High-Frequency Sensorineural Hearing Loss and Its Underlying Genetics (<Emphasis Type="Italic">Hfhl1</Emphasis> and <Emphasis Type="Italic">Hfhl2</Emphasis>) in NIH Swiss Mice

Studies using inbred strains of mice have been invaluable for identifying alleles that adversely affect hearing. However, the efficacy of those studies is limited by the phenotypes that these strains express and the alleles that they segregate. Here, by selectively breeding phenotypically and genetically heterogeneous NIH Swiss mice, we generated two lines—the all-frequency hearing loss (AFHL) line and the high-frequency hearing loss (HFHL) line—with differential hearing loss. The AFHL line exhibited characteristics typical of severe, early-onset, sensorineural hearing impairment. In contrast, the HFHL line expressed a novel early-onset, mildly progressive, and frequency-specific sensorineural hearing loss. By quantitative trait loci (QTLs) analyses in these two lines, we identified QTLs on chromosomes 7, 8, and 10 that significantly affected hearing function. The loci on chromosomes 7 and 8 (Hfhl1 and Hfhl2, respectively) are novel and appear to adversely affect only high frequencies (≥30 kHz). Mice homozygous for NIH Swiss alleles at either Hfhl1 or Hfhl2 have 32-kHz auditory-evoked brain stem response thresholds that are 8–14 dB SPL higher than the corresponding heterozygotes. DNA sequence analyses suggest that both the Cdh23 ^ahl and Gipc3 ^ahl5 variants contribute to the chromosome 10 QTL detected in the AFHL line. The frequency-specific hearing loss indicates that the Hfhl1 and Hfhl2 alleles may affect tonotopic development. In addition, dissecting the underlying complex genetics of high-frequency hearing loss may prove relevant in identifying less severe and common forms of hearing impairment in the human population.     

Mapping quantitative trait loci for hearing loss in Black Swiss mice

In common inbred mouse strains, hearing loss is a highly prevalent quantitative trait, which is mainly controlled by the Cdh23(753A) variant and alleles at numerous other strain-specific loci. Here, we investigated the genetic basis of hearing loss in non-inbred strains. Mice of Swiss Webster, CF-1, NIH Swiss, ICR, and Black Swiss strains exhibited hearing profiles characteristic of progressive, sensorineural hearing impairment. In particular, CF-1, Black Swiss, and NIH Swiss mice showed early-onset hearing impairment, ICR and Swiss Webster mice expressed a delayed-onset hearing loss, and NMRI mice had normal hearing. By quantitative trait locus (QTL) mapping, two significant QTLs were identified underlying hearing loss in Black Swiss mice: one QTL mapped to chromosome (chr) 10 (named ahl5, LOD 8.9, peak association 35-42 cM) and a second QTL localized to chr 18 (ahl6, LOD 3.8, 38-44 cM). Ahl5 and ahl6 account for 61% and 32% of the variation in the backcross, respectively. Cadherin 23 (Cdh23) and protocadherin 15 (Pcdh15), mapping within the 95% confidence interval of ahl5, bear nucleotide polymorphisms in coding exons, but these appear to be unrelated to the hearing phenotype. Haplotype analyses across the Cdh23 locus demonstrated the phylogenetic relationship between Black Swiss and common inbred strains.     

Applications of the NTID speech recognition test (NSRT®)

Objective: This study evaluated the diagnostic capabilities of an adaptive speech recognition protocol (NSRT^®) that can be self-administered in non-clinical venues by listeners using internet-based software. Design: All participants were given an audiological evaluation, including pure-tone testing, and responded to the NSRT administered in quiet and + 5 dB SNR listening conditions. The NSRT test materials are sentence-length utterances containing phonetic contrasts, primarily minimal pairs. Study sample: Subjects were 123 adults with normal hearing to moderately severe sensorineural hearing loss (mean age = 55 years, SD = 23). Results: Performance on the NSRT is strongly related to pure-tone thresholds. Linear regression analyses support the utility of the NSRT as a proxy for clinically-obtained hearing thresholds across the octave frequencies 0.5 to 8 kHz, primarily for individuals in the ? 10 to 55 dB HL range. Other NSRT results are linked to analyses of phonetic errors and components of aural rehabilitation. Conclusions: Among its numerous results, the NSRT yields quantitative predictions of frequency-specific hearing thresholds, provides insight into the phonetic errors that affect speech understanding in adults who suffer from sensorineural hearing loss, primarily in the ? 10 to 55 dB HL range, and has implications for the design of individualized auditory training programs.     

