who were submitted to CAEPs in two conditions: 1) without noise; 2) with white noise at 100 dBSPL intensity, contralaterally and simultaneously. To compare these conditions, the Student t test or the Wilcoxon test were used, depending on the sample normality. Differences with p values < 0.05 were considered significant. Results : When white noise was presented contralaterally and simultaneously to the CAEPs with speech stimulus, an increase in P1, N1 and P2 wave latencies was observed. P1 and P2 amplitudes and N1-P2 peak to peak amplitude also increased, unlike N1 amplitude, which decreased. The differences were significant for P1 and P2 wave latencies and for P2 wave amplitude. Conclusion The simultaneous masking effect was observed from the morphological alterations of the CAEPs with speech stimulus when white noise was presented in the contralateral ear. There was a significant increase in P1 and P2 wave latencies, as well as in P2 wave amplitude.

Surface scanning and 3D printing for optimized partial auricular reconstruction

We present the resolution of a case of a 50-year-old patient who presented for excision and reconstruction of a malignant skin lesion at the auricular tubercle of the right helix. The patient reported great concern for the aesthetic outcome. The auricular helix has a unique projection, relief, consistency, and size determined by the contralateral side. Its reconstruction is a surgical challenge and requires sophisticated techniques to achieve good results. Therefore, in cases where we are looking for precision and predictability, 3D technology is a great help for the surgeon as it allows pre-surgical patient-specific planning and the printing of sterilisable models that serve as surgical 3D guides. This case was solved with a two-stage reconstruction. First, the lesion was excised, and a retro auricular advancement flap was placed. In the second stage, the placement of cartilage was sectioned using a customised surgical model obtained from the scanning of the contralateral ear surface. This way, the cartilage donor area was optimised, choosing the most similar shape and size with great precision.

New Strategies for Remnant Ear Treatment in Microtia Reconstruction Based on Morphometric Studies.

Given the lack of specific evaluation indices, it is difficult to determine whether to transpose or abandon remnant ears in lobule-type microtia reconstruction. The authors illuminate referable parameters beneficial for proper treatment of remnant ear in an efficient manner. A series of 359 lobule-type microtia patients underwent autogenous costal cartilage auricular reconstruction between 2016 and 2021. Fourteen measuring points and defined distances as well as six ratios of specific distances based on position, plumpness, similarity and the width-to-length ratio of the remnant ear have been described, and relevant tactics for appropriate treatments are introduced. Definite morphometric results contribute to attaining satisfactory contours of reconstructed auricles with harmonious earlobes, which exhibit highly similar dimensions and appearances compared to the contralateral normal ears. With the help of the proposed locating points and measuring approaches, the procedure of remnant ear treatment is systematically clarified. This technique ensures operation safety and contributes to the aesthetic contour of the auricle. IV Laryngoscope, 134:2741-2747, 2024.

Endolymphatic hydrops asymmetry distinguishes patients with Meniere's disease from normal controls with high sensitivity and specificity.

Many endolymphatic hydrops (EH) MRI studies in the literature do not include a normal control group. Consequently, it remains unclear which outcome measure in EH MRI can most effectively distinguish between MD patients and normal controls. Gadolinium-enhanced EH imaging was performed to quantitatively evaluate the extents of hydrops in MD patients and age-/sex-matched normal controls. Four hours after intravenous injection of contrast agent, MRI was performed using a 3-T MR platform fitted with a 32-channel phased-array coil receptor. MR images (10-15 slices) covering an inner ear were 3D-stacked. Analyses of all images that included the vestibule or the cochlea yielded the volumes (in μL) of the endolymphatic and perilymphatic spaces. For the vestibule, they were significantly greater EH% in ipsilateral (52.4 ± 12.5) than in contralateral MD ears (40.4 ± 8.5, p = 0.001) and in ipsilateral MD ears than in control ears (42.4 ± 13.7, p = 0.025). For the cochlea, the values were slightly higher EH% in ipsilateral MD ears (49.7 ± 10.4, p = 0.061) but did not significantly differ from contralateral (41.3 ± 12.6) or control ears (39.6 ± 18.9, p = 0.858). In the MD group, the EH asymmetries were 12.0 ± 10.2% (vestibule) and 8.4 ± 8.6% (cochlea), significantly larger than those of controls. Compared to conventional semiquantitative grading or quantitative EH% analysis, EH asymmetry may better distinguish MD patients from normal controls. Quantitative hydrops volumetric analysis yields clinically relevant information on inner ear function.

