Association of Glycosylated Hemoglobin A1c Level With Sudden Sensorineural Hearing Loss: A Prospective Study

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 HbA1c and hearing loss: a tertiary care center-based study

The purpose of this study was to investigate the correlation between glycated hemoglobin (HbA1c) levels and hearing loss (HL) using data from a tertiary hospital. Our hypothesis regarding the relationship between HL and HbA1c levels was that elevated HbA1c levels are associated with an increased risk of HL. We retrospectively reviewed the medical charts of patients diagnosed with sensorineural HL or diabetes between 2006 and 2021 at the Catholic Medical Center (CMC). Data were collected from the CMC's Clinical Data Warehouse. Participants were selected from patients who were prescribed pure-tone audiometry and an HbA1c blood test. The survey was completed for 5287 participants. The better ear pure-tone audiometry (PTA) for air conduction thresholds at 500, 1000, 2000, and 4000 Hz was calculated. Sensorineural HL was defined as a better ear PTA of 25 dB or higher. We used the HbA1c level as a diagnostic criterion for diabetes. The following criteria were used to define the HbA1c level: normal, HbA1c level below 5.6%; prediabetes, level between 5.6 and 6.4%; and diabetes, level of 6.5% or more. Among 5287 participants, 1129 were categorized as normal, 2119 as prediabetic, and 2039 as diabetic. The diabetic group was significantly older (p < 0.05). The PTA also significantly deteriorated in the diabetes group (p < 0.05). We analyzed the effects of age, sex, and HbA1c level on frequency-specific hearing using multiple regression. The hearing thresholds at all frequencies deteriorated significantly with increasing age and HbA1c level (p < 0.05). A case-control study was also performed to facilitate a comprehensive comparison between distinct groups. The participants were categorized into two groups: a case (PTA > 25 dB) and control group (PTA ≤ 25 dB), based on their PTA threshold of four frequencies. After adjusting for age and sex, we found no significant odds ratio (OR) of HL between the prediabetes group and the normal group. Notably, the OR of HL was significantly higher in the diabetes group with each PTA threshold and frequency. The 6.3% HbA1c level cutoff value was determined by analyzing the receiver operating characteristic curve for predicting hearing impairment > 25 dB. Diabetes was associated with hearing loss in all frequency ranges, particularly at high frequencies. Screening for HL is strongly recommended for patients with elevated HbA1c levels.

Diabetes mellitus and hearing loss

Diabetes mellitus (DM) is a major disease threatening human health and its incidence is increasing year on year. As a chronic complication of DM, hearing loss mostly occurs undetectably. However, the mechanism of this diabetes-related hearing loss (DRHL) remains unclear and there is no effective clinical treatment. Studies of animal or human pathology show that DM causes damage to the blood vessels, spiral ganglion neurons, afferent nerve fibers, the organ of Corti, and the stria vascularis of the inner ear. In recent years, more advances in pathological research have revealed the possible mechanism of DRHL. In addition, a large number of clinical studies suggest that the duration and severity of DM are closely related to the incidence and severity of DRHL. This review focuses on the relationship between DM and hearing loss. The clinical audiological characteristics of diabetic patients, risk factors for DRHL, typical pathology, and potential interventions of DRHL are summarized. This will help reveal the pathogenesis and intervention approaches for DRHL.

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.

A Prospective Study on Post Covid Sudden Onset Sensory Neural Hearing Loss and Its Recovery

Sudden sensorineural hearing loss (SSNHL) is a known complication of a number of viral infections, but there is little literature to date on its association to Corona virus disease 2019(COVID-19).This study aimed to investigate the incidence and recovery from SSNHL in post COVID-19 patients. A study was conducted in 6 months of duration at our tertiary care COVID dedicated hospital. Total 280 patients with age group of 12-70 years, laboratory confirmed COVID 19 positive patients having mild to moderate COVID symptoms were included. Patients were examined clinically along with all safety measures to analyze incidence and their recoveries from SSNHL by clinical examination and using Pure Tone Audiometry (PTA). Out of 280 patients the incidence of only SSNHL is 1.07% (3 patients) and SSNHL with tinnitus is 2.14%(6 patients).Total recovery(TR) regained in 2 patients of SSNHL, Partial recovery(PR) in 4 patients, Slight improvement(SI) in 1 patient and no recovery(NR) in 2 patients. The incidence of SSNHL in time of COVID 19 pandemic appears to be higher (3.2%) than before the pandemic (0.005%-0.16%). Incidence among younger age group and patients with no comorbidities has been also increased. In diagnosed case of SSNHL, early treatment with short term course of oral steroids and neuromodulator drugs are the mainstay treatment. Awareness of such non-specific presentation of COVID 19 patients is crucial and shared decision making with the patient and providing health care personnel is necessary for decreasing the hearing loss associated morbidity.