Association of different severity of diabetic retinopathy and hearing loss in type 2 diabetes mellitus

PurposeMicrovascular involvement in patients with diabetes mellitus is one of the causes of retinopathy, nephropathy, and neuropathy. The same pathologic processes may occur in the inner ear structures. This case-control study aimed to evaluate the hearing thresholds in type 2 diabetic patients with different severity of diabetic retinopathy (DR) and to compare these findings with controls.Materials and methodsWe evaluated the hearing threshold in four groups of eligible subjects aged 20–70 years. These groups were controls, diabetic patients with no-DR, with mild-moderate non-proliferative DR (NPDR), and with severe NPDR/proliferative DR (PDR). Each group consisted of 105 subjects. Speech-frequency and high-frequency hearing levels (SFHL and HFHL, respectively) were measured and log-transformed. Analysis of covariance was used. The prevalence rate of moderate or more hearing loss in the groups was estimated.ResultsIn total, 194 men and 226 women participated. The ratio of means of SFHL and HFHL between PDR and controls was 0.18 and 0.20, respectively. Hearing loss was prevalent in severe NPDR/PDR (adjusted prevalence ratio 3.36 for SFHL and 1.51 for HFHL) compared to controls. Also, the prevalence of high-frequency hearing loss was more in mild-moderate NPDR (adjusted prevalence ratio 1.33).ConclusionsThe magnitude of the increase in hearing impairment prevalence between the severe NPDR/PDR patients and controls was about 24% for both SFHL and HFHL. We recommend hearing assessment in the screening of the DR patients.     

Basilar artery tortuosity as a predictive factor for the efficacy of heparin adjuvant therapy in unilateral idiopathic sudden sensorineural hearing loss

IntroductionCochlear ischemia is hypothesized as one of the major etiologies of idiopathic sudden sensorineural hearing loss. Therefore, anticoagulant therapies are designed to be beneficial in certain patients with this condition.ObjectiveThis study aimed to determine which patients with idiopathic sudden sensorineural hearing loss would benefit from heparin treatment as adjuvant therapy.MethodsIn total, 134 patients who underwent magnetic resonance imaging for unilateral idiopathic sudden sensorineural hearing loss at a tertiary referral hospital between January 2014 and December 2018 were included in this retrospective study. All patients received Intratympanic steroid injections or heparin therapy plus oral corticosteroids. Radiological parameters of the vertebrobasilar system and clinical data from pre- and post-treatment assessments were analyzed.ResultsMost patients (71.6%) had a tortuous basilar artery The 65 patients with severe-to-profound idiopathic sudden sensorineural hearing loss showed a significant relationship between idiopathic sudden sensorineural hearing loss laterality and basilar artery displacement to the opposite side (p = 0.036), while the 69 patients with mild-to-moderate idiopathic sudden sensorineural hearing loss did not (p = 0.950). Additionally, the degree of basilar artery tortuosity was significantly associated with the degree of hearing impairment in the severe-to-profound idiopathic sudden sensorineural hearing loss group (p = 0.015). When idiopathic sudden sensorineural hearing loss occurred on the opposite side to basilar artery displacement, the improvement of hearing was significantly greater in patients treated with heparin than in those treated with intratympanic steroids (p = 0.041).ConclusionIn a subset of patients with severe-to-profound idiopathic sudden sensorineural hearing loss, basilar artery tortuosity had a significant directional relationship with idiopathic sudden sensorineural hearing loss laterality. In these selected patients, a significant effect of heparin therapy on improving hearing was observed.     

