Mid-frequency Hearing Loss Research Articles

Hearing Loss Secondary to TECTA Gene Mutations.

To assess the prevalence and clinical characterization of variants in the TECTA gene among individuals with bilateral sensorineural hearing loss of unknown etiology in northern Spain. A 6-year (2018-2024) observational, prospective, and descriptive study was conducted on patients with bilateral sensorineural hearing loss at a tertiary hospital. Next generation sequencing using a gene panel for sensorineural hearing loss was performed to detect pathogenic, likely pathogenic, or variants of unknown significance in the TECTA gene. Among 326 patients, pathogenic or likely pathogenic TECTA variants were found in 7 patients (2.14%), including c.3107G>A (n = 6) and c.5383+6T>A (n = 1). Variants of unknown significance were found in 8 patients (2.45%). About 14 of 15 probands had a family history of hearing loss with autosomal dominant inheritance. Eight relatives with confirmed pathogenic variants were also included, totalling 23 cases. Six patients with pathogenic variants and 3 with variants of unknown significance had moderate mid-frequency hearing loss, while others had severe high-frequency loss. Hearing loss was typically progressive, ranging from congenital onset to the fifth decade. Most were treated with hearing aids; none required cochlear implants. TECTA gene variants are relatively common in this population, with c.3107G>A being the most frequent. The typical phenotype is slowly progressive, mid-to-high frequency sensorineural hearing loss, often starting in childhood and usually requiring hearing aids fitting with good results in improving speech intelligibility.

Sensitivity of Methods for Diagnosing Noise-Induced Hearing Loss in Cases of Exposures Including Intense Low-Frequency Noise.

Exposure to intense low-frequency sounds, for example inside tanks and armoured vehicles, can lead to noise-induced hearing loss (NIHL) with a variable audiometric pattern, including low- and mid-frequency hearing loss. It is not known how well existing methods for diagnosing NIHL apply in such cases. Here, the audiograms of 68 military personnel (mostly veterans) who had been exposed to intense low-frequency noise (together with other types of noise) and who had low-frequency hearing loss (defined as a pure-tone average loss at 0.25, 0.5 and 1 kHz ≥20 dB) were used to assess the sensitivity of three diagnostic methods: the method of Coles, Lutman and Buffin, denoted CLB, which depends on the identification of a notch or bulge in the audiogram near 4 kHz, and two methods specifically intended for diagnosing NIHL sustained during military service, the rM-NIHL method, which depends on the identification of a notch or bulge in the audiogram near 4 kHz and/or a hearing loss at high frequencies greater than expected from age alone, and the MLP(18) method based on a multi-layer perceptron. The proportion of individuals receiving a positive diagnosis for either or both ears, which provides an approximate measure of sensitivity, was 0.40 for the CLB method, 0.79 for the rM-NIHL method and 1.0 for the MLP(18) method. It is concluded that the MLP(18) method is suitable for diagnosing NIHL sustained during military service whether or not the exposure includes intense low-frequency sounds.

Cardiometabolic diseases according to the type and degree of hearing loss in noise-exposed workers.

This study aimed to determine the association between cardiometabolic diseases, including metabolic syndrome, hypertension, and diabetes, and the type and degree of hearing loss in noise-exposed workers. A total of 237,028 workers underwent air conduction pure tone audiometry in 2015 to assess their health and diagnose cardiometabolic diseases. The study defined metabolic syndrome, hypertension, and diabetes using blood pressure, fasting blood sugar, cholesterol, and triglyceride levels. Mid-frequency hearing loss was defined as ≥ 30 dB at 2,000 Hz, whereas high-frequency hearing loss was ≥ 40 dB at 4,000 Hz. The average air conduction hearing thresholds at these frequencies were used to determine hearing loss degrees. The odds ratio (OR) of combined exposure to noise and night-shift work in all cardiometabolic diseases was higher than that of noise exposure alone. The risk of cardiometabolic diseases was dose-response, with higher hearing loss causing higher ORs. The ORs of hypertension compared with the normal group were 1.147 (1.098-1.198), 1.196 (1.127-1.270), and 1.212 (1.124-1.306), and those of diabetes were 1.177 (1.119-1.239), 1.234 (1.154-1.319), and 1.346 (1.241-1.459) for mild, moderate, and moderate-severe hearing loss, respectively. Workers who are exposed to noise tend to demonstrate high risks of hearing loss and cardiometabolic diseases; thus, bio-monitoring of cardiometabolic diseases, as well as auditory observation, is necessary.

