Systematic review of the evidence for the etiology of adult sudden sensorineural hearing loss

Access to Sudden Hearing Loss Care at Urgent Care Centers

OBJECTIVES

To compare patient access to urgent care centers (UCCs) with a diagnosis of sudden hearing loss based on insurance.

METHODS

One hundred twenty-five random UCCs in states with Medicaid expansion and 125 random UCCs in states without Medicaid expansion were contacted by a research assistant posing as a family member seeking care on behalf of a patient with a one-week history of sudden, unilateral hearing loss. Each clinic was called once as a Medicaid patient and once as a private insurance (PI) patient for 500 total calls. Each phone encounter was evaluated for insurance acceptance and self-pay price. Secondary outcomes included other measures of timely/accessible care. Chi-square/McNemar's tests and independent/paired sample t-tests were performed to determine whether there were statistically significant differences between expansion status and insurance type. Calls ended before answering questions were not included in the analysis.

RESULTS

Medicaid acceptance rate was significantly lower than PI (68.1% vs. 98.4%, p < 0.001). UCCs in Medicaid expansion states were significantly more likely to accept Medicaid (76.8% vs. 59.2%, p = 0.003). The mean wage-adjusted self-pay price was significantly greater in states with Medicaid expansion at $169.84 than in states without at $145.34 when called as a Medicaid patient (mean difference: $24.50, 95% Confidence Interval: $0.45-$48.54, p = 0.046). The rates of referral to an emergency department and self-pay price nondisclosure rates were greater for Medicaid calls than for private insurance calls (8.2% vs. 0.4% and 17.4% vs. 5.8%; p < 0.001 for both).

CONCLUSION

Medicaid patients with otologic emergencies face reduced access to care at UCCs.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:5066-5072, 2024.

Idiopathic sudden sensorineural hearing loss after COVID-19 vaccination: a systematic review and meta-analysis

OBJECTIVE

To provide pooled analyses on the association between COVID-19 vaccine and the incidence of idiopathic sudden sensorineural hearing loss (ISSNHL).

DATA SOURCES

"Medline" via "PubMed", "EMBASE", and "Google scholar".

REVIEW METHODS

Data sources were inspected from January 2020 to January 2024 using search terms relevant to vaccines for COVID-19. Included were papers with reported numbers of vaccinated populations and incidence if ISSNHL in those populations. Quality assessment was performed with the Newcastle-Ottawa Quality Assessment Scale Criteria.

RESULTS

Three publications encompassing more than 191.8 million patients and at least 283 million vaccine doses were included in the quantitative data synthesis. The pooled reported incidence (95%confidence interval) of ISSNHL among COVID-19 vaccine recipients was 1.2588 per 100,000 (0.1385-3.4836). This incidence is significantly lower than the incidence of 5-27 and 60 per 100,000/year reported in the United States and in the European Union, respectively (P < 0.0001).

CONCLUSION

There is no evidence to indicate that the COVID-19 vaccine is associated with the incidence of ISSNHL.

Effect of pre-incident antiplatelet therapy on sudden sensorineural hearing loss

OBJECTIVE

Identify if pre-incident aspirin influences severity and outcome of idiopathic sudden sensorineural hearing loss (SSNHL).

STUDY DESIGN

Retrospective review.

SETTING

Tertiary care center.

METHODS

Patients with idiopathic SSNHL were identified and separated into aspirin and non-aspirin groups. Variables, including demographics, comorbid conditions, audiologic outcomes were identified and compared between groups.

RESULTS

One hundred forty-eight patients were included that met inclusion criteria. There were 38 patients who were on pre-incident aspirin therapy and 110 patients not on aspirin prior to the onset of SSNHL. Pre- and post-treatment audiologic status was worsened in the aspirin group. Other comorbid conditions, including hyperlipidemia, coronary artery disease (CAD), cerebrovascular accident (CVA), and vertigo symptoms had an effect as well. With multivariate analysis, CAD, CVA, and vertigo symptoms appeared to have an effect more than aspirin.

CONCLUSIONS

Patients on aspirin have a worsened pre- and post-treatment audiologic status. This appears to be more due to the underlying CAD or history of CVA rather than aspirin use itself.

Natural History of Untreated Idiopathic Sudden Sensorineural Hearing Loss

OBJECTIVE

Although corticosteroids and other treatments for idiopathic sudden sensorineural hearing loss (ISSNHL) have been described, understanding its prognosis without intervention provides valuable information for patient management. The objective of this study is to provide a comprehensive, quantitative statistical analysis of the natural history of untreated idiopathic sudden sensorineural hearing loss (ISSNHL).

STUDY TYPE AND DESIGN

A systematic review and meta-analyses.

METHODS

Two independent searches of PubMed, Scopus, Web of Science, and Cochrane Library databases up to June 30, 2022, were performed. Adults with idiopathic sudden sensorineural hearing loss who received placebo or were untreated and had audiometric outcome measures in all study types were reviewed. These data indicative of the natural history of ISSNHL were analyzed, as were study characteristics related to risk of bias. Heterogeneity as assessed via I2 and random effects analyses were performed.

RESULTS

Six studies meeting the inclusion criteria yielded 319 untreated patients whose natural history could be assessed. Heterogeneity among studies was moderate, with a variety of reported outcomes. A hearing improvement of at least 30 dB HL was observed in 36% (95% CI 0.28-0.44) of untreated patients, and of at least 10 dB HL was observed in 70% (95% CI 0.57-0.82) of untreated patients at 3 months. The mean hearing gain among untreated patients was 24.0 dB HL (95% CI 2.65-45.37) at 2-3 months.

CONCLUSIONS

The observed natural history of ISSNHL suggests that patients can regain some hearing without active treatment. In the absence of future studies collecting prospective natural history data from untreated or placebo-treated ISSNHL patients, the data presented here provide the best available historical control data for reconsideration of results in past ISSNHL studies, as well as a roadmap for design and interpretation of future ISSNHL treatment clinical trials. Furthermore, knowing there is a statistically significant mean hearing gain of 24.0 dB HL in the untreated/placebo group provides an ethical basis for future placebo study of ISSNHL. The current status on ISSNHL management calls for a multi-institutional, randomized, double-blind placebo-controlled trial with validated outcome measures to provide science-based treatment guidance. Laryngoscope, 134:S1-S15, 2024.

Bilaterally positive head-impulse tests can differentiate AICA infarction from labyrinthitis

Introduction

Video head-impulse tests (video-HITs) often fail to detect anterior inferior cerebellar artery (AICA) infarction due to peripheral and central vestibular system involvement. Anecdotal studies suggest that video-HITs may reveal bilateral impairment in AICA infarction. However, the diagnostic utility of video-HITs has not been established, particularly when compared to labyrinthitis, which accounts for the majority of acute audiovestibular syndrome (AAVS) cases.

Methods

We reviewed the medical records of consecutive patients presenting with new-onset acute hearing loss and spontaneous vertigo (i.e., AAVS) between March 2018 and July 2023 at a tertiary hospital in South Korea. Video-HIT patterns were categorized as follows: (1) ipsilaterally positive, (2) contralaterally positive, (3) bilaterally normal, and (4) bilaterally positive.

Results

Twenty-eight patients with AICA infarction (mean age ± standard deviation = 67 ± 15 years; 14 men) and 51 with labyrinthitis (63 ± 17 years, 26 men) were included in the analyses. Among the 28 patients with AICA infarction, 15 presented with AAVS in isolation, without other co-morbid neurologic deficits (15/28, 54%). The vestibulo-ocular reflex (VOR) gains of ipsilesional horizontal canals (HCs) ranged from 0.21 to 1.22 (median = 0.81, interquartile range [IQR] = 0.50-0.89). However, those for contralateral HC gain ranged from 0.57 to 1.19 (median = 0.89 [IQR = 0.73-0.97]). Collectively, HITs were bilaterally positive in 13 patients (including 12 patients with bilaterally positive HITs for the horizontal canal), normal in eight, ipsilesionally positive in six, and contralesionally positive in one patient with AICA infarction. The VOR gains were typically decreased ipsilaterally in 28 (28/51, 55%), normal in 17 (17/51, 33%), and decreased bilaterally in six patients with labyrinthitis (6/51, 12%). Logistic regression analysis revealed that bilaterally positive HITs (p = 0.004) and multiple vascular risk factors (p = 0.043) were more frequently associated with AICA infarction than labyrinthitis.

Discussion

Among patients presenting with AAVS, bilaterally positive HITs can be indicative of AICA infarction in patients with multiple vascular risk factors.

Comparison of Recovery Rates of Sudden Sensorineural Hearing Loss by Age Group

Background: While numerous studies have been conducted on sudden sensorineural hearing loss (SSNHL), research on how treatment outcomes and prognosis vary by age remains insufficient. This study aims to investigate the differences in recovery rates among SSNHL patients divided by age groups. Methods: A retrospective study was conducted on 177 patients diagnosed with SSNHL from 2020 to 2023. The patients were categorized into four age groups: under 20, 30-40, 50-60, and over 70. Recovery rates and associated symptoms were compared across these groups. Results: Significant recovery rates were observed in all age groups except for those over 70 (p = 0.006, p = 0.003, p = 0.009). No significant differences were found in recovery rates based on gender (p > 0.75) or symptoms such as tinnitus, ear fullness, and dizziness (p > 0.05). Conclusions: The study revealed that younger and middle-aged adults showed statistically significant improvements in recovery rates, while the elderly exhibited relatively lower recovery rates.