Polygenic inheritance of sensorineural hearing loss (Snhl2, -3, and -4) and organ of Corti patterning defect in the ALR/LtJ mouse strain

Progressive sensorineural hearing loss in humans is a common and debilitating impairment. Sensorineural deafness in inbred strains of mice is a similarly common and genetically diverse phenotype providing experimental models to study the underlying genetics and the biological effects of the risk factors. Here, we report that ALR/LtJ mice develop early-onset profound sensorineural hearing loss as evidenced by high-to-low frequency hearing threshold shifts, absent distortion-product otoacoustic emissions, and normal endocochlear potentials. Linkage analyses of a segregating backcross revealed three novel quantitative trait loci named sensorineural hearing loss (Snhl) -2, -3, and -4. The QTLs achieved very high LOD scores with markers on chromosome 1 (Snhl2, LOD: 12), chromosome 6 (Snhl3, LOD: 24) and chromosome 10 (Snhl4, LOD: 11). Together, they explained 90% of the phenotypic variance. While Snhl2 and Snhl3 affected hearing thresholds across a broad range of test frequencies, Snhl4 caused primarily high-frequency hearing loss. The hearing impairment is accompanied by an organ of Corti patterning defect that is characterized by the ectopic expression of supernumerary outer hair cells organized in rows along the abneural site of the sensory epithelium in the presence of unaltered planar polarity and otherwise normal cochlear duct morphology. Cloning the Snhl2, -3, and -4 genes in the ALR/LtJ mice may provide important genetic and mechanistic insights into the pathology of human progressive sensorineural deafness.     

Idiopathic Sudden Sensorineural Hearing Loss With Minimal Hearing Impairment

Objectives

The aim of the study was to determine the characteristics of patients who did not match the audiometric criteria of idiopathic sudden sensorineural hearing loss (SSNHL) but complained of acute hearing loss.

Methods

By thorough medical chart reviews, historical cohort study was performed with consecutive data of 589 patients complaining of acute unilateral sensorineural hearing loss without identifiable causes between 2005 and 2013. Those patients demonstrating a hearing loss of at least 30 dB at three consecutive frequencies based on pure tone audiometry were classified as group I; the others were classified as group II. Patients'' characteristics, final hearing, and hearing improvement rate (HIR) between the two groups were compared.

Results

Group II exhibited distinctive characteristics, including an early age of onset of the hearing loss (P<0.01), an absence of accompanying diabetes (P<0.01) and hypertension (P<0.01), and better unaffected hearing and final hearing compared with group I (P<0.001). However, the HIR of the patients in the two groups was not significantly different (P>0.05).

Conclusion

Patients who did not meet the audiological criteria of SSNHL exhibited distinctive characteristics compared to SSNHL patients.     

Sensorineural hearing loss in children: The association with Apgar score. A registry-based study of 392 371 children in Norway

ObjectivesThe causes of congenital permanent hearing loss in children are insufficiently understood. We studied the association of Apgar score 5 min after birth with sensorineural hearing loss diagnosed before the age of 5 years.MethodsWe performed an epidemiological cohort study with data obtained by linkage between The Medical Birth Registry of Norway and the Norwegian County Registry of Children with Hearing Loss. Cases were 327 children born in Norway during the period 1978–1998 with sensorineural hearing loss. Controls were all children in Norway without sensorineural hearing loss born in the same counties and during the same period as the cases (n = 392 044). The associations of Apgar score 5 min after birth with sensorineural hearing loss were estimated as odds ratios (OR) with 95% confidence intervals (CI) by applying logistic regression analyses.ResultsAmong children with sensorineural hearing loss 0.9% (3/327) had Apgar score <3, whereas that was true for 0.1% (304/392 044) of children without hearing loss (p = 0.001, chi square test). The aOR for sensorineural hearing loss was 7.5 [95% CI 2.3–, 24.2] comparing Apgar score <3 to Apgar score 10, after adjustment for birthweight and concurrent birth defects. Most children with sensorineural hearing loss (90%) had Apgar score >8 five minutes after birth.ConclusionsLow Apgar score was associated with childhood sensorineural hearing loss. However, most children with sensorineural hearing loss, had Apgar score >8.     