Comprehensive molecular-genetic analysis of mid-frequency sensorineural hearing loss

The genetic heterogeneity of sensorineural hearing loss (SNHL) is a major hurdle to the detection of disease-causing variants. We aimed to identify underlying causal genes associated with mid-frequency hearing loss (HL), which contributes to less than about 1% of SNHL cases, by whole exome sequencing (WES). Thirty families segregating mid-frequency SNHL, in whom biallelic GJB2 mutations had been previously excluded, were selected from among 851 families in our DNA repository of SNHL. DNA samples from the probands were subjected to WES analysis and searched for candidate variants associated with SNHL. We were able to identify the genetic aetiology in six probands (20%). In total, we found three pathogenic and three likely pathogenic variants in four genes (COL4A5, OTOGL, TECTA, TMPRSS3). One more proband was a compound heterozygote for a pathogenic variant and a variant of uncertain significance (VUS) in MYO15A gene. To date, MYO15A and TMPRSS3 have not yet been described in association with mid-frequency SNHL. In eight additional probands, eight candidate VUS variants were detected in five genes (DIAPH1, MYO7A, TECTA, TMC1, TSPEAR). Seven of these 16 variants have not yet been published or mentioned in the available databases. The most prevalent gene was TECTA, identified in 23% of all tested families. Furthermore, we confirmed the hypothesis that a substantive portion of cases with this conspicuous audiogram shape is a consequence of a genetic disorder.

A Missense POU4F3 Variant Associated with Autosomal Dominant Midfrequency Hearing Loss Alters Subnuclear Localization and Transcriptional Capabilities.

Background The pathogenic variant, POU class 4 transcription factor 3 (POU4F3), is reported to cause autosomal dominant nonsyndromic hearing loss (ADNSHL). Previously, we have examined a four-generation midfrequency sensorineural hearing loss (MFSNHL) family (no. 6126) and established POU4F3 c.602T>C (p.Leu201Pro) as a potential disease-causing variant. Objectives We explored the structural and functional alterations that the c.602T>C (p.Leu201Pro) variant enforces on the POU4F3 protein. Methods We utilized wild-type (WT) and mutant (MUT) POU4F3 c.602T>C plasmid incorporation into HeLa cells to assess functional changes, by immunofluorescence and luciferase assays. To predict protein structural alterations in the MUT versus WT POU4F3, we also generated 3D structures to compare both types of POU4F3 proteins. Results The WT POU4F3 is ubiquitously present in the nucleus, whereas the MUT form of POU4F3 exhibits a more restricted nuclear presence. This finding is different from other publications, which report a cytoplasmic localization of the MUT POU4F3. We also demonstrated that, as opposed to WT POU4F3, the MUT POU4F3 had 40% reduced luciferase activity. Conclusions The reduced nuclear presence, combined with reduced transcriptional activity, suggests that the POU4F3 c.602T>C variant alters cellular activity and may contribute to the pathogenicity of POU4F3-related hearing loss. It, also, provides more evidence of the pathophysiological characteristics of MFSNHL.

A CASE OF MID-FREQUENCY SENSORINEURAL HEARING LOSS

Introduction: Mid-frequency sensorineural hearing loss (MFSNHL) is an unusual audiometric finding with a debatable etiology with unclear long-term results. In general, the middle frequencies are affected first, and the process progresses slowly to include all frequencies. There are also some cases where provocative factors have been reported. Purpose: The aim of the work is to present a clinical case in our practice of the rare occurrence of mid-frequency acoustic hearing loss and its diagnostic approach. Material and methods: The patient has undergone a number of manual and instrumental tests to confirm or reject a specific cause of the hearing loss condition. Results: A 52-year-old man was hospitalised with complaints of hearing loss for about a year, judging by the growing difficulty in making a phone call. Conclusions: Generally, a U-shaped audiogram is thought to indicate hearing loss of genetic origin. However, this type of deafness is not unique to one particular type of genetic mutation. There are also numerous descriptions of non-genetic mid-frequency hearing loss in the literature. In the particular clinical case presented by us, it was concluded that this was a hearing loss, possibly of hereditary nature, after excluding another provocative cause, as well as due to anamnestic data on premature hearing loss in one of the parents.

The Prevalence and Clinical Characteristics of TECTA-Associated Autosomal Dominant Hearing Loss.