Efficacy and safety of SENS-401 in sudden sensorineural hearing loss: The AUDIBLE-S randomized placebo-controlled phase IIb trial

PURPOSE

Safety and efficacy of SENS-401, a serotonin type 3 (5-HT3) receptor antagonist and calcineurin inhibitor, in patients with acute sudden sensorineural hearing loss (SSNHL).

METHODS

Multicentre randomized, double blind, placebo-controlled trial enrolled adult subjects with sudden sensorineural hearing loss (SSNHL) or unilateral/bilateral acute acoustic trauma leading to SSNHL within 96 h of disease onset. Subjects were randomly assigned to one of the three oral dose groups: 29 mg, 43.5 mg or placebo given twice daily for 28 days. The primary endpoint was the change from baseline in Pure Tone Average (PTA) in the affected ear to the end of treatment visit (day 28). Subjects were further followed up 8 weeks after the end of the treatment period (day 84).

RESULTS

A total of 115 subjects were randomized. SENS-401 was well tolerated. Although the primary efficacy endpoint was not met at day 28, post-hoc analyses revealed clinically significant and meaningful efficacy outcomes with SENS-401 when compared to placebo in a substantial group of participants diagnosed with idiopathic SSNHL and who had received corticosteroid treatment. Notable improvements were observed in the PTA change from baseline, the complete hearing recovery rate, and the Word Recognition Score (WRS), particularly at day 84. The responder rate consistently favored treated subjects over those who received the placebo.

CONCLUSION

While the primary endpoint was not achieved at the end of the treatment period, the study revealed consistently positive efficacy results of clinical relevance in patients with idiopathic SSNHL who received SENS-401, particularly in the 8-weeks follow-up phase after the completion of the treatment.

Sudden Sensorineural Hearing Loss in Patients Aged from 15 to 40 Years

Objectives: The purpose of this study was to investigate the hearing characteristics and causes of sudden sensorineural hearing loss (SSNHL) in patients aged from 15 to 40 years, focusing on audiological outcomes one year after the diagnosis. Methods: The medical records of individuals with SSNHL who were referred to our tertiary-level audiologic center were reviewed. All patients had undergone comprehensive diagnostic evaluations, including high-resolution 3D-FLAIR delayed magnetic resonance imaging (MRI), cone beam computed tomography (CBCT), and screening for coagulation, infectious, and autoimmune diseases. Results: Overall, 56 patients (mean age 28.1 ± 7.6 years) were included in the study. The hearing threshold in the affected ear improved significantly from 56.0 ± 18.0 dB at the diagnosis to 46.9 ± 22.3 dB after one year (p = 0.02). The degree of hearing loss, audiometric configurations, hearing improvements, and adherence to hearing treatments showed considerable variability among patients. Aural fullness, tinnitus, and hyperacusis were the predominant symptoms associated with SSNHL, and their prevalence decreased significantly over time. The diagnostic protocol led to the identification of the specific cause of SSNHL in 75% (42/56) of patients. The known etiology was found to be otological (39.3%), infectious (21.4%), autoimmune (7.1%), vascular (5.4%), or neoplastic (1.8%). In particular, Menière's disease (n = 12), isolated cochlear endolymphatic hydrops (n = 6), HSV-1 (n = 5), and EBV (n = 4) infections were the most frequent causes of SSNHL. Conclusions: The identification of the specific etiology of SSNHL may facilitate a more personalized approach to management and treatment.

Association of sudden sensorineural hearing loss with meteorological factors: a time series study in Hefei, China, and a literature review

Air pollution can cause disease and has become a major global environmental problem. It is currently believed that air pollution may be related to the progression of SSNHL. As a rapidly developing city in recent years, Hefei has serious air pollution. In order to explore the correlation between meteorological variables and SSNHL admissions, we conducted this study. This study investigated the short-term associations between SSNHL patients admitted to the hospital and Hefei climatic variables. The daily data on SSNHL-related hospital admissions and meteorological variables containing mean temperature (T-mean; °C), diurnal temperature range (DTR; °C), atmospheric pressure (AP; Hp), and relative humidity (RH; %), from 2014 to 2021 (2558 days), were collected. A time-series analysis integrating distributed lag non-linear models and generalized linear models was used. PubMed, Embase, Cochrane Library, and Web of Science databases were searched. Literature published up to August 2023 was reviewed to explore the potential impact mechanisms of meteorological factors on SSNHL. The mechanisms were determined in detail, focusing on wind speed, air pressure, temperature, humidity, and air pollutants. Using a median of 50.00% as a baseline, the effect of exceedingly low T-mean in the single-day hysteresis effect model began at a lag of 8 days (RR = 1.032, 95% CI: 1.001 ~ 1.064). High DTR affected the admission rate for SSNHL on lag 0 day. The significance of the effect was the greatest on that day (RR = 1.054, 95% CI: 1.007 ~ 1.104) and then gradually decreased. High and exceedingly high RH affected the admission rate SSNHL on lag 0 day, and these effects lasted for 8 and 7 days, respectively. There were significant associations between all grades of AP and SSNHL. This is the first study to assess the effect of meteorological variables on SSNHL-related admissions in China using a time-series approach. Long-term exposures to high DTR, RH values, low T-mean values, and all AP grades enhance the incidence of SSNHL in residents. Limiting exposure to extremes of ambient temperature and humidity may reduce the number of SSNHL-related hospital visits in the region. It is advisable to maintain a suitable living environment temperature and avoid extreme temperature fluctuations and high humidity. During periods of high air pollution, it is recommended to stay indoors and refrain from outdoor exercise.

White Matter Hyperintensity in Patients with Sudden Sensorineural Hearing Loss

OBJECTIVE

To compare white matter hyperintensities (WMHs) on T2-weighted magnetic resonance imaging (MRI) of patients with sudden sensorineural hearing loss (SSNHL) and analyze subpopulations with age-matched controls.

METHODS

T2-weighted MRI scans of 150 patients with SSNHL were assessed for WMHs and compared with the data of 148 healthy age-matched adults. Assessments of WMHs included independent grading of deep white matter hyperintensities (DWMHs) and periventricular hyperintensities (PVHs). WMH severity was visually rated using the Fazekas and Mirsen scales by two independent observers.

RESULTS

Fazekas grades for PVHs (p < 0.001) and DWMHs (p < 0.001) of SSNHL patients were found to be significantly greater than those of healthy participants. The average Mirsen grades for DWMHs of healthy and SSNHL patients were evaluated to be 0.373 ± 0.550 and 2.140 ± 0.859, respectively. Mirsen grades for DWMHs of SSNHL patients were found to be significantly greater (p < 0.001) than those of healthy participants. The Mirsen scale was found to have higher sensitivity (p < 0.001) than the Fazekas scale in grading PVHs and DWMHs. No significant difference (p = 0.24) was found in specificities between the two scales.

CONCLUSIONS

Patients with sudden hearing loss have a much higher likelihood of having periventricular and deep white matter hyperintensities compared to age-matched controls. These findings indicate that sudden hearing loss patients are more likely to have microvascular changes in the brain, which may indicate a vascular and/or migraine origin to sudden sensorineural hearing loss.

Sensorineural hearing loss among type 2 diabetic patients and its association with peripheral neuropathy: a cross-sectional study from a lower middle-income country

INTRODUCTION

Despite potential links between diabetes and sensorineural hearing loss (SNHL), routine hearing assessments for diabetic patients are not standard practice. Our study aimed to investigate the prevalence of SNHL and its association with diabetes-related factors among patients with type 2 diabetes mellitus (T2DM).

RESEARCH DESIGN AND METHODS

This cross-sectional study was conducted at the Diabetes Clinic, Jinnah Postgraduate Medical Centre, Karachi, Pakistan, from May to September 2021. A total of 396 patients fulfilling the inclusion criteria participated after informed consent. Data collection involved a sociodemographic profile, Michigan Neuropathy Screening Instrument examination followed by pure-tone audiometry and laboratory tests including haemoglobin A1C (HbA1c). HL was defined using better ear four-frequency pure-tone average of ≥26 dB HL and graded as per WHO criteria. Statistical analyses were performed using SPSS. χ2, independent t-test and multinomial logistic regression analyses were applied. P<0.05 at 95% CI was considered significant.

RESULTS

Our study revealed a high prevalence of SNHL among patients with T2DM. Mild HL was seen in 55.8%, while 18.7% suffered from moderate HL. Common audiological symptoms included difficulty understanding speech in noisy surroundings (44.2%), balance problems (42.9%), sentence repetition (35.9%), tinnitus (32.3%) and differentiating consonants (31.1%). Hearing impairment predominantly affected low (0.25-0.5 kHz) and high (4-8 kHz) frequencies with a significant difference at 4 kHz among both sexes (t (394)=2.8, p=0.004). Peripheral neuropathy was significantly associated with SNHL on multinomial logistic regression after adjusting with age, sex, body mass index and the presence of any comorbidities. Diabetes duration, HbA1c or family history of diabetes was found unrelated to SNHL severity.