Distribution of HLA-A, -B and -DRB1 Alleles in Patients with Sudden Sensorineural Hearing Loss

This study was performed to investigate the association between human leukocyte antigen (HLA) and susceptibility to sudden sensorineural hearing loss in the Korean population. HLA-A and HLA-B typing using a standard microlymphocytotoxicity technique and HLA-DRB1 genotyping were performed in 35 patients with sudden sensorineural hearing loss and in 206 healthy controls. Prednisone (usual dose 60 mg/day) was administered for 6 days and tapered for an additional 4-6 days. Both initial hearing levels at the onset of deafness and final hearing levels after treatment were examined and evaluated for association with HLA alleles. The frequency of HLA-DRB1*14 was increased in patients with sudden sensorineural hearing loss compared with controls (relative risk [RR]=2.7, p=0.016). The frequencies of HLA-A2, -A31, -B52, -B61, -DRB1*04, -DRB1*11 and -DRB1*12 were slightly higher than in the controls, but did not reach statistical significance. When an association between the treatment results and HLA alleles was also evaluated, the frequency of HLA-DRB1*04 was found to be increased in the patients who did not respond to steroid treatment compared with both patients who responded well to steroid (50% vs 16%, p=0.034) and controls (RR=3.0, p=0.046). These results suggest that there is an association between HLA-DRB1*14 and disease susceptibility and that the presence of HLA-DRB1*04 may be an useful marker for predicting a poor prognosis in Korean patients with sudden sensorineural hearing loss     

Device optimised chirp stimulus for ABR measurements with an active middle ear implant

Objective: Active middle ear implants are widely used to treat adults and children with sensorineural, conductive, or mixed hearing loss. Currently, there is no adequate method to determine the performance of active middle ear implant systems.

Design: The proposed method is based on measuring the auditory brainstem response while stimulating the hearing system via the active middle ear implant (Vibrant Soundbridge^TM, VSB; MEDEL, Austria). The acoustic stimulation was achieved via an optimised chirp stimulus (CE-Chirp), implemented in the Eclipse system (Interacoustics, Denmark). To compensate for the frequency-specific delays in the VSB system, the underlying model function of the CE-Chirp was adjusted accordingly (VSB-CE-Chirp).

Study samples: The study includes 12 subjects having mild to profound sensorineural, conductive or mixed hearing loss.

Results: The use of an optimised VSB-CE-Chirp instead of the CE-Chirp increases significantly the ABR wave V amplitudes (1.63 times) and so also increases their identifiability (by 15.2%). On average, wave V could be identified at a 7.5?dB lower stimulation level.

Conclusion: The constructed VSB-CE-Chirp stimulus, after it had been transmitted through the VSB system, follows well the shape of the original CE-Chirp. Preliminary measurements in VSB patients demonstrated a significantly improved ABR amplitude with the VSB-CE-Chirp.     

Clinical effect of an active transcutaneous bone-conduction implant on tinnitus in patients with ipsilateral sensorineural hearing loss

ObjectivesThis study investigated the effect of an active transcutaneous bone conduction implant (BoneBridge^?) in the management of tinnitus in patients with unilateral sensorineural hearing loss.MethodsFrom October 2016 to July 2018, 15 patients with unilateral tinnitus accompanied by ipsilateral sensorineural hearing loss received BoneBridge^? implants. Pure-tone average, tinnitus handicap inventory (THI), and a visual analogue scale (VAS) for awareness, loudness, and annoyance were measured before and 6 months after surgery. We defined improvement as a reduction of more than 20% between preoperative and postoperative VAS and THI scores, and changes in the THI of over 7 points were also assessed.ResultsMean THI scores before surgery (72.8 ± 16.1) had significantly improved by 6 months postoperatively (50.9 ± 18.9) (p = 0.003). VAS scores for loudness and annoyance also statistically significantly improved (p = 0.011 and 0.002). The amount of functional hearing gain correlated with changes in VAS scores for annoyance. This correlation was stronger with the improvement of high frequency hearing.ConclusionBoneBridge^? is beneficial in patients with tinnitus accompanied by sensorineural hearing loss. This finding can help select patients who will benefit most from bone conduction implants.     

