Ipsilateral Ear Research Articles

Extent of Pain Distribution in Entrapment of the Greater Occipital Nerve Identified Through Skin Lesions of Herpes Zoster Involving the Greater Occipital Nerve

Herpes zoster (HZ) involving the upper cervical nerves (C2-C4), which innervate the posterior head, is rare. There have also been few reports of HZ lesions involving the greater occipital nerve (GON), which refers to the medial branch of the dorsal ramus of the second cervical nerve. Pain due to GON entrapment radiates not only to the temporo-occipital region, but also to the ear, retro-auricular and sub-auricular areas of the neck, the angle of the jaw, and the posterolateral neck. Herein, we present the case of a patient who underwent decompression surgery for referred trigeminal pain due to GON entrapment and who developed HZ one week later. Skin lesions of HZ involving the GON occurred not only in the occipital area but also in the ipsilateral ear, auricle, posterior and anterolateral neck. This case of HZ involved all cutaneous areas innervated by the C2, C3, and C4 spinal nerves. The extent of the skin lesions indicated where the pain from the GON radiated.

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.

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.

COX inhibitor use during definitive radiotherapy is associated with worse hearing preservation in patients with vestibular schwannoma.

Patients with vestibular schwannoma undergoing definitive radiotherapy commonly experience hearing loss due to tumor and treatment effects; however, there is limited data evaluating concurrent medication use and other clinicopathologic factors associated with hearing preservation during and after radiotherapy. We performed a retrospective cohort study reviewing consecutive patients from 2004 to 2019 treated with radiotherapy for vestibular schwannoma at our institution. Ninety four patients with concurrent medications, baseline audiograms, and post-radiotherapy audiograms available were evaluable. We performed chi-squared analyses of the frequency of various clinicopathologic factors and t-tests evaluating the degree of hearing loss based on audiograms. At a median follow-up of 35.7months (mean: 46.5months), the baseline pure-tone average (PTA) of the ipsilateral ear worsened from 38.4 to 59.5dB following completion of radiotherapy (difference: 21.1, 95% CI 17.8-24.4dB, p < 0.001). 36 patients (38.3%) reported regular use of cyclooxygenase (COX) inhibitors (including acetaminophen and NSAIDs) during radiotherapy. The mean increase in PTA was significantly higher for patients taking COX inhibitors (25.8dB vs 18.1dB, p = 0.024) in the ipsilateral ear but not for the contralateral side. COX inhibitor use remained independently associated with worse PTA in the multivariate analysis. COX inhibitor use during definitive radiotherapy is associated with worse hearing loss in the affected ear but not for the contralateral side. This suggests the ototoxic effects of COX inhibitors may influence the effects of radiotherapy. These results could have clinical implications and warrant further investigation.

Voice matching in sung duos: Is it related to spectrum envelopes?

Choir singers report anecdotally that two voices can be perceived as a good match for each other, or not. Could “matching voices” be explained by the spectrum envelopes? Thirteen singers sang a duo in unison or canon with an adjacent prerecorded reference singer, in a moderately reverberant room. Singers controlled the stimulus timbre, using variable filters in medium and high frequency bands. They were asked to adjust the filters, while singing, for “best” and “worst” perceived matching. The singers then performed the song again, but with the filters automatically set to their chosen (dis-)preferences. The Self-to-Other ratio as a function of frequency [SOR(f)] at the ipsilateral ear of the participant was estimated from multiple microphone signals to predict separately the long-time average spectra of Self and Other. Most participants rated the sound with extreme filter settings at ±15 dB as the “worst” match, while “best” matches were fairly evenly distributed. Some but not all participants preferred the spectra to be complementary. However, at low frequencies, SOR(f) was about +10 dB, and very irregular but rarely negative at medium and high frequencies; so how an adjacent singer can be heard at all will require further investigation.

A Novel Method to Determine the Maximum Output of Individual Patients for an Active Transcutaneous Bone Conduction Implant Using Clinical Routine Data.