CONCLUSIONS

The study highlights the substantial prevalence of SNHL among patients with T2DM and emphasises the importance of targeted audiological care as part of a holistic approach to diabetes management. Addressing HL early may significantly improve communication and overall quality of life.

Causal role of immune cell phenotypes in idiopathic sudden sensorineural hearing loss: a bi-directional Mendelian randomization study

Background

A growing body of evidence suggests that immunological processes have a significant role in developing idiopathic sudden sensorineural hearing loss (SSHL). However, few studies have examined the association between immune cell phenotype and SSHL using Mendelian Randomization (MR).

Methods

The online genome-wide association studies (GWAS) database was used to compile data from GWAS covering 731 immunophenotypes and SSHL. Inverse variance weighted (IVW) analysis was primarily used for MR study, and single nucleotide polymorphisms (SNPs) associated with immunophenotypes served as dependent variables. A sensitivity study and the false discovery rate (FDR) correction were used to examine the MR hypothesis. In addition, the possibility of reverse causality between immunophenotype and SSHL was validated by reverse MR. Reverse MR was analyzed in a manner consistent with forward MR.

Results

After FDR correction and sensitivity analysis, we screened 7 immunophenotypes, including IgD+ CD38dim %lymphocyte (95% CI: 1.0019, 1.0742, p = 3.87 × 10-2, FDR = 1.15 × 10-2); Unsw mem AC (95% CI: 1.004, 1.2522, p = 4.23 × 10-2, FDR = 2.25 × 10-2); CD86+ myeloid DC AC (95% CI: 1.0083, 1.1147, p = 2.24 × 10-2, FDR = 4.27 × 10-2); CD33dim HLA DR- AC (95% CI: 1.0046, 1.0583, p = 2.12 × 10-2, FDR = 4.69 × 10-2); SSC-A on CD8br (95% CI: 1.0028, 1.1461, p = 4.12 × 10-2, FDR = 4.71 × 10-2); CD45RA- CD4+ %T cell (95% CI: 1.0036, 1.0503, p = 2.32 × 10-2, FDR = 4.82 × 10-2); DP (CD4+CD8+) AC (95% CI: 1.011, 1.2091, p = 2.78 × 10-2, FDR = 4.97 × 10-2). There was a strong causal relationship with SSHL onset, and the reliability of the results was verified. Furthermore, the immunological cell profile and SSHL did not appear to be closely associated, as shown by reverse MR analysis.

Conclusion

Our study provides more support for the current hypothesis that immunophenotypes and the pathophysiology of SSHL are closely associated. Further validation is needed to assess the role of these immunophenotypes in SSHL.

A single dose of AC102 restores hearing in a guinea pig model of noise-induced hearing loss to almost prenoise levels

Although sudden sensorineural hearing loss (SSNHL) is a serious condition, there are currently no approved drugs for its treatment. Nevertheless, there is a growing understanding that the cochlear pathologies that underlie SSNHL include apoptotic death of sensory outer hair cells (OHCs) as well as loss of ribbon synapses connecting sensory inner hair cells (IHCs) and neurites of the auditory nerve, designated synaptopathy. Noise-induced hearing loss (NIHL) is a common subtype of SSNHL and is widely used to model hearing loss preclinically. Here, we demonstrate that a single interventive application of a small pyridoindole molecule (AC102) into the middle ear restored auditory function almost to prenoise levels in a guinea pig model of NIHL. AC102 prevented noise-triggered loss of OHCs and reduced IHC synaptopathy suggesting a role of AC102 in reconnecting auditory neurons to their sensory target cells. Notably, AC102 exerted its therapeutic properties over a wide frequency range. Such strong improvements in hearing have not previously been demonstrated for other therapeutic agents. In vitro experiments of a neuronal damage model revealed that AC102 protected cells from apoptosis and promoted neurite growth. These effects may be explained by increased production of adenosine triphosphate, indicating improved mitochondrial function, and reduced levels of reactive-oxygen species which prevents the apoptotic processes responsible for OHC death. This action profile of AC102 might be causal for the observed hearing recovery in in vivo models.

A prognostic value of estimated pulse wave velocity in idiopathic sudden sensorineural hearing loss

PURPOSE

Arterial stiffness, represented by estimated pulse wave velocity (ePWV), is the independent surrogate marker for cardiovascular event. The aim of the study was to investigate the significance of ePWV in the treatment outcome of idiopathic sudden sensorineural hearing loss (SSNHL).

METHODS

One hundred and ten patients with idiopathic SSNHL who hospitalized between April 2019 and March 2022 were evaluated. Arterial stiffness was calculated with formula for ePWV and other cardiovascular parameters of body mass index (BMI), and serum lipid level was determined. All patients received systemic high-dose steroid therapy and intratympanic steroid injections as a salvage management. Treatment outcome was assessed at 6 months after treatment, and classified as recovery and nonrecovery groups according to hearing recovery.

RESULTS

The initial pure-tone hearing threshold was 72.6 ± 23.8 dB and final hearing threshold was 52.63 ± 31.10 dB. After treatment, 60 (54.5%) patients included in recovery group and other 50 (45.5%) were classified as nonrecovery group. Age, days of onset to treatment, BMI, waist circumference, and ePWV were higher in the nonrecovery group compared to recovery group in univariate analysis (p = 0.039, p = 0.049, p = 0.003, p = 0.004, p = 0.007, respectively). In multivariate analysis, days of onset to treatment, BMI, and ePWV were associated with recovery (p = 0.030, p = 0.007, p = 0.022).

CONCLUSION

Higher ePWV, a measure of arterial stiffness, was associated with a poor hearing recovery of SSNHL.

The acute vestibular syndrome: prevalence of new hearing loss and its diagnostic value

OBJECTIVES

To assess the prevalence of new hearing losses in patients with acute vestibular syndrome (AVS) and to start to evaluate its diagnostic value for the differentiation between peripheral and central causes.

DESIGN

We performed a cross-sectional prospective study in AVS patients presenting to our Emergency Department (ED) from February 2015 to November 2020. All patients received an MRI, Head-impulse test, Nystagmus test and Test of skew ('HINTS'), caloric testing and a pure-tone audiometry.

RESULTS

We assessed 71 AVS patients, 17 of whom had a central and 54 a peripheral cause of dizziness. 12.7% had an objective hearing loss. 'HINTS' had an accuracy of 78.9% to diagnose stroke, whereas 'HINTS' plus audiometry 73.2%. 'HINTS' sensitivity was 82.4% and specificity 77.8% compared to 'HINTS' plus audiometry showing a sensitivity of 82.4% and specificity of 70.4%. The four patients with stroke and minor stroke had all central 'HINTS'. 55% of the patients did not perceive their new unilateral hearing loss.

CONCLUSIONS

We found that almost one-eighth of the AVS patients had a new onset of hearing loss and only half had self-reported it. 'HINTS' plus audiometry proved to be less accurate to diagnose a central cause than 'HINTS' alone. Audiometry offered little diagnostic accuracy to detect strokes in the ED but might be useful to objectify a new hearing loss that was underestimated in the acute phase. Complete hearing loss should be considered a red flag, as three in four patients suffered from a central cause.

Normal Weight Central Obesity is a Poor Prognostic Factor for Sudden Sensorineural Hearing Loss

OBJECTIVES

To investigate the role of normal weight central obesity (NWCO) in the prognosis of sudden sensorineural hearing loss (SSNHL).

METHODS

We retrospectively investigated 807 cases of SSNHL from January of 2008 to August of 2019 from the Department of Otorhinolaryngology at Kaohsiung Medical University Hospital in southern Taiwan. We analyzed the association between overweight and obesity, NWCO, and the prognosis of SSNHL. The demographic and clinical characteristics, audiometry results, and outcomes were also reviewed.

RESULTS

The nonobese (body mass index [BMI] < 24 kg/m2) and overweight and obese groups (BMI ≥ 24 kg/m2) comprised 343 (42.50%) and 464 (57.50%) patients, respectively. The favorable prognosis rates in the nonobese and the overweight and obese groups were 45.48% and 45.91%, respectively, without a significant difference (P = .9048). Multivariate logistic regression revealed that BMI (adjusted odds ratio [aOR] = 1.00, 95% CI = 0.948-1.062, P = .9165) was not significantly associated with SSNHL recovery. The normal weight noncentral obesity (NWNCO) and NWCO groups comprised 266 (77.55%) and 77 (22.45%) patients, respectively, and had favorable prognosis rates of 48.50% and 35.06%, respectively. The difference between the groups was significant (P = .0371). Multivariate logistic regression analysis revealed that NWCO (aOR = 2.51, 95% CI = 1.292-5.019, P = .0075) was significantly associated with SSNHL recovery.

CONCLUSIONS

NWCO may significantly affect the prognosis of SSNHL.

A Scoping Review of Otologic Manifestations of Hematologic Malignancies

OBJECTIVE

To examine the otologic and neurotologic symptoms, physical examination findings, and imaging features secondary to hematologic malignancies.

METHODS

Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, databases, including PubMed, Scopus, and CINAHL, were searched for articles including patients with otologic manifestations of leukemia, lymphoma and multiple myeloma. Data collected included patient and study demographics, specific hematologic malignancy, timing and classification of otologic symptoms, physical examination findings, imaging features and methods of diagnosis. Pooled descriptive analysis was performed.