Association of glutamate metabotropic receptor polymorphisms and sensorineural hearing loss in adults of different age groups

IntroductionSensorineural hearing loss is a common challenge all over the world, including a section of the young population. While there have been many published reports associating glutamate metabotropic receptor 7 with sensorineural hearing loss, there is no report, till date, about the association of glutamate metabotropic receptor 7 polymorphisms with sensorineural hearing loss at different ages.ObjectiveTo test the association between the single nucleotide polymorphisms rs11928865 and rs11920109 of the glutamate metabotropic receptor 7 with sensorineural hearing loss in adults of different age groups.MethodsA total of 1661 subjects were studied. The individuals aged between 30 and 50, and between 51 and 70 years with sensorineural hearing loss comprised group A and group B, respectively. Individuals aged between 30 and 50; and between 51 and 70 years without hearing loss comprised control groups C and D, respectively. The MassARRAY method was used to analyze the genotypes.ResultsThe difference in genotypes for the glutamate metabotropic receptor 7 rs11928865 single nucleotide polymorphism between patients in the groups B and D was statistically significant (p = 0.018). The distribution frequencies of genotypes in patients that were aged between 30 and 50 years were not significantly different. The difference in genotypes for the rs11920109 single nucleotide polymorphism between the sensorineural hearing loss groups and control groups showed no statistical significance.ConclusionThe rs11928865 single nucleotide polymorphism was associated with the susceptibility to hearing loss in patients in group B but not with those in group A.     

Postural control assessment in students with normal hearing and sensorineural hearing loss

IntroductionChildren with sensorineural hearing loss can present with instabilities in postural control, possibly as a consequence of hypoactivity of their vestibular system due to internal ear injury.ObjectiveTo assess postural control stability in students with normal hearing (i.e., listeners) and with sensorineural hearing loss, and to compare data between groups, considering gender and age.MethodsThis cross-sectional study evaluated the postural control of 96 students, 48 listeners and 48 with sensorineural hearing loss, aged between 7 and 18 years, of both genders, through the Balance Error Scoring Systems scale. This tool assesses postural control in two sensory conditions: stable surface and unstable surface. For statistical data analysis between groups, the Wilcoxon test for paired samples was used.ResultsStudents with hearing loss showed more instability in postural control than those with normal hearing, with significant differences between groups (stable surface, unstable surface) (p < 0.001).ConclusionsStudents with sensorineural hearing loss showed greater instability in the postural control compared to normal hearing students of the same gender and age.     

Sensorineural hearing loss in the unoperated-on otosclerotic ear

Severe sensorineural hearing loss occurs in less than 1% of stapedectomized ears.^1?2 This low percentage remains as an irreducible minimum even among the most experienced and competent surgeons. The etiology has been hypothesized; however, the actual cause remains unknown. The rare occurrence of sensorineural hearing loss of undetermined etiology in the un-operated-on side was reported first in 1967 by Armstrong³ who presented a series of three patients. No other references have been found since this initial report. Recently three unilateral stapedectomized patients who developed sudden severe sensorineural hearing loss in the unoperated-on ear were studied during the years 1971 through 1979. The hearing loss occurred within 1 week, 6 weeks, and 12 years postoperatively. Although the number is small, a study of this group, in addition to Armstrong's, leads to several interesting considerations:

• 1 Is the incidence of sudden sensorineural type hearing loss greater, the same as, or less than that which develops in the non-otosclerotic general population?
• 1 Is there a possibility that the sudden sensorineural hearing loss of undetermined origin would occur at the time of surgery? Would this then be considered as a predisposing if not the actual etiology?