TECTA is well known as a causative gene for autosomal dominant mid-frequency hearing loss observed in various populations. In this study, we performed next-generation sequencing analysis of a large Japanese hearing loss cohort, including eight hundred and twelve (812) subjects from unrelated autosomal dominant hearing loss families, to estimate the prevalence and phenotype-genotype correlations in patients with TECTA mutations. The prevalence of TECTA mutations in Japanese autosomal dominant sensorineural hearing loss families was found to be 3.2%. With regard to the type of hearing loss, the patients with mutations in the nidogen-like domain or ZA domain of TECTA showed varied audiograms. However, most of the patients with mutations in the ZP domain showed mid-frequency hearing loss. The rate of hearing deterioration in TECTA-associated hearing loss patients and in the normal hearing Japanese control population were the same and regression lines for each group were parallel. We carried out haplotype analysis for four families which had one recurring missense variant, c.5597C>T (p.Thr1866Met). Our results revealed four different haplotypes, suggesting that this mutation occurred independently in each family. In conclusion, TECTA variants represent the second largest cause of autosomal dominant sensorineural hearing loss in Japan. The hearing loss progression observed in the patients with TECTA mutations might reflect presbycusis. The c.5597C>T mutation occurred in a mutational hot spot and is observed in many ethnic populations.

Mid-Frequency Hearing Loss Is Characteristic Clinical Feature of OTOA-Associated Hearing Loss.

The OTOA gene (Locus: DFNB22) is reported to be one of the causative genes for non-syndromic autosomal recessive hearing loss. The copy number variations (CNVs) identified in this gene are also known to cause hearing loss, but have not been identified in Japanese patients with hearing loss. Furthermore, the clinical features of OTOA-associated hearing loss have not yet been clarified. In this study, we performed CNV analyses of a large Japanese hearing loss cohort, and identified CNVs in 234 of 2262 (10.3%, 234/2262) patients with autosomal recessive hearing loss. Among the identified CNVs, OTOA gene-related CNVs were the second most frequent (0.6%, 14/2262). Among the 14 cases, 2 individuals carried OTOA homozygous deletions, 4 carried heterozygous deletions with single nucleotide variants (SNVs) in another allele. Additionally, 1 individual with homozygous SNVs in the OTOA gene was also identified. Finally, we identified 7 probands with OTOA-associated hearing loss, so that its prevalence in Japanese patients with autosomal recessive hearing loss was calculated to be 0.3% (7/2262). As novel clinical features identified in this study, the audiometric configurations of patients with OTOA-associated hearing loss were found to be mid-frequency. This is the first study focused on the detailed clinical features of hearing loss caused by this gene mutation and/or gene deletion.

A Missense Mutation in POU4F3 Causes Midfrequency Hearing Loss in a Chinese ADNSHL Family.

Hereditary nonsyndromic hearing loss is extremely heterogeneous. Mutations in the POU class 4 transcription factor 3 (POU4F3) are known to cause autosomal dominant nonsyndromic hearing loss linked to the loci of DFNA15. In this study, we describe a pathogenic missense mutation in POU4F3 in a four-generation Chinese family (6126) with midfrequency, progressive, and postlingual autosomal dominant nonsyndromic hearing loss (ADNSHL). By combining targeted capture of 129 known deafness genes, next-generation sequencing, and bioinformatic analysis, we identified POU4F3 c.602T>C (p.Leu201Pro) as the disease-causing variant. This variant cosegregated with hearing loss in other family members but was not detected in 580 normal controls or the ExAC database and could be classified as a “pathogenic variant” according to the American College of Medical Genetics and Genomics guidelines. We conclude that POU4F3 c.602T>C (p.Leu201Pro) is related to midfrequency hearing loss in this family. Routine examination of POU4F3 is necessary for the genetic diagnosis of midfrequency hearing loss.

Research progress in pathogenic genes of hereditary non-syndromic mid-frequency deafness.

Hearing impairment is considered as the most prevalent impairment worldwide. Almost 600 million people in the world suffer from mild or moderate hearing impairment, an estimated 10% of the human population. Genetic factors play an important role in the pathogenesis of this disorder. Hereditary hearing loss is divided into syndromic hearing loss (associated with other anomalies) and non-syndromic hearing loss (not associated with other anomalies). Approximately 80% of genetic deafness is non-syndromic. On the basis of the frequency of hearing loss, hereditary non-syndromic hearing loss can be divided into high-, mid-, low-, and total-frequency hearing loss. An audiometric finding of mid-frequency sensorineural hearing loss, or a "bowl-shaped" audiogram, is uncommon. Up to now, merely 7 loci have been linked to mid-frequency hearing loss. Only four genetic midfrequency deafness genes, namely, DFNA10 (EYA4), DFNA8/12 (TECTA), DFNA13 (COL11A2), DFNA44 (CCDC50), have been reported to date. This review summarizes the research progress of the four genes to draw attention to mid-frequency deafness genes.