RESULTS

Two hundred seventy-two articles, of which 255 (93.8%) were case reports and 17 (6.2%) were case series, reporting on 553 patients were identified. Otologic manifestations were reported on 307 patients with leukemia, 204 patients with lymphoma and 42 patients with multiple myeloma. Hearing loss and unilateral facial palsy were the most common presenting symptoms for 111 reported subjects with leukemia (n = 46, 41.4%; n = 43, 38.7%) and 90 with lymphoma (n = 38, 42.2%; n = 39, 43.3%). Hearing loss and otalgia were the most common presenting symptoms for 21 subjects with multiple myeloma (n = 10, 47.6%; n = 6, 28.6%). Hearing loss and unilateral facial palsy were the most common otologic symptoms indicative of relapse in subjects with leukemia (n = 14, 43.8%) and lymphoma (n = 5, 50%).

CONCLUSION

Hearing loss, facial palsy, and otalgia might be the first indication of a new diagnosis or relapse of leukemia, lymphoma, or multiple myeloma. Clinicians should have a heightened level of suspicion of malignant etiologies of otologic symptoms in patients with current or medical histories of these malignancies.

Machine Learning Models for Predicting Sudden Sensorineural Hearing Loss Outcome: A Systematic Review

BACKGROUND

Machine Learning models have been applied in various healthcare fields, including Audiology, to predict disease outcomes. The prognosis of sudden sensorineural hearing loss is difficult to predict due to the variable course of the disease. Hence, researchers have attempted to utilize ML models to predict the outcome of patients with sudden sensorineural hearing loss. The objectives of this study were to review the performance of these machine learning models and assess their applicability in real-world settings.

METHODS

A systematic search was conducted in PubMed, Web of Science and Scopus. Only studies that built machine learning prediction models were included, and studies that used algorithms such as logistic regression only for the purpose of adjusting for confounding variables were excluded. The risk of bias was assessed using the Prediction model Risk of Bias Assessment Tool (PROBAST).

RESULTS

After screening, a total of 7 papers were eligible for synthesis. In total, these studies built 48 ML models. The most common utilized algorithms were Logistic Regression, Support Vector Machine (SVM) and boosting. The area under the curve of the receiver operating characteristic curve ranged between 0.59 and 0.915. All of the included studies had a high risk of bias; hence there are concerns regarding their applicability.

CONCLUSION

Although these models showed great performance and promising results, future studies are still needed before these models can be applied in a real-world setting. Future studies should employ multiple cohorts, different feature selection methods, and external validation to further validate the models' applicability.

Sudden Sensorineural Hearing Loss after COVID-19 Vaccination: A Review of the Available Evidence through the Prism of Causality Assessment

Sudden sensorineural hearing loss (SSNHL), a rare audiological condition that accounts for 1% of all cases of sensorineural hearing loss, can cause permanent hearing damage. Soon after the launch of global COVID-19 vaccination campaigns, the World Health Organization released a signal detection about SSNHL cases following administration of various COVID-19 vaccines. Post-marketing studies have been conducted in different countries using either pharmacovigilance or medico-administrative databases to investigate SSNHL as a potential adverse effect of COVID-19 vaccines. Here, we examine the advantages and limitations of each type of post-marketing study available. While pharmacoepidemiological studies highlight the potential association between drug exposure and the event, pharmacovigilance approaches enable causality assessment. The latter objective can only be achieved if an expert evaluation is provided using internationally validated diagnostic criteria. For a rare adverse event such as SSNHL, case information and quantification of hearing loss are mandatory for assessing seriousness, severity, delay onset, differential diagnoses, corrective treatment, recovery, as well as functional sequelae. Appropriate methodology should be adopted depending on whether the target objective is to assess a global or individual risk.

The therapeutic effect of hyperbaric oxygen therapy in patients with severe to profound idiopathic sudden sensorineural hearing loss

The optimal treatment for sudden sensorineural hearing loss (SSNHL) is unclear. Hyperbaric oxygen therapy (HBOT) has been suggested as a viable option for treatment of SSNHL as it improves vascular dysfunction. In this study, we evaluated the therapeutic effects of HBOT by retrospectively reviewing the records of 2206 patients with SSNHL. 54 who had received HBOT were selected for the HBOT groups, while 59 age-matched controls who had not were selected for the control groups. The HBOT and control groups were divided into subgroups according to intratympanic steroid (ITS) use. Groups A-D had received oral steroids + HBOT, oral steroids only, oral steroids + ITS + HBOT, and oral steroids + ITS, respectively. Of the 113 SSNHL patients, 21 had diabetes mellitus (DM) (2, 0, 9, and 10 patients in Groups A-D, respectively). There was no notable difference in hearing improvement between patients receiving HBOT and those in the control group. However, among diabetic patients, those who underwent HBOT demonstrated a significant improvement in hearing when compared to the control group. The combination of HBOT and steroids could potentially be beneficial for treating severe to profound SSNHL patients with DM.

The Importance of Lassa Fever and Its Disease Management in West Africa

Lassa virus (LASV) is a zoonotic pathogen endemic throughout western Africa and is responsible for a human disease known as Lassa fever (LF). Historically, LASV has been emphasized as one of the greatest public health threats in West Africa, with up to 300,000 cases and 5000 associated deaths per year. This, and the fact that the disease has been reported in travelers, has driven a rapid production of various vaccine candidates. Several of these vaccines are currently in clinical development, despite limitations in understanding the immune response to infection. Alarmingly, the host immune response has been implicated in the induction of sensorineural hearing loss in LF survivors, legitimately raising safety questions about any future vaccines as well as efficacy in preventing potential hearing loss. The objective of this article is to revisit the importance and prevalence of LF in West Africa, with focus on Nigeria, and discuss current therapeutic approaches and ongoing vaccine development. In addition, we aim to emphasize the need for more scientific studies relating to LF-associated hearing loss, and to promote critical discussion about potential risks and benefits of vaccinating the population in endemic regions of West Africa.

Differences in semicircular canal function in the video head impulse test in patients in the chronic stage of sudden sensorineural hearing loss with vertigo and vestibular neuritis

BACKGROUND

Sudden sensorineural hearing loss with vertigo (SHLV) and vestibular neuritis (VN) can result in prolonged dizziness.

OBJECTIVES

This study aimed to compare the video head impulse test (vHIT) of patients with SHLV and VN.

METHODS

Fifteen patients with SHLV and 21 patients with VN who visited the Vertigo/Dizziness Center of our hospital between December 2016 and February 2023 were included. vHIT was performed at the time of admission, and the VOR gain and catch up saccade (CUS) in the three types of semicircular canals (SCCs) were analyzed.

RESULTS

Pathologic vHIT results were observed most frequently in the posterior SCC (73%), followed by lateral (53%) and anterior (13%) SCCs in the SHLV group. In contrast, pathologic vHIT results were observed most frequently in the lateral SCC (100%), followed by the anterior (43%) and posterior SCC (24%) SCCs in the VN group. Pathological vHIT results in the lateral and posterior SCC showed significant differences between the two groups, but for anterior SCC, no significant differences were found.

CONCLUSIONS AND SIGNIFICANCE

Comparison of the two vHIT results revealed differences in the SCC dysfunction patterns. This may be due to the different pathophysiological mechanisms of the two vestibular disorders, which may result in prolonged vertigo.

Salvage therapy for refractory sudden sensorineural hearing loss (RSSNHL): a systematic review and network meta-analysis

OBJECTIVE

Approximately 30-50% of sudden sensorineural hearing loss (SSNHL) patients show poor response to systemic steroid therapy. Additionally, the most appropriate treatment for patients with refractory sudden sensorineural hearing loss (RSSNHL) is unknown. This study aimed to explore the best treatment for RSSNHL.

DESIGN

Using a frequentist contrast-based model and PRISMA guidelines, this study compared five salvage regimes: intratympanic injection of steroids (ITS), hyperbaric oxygen (HBO) therapy, post auricle steroid injection (PSI), ITS combined with HBO therapy, and continued systemic steroids.

STUDY SAMPLE

We searched the PubMed, EMBASE, Web of Science, and Cochrane Library databases for randomised controlled trials and cohort studies comparing treatment regimens for RSSNHL.

RESULTS

Compared with the control group (no additional treatment), PSI and ITS demonstrated significant improvements. The mean hearing gain was greater after PSI (11.1 dB [95% CI, 4.4-17.9]) than after ITS (7.7 dB [95% CI, 4.8-10.7]). When a restricted definition of RSSNHL was used, the ITS + HBO therapy showed the largest difference in improvement for pure tone average compared with the control group (14.5 dB [95% CI, 4.2-25.0]).

CONCLUSIONS

The administration of either PSI or ITS leads to the greatest therapeutic effect in patients with RSSNHL. However, a consensus on the definition of RSSNHL is needed.