The present series of six cases is so small that a conclusion is not possible and inference is only conjecture. It is hoped, however, that this may stimulate past, present, and future search for this unusual occurrence. This may help determine whether or not there is a causal or merely a coincidental relationship.     

Click- and tone-burst-evoked otoacoustic emissions in normally hearing ears and in ears with high-frequency sensorineural hearing loss

Summary Otoacoustic emissions (OAEs) evoked by clicks and tone bursts (TBs) were measured using a minor modification of the 1987 Bray and Kemp system in normal and hearing-impaired ears with high-frequency sensorineural hearing loss. Sixty ears of 60 subjects were tested. The average behavioral hearing threshold of 20 normally hearing ears was measured for the different nonlinear stimulus groups and defined as 0 dBnHL. Emissions were recorded in another 20 normally hearing ears and in 20 ears with steep high-frequency sensorineural hearing loss above 2 kHz. An unfiltered click of 80 s duration and TBs at frequencies of 0.5, 1, 2, 3, 4, 5, and 6 kHz served as stimuli. The ears with high-frequency hearing loss were clearly distinguished from the normal ears in that emission energy decreased with higher frequency stimuli above 2 kHz. The mean slopes of the response-growth functions were significantly higher at lower audiometric thresholds. The normal ears showed a slope of 0.21–0.35dB/dBnHL above 2kHz while the slope of the pathological ears was 0.04–0.13 dB/dBnHL. These differences in TBOAEs could possibly be used clinically to carry out hearing tests that are more frequency-specific than those measuring solely click-evoked OAEs. Pathological ears had emissions in the lower frequency range, where they had a normal audiometric threshold. However, these emissions had significantly far lower amplitudes at frequencies around 0.5 and 1 kHz when compared to normal ears. This reduced emission energy may indicate a cochlear impairment of the pathological ears in frequency ranges where they still had normal audiometric thresholds.Portions of this report were presented at the ADANO (Arbeitsgemeinschaft Deutscher Audiologen und Neurotologen) Meeting in Flims, Switzerland, March 29–31, 1990 Offprint requests to: R. Hauser     

Quantification of hearing loss associated with superior semi-circular canal dehiscence

Introduction

Superior semi-circular canal dehiscence (SSCD) is a known cause of hearing loss. This study quantifies hearing loss in SSCD ears in a frequency-specific fashion.

Methods

A meta-analysis of English language literature pertaining to SSCD was performed, with extraction and evaluation of available human audiometric data. Our own institution's case series of SSCD patients was also similarly analysed. Hearing loss in SSCD ears was compared to same patient control ears and to age-matched normative audiometric data.

Results

Ears with SSCD had statistically significant worse hearing as compared to both normative data and to own normal ear controls at 2000 Hz and below. The effect appears to diminish with increasing frequency.

Discussion

The presence of statistically significant conductive hearing loss in the low frequencies was confirmed for SSCD ears. SSCD may also predispose ears to high frequency sensorineural hearing loss.     

Effect of N‐acetyl‐cysteine treatment on sensorineural hearing loss: a meta‐analysis

N‐acetyl‐cysteine (NAC) is an efficacious treatment for sensorineural hearing loss in animal models, such as noise‐induced hearing loss (NIHL), however previous research into the effect of NAC on patients with hearing loss produced contradictory results. In this study, we investigated the effect of NAC treatment on sensorineural hearing loss. PubMed, Web of Science and Embase databases were searched in their entirety using the key words: hearing loss, NAC, N‐acetylcysteine, and sensorineural hearing loss. Studies which included assessment of hearing loss with pure‐tone threshold (PTA) data were selected. Eligible studies regarding the effects of NAC treatment on patients with hearing loss were collected by two independent reviewers. A total of 1197 individuals were included from seven published studies. Two studies reported data for a sudden idiopathic sensorineural hearing loss (SISNHL) group. Three studies reported data for a NIHL group. Other studies reported data for drug‐induced hearing loss. The meta‐analysis demonstrated that the overall effect of NAC treatment on sensorineural hearing loss was invalid. However, NAC treatment was linked with improved patient outcomes of hearing tests in cases of sudden hearing loss, but did not prevent hearing loss induced by noise or ototoxicity. However, there is a need for better‐designed studies with larger samples to further prove the correlation between the effect of NAC and hearing loss.     