Investigation of the phytochemical composition and anti-inflammatory properties of Afzelia africana leaves

Introduction: Afzelia africana is a large tree that is widespread in West Africa. Its bark is used in traditional medicine to treat rheumatism, edema, and pain. In our previous researches, we studied the phytochemical characteristics of the aqueous extract of trunk bark, which showed a high content of phenolic compounds and particularly flavonoids, which are known to have anti-inflammatory properties. This extract has been formulated as a topical hydrogel, and preclinical animal studies on the chronic and acute inflammation model have demonstrated anti-inflammatory activity comparable to that of diclofenac with an inhibition rate of 85.31%. With the aim of industrial production of improved traditional medicine, while preserving biodiversity, we investigated whether the leaves of A. africana could advantageously replace the trunk back. The objectives were to first study the phytochemically composition of the aqueous and hydroethanolic extracts of the leaves in comparison to that of the trunk bark, and then to evaluate its anti-inflammatory activity in an animal model.&#x0D; Methodology: The main families of secondary metabolites were investigated in the aqueous and hydroethanolic extracts. The polyphenol and flavonoid contents were determined by spectrophotometric assay, and the results were expressed as gallic acid equivalents and quercetin equivalents, respectively. Anti- inflammatory activity was determined using an acute ear inflammation model induced by topical application of xylene in mice. Mice were divided into four groups. In the negative control group, mice were not treated; betamethasone was used as a positive control; aqueous and hydroethanolic extracts were administered at a dose of 20 mg per ear. Doses were administered topically to mice. The contralateral ear served as a control. All animals were sacrificed 0.5, 1, and 4 hours after xylene, and then two ears were cut along the pinna. The pinna was harvested and weighed. The inhibition rate was calculated in the different groups. Structural changes in the inner ear wall after xylene application were evaluated by histology on sections of the animals' ears.&#x0D; Results: The results showed that, the aqueous leaf extract of A. Africana has a similar secondary metabolite composition to the trunk bark extract, containing tannins, alkaloids, flavonoids, steroids, coumarins, and quinones. The aqueous and hydroethanolic leaf extracts contained similar levels of total polyphenols, with&#x0D; 196.44 ± 4.22 and 214.58 ± 1.78 mg/g in gallic acid equivalents, respectively. The hydroethanolic leaf extract contained significantly higher levels of flavonoids than the aqueous leaf extract, with 59.16 ± 0.22 mg/g in&#x0D; &#x0D; quercetin equivalents compared to 32.23 ± 4.22 mg/g. In addition, the flavonoid content of the aqueous leaf extract was comparable to that of the trunk bark, with 25.8 mg/g ± 0.26. Treatment with the aqueous and hydroethanolic extracts of A. Africana leaves significantly inhibited ear edema 0.5, 1, and 4 hours after xylene application, with inhibition percentages of 44.49% and 12.39% after 0.5 hour, 80.26% and 80.67% after 1 hour, and 63.97% and 49.44% after 4 hours respectively. These inhibition percentages were comparable to those of animals treated with betamethasone, which had inhibition percentages of 56.38%, 75.30%, and 76.39% after 0.5, 1, and 4 hours, respectively.&#x0D; Conclusion: The trunk bark of A. Africana is used in traditional medicine to treat inflammatory diseases and pain. Its topical application inspired us to study the phytochemical composition and anti-inflammatory activity of the trunk bark. Although it demonstrated an interesting anti-inflammatory potential, in order to protect this precious resource, we investigated the potential of the leaves. The phytochemical study showed that, as for the trunk bark, the leaves have a high content of active metabolites, particularly polyphenols, which are known for their anti-inflammatory potential. The anti-inflammatory activity of the leaf extracts has been demonstrated, making the leaves a good candidate for the development of improved traditional medicines.