Management of Sudden Sensorineural Hearing Loss in Multiple Sclerosis: A Comprehensive Case Report of a Patient with Bilateral Loss and Literature Review

In multiple sclerosis (MS), the occurrence of sudden sensorineural hearing loss (SSNHL) is considered rare, with reported cases predominantly being unilateral. Bilateral cases are even rarer. Here, we report a case of bilateral SSNHL in a 20-year-old male diagnosed with MS. The patient, undergoing corticosteroid therapy for the management of MS, additionally received an intratympanic dexamethasone injection; however, it could not achieve significant improvement. Subsequently, the systemic dosage was increased for one week, resulting in substantial hearing improvement in both ears after three months. A review of MS-related SSNHL cases from 1987 to 2022 revealed 39 ears in the literature, with only five ears showing no hearing recovery. A remarkable 87.2% exhibited restored hearing, presenting a more favorable prognosis compared with idiopathic SSNHL. Although there were slight variations in administration methods and duration, all documented treatment approaches involve systemic corticosteroids. In some instances, SSNHL manifested as the initial symptom of MS. When SSNHL occurs in MS, auditory brainstem response (ABR) tests may reveal prolonged abnormalities, making ABR testing effective in cases where MS is suspected following SSNHL. In conclusion, the treatment of MS-related SSNHL appears appropriate with systemic corticosteroids, showing a significantly superior prognosis compared with idiopathic SSNHL.

Sudden Hearing Loss Waves: The Effect of COVID-19 Infection and Vaccination on the Inner Ear

Sudden sensorineural hearing loss (SSNHL) has emerged as a potential complication of COVID-19 infection and vaccination. Various mechanisms by which the SARS-CoV-2 virus can cause hearing loss have been reported, including direct viral invasion, neuroinflammation, blood flow disturbances, and immune-mediated response. However, the temporal relationship between COVID-19 infection and SSNHL remains unclear, with mixed findings and conflicting results reported in different studies. Similarly, while anecdotal reports have linked COVID-19 vaccination to SSNHL, evidence remains scarce. Establishing a correlation between COVID-19 vaccines and SSNHL implies a complex and multifactorial pathogenesis involving interactions between the immune system and the body's stress response. Nevertheless, it is important to consider the overwhelming evidence of the vaccines' safety and efficacy in limiting the spread of the disease and remains the primordial tool in reducing death.

The value of gadolinium-enhanced MRI in predicting the development of sudden hearing loss into Ménière's disease

OBJECTIVE

To compare the clinical features of sudden hearing loss (SHL) in patients with and without endolymphatic hydrops (EH), and to investigate the association between SHL with EH and Ménière's disease (MD).

METHODS

The clinical data of 63 SHL patients with first symptoms were evaluated retrospectively. Patients were separated into two groups based on the results of gadolinium-enhanced magnetic resonance imaging: EH and non-EH groups. Independent sample t-test and U-test were used to compare groups for continuous variables, and the chi-squared test, corrected chi-squared test and Bonferroni correction test were used to compare groups for binary and ordinal variables. The binary logistic regression model was utilised for univariate and multivariate analysis of follow-up patient prognosis.

RESULTS

The EH and non-EH groups contained 32 and 31 patients, respectively. The EH group had a higher prevalence of low-tone descending hearing loss. Fifty-one patients were followed for more than 2 years. In the EH group, 11 and 15 patients were diagnosed with sudden sensorineural hearing loss (SSNHL) and MD, respectively, while in the non-EH group, 24 patients were diagnosed with SSNHL and only one with MD. EH, low-tone descending hearing loss and vertigo were risk factors for the diagnosis of MD in a subgroup univariate regression analysis of patients experiencing SHL. EH was found to be a risk factor for the progression of SHL into MD in a multifactor regression analysis.

CONCLUSIONS

Patients with SHL who have EH are more likely to present with low-tone descending hearing loss. EH is a risk factor for the subsequent development of MD.

A review on the impacts of COVID-19 on the auditory system: Implications for public health promotion research

Background

Currently, there are few studies on the relationship between COVID-19 and the auditory system. In the current study, a review of the studies conducted in the fields of etiopathology, clinical manifestations, research, and treatment of hearing loss caused byCOVID-19 was conducted, which can be used as a baseline for future studies.

Methods

We utilized the research approach suggested by Arksey and O'Malley to carry out this scoping review. Search was conducted in Farsi and English with a focus on the onset of hearing loss in patients with COVID-19 through Medline and PubMed, and Google Scholar search engine. Studies included were those involving adult patients diagnosed with COVID-19 who experienced hearing loss, ear pain, ear discharge, and otitis media. Studies were eligible for inclusion if there was a description of the otologic dysfunction, specifically onset, duration, or clinical outcomes.

Results

Among 90 studies identified, 35 studies were included in the review process. Our findings suggest several possible mechanisms for sudden sensorineural hearing loss (SSNHL) in COVID-19 patients, and COVID-19 infection could have deleterious effects on the inner ear, specifically on the hair cells of the cochlea despite patients being asymptomatic and early identification of SSNHL in COVID-19patients can save the hearing and also patient.

Conclusion

Hearing loss in COVID-19 infection has not received much attention by health care professionals. Sensorineural hearing loss (SNHL), tinnitus, and/or vertigo have been shown to occur during and following COVID-19 infection. Due to lack of research studies, and the inconsistency and even contradictory of the findings, it remains questionable whether COVID-19 contributes to the high incidence of hearing loss. The proper understanding of the mechanisms behind hearing loss in COVID-19 infections needs further research. However, it seems likely that SNHL could be included among the manifestations of those-called "long COVID" syndrome.

Cochlear Implantation in Patients with Bilateral Sudden Sensorineural Hearing Loss after COVID-19 Infection

COVID-19 infection is associated with a variety of neurological manifestations. Since the inner ear is vulnerable to viruses, sensorineural hearing loss (SNHL) has been reported to occur following SARS-CoV-2 infection. We present here two cases of profound SNHL following SARS-CoV-2 infection. Pure-tone audiograms confirmed profound SNHL. The tympanogram and Auditory Brainstem Responses showed no abnormal symptoms. MRIs and CTs identified some changes but no significant anatomical nor physiological manifestations explaining the obvious cause for hearing loss. High doses of oral corticosteroids with additional conservative therapy were given with no therapeutic response, and therefore, cochlear implant surgery was performed. One case was bilaterally treated, and the other one received an implantation on one side. Both surgeries were carried out without intra- nor postoperative complications. Interestingly, in both cases, advanced fibrotic tissue was found during surgery. Both cases reported successful rehabilitation and are satisfied with their new sound perception following cochlear implantation.

Intratympanic Triamcinolone or Dexamethasone in Sudden Sensory Neural Hearing Loss: A Randomized Clinical Trial

Sudden sensorineural hearing loss (SSNHL) is a condition in which a person experiences a rapid loss of hearing, often in one ear. The cause of SSNHL is not always clear, but it is thought to be related to issues with the inner ear, auditory nerve, or other parts of the hearing pathway. Intratympanic injection is a treatment method for SSNHL in which a medication (corticosteroids) is injected directly into the middle ear space through the tympanic membrane. This randomized clinical trial was conducted in two hospitals in Tehran, Iran. Patients with SSNHL were randomized (using the 4-block method) and included in this study. 0.5 cc of dexamethasone or triamcinolone was injected via a 25-gauge spinal needle into the cone of light of tympanic membrane. This procedure was repeated six times. In the present study, the rate of response to treatment was compared in the two groups of triamcinolone and dexamethasone, which showed that in the group where intratympanic injection of dexamethasone was performed, 70.9% of patients responded to treatment (48.4% had a complete response and 22.5% had a partial response), and in the group receiving intratympanic triamcinolone, 72.5% responded to the treatment and improved, 50% showed a complete response and 22.5% showed a partial response, and no significant difference was found in the statistical analysis of the two groups. Also, the comparison of audiometric parameters (SDS and SRT) did not show any significant difference before and after the treatment based on the treatment group, and the treatment response was found in the same group. No significant differences were noted in terms of outcome. Intratympanic dexamethasone injection was associated with a 70.9% response and triamcinolone injection with a 72.5% response.

The Role of Fibrinogen, Homocysteine and Metabolic Syndrome's Alterations in Sudden Sensorineural Hearing Loss (SSHL): A Narrative Review

Fibrinogen and homocysteine (HCY) are molecules known to play a role in vascular homeostasis, and their blood levels are often elevated in patients with metabolic syndrome. Recent evidence suggests that sudden sensorineural hearing loss (SSHL) may have a vascular origin. This has led many authors to advocate that fibrinogen, homocysteine, and metabolic syndrome (MetS) may play a direct role in SSHL. The aim of this brief review is to examine the role and influence of these molecules and MetS on the mechanisms of SSHL. Elevated fibrinogen levels have been associated with a worse prognosis in SSHL, possibly due to increased blood viscosity and decreased blood flow. Similarly, HCY has been associated with vascular damage, particularly in hyperhomocysteinemia, although the exact association with SSHL remains controversial. MetS has been demonstrated to function both as a causative factor and as a contributor to poorer recovery in cases of SSHL. However, although some studies suggest a possible role for these biomarkers and MetS in the prognosis and treatment of SSHL, specific therapeutic and preventive strategies based solely on these factors have yet to be developed. Given their potential role in prognosis and treatment and the global epidemic of metabolic syndrome, this issue needs to be analyzed comprehensively. Thus, further quality studies need to be conducted, even though it is difficult to determine the actual impact of MetS on the development of SSHL, as it is a multifactorial disease affecting multiple organs.