Unrelated sensorineural hearing loss in patients with otosclerosis: A report of three cases

Although it is generally accepted that 20% or more of patients with clinically manifest otosclerosis have a concomitant sensorineural hearing loss,¹ it is still debated whether otosclerosis is the cause of the neural loss.² Three cases are presented of other causes of sensorineural loss in oto-sclerotic patients who underwent stapes surgery. One of these cases, the Mondini malformation, is discussed in detail.     

Hearing Loss With a Mitochondrial Gene Mutation Is Highly Prevalent in Japan

Objectives/Hypothesis: Mutations in the mitochondrial genome may predispose people to sensorineural hearing loss. An adenine to guanine point mutation in the tRNA^Leu(UUR) gene at nucleotide 3,243 is one of the deaf-related mutations. This mutation is reported to be associated with 0.9% of diabetes mellitus patients. However, the prevalence of this mutation in hearing-impaired patients still remains unknown. The aim of this study was to determine the prevalence of this mutation among bilaterally sensorineural hearing-impaired patients in Japan. Study Design: Retrospective survey of 100 patients with bilateral sensorineural hearing loss without any evident causes. Methods: Mitochondrial DNA fragments from the patients were amplified by polymerase chain reaction, followed by a restriction enzyme fragment length polymorphism method. Results: Three patients with this mutation were identified. Their clinical profiles were different from the category which had been considered as hearing loss caused by this mitochondrial gene mutation. Conclusions: The mutation is associated with approximately 3% of bilateral sensorineural hearing loss cases of unknown origin and is possibly distributed widely in sensorineural hearing-impaired patients in Japan.     

Vestibular and cochlear nerve enhancement on MRI and its correlation with vestibulocochlear functional deficits in patients with Ramsay Hunt syndrome

ObjectiveThe correlation between enhancement of the vestibulocochlear nerves on gadolinium-enhanced magnetic resonance imaging (MRI) and vestibulocochlear functional deficits was examined in patients with Ramsay Hunt syndrome (RHS).MethodsNineteen patients with RHS who showed herpes zoster oticus, peripheral facial palsy, and vertigo were enrolled. Canal paresis (CP) in the caloric test, abnormal response to ocular and cervical vestibular myogenic potentials (oVEMP and cVEMP), and refractory sensorineural hearing loss were evaluated. MRI images perpendicular to the internal auditory canal were reconstructed to identify the superior (SVN) and inferior vestibular nerves (IVN) and the cochlear nerve (CV). The signal intensity increase (SIinc) of the four-nerve enhancement was calculated as an index.ResultsAmong RHS patients, 79%, 53%, 17% and 26% showed CP in the caloric test, abnormal responses to oVEMP and cVEMP, and refractory sensorineural hearing loss, respectively. SIinc rates of the SVN were significantly increased in RHS patients with CP in the caloric test, and with abnormal responses to oVEMP and cVEMP. SIinc rates of the SVN tended to increase in RHS patients with refractory sensorineural hearing loss (p = 0.052). SIinc rates of the IVN were significantly increased in RHS patients with abnormal responses to oVEMP and cVEMP, and refractory sensorineural hearing loss, but not in those with CP in the caloric test. SIinc rates of the CN were significantly increased in RHS patients with CP in the caloric test, abnormal response to oVEMP and refractory sensorineural hearing loss, but not in those with abnormal response to cVEMP.ConclusionIn patients with RHS, the origin of vertigo may be superior vestibular neuritis, which is affected by reactive varicella-zoster virus from the geniculate ganglion of the facial nerve through the faciovestibular anastomosis. The results also suggested that in some RHS patients, inferior vestibular neuritis contributes to the development of vertigo and that the origin of refractory sensorineural hearing loss is cochlear neuritis.