Variations in otological presentation of lightning strike victims: Clinical report of 3 patients.

Lightning strike can cause fatal or nonfatal injuries. Some nonfatal injuries are associated with otological symptoms and findings. Conductive hearing loss due to rupture of the tympanic membrane is the most common audiovestibular lesion of lightning strike. Various forms of sensorineural hearing loss and dizziness have also been reported. Presently described are 3 cases of lightning strike injury. First patient had mid-frequency hearing loss in right ear and high frequency sensorineural hearing loss in left ear. Second patient had high frequency sensorineural hearing loss in left ear, and the third had peripheral facial palsy with perilymphatic fistula on same side. This is the first documented case of mid-frequency hearing loss occurring after lightning strike.

Prognostic Factors in Sudden Sensorineural Hearing Loss.

Sudden sensorineural hearing loss (SSNHL) is still a complex and challenging process which requires clinical evidence regarding its etiology, treatment and prognostic factors. Therefore, determination of prognostic factors might aid in the selection of proper treatment modality. The aim of this study is to analyze whether there is correlation between SSNHL outcomes and (1) systemic steroid therapy, (2) time gap between onset of symptoms and initiation of therapy and (3) audiological pattern of hearing loss. Retrospective chart review. Patients diagnosed at our clinic with SSNHL between May 2005 and December 2011 were reviewed. A detailed history of demographic features, side of hearing loss, previous SSNHL and/or ear surgery, recent upper respiratory tract infection, season of admission, duration of symptoms before admission and the presence of co-morbid diseases was obtained. Radiological and audiological evaluations were recorded and treatment protocol was assessed to determine whether systemic steroids were administered or not. Treatment started ≤5 days was regarded as "early" and >5 days as "delayed". Initial audiological configurations were grouped as "upward sloping", "downward sloping", "flat" and "profound" hearing loss. Significant recovery was defined as thresholds improved to the same level with the unaffected ear or improved ≥30 dB on average. Slight recovery was hearing improvement between 10-30dB on average. Hearing recovery less than 10 dB was accepted as unchanged. Among the 181 patients who met the inclusion criteria, systemic steroid was administered to 122 patients (67.4%), whereas 59 (32.6%) patients did not have steroids. It was found that steroid administration did not have any statistically significant effect in either recovered or unchanged hearing groups. Early treatment was achieved in 105 patients (58%) and 76 patients (42%) had delayed treatment. Recovery rates were no different in these two groups; however, when unchanged hearing rates were compared, it was statistically significantly lower in the early treatment group (p<0.05). When hearing outcomes were compared according to initial audiological pattern, significant recovery and unchanged hearing rates did not differ between groups; however, slight recovery rate was highest in the "flat" type audiological configuration (p<0.05). According to this patient series, oral steroid therapy does not have any influence on the outcomes of SSNHL. However, mid-frequency hearing loss of flat type and initiation of treatment earlier than 5 days from the onset of symptoms, seem to have positive prognostic effects. Further randomized controlled subject groups might contribute to determine prognostic factors of SSNHL.

Novel TECTA Mutations Identified in Stable Sensorineural Hearing Loss and Their Clinical Implications

TECTA is a causative gene of autosomal dominant (DFNA8/A12) and autosomal recessive (DFNB 21) nonsyndromic sensorineural hearing loss (NSHL). Mutations in TECTA account for 4% of all autosomal dominant NSHL cases in some populations and are thus thought to be one of the major causes of autosomal dominant NSHL. A genotype-phenotype correlation for autosomal dominant mutations in the TECTA gene has been proposed. Two families (SB146 and SB149), which segregated moderate NSHL in an autosomal dominant fashion, were included in this study. We performed targeted resequencing of 134 known deafness genes (TRS-134) and bioinformatics analyses to find causative mutations for NSHL in these 2 families. Through TRS-134, we detected 2 novel mutations, i.e. c.3995G>T (p.C1332F) and c.5618C>T (p.T1873I), in the TECTA gene. These mutations cosegregated with NSHL in the studied families and were not detected in normal controls. The mutations c.3995G>T and c.5618C>T reside in the von Willebrand factor type D3-D4 (vWFD3-D4) interdomain of the zonadhesin (ZA) domain and the zona pellucida (ZP) domain, respectively. p.C1332F is the first mutation detected in the vWFD3-D4 interdomain of the ZA domain. The mutations p.C1332F and p.T1873I were associated with stable high-frequency and mid-frequency hearing loss, respectively. Notably, the cysteine residue mutated to phenylalanine in SB146 was not related to progression of sensorineural hearing loss, which argues against the previous hypothesis. Here we confirm a known genotype-phenotype correlation for the ZP domain and propose a hypothetical genotype-phenotype correlation which relates mutations in vWFD3-D4 to stable high-frequency NSHL in Koreans. This clinical feature makes subjects with the missense mutation in the vWFD3-D4 interdomain of TECTA potentially good candidates for middle ear implantation. i 2014 S. Karger AG, Basel