High Cardio-Ankle Vascular Index Values in Idiopathic Sudden Sensorineural Hearing Loss Patients Indicate Better Prognosis

OBJECTIVE

Vascular disorders and viral infections are the presumed etiologies of idiopathic sudden sensorineural hearing loss (ISSNHL) and acute sensorineural hearing loss, with no identifiable cause. However, no clinical test for estimating the extent of vascular involvement in ISSNHL has been reported despite its potential impact on prognosis and treatment. We investigated the correlation between the cardio-ankle vascular index (CAVI), which reflects arterial stiffness and elasticity, and hearing improvement to ascertain its usefulness as an additional indicator of ISSNHL prognosis and etiology.

METHODS

We enrolled 182 patients diagnosed with definite ISSNHL. The percentage of mild ISSNHL patients and that of patients experiencing no change were compared between the high-CAVI and low-CAVI groups. Age, initial and final pure-tone average (PTA) values, CAVI, presence or absence of vertigo, and medical histories were retrospectively reviewed and included in univariate and multivariate analyses.

RESULTS

The percentage of mild ISSNHL patients was smaller in the high-CAVI group than in the low-CAVI group, whereas the percentage of patients experiencing no change was smaller in the high-CAVI group than in the low-CAVI group, although patients in the high-CAVI group were significantly older than those in the low-CAVI group. The Cox proportional hazard model revealed that high CAVI, hypertension, younger age, and initial PTA <90 dB were associated with hearing improvement.

CONCLUSIONS

ISSNHL in patients with high CAVI was more severe but had a better prognosis than that in those with low CAVI. CAVI may help evaluate diseases of vascular and other etiologies, as well as ISSNHL.

Bidirectional Association Between Sudden Sensorineural Hearing Loss and Glaucoma: A Cohort Study

OBJECTIVES

To investigate the bidirectional association between sudden sensorineural hearing loss (SSNHL) and open-angle glaucoma (OAG) over a 12-year follow-up period using nationwide, population-based data.

METHODS

The study was conducted using the National Health Information Database of the National Health Insurance Service (NHIS-NHID), which covered 3.5 million individuals from 2008 to 2019. In Study 1, we evaluated the effect of OAG on SSNHL, and in Study 2, we evaluated the effect of SSNHL on OAG. Participants of the control group were enrolled through "greedy nearest-neighbor" 1:1 propensity score matching.

RESULTS

In Study 1, 26,777 people were included in each group. The hazard ratio (HR) for SSNHL of the OAG group was 1.27 (95% confidence interval [CI], 1.15-1.39). In subgroup analysis, there was significant HR value regarding (old age: 1.17, hyperlipidemia: 1.19). In Study 2, 15,433 people were included in each group. The HR for OAG of the SSNHL group was 1.18 (95% CI, 1.07-1.30). In subgroup analysis, the HRs were significant for old age (2.31), hypertension (1.17), diabetes (1.39), and hyperlipidemia (1.26).

CONCLUSION

Over the 12-year follow-up, we found a bidirectional association between SSNHL and OAG, suggesting a shared pathogenesis.

LEVEL OF EVIDENCE

N/A. Laryngoscope, 133:3169-3177, 2023.

Assessment of prognostic biomarkers in sudden sensorineural hearing loss: A systematic review and meta-analysis

Sudden sensorineural hearing loss (SSNHL) is defined as hearing loss of more than 30 dB in less than 72 h. SSNHL is a frequent complaint and an emergency in otolaryngology. Various biomarkers have been used to determine the prognosis of SSNHL. This systematic review and meta-analysis aims to evaluate the relationship between the different biomarkers and the prognosis of SSNHL. We searched English-language literature up to October 2022 in four databases, including PubMed, Google Scholar, Cochrane, and Science Direct. This search was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. This study was reported in the International Prospective Register of Systematic Reviews (PROSPERO) database (ID = CRD42022369538). All studies examining the role of neutrophil to lymphocyte ratio (NLR) concluded that higher NLR is associated with a worse prognosis. The results of studies regarding the relationship between platelet to lymphocyte ratio (PLR) and tumor necrosis factor (TNF) are controversial. Other factors shown to be associated with SSNHL include Glycated hemoglobin (HbA1C), blood glucose, iron levels, serum endocan, salusin-beta, and bone turnover biomarkers. This meta-analysis showed that PLR, NLR, and neutrophils were significantly different between recovered and non-recovered patients. PLR, NLR, and neutrophil count are reliable tools to assess the prognosis of patients with SSNHL.

Association between gut microbiota and sensorineural hearing loss: a Mendelian randomization study

Background

Several recent studies speculated that the gut microbiota is associated with sensorineural hearing loss (SNHL) and proposed the concept of the gut-inner ear axis. However, the causal effect of gut microbiota on SNHL is still unknown. In this study, we performed a two-sample Mendelian randomization (MR) analysis to estimate the causal effect of gut microbiota on SNHL.

Methods

Gut microbiota data were obtained from the largest available genome-wide association study (n = 18,340) conducted by the MiBioGen consortium. The summary statistics of SNHL were obtained from the FinnGen consortium R8 release data (28,310 cases and 302,750 controls). The causal effects were estimated with inverse-variance weighted, MR-Egger, and weighted median. Reverse Mendelian randomization analysis was performed on the bacteria that were found to be associated with SNHL in forward Mendelian randomization analysis. We then performed sensitivity analyses, including Cochran's Q-test, MR-Egger intercept test, MR-PRESSO, cML-MA-BIC, and leave-one-out analysis, to detect heterogeneity and pleiotropy.

Results

The inverse-variance weighted results suggested that Lachnospiraceae (UCG001) had a significant protective effect against SNHL (odds ratio = 0.85, 95% confidence interval: 0.78-0.93, P = 6.99 × 10-4). In addition, Intestinimonas (odds ratio = 0.89, 95% confidence interval: 0.82-0.97, P = 8.53 × 10-3) presented a suggestively protective effect on SNHL. Rikenellaceae (RC9gutgroup) (odds ratio = 1.08, 95% confidence interval: 1.02-1.15, P = 0.01) and Eubacterium (hallii group) (odds ratio = 1.12, 95% confidence interval: 1.00-1.24, P = 0.048) suggestively increase the risk of SNHL. The results of the reverse MR analysis showed that there is no significant causal effect of SNHL on the gut microbiota. No significant heterogeneity of instrumental variables or pleiotropy was detected.

Conclusion

The evidence that the four genera mentioned above are associated with SNHL supports the hypothesis of a gut-inner ear axis. Our study provides microbial markers for the prevention and treatment of SNHL, and further studies are needed to explore the mechanisms of the gut microbiome-inner ear axis in health and diseases.

Randomized, placebo-controlled study on efficacy, safety and tolerability of drug-induced defibrinogenation for sudden sensorineural hearing loss: the lessons learned

PURPOSE

Disturbance of cochlear microcirculation is discussed as final common pathway of various inner ear diseases. Hyperfibrinogenemia causing increased plasma viscosity is a possible factor for a critical reduction of cochlear blood flow that might lead to sudden sensorineural hearing loss (SSHL). The aim was to determine the efficacy and safety of drug-induced defibrinogenation by ancrod for SSHL.

METHODS

Double-blind, randomized, placebo-controlled, multicenter, parallel group, phase II (proof-of-concept) study (planned enrollment: 99 patients). Patients received an infusion of ancrod or placebo (day 1) followed by subcutaneous administrations (day 2, 4, 6). Primary outcome was the change in pure tone audiogram air conduction average until day 8.

RESULTS

The study was terminated early due to slow recruiting (31 enrolled patients: 22 ancrod, 9 placebo). A significant improvement of hearing loss was registered in both groups (ancrod: - 14.3 dB ± 20.4 dB, - 39.9% ± 50.4%; placebo: - 22.3 dB ± 13.7 dB, - 59.1% ± 38.0%). A statistically significant group-difference was not detected (p = 0.374). Placebo response of 33.3% complete and 85.7% at least partial recovery was observed. Plasma fibrinogen levels were reduced significantly by ancrod (baseline: 325.2 mg/dL, day 2: 107.2 mg/dL). Ancrod was tolerated well, no adverse drug reaction was of severe intensity, no serious adverse events occurred.

CONCLUSION

Ancrod reduced fibrinogen levels that support its mechanism of action. The safety profile can be rated positively. Since the planned number of patients could not be enrolled, no efficacy conclusion can be drawn. The high rate of placebo response challenges clinical trials for SSHL and needs to be considered in future investigations. Trial registrations This study was registered in the EU Clinical Trials Register, EudraCT-No. 2012-000066-37 at 2012-07-02.