Distributional comparison of different AAV vectors after unilateral cochlear administration.

The adeno-associated virus (AAV) gene therapy has been widely applied to mouse models for deafness. But, AAVs could transduce non-targeted organs after inner ear delivery due to their low cell-type specificity. This study compares transgene expression and biodistribution of AAV1, AAV2, Anc80L65, AAV9, AAV-PHP.B, and AAV-PHP.eB after round window membrane (RWM) injection in neonatal mice. The highest virus concentration was detected in the injected cochlea. AAV2, Anc80L65, AAV9, AAV-PHP.B, and AAV-PHP.eB transduced both inner hair cells (IHCs) and outer hair cells (OHCs) with high efficiency, while AAV1 transduced IHCs with high efficiency but OHCs with low efficiency. All AAV subtypes finitely transduced contralateral inner ear, brain, heart, and liver compared with the injected cochlea. In most brain regions, the enhanced green fluorescent protein (eGFP) expression of AAV1 and AAV2 was lower than that of other four subtypes. We suggested the cochlear aqueduct might be one of routes for vectors instantaneously infiltrating into the brain from the cochlea through a dye tracking test. In summary, our results provide available data for further investigating the biodistribution of vectors through local inner ear injection and afford a reference for selecting AAV serotypes for gene therapy toward deafness.

Symmetrical placement of bilateral percutaneous bone-anchored hearing systems via guide-marker.

To investigate the use of a novel technique to estimate the symmetrical placement of percutaneous bone-anchored hearing systems (BAHS) with a guide-marker in patients undergoing bilateral surgery with this device. Prospective cohort study. A guide-marker and anatomical landmarks were used to estimate the implant placement and transferred to the contralateral ear in 12 subjects eligible for bilateral BAHS surgery. To investigate the bilateral symmetry, preoperative tri-dimensional (3D) computed tomography (CT) image reconstruction was used to compare the distances between the mandibular condyle and implant placement estimation (mandible-implant distance) in both the right and left ears of the subjects. The guide-marker could be used to estimate the bilateral implant placement in all subjects included in this study, simply and easily, including one subject with craniofacial malformation. The mean mandible-implant distances were 5.37 and 5.38 cm, in the right and left ears of the subjects, respectively, and no differences were observed between them, thereby indicating optimal bilateral symmetry. The use of the guide-marker proved to be an effective tool to provide symmetrical placement of bilateral BAHS. We propose a novel method employing a simple guide-marker and tracing based on symmetrical anatomical landmarks to achieve precise placement and optimal symmetry and which may be easily adopted in the surgical routine of BAHS. 3.

Audiometric evaluation in different clinical presentations of otitis media

ObjectivesTo assess the hearing thresholds in acute otitis media, otitis media with effusion and chronic otitis media (non-suppurative, non-cholesteatomatous suppurative and cholesteatomatous) and to compare the hearing outcomes with non-diseased ears (in bilateral cases) or contralateral healthy ears (in unilateral cases), since hearing loss is the most frequent sequel of otitis media and there is no previous study comparing the audiometric thresholds among the different forms of otitis media. MethodsCross sectional, controlled study. We performed conventional audiometry (500–8000Hz) and tympanometry in patients with otitis media and healthy individuals (control group). Hearing loss was considered when the hearing thresholds were > 25 dBHL. ResultsOf the 112 patients diagnosed with otitis media (151 ears), 48 were men (42.86%) and 64 were women (57.14%). The average age was 42.72 years. Of those, 25 (22.32%) were diagnosed as AOM, 15 (13.39%) were diagnosed with OME and the remaining 72 (63.28%) were diagnosed with COM (non-suppurative COM, n=31; suppurative COM, n=18; cholesteatomatous COM, n=23). As compared with controls, all forms of otitis media had significantly higher bone-conduction thresholds (500–4000Hz). Conductive hearing loss was the most frequent type of hearing loss (58.94%). However, the number of patients with mixed hearing loss was also relevant (39.07%). We noted that the presence of sensorioneural component occurred more frequently in 1) Higher frequencies; and 2) In groups of otitis media that were more active or severe in the inflammatory/infective standpoint (AOM, suppurative COM and cholesteatomatous COM). ConclusionAll types of otitis media, even those with infrequent episodes of inflammation and otorrhea, had worse bone conduction thresholds as compared with nondiseased ears (p<0.01). We observed worse hearing outcomes in ears with recurrent episodes of otorrhea and in ears with AOM, especially in high frequencies.