Whole-exome sequencing identifies a novel genotype-phenotype correlation in the entactin domain of the known deafness gene TECTA.

Postlingual progressive hearing loss, affecting primarily the high frequencies, is the clinical finding in most cases of autosomal dominant nonsyndromic hearing loss (ADNSHL). The molecular genetic etiology of ADNSHL is extremely heterogeneous. We applied whole-exome sequencing to reveal the genetic etiology of high-frequency hearing loss in a mid-sized Korean family without any prior linkage data. Whole-exome sequencing of four family members (two affected and two unaffected), together with our filtering strategy based on comprehensive bioinformatics analyses, identified 21 potential pathogenic candidates. Sanger validation of an additional five family members excluded 20 variants, leaving only one novel variant, TECTA c.710C>T (p.T237I), as the strongest candidate. This variant resides in the entactin (ENT) domain and co-segregated perfectly with non-progressive high-frequency hearing loss in the family. It was absent among 700 ethnically matched control chromosomes, and the T237 residue is conserved among species, which supports its pathogenicity. Interestingly, this finding contrasted with a previously proposed genotype-phenotype correlation in which variants of the ENT domain of TECTA were associated with mid-frequency hearing loss. Based upon what we observed, we propose a novel “genotype to phenotype” correlation in the ENT domain of TECTA. Our results shed light on another important application of whole-exome sequencing: the establishment of a novel genotype-phenotype in the molecular genetic diagnosis of autosomal dominant hearing loss.

Three deaf mice: mouse models for TECTA-based human hereditary deafness reveal domain-specific structural phenotypes in the tectorial membrane

Tecta is a modular, non-collagenous protein of the tectorial membrane (TM), an extracellular matrix of the cochlea essential for normal hearing. Missense mutations in Tecta cause dominant forms of non-syndromic deafness and a genotype–phenotype correlation has been reported in humans, with mutations in different Tecta domains causing mid- or high-frequency hearing impairments that are either stable or progressive. Three mutant mice were created as models for human Tecta mutations; the TectaL1820F,G1824D/+ mouse for zona pellucida (ZP) domain mutations causing stable mid-frequency hearing loss in a Belgian family, the TectaC1837G/+ mouse for a ZP-domain mutation underlying progressive mid-frequency hearing loss in a Spanish family and the TectaC1619S/+ mouse for a zonadhesin-like (ZA) domain mutation responsible for progressive, high-frequency hearing loss in a French family. Mutations in the ZP and ZA domains generate distinctly different changes in the structure of the TM. Auditory brainstem response thresholds in the 8–40 kHz range are elevated by 30–40 dB in the ZP-domain mutants, whilst those in the ZA-domain mutant are elevated by 20–30 dB. The phenotypes are stable and no evidence has been found for a progressive deterioration in TM structure or auditory function. Despite elevated auditory thresholds, the Tecta mutant mice all exhibit an enhanced tendency to have audiogenic seizures in response to white noise stimuli at low sound pressure levels (≤84 dB SPL), revealing a previously unrecognised consequence of Tecta mutations. These results, together with those from previous studies, establish an allelic series for Tecta unequivocally demonstrating an association between genotype and phenotype.