Cardiovascular Risk Factors, Cerebral Small Vessel Disease, and Subsequent Risk of Stroke in Patients with Idiopathic Sudden Sensorineural Hearing Loss: Systematic Review and Meta-Analyses of the Current Literature

Vascular involvement in the pathophysiology of idiopathic sudden sensorineural hearing loss (iSSNHL) has been previously proposed. The objective of this study was to perform a systematic review of the current literature and conduct meta-analyses to evaluate associations between cardiovascular risk factors, cerebral small vessel disease, and subsequent stroke after presentation with iSSNHL. Three systematic literature reviews and meta-analyses were conducted using PubMed, Embase, and CINAHL. All studies investigating associations between iSSNHL and the cardiovascular risk factors: body mass index (BMI), diabetes mellitus, hyperlipidemia, hypertension, medical history of myocardial infarction (MI), smoking, the degree of white matter hyperintensities, and incidence of stroke were included. Adhering to the PRISMA guidelines, two independent reviewers reviewed the articles and assessed risk of bias. The cardiovascular risk factors of abnormal BMI, diabetes, hypertension, total cholesterol, low-density lipoprotein cholesterol, and a medical history of MI were significantly associated with iSSNHL. The adjusted hazard ratio of a higher degree of white matter hyperintensities was 0.70 (95% CI 0.44, 1.12). Patients with iSSNHL showed a higher risk of stroke compared to controls, with hazard ratios ranging from 1.22 up to 4.08. Several cardiovascular risk factors are more frequently present in patients with iSSNHL than in the general population. The degree of white matter hyperintensities does not appear to be increased in patients with iSSNHL, while the risk of stroke following ISSNHL is increased. Prospective studies with larger study populations are needed to confirm the associations between generalized cardiovascular disease and iSSNHL and to assess whether these patients benefit from cardiovascular risk management to prevent future cardiovascular and cerebrovascular disease.

Vascular Loop of the Anterior Inferior Cerebellar Artery (AICA) as a Cause of Sensorineural Hearing Loss (SNHL): A Case Report

Sensorineural hearing loss (SNHL) is one of the most common causes of hearing loss worldwide. Although highly prevalent, many patients often present with SNHL of unknown cause. Related to SNHL is tinnitus, which often presents with SNHL and can have debilitating effects on patients. The idiopathic nature of SNHL and tinnitus often makes treatment difficult, however, a relatively new etiology has been suggested as a cause of SNHL and tinnitus -- vascular loops within the internal auditory canal (IAC). This report presents the case of a 36-year-old male with bilateral SNHL and tinnitus treated with oral steroids. The patient reported subjective improvement of hearing loss and tinnitus, and the audiogram demonstrated hearing improvement, except in higher frequencies. After initial treatment, MRI revealed a vascular loop of the anterior inferior cerebral artery (AICA) in the right IAC, in contact with the vestibulocochlear nerve. Thus, this case report seeks to present a conservative strategy for SNHL and tinnitus in the presence of a vascular loop of the AICA. As a controversial cause of SNHL and tinnitus, there is no standard of treatment for AICA loops of the IAC which are often treated surgically. This case highlights the importance of an initial conservative prior to surgical intervention. Thus, we seek to contribute to the growing body of literature by further elucidating the relationship between SNHL, tinnitus, and vascular loops and discussing potential pathophysiological mechanisms to guide optimal management strategies.

Urgency in the Treatment of Sudden Sensorineural Hearing Loss

Sudden sensorineural hearing loss (SSNHL) is considered an otolaryngologic emergency that must be treated within 72 hours. Failure to treat within that time frame typically results in permanent hearing loss. Here, we present a case of SSNHL confirmed by an audiogram that was treated as eustachian tube dysfunction. Aggressive management measures started at follow-up failed to improve the hearing loss. This case demonstrates the need for early recognition and ENT referral for SSNHL.

Experience of sudden sensorineural hearing loss following a mild COVID-19 infection

A woman in her 30s was referred to an otolaryngologist with an acute onset of aural fullness, noise sensitivity, unilateral sudden onset hearing loss, vertigo and tinnitus. She had a confirmed COVID-19 infection 5 weeks prior. A pure tone audiogram confirmed sensorineural hearing loss. MRI identified an empty sella of the pituitary gland and without an obvious cause for hearing loss. Oral prednisolone and betahistine were prescribed, and her audiovestibular symptoms slowly improved over the subsequent months. The patient continues to experience intermittent tinnitus.

COVID-19 Vaccination and Sudden Sensorineural Hearing Loss: A Case Study

This article highlights a client with sensorineural hearing loss reported after 2 days of 2nd dose of COVID-19 vaccination. The audiological evaluations suggest unilateral hearing loss which recovered after the treatment. This article focuses on spreading awareness about the complications after vaccination and the importance of treatment.

Cardiovascular Risk Factors in Patients With Sudden Sensorineural Hearing Loss: A Systematic Review and Meta-Analysis

OBJECTIVE

The interruption of vascular supply to the inner ear is one of several proposed etiologies of sudden sensorineural hearing loss (SSNHL). The increased presence of cardiovascular risk factors may predispose patients to SSNHL through this pathway. This systematic review and meta-analysis studies the presence of cardiovascular risk factors in patients diagnosed with SSNHL.

DATA SOURCES

Databases included PubMed/Medline, OVID, EMBASE, Cochrane, and Web of Science.

REVIEW METHODS

Inclusion criteria included studies featuring SSNHL patients presenting with 1+ cardiovascular risk factors. Exclusion criteria included case reports and studies without outcome measures. Two investigators independently reviewed all manuscripts and performed quality assessments using validated tools.

RESULTS

Of 532 identified abstracts, 27 studies met inclusion criteria (19 case-control, 4 cohorts, 4 case series). Of these, 24 underwent meta-analysis encompassing a total of 77,566 patients (22,620 SSNHL patients, 54,946 matched controls). The mean age was 50.43 years. SSNHL patients were more likely to have concomitant diabetes (odds ratio [OR] 1.61 [95% confidence interval [CI]: 1.31, 1.99; p < .00001]) and hypertension (OR 1.5 [95% CI: 1.16, 1.94; p = .002]). An increased standard mean difference of total cholesterol of 11.09 mg/dL (95% CI; 3.51, 18.67; p = .004) was noted in the SSNHL group compared with the controls. No significant differences in smoking, high-density lipoprotein, triglycerides, or body mass index were detected.

CONCLUSION

Patients presenting with SSNHL have a significantly higher risk of concomitant diabetes, hypertension, and higher total cholesterol in comparison to matched controls. This may indicate a higher cardiovascular risk profile in this population. More prospective and matched cohort studies are needed to understand the role of cardiovascular risk factors in SSNHL.

Could the Audiometric Criteria for Sudden Sensorineural Hearing Loss Miss Vestibular Schwannomas?

OBJECTIVE

To investigate the likelihood of missing a vestibular schwannoma (VS) diagnosis in patients who present with a sudden hearing loss (SHL) that does not meet the most accepted audiometric criteria for sudden sensorineural hearing loss (SSNHL) (a decrease of ≥30 dB at three consecutive frequencies).

METHODS

All adult patients (>18 years) diagnosed with SHL of any severity in a tertiary care referral medical center between 2015 and 2020 and who underwent an MRI scan to rule out VS were included. Statistical analyses were conducted to evaluate the difference between the rate of VS among patients with an initial audiogram, which met the abovementioned criteria, and those who did not. Other audiometric criteria for SNHL were also evaluated (≥10 dB at ≥2 frequencies and ≥ 15 dB at one frequency).

RESULTS

Of the 332 patients included in the study, 152 met the audiometric criteria for SSNHL, and 180 did not. Both groups had a similar VS rate (8.6% vs. 8.9%, p = 0.914). Similar results were found when other audiometric criteria for asymmetric SNHL were analyzed. In a subgroup analysis of patients with VS-associated SSNHL, neither the tumor size nor the Koos classification was associated with any of the audiometric criteria systems.

CONCLUSION

There should be a high index of suspicion for the presence of VS in patients with an SHL of any severity.

LEVEL OF EVIDENCE

3 Laryngoscope, 133:670-675, 2023.

Short-term effects of intravenous batroxobin in treatment of sudden sensorineural hearing loss: a propensity score-matched study

Background

Sudden sensorineural hearing loss (SSNHL) can cause great panic in patients. Whether it is advantageous to add intravenous batroxobin in the treatment of SSNHL remains to be determined. This study aimed to compare the short-term efficacy of therapy combined with intravenous batroxobin and that without intravenous batroxobin in SSNHL patients.

Methods

This retrospective study harvested the data of SSNHL patients hospitalized in our department from January 2008 to April 2021. The hearing levels on the admitted day (before treatment) and the discharge day were considered pre-treatment hearing and post-treatment hearing, respectively. The hearing gain was the difference value of pre-treatment hearing and post-treatment hearing. We used Siegel's criteria and the Chinese Medical Association of Otolaryngology (CMAO) criteria to evaluate hearing recovery. The complete recovery rate, overall effective rate, and hearing gain at each frequency were considered outcomes. Propensity score matching (PSM) was conducted to balance the baseline characteristics between the batroxobin group and the non-batroxobin group. Sensitivity analysis was carried out in flat-type and total-deafness SSNHL patients.

Results

During the study period, 657 patients with SSNHL were admitted to our department. Among them, a total of 274 patients met the enrolled criteria of our study. After PSM, 162 patients (81 in each group) were included in the analysis. Once the hospitalized treatment was completed, the patients would be discharged the next day. Logistic regression analysis of the propensity score-matched cohort indicated that both the complete recovery rates [Siegel's criteria, OR: 0.734, 95% CI: 0.368-1.466, p = 0.381; CMAO criteria, OR: 0.879, 95% CI: 0.435-1.777, p = 0.720] and the overall effective rates [Siegel's criteria and CMAO criteria, OR: 0.741, 95% CI: 0.399-1.378, p = 0.344] were not significantly different between the two treatment groups. Sensitivity analysis has shown similar results. For flat-type and total-deafness SSNHL patients, no significant difference was found in post-treatment hearing gain at each frequency between the two groups after PSM.