Idiopathic Sudden Sensorineural Hearing Loss, But Not Compatible With the Classical Definition.

The purpose of this study was to raise awareness for patients who did not meet the audiometric criteria of idiopathic sudden sensorineural hearing loss (SSNHL) but complained of acute hearing loss. Medical records of patients who were diagnosed with SSNHL from October 2021 to March 2023 were examined retrospectively. Among 223 patients with SSNHL, 40 cases with atypical SSNHL and fitting in the criteria were included in the study. The patients who were included in this study were the ones who were given one bolus dose of IV systemic steroid (250 mg methylprednisolone with a proton pump inhibitor) and betahistine 2x24 mg po for a month. Pure tone audiometry was performed during the initial visit, on the fifth day, and at the end of the one-month usage of betahistine tablets. Hearing levels on the 250, 500, 1,000, 2,000, 4,000, and 8,000 Hz of the affected ear were compared with those of the contralateral ear. Hearing improvement was calculated as the hearing gain (in decibels) on the control audiograms and the resolution of the patients' complaints. These patients were suffering from idiopathic SSNHL with minimal hearing impairment. A total of 36 of the cases had hearing recovery on the fifth-day audiogram, and the remaining four patients showed hearing improvement on the first-month audiogram. The changes between the initial and the control audiogram values were found to be statistically significant (p<0.001). Additionally, these patients showed distinctive characteristics, such as being younger than the classical SSNHL population, lacking systemic diseases (diabetes or hypertension), and having good unaffected hearing. Although there have been lots of studies to understand the pathophysiology, prognostic factors, and treatment options for SSNHL, atypical SSNHL patients have been underestimated and generally excluded from studies, and there have been a small number of studies on this issue. These patients might be accepted as having mild hearing loss. However, when the nerve injury is proven by audiograms, it is hard to decide what to do due to the lack of a treatment approach. This study is important as it focuses on atypical SSNHL cases. Further studies with larger group patients or prospective randomized-controlled group studies are needed to define these patients and decide how to treat this type of acute nerve dysfunction.

Otoscopic, radiological and audiological status of the contralateral ear in patients with unilateral chronic suppurative otitis Media

As the disease process does not affect both the ears simultaneously in all the cases, it is possible to identify in early stages of the disease process and arrest further progression by timely intervention. Hence, we aim to study the anatomical and functional changes in contralateral ear (CLE) in pts with unilateral CSOM. prospective observational study, of 75 patients attending the OPD of JLN hospital and research center, Bhilai, with unilateral CSOM, with intact TM in CLE were evaluated by otoscope, PTA, Impedance audiometry and CT temporal bone. Above observations were recorded and analyzed. 44% in our study showed abnormal TM, most common was TM retraction, seen in 22.66%. PTA showed mixed hearing loss in 5.33% and normal hearing in 66.66%. Impedance audiometry had A type graph in 82.66%, As type in 10.66%. Compliance was normal in 82.66% and decreased in 10.66%. Pressure was normal in 97.33% and was decreased in 2.66%. Normal, well pneumatized air cells in HRCT temporal bone seen in 90.66% and opacified in 12%.A detailed otoscopic evaluation of the contralateral ear plays a vital role in early diagnosis of the pathology affecting the contralateral ear. Audiological evaluation of the contralateral ear by audiometry and tympanometry provides a pathway for detecting the functional abnormalities in the contralateral ear at an early stage. Knowing the radiological status of the contralateral ear can guide us to monitor the disease progression and plan accordingly.