A commentary on ‘TECTA mutations in Japanese with mid-frequency hearing loss affected by Zona Pellucida domain protein secretion’

A commentary on ‘ TECTA mutations in Japanese with mid-frequency hearing loss affected by Zona Pellucida domain protein secretion’

TECTA mutations in Japanese with mid-frequency hearing loss affected by zona pellucida domain protein secretion

TECTA gene encodes α-tectorin, the major component of noncollagenous glycoprotein of the tectorial membrane, and has a role in intracochlear sound transmission. The TECTA mutations are one of the most frequent causes of autosomal dominant (AD) hearing loss and genotype-phenotype correlations are associated with mutations of TECTA in exons according to α-tectorin domains. In this study, we investigated the prevalence of hearing loss caused by TECTA mutations in Japanese AD hearing loss families, and confirmed genotype-phenotype correlation, as well as the intracellular localization of missense mutations in the α-tectorin domain. TECTA mutations were detected in 2.9% (4/139) of our Japanese AD hearing loss families, with the prevalence in moderate hearing loss being 7.7% (4/52), and all patients showed typical genotype-phenotype correlations as previously described. The present in vitro study showed differences of localization patterns between wild type and mutants, and suggested that each missense mutation may lead to a lack of assembly of secretion, and may reduce the incorporation of α-tectorin into the tectorial membrane.

Intratympanic injection with dexamethasone for sudden sensorineural hearing loss

To investigate the efficacy of intratympanic steroid therapy in adults with sudden sensorineural hearing loss, and to analyse the factors associated with treatment outcome. Retrospective study of patients undergoing intratympanic steroid injection for sudden sensorineural hearing loss between 1 January 2006 and 30 June 2007 at a teaching hospital in Taipei, Taiwan. Patients who received intratympanic steroid therapy within seven days of disease onset achieved a significantly better response rate (76.1 per cent), compared with the delayed treatment group (50 per cent). The total response rate, after four steroid injections, was 68.9 per cent. Patients with low and mid-frequency hearing loss were more responsive to steroid treatment. Vertigo was a negative prognostic factor for recovery. There were no long-term sequelae of intratympanic steroid treatment. Intratympanic steroid injection may be a simple and effective treatment for patients with sudden sensorineural hearing loss.

Genotype-Phenotype Correlation for DFNA22: Characterization of Non-Syndromic, Autosomal Dominant, Progressive Sensorineural Hearing Loss due to MYO6 Mutations

Clinical and audiological examination was done in 2 Belgian families with autosomal dominant sensorineural hearing loss (SNHL) linked to DFNA22. Nineteen subjects in family 1 had mild to moderate SNHL starting in the third decade. The hearing loss was characterized by a flat audiogram affecting all tested frequencies with statistically significant progression. In family 2 eleven subjects were affected with mild to moderate SNHL starting in the second decade. Most of them showed a flat audiogram, but some had mid-frequency hearing loss. Significant progression of thresholds was present at 4 and 8 kHz. For all hitherto known DFNA22 families the audiological and clinical characteristics were correlated with the molecular data. This study describes the phenotype of 2 Belgian families with SNHL linked to DFNA22, both with a pathogenic change in the deafness gene MYO6. The phenotypes of all hitherto reported DFNA22 families with mutations in the MYO6 gene have been studied and compared. It seems that genetic defects that spare the motor domain of the myosin VI protein have a milder phenotype.

Glossopharyngeal schwannomas: A 100 year review

To review the literature on glossopharyngeal schwannomas with a focus on clinical presentation, radiologic/audiologic characteristics, and management options, and to propose a mechanism explaining the nature of vestibulocochlear dysfunction seen with these tumors. Contemporary review. English literature search for cases of primary isolated glossopharyngeal schwannomas and chart review of two new cases. A total of 42 glossopharyngeal schwannoma cases between 1908-2008 were reviewed. Of these 84% presented with vestibulocochlear symptoms whereas only 30% presented with glossopharyngeal symptoms. Tumors can occur anywhere along the CNIX; however, the majority of symptomatic cases are intracranial/intraosseous, which present with vestibulocochlear dysfunction. Reviewed cases typically described the caliber of CNVII and VIII on CT/MRI as normal. We present a case where notching and displacement of CNVIII by the tumor can be appreciated on MRI, allowing for the first correlation between clinical symptoms and imaging findings. Mid frequency SNHL was prevalent in contrast to the high-frequency pattern typical of vestibular schwannomas. Tonotopic studies of CNVIII mapped low-to-mid frequency fibers along the posterior medial surface corresponding to the area of greatest compression by glossopharyngeal schwannomas. Glossopharyngeal schwannomas usually present with vestibulocochlear rather than glossopharyngeal symptoms, likely due to CNVIII compression and displacement by tumor, which can be better appreciated with modern imaging. The tumor's location posterior and medial to CNVIII combined with the complex CNVIII tonotopic organization may account for the preferential mid-frequency hearing loss seen in these patients.