Diabetes Mellitus and Hearing Loss: A Complex Relationship

Background and Objectives: Discussion is open about the relationship between diabetes (DM) and hearing loss (HL). There is a lot of evidence in the literature suggesting a causal link between these conditions, beyond being considered simple comorbidities. The difficulty in identifying populations free from confounding factors makes it difficult to reach definitive conclusions on the pathophysiological mechanisms at play. Nonetheless, there is numerous evidence that demonstrates how the population affected by DM is more affected by sensorineural HL (SNHL) and exhibit a higher prevalence of idiopathic sudden sensorineural HL (ISSNHL). Materials and Methods: Articles reporting potentially relevant information were reviewed, and the most significant results are discussed in this article. Starting from the possible mechanisms relating to auditory impairment in the diabetic condition, this article summarizes the studies on auditory evaluation in subjects with DM1 and DM2 and addresses the relationship between DM and ISSNHL. Results: DM is considered a risk factor for SNHL, although some studies have reported no relationship when the associations were adjusted for age, gender, and hypertension. Macro and microvascular insults that cause decreased blood flow, oxygen exchange, and ion transport are major complications of hypertension and DM and can have a direct effect on the sensory and support cells of the cochlea. Conclusions: Given the difficulty of carrying out studies on populations without confounding factors, new laboratory studies are strongly required to clarify which specific physiopathological mechanisms underlie the diabetic damage caused to the hearing organs and how pharmacological management may contribute to counteracting the pathophysiological effects of the diabetic condition on the auditory system.

Vulnerable frequency as an independent prognostic factor for sudden sensorineural hearing loss

Objectives

Sudden sensorineural hearing loss (SSNHL) is a common otology emergency in the practice. Its severe hearing impairment and prognosis impair the quality of life. Given that cochlear hair cell vulnerability is not consistent across frequencies, this study aims to investigate the impact of frequency-specific hearing loss on prognosis in SSNHL.

Methods

The study included 255 patients with full-frequency SSNHL. The baseline, clinical, and hearing characteristics, as well as possible cardiovascular predictors in blood, were collected for analysis.

Results

The 4,000 and 8,000 Hz hearing levels in the responder group were significantly lower than those in the non-responder group (p = 0.008, p &lt; 0.001), while the average hearing was not (p = 0.081). Logistic regression showed that only vertigo (OR, 95% CI, 0.265, 0.102–0.684, p = 0.006) and 8,000 Hz hearing level (OR, 95% CI, 0.943, 0.916–0.971, p &lt; 0.001) were strongly associated with treatment outcome.

Conclusions

Compared with other frequencies, 8,000 Hz hearing level was closely related to prognosis in SSNHL. In an adjusted model, our study did not find an effect of mean hearing on prognosis in SSNHL. However, further multicenter prospective studies are needed for validation.

Diagnostic and predictive values of serum metabolic profiles in sudden sensorineural hearing loss patients

Sudden sensorineural hearing loss (SSNHL) is an otologic emergency, and metabolic disturbance is involved in its pathogenesis. This study recruited 20 SSNHL patients and 20 healthy controls (HCs) and collected their serum samples. Serum metabolites were detected by liquid chromatography-mass spectrometry, and metabolic profiles were analyzed. All patients were followed up for 3 months and categorized into recovery and non-recovery groups. The distinctive metabolites were assessed between two groups, and their predictive values for hearing recovery were evaluated. Analysis results revealed that SSNHL patients exhibited significantly characteristic metabolite signatures compared to HCs. The top 10 differential metabolites were further analyzed, and most of them showed potential diagnostic values based on receiver operator characteristic (ROC) curves. Finally, 14 SSNHL patients were divided into the recovery group, and six patients were included in the non-recovery group. Twelve distinctive metabolites were observed between the two groups, and ROC curves demonstrated that N4-acetylcytidine, p-phenylenediamine, sphingosine, glycero-3-phosphocholine, and nonadecanoic acid presented good predictabilities in the hearing recovery. Multivariate analysis results demonstrated that serum N4-Acetylcytidine, sphingosine and nonadecanoic acid levels were associated with hearing recovery in SSNHL patients. Our results identified that SSNHL patients exhibited distinctive serum metabolomics signatures, and several serum biomarkers were proved to be potential in predicting hearing recovery. The discriminative metabolites might contribute to illustrating the mechanisms of SSNHL and provide possible clues for its treatments.