The maximum output provided by a bone conduction (BC) device is one of the main factors that determines the success when treating patients with conductive or mixed hearing loss. Different approaches such as sound pressure measurements using a probe microphone in the external auditory canal or a surface microphone on the forehead have been previously introduced to determine the maximum output of active transcutaneous BC devices that are not directly accessible after implantation. Here, we introduce a method to determine the maximum output hearing level (MOHL) of a transcutaneous active BC device using patients' audiometric data. We determined the maximum output in terms of hearing level MOHL (dB HL) of the Bonebridge using the audiometric and direct BC threshold of the patient together with corresponding force levels at hearing threshold and the maximum force output of the device. Seventy-one patients implanted with the Bonebridge between 2011 and 2020 (average age 45 ± 19 years ranging from 5 to 84 years) were included in this study. The analyses of MOHLs were performed by (1) dividing patients into two groups with better or worse average audiometric BC threshold (0.5, 1, 2, 4 kHz), on the ipsilateral side or (2) by separating the MOHLs based on better or worse frequency-by-frequency specific audiometric BC thresholds on the ipsilateral (implanted) side. When using a frequency-by-frequency analysis obtained average ipsilateral MOHLs were in the range between 51 and 73 dB HL for frequencies from 0.5 to 6 kHz in the group with better audiometric BC threshold on the ipsilateral ears. The average contralateral MOHLs in the group with better contralateral hearing were in the range from 43 to 67 dB HL. The variability of the data was approximately 6 to 11 dB (SDs) across measured frequencies (0.5 to 6 kHz). The average MOHLs were 4 to 8 dB higher across frequencies in the group with better audiometric BC threshold on the ipsilateral ears than in the group with better audiometric BC threshold on the contralateral ears. The differences between groups were significant across measured frequencies ( t test; p < 0.05). Our proposed method demonstrates that the individual frequency-specific MOHL on the ipsilateral and contralateral side of individual patients with a transcutaneous BC device can be determined mainly using direct and audiometric BC threshold data of the patients from clinical routine. The average MOHL of the implant was found 4 to 8 dB higher on the ipsilateral (implanted) side than on the contralateral side.

Why should multiple dehiscences of the otic capsule be considered before surgically treating patients with superior semicircular canal dehiscence? A radiological monocentric review and a case series.

This review aims to draw attention to the multiple ipsilateral otic capsule dehiscences (OCDs), which may cause therapeutic failure in operated patients. A series of six severely disabled patients with symptoms and signs consistent with a superior semicircular canal dehiscence (SSCD) diagnosis, confirmed by a high-resolution CT scan, is presented here. Five of the patients underwent surgery, and in four of the cases, the postoperative results were poor and/or disappointing. The ethical principles underlying modern medicine encourage medical staff to learn from past experience even when the results are modest despite the accuracy of the treatment applied to a patient. Consequently, we reviewed the radiological records of symptomatic and asymptomatic patients diagnosed or referred to our center for confirmation over the past 5 years to determine the incidence of multiple OCD in this population. Multiple localizations of suspected OCD in the ipsilateral ear did not appear to be rare and were found in 29 of 157 patients (18.47%) in our retrospective review using high-resolution thin-sliced CT scans. The decision to perform surgery for a documented symptomatic superior SSCD should be made with caution only after ruling out concomitant lesser-known variants of OCD in the ipsilateral ear.

Automated Radiomic Analysis of Vestibular Schwannomas and Inner Ears Using Contrast-Enhanced T1-Weighted and T2-Weighted Magnetic Resonance Imaging Sequences and Artificial Intelligence.