Application of stereoscopic unequal S-plasty for reconstuction of the congenital hypoplastic ear lobe cleft associated with soft tissue deficiency

Objective: To explore the ideal way of using the stereoscopic unequal S-plasty in reconstruction of the congenital hypoplastic ear lobe cleft with soft tissue deficiency. Methods: Data of 10 patients with the congenital hypoplastic ear lobe cleft associated with soft tissue deficiency who were treated using the stereoscopic unequal S-plasty in the plastic cosmetic surgery of Xuzhou Central Hospital from Aug 2018 to Aug 2022 were retrospectively analyzed. Six patients were male, 4 were female. Their ages ranged from 6 years to 19 years old, with a mean age of 13 years. Lobe deficiency size ranged from 0.8 cm×0.5 cm to 1.2 cm×1.0 cm. Results: The post-operation flaps had no venous congestion, infection or necrosises. During 3 to 12 months of follow-up, the technique made the shape of the ear lobe smoother. The incisions left inconspicuous scars. The result was satisfactory in terms of matching the contralateral normal ear lobe in shape and symmetry. Doctors and patients were satisfied with the results. Conclusions: The stereoscopic unequal S-plasty is an effective way to correct the the severe congenital ear lobe deformity. The good result,simple manipulation and short operation time are the advantages of this method.

Comparing the influence of auditory streaming cues on binaural pitch fusion in normal-hearing and hearing-impaired listeners

Binaural pitch fusion occurs when dichotic signals eliciting a different pitch are perceived as one sound. Previously, we investigated the effects of auditory streaming cues on binaural fusion using a modification of the ABA streaming paradigm. A dichotic stimulus (fixed tone at frequency fref in the reference ear and variable frequency in the contralateral ear) was presented at alternating intervals with up to 3 “capture” tones at fref. Participants reported whether they perceived galloping or two streams. Binaural fusion frequency range decreased with the number of capture tones and longer inter-stimulus intervals (ISIs), suggesting competition of sequential grouping with capture tones versus simultaneous grouping (fusion) with the dichotic tone. In the present study, we compared the effects in NH and hearing-impaired (HI) listeners. Preliminary data from 13 NH and 5 HI listeners suggest greater reductions in fusion range with number of capture tones and with longer ISI in HI listeners, especially in listeners with broad binaural fusion. These findings indicate that auditory grouping cues can reduce binaural fusion in both NH and HI listeners. Funded by NIH/NIDCD R01DC013307.

Investigating the effect of cochleotopic region on temporal processing using binaural fusion

Processing of temporal information in a signal may vary across apical, mid and basal regions of the cochlea—there is evidence for this in both cochlear-implant and typical-hearing listeners. This effect may also be task dependent and has not been studied with respect to binaural fusion. Fusion depends on tracking the temporal fluctuations across ears which can be manipulated by varying the interaural correlation (IC) of a signal. To investigate the effect of place of stimulation on fusion, 9 bilateral cochlear implant users were presented with 1000 Hz pulse trains with varying envelope IC. An apical, mid, and basal electrode were separately selected as reference, each of which was then paired with five electrodes in the contralateral ear, spread across the array. Listeners indicated the spatial diffuseness and the number of auditory “images” of the perceived sound by manipulating a visual representation of their perception superimposed on a picture of a head. Preliminary results indicate that, for optimally paired electrodes, fusion increases similarly for the three regions of the cochlea with increasing IC, and when IC is 1, the degree of fusion is comparable across regions. Processing of temporal information for binaural fusion is not significantly different across cochleotopic regions.

What, if anything, is coincidence detection?