Conclusion

There was no significant difference in short-term hearing outcomes between treatment with batroxobin and treatment without batroxobin in SSNHL patients by Siegel's and CMAO criteria after PSM. Future studies for better therapy regimens of SSNHL are still needed.

Triple network activation causes tinnitus in patients with sudden sensorineural hearing loss: A model-based volume-entropy analysis

Tinnitus can be defined as the conscious perception of phantom sounds in the absence of corresponding external auditory signals. Tinnitus can develop in the setting of sudden sensorineural hearing loss (SSNHL), but the underlying mechanism is largely unknown. Using electroencephalography, we investigated differences in afferent node capacity between 15 SSNHL patients without tinnitus (NT) and 30 SSNHL patients with tinnitus (T). Where the T group showed increased afferent node capacity in regions constituting a "triple brain network" [default mode network (DMN), central executive network (CEN), and salience network (SN)], the NT group showed increased information flow in regions implicated in temporal auditory processing and noise-canceling pathways. Our results demonstrate that when all components of the triple network are activated due to sudden-onset auditory deprivation, tinnitus ensues. By contrast, auditory processing-associated and tinnitus-suppressing networks are highly activated in the NT group, to overcome the activation of the triple network and effectively suppress the generation of tinnitus.

Epidemiology of idiopathic sudden sensorineural hearing loss in the era of big data

OBJECTIVES

Idiopathic sudden sensorineural hearing loss (ISSNHL) is a medical emergency, and delayed treatment can have permanent sequelae. However, the etiology of ISSNHL is diverse and unclear; thus, it is idiopathic. To develop an insight into this condition, patients with ISSNHL must be clearly identified. We propose an operational definition for the unambiguous identification of ISSNHL patients. Patients are identified through suggested definitions, and prevalence and general information are investigated.

METHODS

A retrospective study of patients with ISSNHL was performed using the Health Insurance and Review Assessment-National Patient Sample from 2009 to 2016. To present a new operational definition, a systematic review was conducted for studies on ISSNHL from January 2007 to June 2021. After constructing several operant definitions using the conditions that can specify patients with ISSNHL in big data, we compared each definition to propose an operational definition.

RESULTS

The important conditions required to classify patients with ISSNHL using big data were the International Classification of Diseases (ICD)-10 code, number of pure tone audiometry (PTA) tests, and whether steroids were prescribed. Among them, those who had undergone PTA tests more than twice could be clearly identified as patients with ISSNHL.

CONCLUSION

As the use of big data becomes smoother, research using national medical data is being conducted; however, the results of the studies may vary depending on how a patient with ISSNHL is classified. Clear identification of patients with ISSNHL will be beneficial for better management of this condition.

Study of Hearing Status in COVID-19 Patients: A Multicentered Review

To evaluate the hearing status of COVID-19 patients and compare with control group. Prospective study carried out in 9 institutes. The pure tone audiogram and impedance audiometry of COVID-19 patients performed initially and at 3 months follow up. The control group consisted COVID-19 negative individuals with no history of ear related diseases. The average of air and bone conduction threshold (AC and BC) were compared between the COVID-19 patients and control group using independent t-test with a p value of less than 0.05 considered significant. Total of 331 patients, age 32 ± 4.3 years, 66.7% males and 33.3% females were included in the study. There were 80 individuals in the control group. Aural symptoms were, tinnitus in 1.8%, aural fullness in 1.4%, hearing loss in 3. 9%, and ear ache in 1.8% were present initially, resolved at 3 months follow up. The impedance audiometry demonstrated type B and type C curve in 5.1% and 1.15% ears, and out of these 64.7% and 40% improved at 3 months follow up respectively. No significant difference observed between the average AC and BC of the COVID-19 patients and control group. The COVID-19 infection may present with aural symptoms; however, it was concluded that there was no significant difference in the hearing status of the COVID-19 positive patients in comparison to the control group. The presence of some changes in the normal functioning of the eustachian tube and middle ear in the COVID-19 infection was also highlighted.

Positive horizontal-canal head impulse test is not a benign sign for acute vestibular syndrome with hearing loss

Background

Diagnosis of acute vestibular syndrome (AVS) with hearing loss is challenging because the leading vascular cause—AICA territory stroke—can appear benign on head impulse testing. We evaluated the diagnostic utility of various bedside oculomotor tests to discriminate imaging-positive and imaging-negative cases of AVS plus hearing loss.

Method

We reviewed 13 consecutive inpatients with AVS and acute unilateral hearing loss. We compared neurologic findings, bedside and video head impulse testing (bHIT, vHIT), and other vestibular signs (including nystagmus, skew deviation, and positional testing) between MRI+ and MRI– cases.

Results

Five of thirteen patients had a lateral pontine lesion (i.e., MRI+); eight did not (i.e., MRI–). Horizontal-canal head impulse test showed ipsilateral vestibular loss in all five MRI+ patients but only in three MRI– patients. The ipsilesional VOR gains of horizontal-canal vHIT were significantly lower in the MRI+ than the MRI– group (0.56 ± 0.11 vs. 0.87 ± 0.24, p = 0.03). All 5 MRI+ patients had horizontal spontaneous nystagmus beating away from the lesion (5/5). One patient (1/5) had direction-changing nystagmus with gaze. Two had skew deviation (2/5). Among the 8 MRI– patients, one (1/8) presented as unilateral vestibulopathy, four (4/8) had positional nystagmus and three (3/8) had isolated posterior canal hypofunction.

Conclusion

The horizontal-canal head impulse test poorly discriminates central and peripheral lesions when hearing loss accompanies AVS. Paradoxically, a lateral pontine lesion usually mimics unilateral peripheral vestibulopathy. By contrast, patients with peripheral lesions usually present with positional nystagmus or isolated posterior canal impairment, risking misdiagnosis as central vestibulopathy.

Sudden Sensorineural Hearing Loss: A Review

The objective of this review is to present and evaluate the current views on sudden sensorineural hearing loss. Sudden sensorineural hearing loss is an otolaryngology emergency requiring immediate diagnosis and treatment. The etiology of the majority of cases is unknown. The etiology can be classified into various categories such as autoimmune diseases, infections, functional, metabolic disorders, vascular disorders, traumatic causes, due to toxins, and neurological disorders. We searched the U.S. National Library of Medicine's PubMed database using the terms "sudden S.N.H.L.," "virus and ssnhl," and "sudden deafness," as well as the keywords such as "etiology," "COVID 19, and ssnhl," “epidemiology,” “clinical characteristics,” “management,” “therapy,” and “prognosis."

Unilateral, permanent hearing loss following severe COVID-19 infection

Hearing loss following COVID-19 infection has been scarcely reported in the literature.

A previously well middle-aged man presented to the emergency department with breathlessness and cough 8 days after testing positive for COVID-19 in the community. The patient was treated in the intensive care unit due to respiratory failure. Following extubation and step down to ward-level care 2 months later, the patient reported sudden left-sided hearing loss and tinnitus. Ear examination was unremarkable and pure tone audiometry revealed profound left sensorineural hearing loss. MRI of the internal acoustic meatus did not show any cerebellopontine lesions. Intravenous steroid therapy as well as oral steroids were not successful in improvement of hearing.

A few cases of COVID-19-associated sensorineural hearing loss have been reported; the majority report irreversible loss. Awareness of this phenomenon and early referral for specialist review and audiological assessment to attempt salvage of hearing can reduce hearing disability.

The Impact of Intratympanic Steroid Dosage on Hearing Recovery in Sudden Sensorineural Hearing Loss

OBJECTIVE

To investigate how dexamethasone dosage impacts intratympanic steroid therapy (IST) for treatment of sudden sensorineural hearing loss (SSNHL).

STUDY DESIGN

Retrospective review.

METHODS

Inclusion criteria identified subjects who received IST between January 1, 2010 and June 1, 2020 for iSSNHL. Subjects with Meniere's disease, autoimmune inner ear disease, subjects who received injections of non-dexamethasone steroid formulations, and subjects with missing audiogram data were excluded. Subjects were stratified by dexamethasone dosage: low-dose (10 mg/ml) versus high-dose (24 mg/ml), time-to-treatment and oral corticosteroid use. Outcome measures included post-treatment improvement in 4-frequency pure tone average (4F-PTA [500, 1000, 2000,4000 Hz]), low- and high-frequency PTA (250-1000 Hz and 2000-8000 Hz, respectively).

RESULTS

Of the 55 included subjects (50.9% male, mean age 48.9 ± 16.4 years), 31 received high-dose while 24 received low-dose injections. 90.9% of subjects were treated with oral steroids prior to or during IST. No significant differences in hearing outcomes were observed between low- and high-dose cohorts or when stratifying by oral steroid use. Time-to-treatment analysis comparing ≤1 month (67.3%) versus >1 month (32.7%) groups demonstrated a significant improvement in post-treatment 4F-PTA (P = .01) in the ≤1 month group.

CONCLUSIONS

Hearing recovery was not significantly different between the 10 mg/ml versus 24 mg/ml doses of intratympanic dexamethasone, suggesting that steroid dose may not impact the efficacy of IST. A shorter time-to-treatment was observed to be favorable for hearing improvement.