To objectively evaluate vestibular schwannomas (VSs) and their spatial relationships with the ipsilateral inner ear (IE) in magnetic resonance imaging (MRI) using deep learning. Cross-sectional study. A total of 490 adults with VS, high-resolution MRI scans, and no previous neurotologic surgery. MRI studies of VS patients were split into training (390 patients) and test (100 patients) sets. A three-dimensional convolutional neural network model was trained to segment VS and IE structures using contrast-enhanced T1-weighted and T2-weighted sequences, respectively. Manual segmentations were used as ground truths. Model performance was evaluated on the test set and on an external set of 100 VS patients from a public data set (Vestibular-Schwannoma-SEG). Dice score, relative volume error, average symmetric surface distance, 95th-percentile Hausdorff distance, and centroid locations. Dice scores for VS and IE volume segmentations were 0.91 and 0.90, respectively. On the public data set, the model segmented VS tumors with a Dice score of 0.89 ± 0.06 (mean ± standard deviation), relative volume error of 9.8 ± 9.6%, average symmetric surface distance of 0.31 ± 0.22 mm, and 95th-percentile Hausdorff distance of 1.26 ± 0.76 mm. Predicted VS segmentations overlapped with ground truth segmentations in all test subjects. Mean errors of predicted VS volume, VS centroid location, and IE centroid location were 0.05 cm 3 , 0.52 mm, and 0.85 mm, respectively. A deep learning system can segment VS and IE structures in high-resolution MRI scans with excellent accuracy. This technology offers promise to improve the clinical workflow for assessing VS radiomics and enhance the management of VS patients.

Location of the AICA influences the severity but not occurrence of ISSNHL: A reappraisal using high-resolution 3 T MRI

ObjectiveTo investigate the potential influence of anatomical variation in the anterior inferior cerebellar artery (AICA) on the occurrence and severity of idiopathic sudden sensorineural hearing loss (ISSNHL). MethodsNinety ISSNHL patients were enrolled. The anatomical location of the AICA was exhibited using high-resolution magnetic resonance imaging (MRI), and the various AICA types classified by previously reported Chavda and Gorrie methods were analyzed. The severity of hearing loss in the ipsilateral ear among different AICA types was compared. ResultsApproximately 85.6% of subjects had unilateral ISSNHL (uISSNHL), and the others had bilateral ISSNHL (bISSNHL). In the uISSNHL group, the ratios of different AICA types were similar between the ipsilateral and contralateral ears. The ratios of the different AICA types in the bISSNHL group were similar to those in the uISSNHL group. In the uISSNHL group, pure tone audiometry (PTA) thresholds at 2 kHz, 4 kHz and 8 kHz of patients with Chavda type II AICA were higher than those of patients with Chavda type I and type III, with a significant difference at 4 kHz between type I and type II. There was a tendency of the PTA threshold in patients with Chavda type II or Gorrie type C to gradually increase from low to high frequency zones. ConclusionWhen the AICA enters the IAC (Chavda type II) or crosses between the 7th and 8th cranial nerves (Gorrie type C), the severity and frequency of hearing impairment in ISSNHL but not the occurrence of ISSNHL will be affected.

Inter-aural separation during hearing by bilateral bone conduction stimulation

Cross-head transmission inherent in bone conduction (BC) hearing is one of the most important factors that limit the performance of BC binaural hearing compared to air conduction (AC) binaural hearing. In AC, cross-head transmission is imperceptible leading to a clear understanding of the nature and position of the sound source(s). In this study, the prominence of cross-head transmission in BC hearing is addressed using the fact that ipsilateral cochlear excitation can be canceled by controlled bilateral BC stimulation.A cancellation experiment was conducted on twenty participants with normal hearing at thirteen third-octave frequencies between 250 and 4000 Hz. Both stationary and transient BC stimulation at the mastoid was used. The technique employed multiple stages of masking enabling adjustments of the stimulation level and phase until the tones got canceled in the ipsilateral ear. In addition, the ear canal sound pressure was obtained for ipsilateral and contralateral BC stimulation in isolation, and with bilateral BC stimulation at perceptual cancellation.The inter-aural level differences of both the types of stimulations were found to be the same. Crosstalk was found to be the lowest around 2 kHz and the highest around 1 kHz. The unwrapped inter-aural phase difference from stationary signal cancellation showed an overall increase with frequency starting at around no difference (35°) at 250 Hz to reach 607° at 4 kHz. Cycle-adjusted inter-aural time difference was very low (61 µs) at 250 Hz and increased to 1.1 ms at 800 Hz before falling to 0.6 ms at 4 kHz. It was also found that the ear canal sound pressure was not cancelled at the same phase as the sound in the cochlea.