Neural delays and coincidence detection are neural operations posited as key elements in temporal processing, in the auditory system and beyond. Although longstanding physiological evidence for coincidence detectors exists at a phenomenological level, mechanistic examinations have only recently been performed. We review intracellular recordings from two cell types which are traditionally regarded as prototypes of coincidence detectors. Neurons in the medial superior olive (MSO) are sensitive to “coincidences” in action potentials from the ipsi- and contralateral ear, making the neurons sensitive to interaural temporal differences. Octopus cells in the cochlear nucleus are sensitive to “coincidences” of action potentials across inputs tuned to a wide range of frequencies. We found that in both cases, the spike output of neurons does not simply reflect coincidences of input spikes. When inputs vary in strength, their sequence of activation is an important determinant of response strength. Maximal output is not just determined by the maximal number of coincidences, but reflects temporal input structure in interaction with intrinsic (membrane) properties. These observations suggest a simpler mechanism of temporal sensitivity than traditional lag and coincidence proposals.

Evaluation of Role of Prognostic Factors on Hearing Outcome in Unilateral Idiopathic Sudden Onset Sensorineural Hearing Loss

Introduction: Owing to its uncertain and multiple possible etiologies, use of multiple empirical treatment regimens and possibility of spontaneous recovery, it becomes important to look for the possible prognostic factors affecting the outcome of sudden sensorineural hearing loss (SSNHL). Material and methods: This prospective observational study was conducted with the primary aim of analyzing the role of various possible prognostic factors on the outcome of idiopathic SSNHL including demographic (Age, gender), audio-vestibular (Pre-treatment hearing loss in the affected ear, hearing in the contralateral ear, time elapse between onset of hearing loss and start of treatment, type of hearing loss in term of frequencies affected), presence of tinnitus / vertigo and Comorbidities (Diabetes, Hypothyroidism &amp; Deranged lipid profile/ dyslipidemia). Result: The absence of vertigo and tinnitus led to better hearing outcomes while raised HbA1c levels, deranged lipids and thyroid profiles adversely affected the outcome. Conclusion: Vertigo, tinnitus, raised HbA1c levels, deranged lipids and thyroid profiles are possible negative prognostic factors. Better pretreatment hearing levels in the affected and unaffected ears prompted improved recovery.

Clinical characteristics and prognosis of sudden sensorineural hearing loss in single-sided deafness patients.

Sudden sensorineural hearing loss (SSNHL) in patients with single-sided deafness (SSD) is rare. The prognosis of the sole serviceable hearing ear is very important for these patients. However, the clinical characteristics and prognosis of SSNHL in SSD patients are not well-documented. This study aimed to investigate the clinical features and treatment outcomes of SSNHL in SSD patients. Clinical data of 36 SSD patients and 116 non-SSD patients with unilateral SSNHL from January 2013 to December 2022 were retrospectively investigated. The clinical characteristics of the SSD patients were analyzed. All SSD patients were treated with intratympanic steroids plus intravenous steroids. Pure-tone average (PTA) and word recognition score (WRS) before and after treatment were recorded. The hearing recovery of SSNHL in SSD patients in comparison with non-SSD patients was explored. Auditory outcomes in SSD patients with different etiologies were also compared. Initial hearing threshold showed no significant differences between the SSD group and the non-SSD group (66.41 ± 24.64 dB HL vs. 69.21 ± 31.48 dB HL, p = 0.625). The SSD group had a higher post-treatment hearing threshold (median (interquartile range, IQR) 53.13(36.56) dB HL) than the non-SSD group (median 32.50(47.5) dB HL, p < 0.01). Hearing gains (median 8.75(13.00) dB) and the rate of significant recovery (13.89%) were lower in the SSD group than in the non-SSD group (median 23.75(34.69) dB, 45.69%). The etiology of SSD was classified as SSNHL, special types of infection, chronic otitis media, and unknown causes. SSNHL accounted for the maximum proportion (38.9%) of causes of SSD in the SSD group. Hearing gains were lower in the SSNHL-SSD group than in other causes of the SSD group. A binary logistic regression analysis demonstrated that SSD serves as an indicator of unfavorable hearing recovery outcomes (OR = 5.264, p < 0.01). The prognosis of SSNHL in SSD patients is unsatisfactory. SSNHL accounts for the maximum proportion of causes of SSD in this group of patients. For SSD patients caused by SSNHL, less hearing improvement after treatment was expected when SSNHL occurred in the contralateral ear in comparison with SSD patients with other causes.