Differentiating Meniere's Disease and Vestibular Migraine: Insights from Gadolinium-Enhanced Magnetic Resonance Imaging and Clinical Features.

To explore the predictive factors between Meniere's disease (MD) and vestibular migraine (VM) by Gadolinium-enhanced Magnetic resonance imaging (MRI) of the inner ear and Clinical Features. Eighty-seven patients (50 MD and 37 VM) underwent intratympanic injection of gadolinium and MRI was performed 24 h later. All patients underwent pure tone audiometry and caloric tests. In the MD group, 46 (92%) of 50 patients developed endolymphatic hydrops, although only 2 (5.4%) in the vestibular migraine (VM) group had positive results groups (p < 0.001). The incidence of migraine was 14% in the MD group and 67.7% in the VM group (p < 0.001). Multivariate logistic regression of the two groups of patients indicated that the greater the sum of the maximum slow phase velocity (SPV) of the ipsilateral ear, the higher the risk of VM occurrence (p = 0.009). The incidence of carsickness was positively correlated with the incidence of VM (p < 0.001) and asymmetric hearing loss (AHL) was negatively correlated with the diagnosis of VM (p = 0.045). Gadolinium-enhanced MRI of the inner ear is helpful for the differential diagnosis of VM and MD. Carsickness, decreased AHL, and increased Sum of the maximum SPV in the ipsilateral side (SSPVI) may act as diagnostic predictors of VM. 3 Laryngoscope, 134:426-432, 2024.

Frontofacial Features of Unilateral Lambdoid Craniosynostosis: A Multicenter Assessment

Background: Unilateral lambdoid craniosynostosis is differentiated from deformational plagiocephaly primarily by assessing the cranium from posterior and bird’s-eye views. Findings include posterior displacement of the ipsilateral ear, ipsilateral occipitomastoid bossing, ipsilateral occipitoparietal flattening, contralateral parietal bossing, and contralateral frontal bossing. Diagnosis based off facial morphology may be an easier approach because the face is less obstructed by hair and head-coverings, and can easily be assessed when supine. However, frontofacial characteristics of unilateral lambdoid craniosynostosis are not well described. Methods: A retrospective cohort review of patients with isolated, unilateral lambdoid craniosynostosis from the Children’s Hospital of Pittsburgh and the Children’s Hospital of Philadelphia was performed. Preoperative frontal and profile photographs were reviewed for salient characteristics. Results: Nineteen patients met inclusion criteria. Eleven patients had left lambdoid craniosynostosis, and eight had right lambdoid craniosynostosis. All patients were nonsyndromic. Patients demonstrated contralateral parietal bossing and greater visibility of the ipsilateral ear. Contralateral frontal bossing was mild. The orbits were tall and turricephaly was present in varying severity. Facial scoliosis as a C-shaped deformity was present in varying severity. The nasal root and chin pointed to the contralateral side. Conclusions: The combination of greater visibility of the ipsilateral ear, contralateral parietal bossing, and C-shaped convex ipsilateral facial scoliosis are hallmark frontofacial features of unilateral lambdoid craniosynostosis. Although the ipsilateral ear is more posterior, the greater visibility may be attributed to lateral displacement from the mastoid bulge. Evaluation of long-term postoperative results is needed to assess if this pathognomonic facial morphology is corrected following posterior vault reconstruction.

Spatial-dependent suppressive aftereffect produced by a sound in the rat's inferior colliculus is partially dependent on local inhibition.

In a natural acoustic environment, a preceding sound can suppress the perception of a succeeding sound which can lead to auditory phenomena such as forward masking and the precedence effect. The degree of suppression is dependent on the relationship between the sounds in sound quality, timing, and location. Correlates of such phenomena exist in sound-elicited activities of neurons in hearing-related brain structures. The present study recorded responses to pairs of leading-trailing sounds from ensembles of neurons in the rat's inferior colliculus. Results indicated that a leading sound produced a suppressive aftereffect on the response to a trailing sound when the two sounds were colocalized at the ear contralateral to the site of recording (i.e., the ear that drives excitatory inputs to the inferior colliculus). The degree of suppression was reduced when the time gap between the two sounds was increased or when the leading sound was relocated to an azimuth at or close to the ipsilateral ear. Local blockage of the type-A γ-aminobutyric acid receptor partially reduced the suppressive aftereffect when a leading sound was at the contralateral ear but not at the ipsilateral ear. Local blockage of the glycine receptor partially reduced the suppressive aftereffect regardless of the location of the leading sound. Results suggest that a sound-elicited suppressive aftereffect in the inferior colliculus is partly dependent on local interaction between excitatory and inhibitory inputs which likely involves those from brainstem structures such as the superior paraolivary nucleus. These results are important for understanding neural mechanisms underlying hearing in a multiple-sound environment.

Medical insurance coverage of radiosurgery for glossopharyngeal neuralgia in Korea

Glossopharyngeal neuralgia (GPN) is a cranial nerve rhizopathic disorder that presents as extreme neuralgic pain in the ipsilateral deep throat, tongue base, or ear. Attacks of pain are usually intense and electric shock-like, occurring either without warning or triggered by swallowing. GPN is roughly estimated to account for 1% of trigeminal neuralgia cases. Microvascular decompression (MVD) surgery for GPN is still challenging, but it can be a safe and efficient option, with an over 90% cure rate for neuralgic pain. However, the glossopharyngeal or vagus nerves are composed of thin and vulnerable bundles of fine fibers, making them sensitive to surgical manipulation, such as traction or compression. Disastrous side effects such as permanent swallowing difficulty, respiration difficulty, or fatal cardiac arrhythmia could occur during or after surgery. Furthermore, MVD may not be a suitable treatment option for elderly patients or those with serious medical conditions. Gamma Knife radiosurgery for patients with GPN has recently been covered by national medical insurance, in Korea.

Cochlear Implantation after Stereotactic Radiosurgery for Vestibular Schwannoma: Initial Hearing Improvement and Longevity of Hearing Restoration.

The following research question was asked: In patients with vestibular schwannoma (VS) that underwent stereotactic radiosurgery (SRS) and cochlear implantation, were improvements in hearing function observed, and what was the cochlear implant (CI) failure rate of in these patients? PubMed/Medline, CINAHL (EBSCOhost), and Web of Science articles without restrictions on publication dates were searched. Inclusion criteria required that the article was a report, a series, or a retrospective review with individual case data available. Non-English articles were excluded. Inclusion criteria required that patients were with VS and underwent subsequent SRS and cochlear implantation. Patients receiving microsurgery or stereotactic radiotherapy on the ipsilateral ear were excluded from this study. Included studies were evaluated using full-text evaluation, and data on study characteristics (author names, gender), clinical data (syndromic information, SRS modality), hearing outcomes, and device failure were extracted. Means and averages were obtained for all continuous variables. Percentages were ascertained for all categorical variables. The majority of patients undergoing CI placement in VS treated with SRS achieved open-set speech perception (79.2%) or environmental sound awareness (6.8%). Twelve implants (20.3%) failed. Three patterns were associated with failure: 1) immediate-onset failure, 2) initial benefit with delayed failure, 3) poor local control with device explantation.

Diagnosis and treatment of glossopharyngeal neuralgia

Background: Glossopharyngeal neuralgia (GPN) is a rare type of cranial nerve rhizopathy that accounts for roughly 1% of trigeminal neuralgia cases and presents as extreme neuralgic pain in the ipsilateral deep throat, tongue base, or ear. Pain is usually intense and electric shock-like, occurring either without warning or triggered by swallowing. The purpose of this article is to provide a comprehensive review of the diagnosis and treatment of GPN and to differentiate it from trigeminal neuralgia.Current Concepts: In this review, our experiences, including cases of misdiagnosis and diagnostic pitfalls, are presented in detail. Treatment of GPN with microvascular decompression (MVD) has a success rate of over 90%. The use of “off-the-root entry zone” MVD, which eliminates the need for an adjuvant rhizotomy, is the best treatment for GPN. In addition, although gamma knife radiosurgery is categorized as a destructive procedure, it can still be another option if a patient is ineligible for MVD.Discussion and Conclusion: Practitioners must consider GPN when diagnosing patients with cranial nerve rhizopathy; it should be distinguished from other pain syndromes, especially trigeminal neuralgia. With an accurate diagnosis, an appropriate treatment plan can be developed.

A Review of Eagle’s Syndrome

Eagle’s syndrome results from a calcified corresponding impact ligament or an elongated styloid process (ES). Neck or throat pain with ipsilateral ear radiation are other symptoms. Symptoms may be mistaken for facial neuralgias. Radiological and physical examinations may diagnose ES. ES is treated surgically. Intraoral or external procedures shorten the styloid process. The primary goal of this research was to investigate all aspects of Eagle’s syndrome that might be significant to its care and prognosis. In this study, we have used secondary research approach. In this paper, we analyzed several papers and articles to comprehensively review the Eagle’s syndrome. Our study demonstrates that an expanded styloid process isn't usually a sign of Eagle’s syndrome. Depending on the etiology, a prominent lateral misconfiguration can induce anything from a little cervicofacial irritation to deadly ischemic damage. The symptoms were caused by the styloid process's length and anterior angulation, not its medial angulation. Keywords: Eagle’s syndrome, elongated styloid, pain, sensation, treatment.

Analysis of auditory brain stem response and otoacoustic emission in unilateral tinnitus patients with normal hearing

ObjectiveIn patients with unilateral tinnitus with normal hearing, several studies have compared the ipsilateral and contralateral ears; however, few studies have investigated its relationship with the duration of tinnitus. We compared the auditory brainstem response and otoacoustic emission parameters between ipsilateral and contralateral ears in adults with unilateral tinnitus and normal hearing. MethodsThis retrospective review included 84 patients with unilateral tinnitus and normal hearing who underwent auditory brainstem response and otoacoustic emission; they were categorized according to the duration of tinnitus. The latencies and amplitudes of waves I, III, and V, and V/I ratio of both ears in auditory brainstem response, and the results of distortion-product otoacoustic emission and transient evoked otoacoustic emission were examined. The auditory brainstem response parameters, distortion-product otoacoustic emission parameters, and transient evoked otoacoustic emission parameters between the ipsilateral and contralateral ears along the duration of tinnitus were analyzed. Moreover, the failure rates of both distortion-product otoacoustic emission and transient evoked otoacoustic emission between the ears along with the duration and the effects of the variables on the amplitude and latency of each wave were examined. ResultsIn this study, laterality seemed to have an effect on wave I latency in the multiple linear regression analysis. The distortion-product otoacoustic emission failure rate of the ipsilateral ear was higher than that of the contralateral ear in all patients. However, there was no remarkable difference between the ears in the distortion-product otoacoustic emission and transient evoked otoacoustic emission parameters throughout the duration. ConclusionWe found that outer hair cells and the distal portion of the cochlear nerve are possible pathologic lesions in tinnitus with normal hearing and cochlear synaptopathy could be suspected. Further studies, including those on inner hair cells and higher central cortex, are needed.

Inter-Subject Variability in the Dependence of Medial-Olivocochlear Reflex Strength on Noise Bandwidth.

The objective of the study was to quantify inter-subject variability in the dependence of the medial-olivocochlear reflex (MOCR) on noise bandwidth. Of specific interest was whether inter-subject variability in MOCR dependence on bandwidth explained variability in the MOCR response elicited by wideband noise. Thirty-two young adults with normal hearing participated in the study. Click-evoked otoacoustic emissions were measured in the ipsilateral ear with and without noise presented in the contralateral ear. Presentation of contralateral noise served to activate the MOCR. The MOCR was activated using five different noise stimuli with bandwidths ranging from 1- to 5-octaves wide (center frequency of 2 kHz; bandwidth incremented in 1-octave steps). Noise spectral levels (19.6 dB SPL/Hz) were held constant across all bandwidths. MOCR metrics included the normalized-percent change in the otoacoustic emission (OAE), the MOCR-induced OAE magnitude shift, and the MOCR-induced OAE phase shift. Linear mixed-effect models were fit to model the dependence of MOCR-induced OAE magnitude and phase changes on noise bandwidth. The use of a mixed-effect modeling approach allowed for the estimation of subject-specific model parameters that capture on- and off-frequency contributions to the MOCR effects. Regression analysis was performed to evaluate the predictive capacity of subject-specific model parameters on the MOCR response elicited by wideband noise. All OAE-based MOCR metrics increased as the noise bandwidth increased from 1- to 5-octaves wide. The dependence of MOCR-induced OAE magnitude and phase shifts on activator bandwidth was well approximated using a linear model with intercept and slope terms. On average, MOCR-induced magnitude and phase shifts increased at a rate of 0.3 dB/octave and 0.01 cycles/octave, respectively, as bandwidth extended beyond the predicted region of OAE generation. A statistically significant random effect of subject was found for both the intercept and slope parameter of each model. Subject-specific slope estimates were statistically significant predictors of a repeated measure of the wideband MOCR response. A higher slope was predictive of larger wideband MOCR effects. MOCR-induced changes to the OAE are greatest when the MOCR is elicited using wideband noise. Variability in the process of spectral integration within the MOCR pathway appears to explain, in part, inter-subject variability in OAE-based estimates of the MOCR response elicited by wideband noise.

The Organs-at-Risk Dose Constraints in Head and Neck Intensity Modulated Radiation Therapy Using Data from a Multi-Institutional Clinical Trial (JCOG1015A1)

<h3>Purpose/Objective(s)</h3> The purpose of this study was to determine the organ specific dose constraints in head and neck carcinoma treated with intensity-modulated radiation therapy (IMRT) using data from a multi-institutional clinical trial (JCOG1015). <h3>Materials/Methods</h3> Dose constraints used in the JCOG1015 were as follows; Spinal cord Dmax <50 Gy, Brain Dmax <70 Gy, Brainstem Dmax <54 Gy, Optic nerve Dmax <50 Gy, Eyeball Dmax <40 Gy, Lens Dmean <6 Gy, Parotid gland Dmean <26 Gy, pharyngeal constrictor muscle (PCM) Dmean <54 Gy, Larynx Dmean <54 Gy, Inner ear Dmean <45 Gy. Brain D1cc, brainstem D1cc, and thyroid Dmean were not stated but recorded. Patient data and dose-volume histograms (DVH) of organs-at-risk (OARs) were collected from 74 patients with nasopharyngeal carcinoma treated with IMRT who enrolled in the JCOG1015 trial. The incidence of late toxicities was evaluated using the cumulative incidence method or prevalence. ROC analysis was used to estimate the optimal DVH cut-off value that predicted toxicities. <h3>Results</h3> Estimated DVH cut-off values were brainstem D1cc:55.8 Gy for G1 myelitis, brain D1cc:72.1 Gy for ≥G1 central nerve necrosis, optic nerve Dmax:53.3 Gy for G2 vision impaired, eye-ball Dmax:36.6 Gy for G2 impaired, PCM Dmean:41.2 Gy for ≥G2 dysphagia, ipsilateral inner ear Dmean:44.0 Gy for ≥G2 hearing impaired, ipsilateral inner ear Dmean:51.5 Gy for ≥G2 middle ear inflammation, and thyroid Dmean: 45.6 Gy for G1 hypothyroidism. The 3- and 5-year cumulative incidence of late toxicity by dose metrics were shown in Table 1. The estimated cut-off values were similar to dose constraints criteria used in the JCOG1015 except for PCM. In patients who received higher dose than the dose constraints in brainstem and inner ear, incidence of myelitis and hearing impaired were notably high. <h3>Conclusion</h3> The dose constraints criteria of the JCO1015 were appropriate for most OARs, although more strict dose constraints might be necessary for PCM. Dose constraints for inner ear and brainstem should be archived with higher priority.