Drug-induced Defibrinogenation as New Treatment Approach of Acute Hearing Loss in an Animal Model for Inner Ear Vascular Impairment

Efficacy and fibrinogen correlations of defibrinogen therapy in idiopathic sudden sensorineural hearing loss

This study aimed to assess the efficacy of Defibrinogen (DF) therapy in addressing total deafness of idiopathic sudden sensorineural hearing loss (TD-ISSNHL) and investigate the relationship between fibrinogen levels and auditory outcomes. A total of 342 cases of TD-ISSNHL were retrospectively analyzed, with patients divided into two main groups: an experimental group receiving batroxobin in conjunction with Ginaton and glucocorticoids, and a control group receiving Ginaton and glucocorticoids only. Auditory outcomes on the 10th day and the 14th day were analyzed and compared across these groups. Subsequently, the correlation between plasma fibrinogen and prognosis were analyzed within these groups. By the 10th day, the overall efficacy rates in the experimental groups were significantly higher than that in the control group (P = 0.039). Patients extending DF therapy to the 14th day showed a substantial improvement in the overall efficacy rate, from 50.98 to 82.35%. Additionally, significant differences in fibrinogen levels were observed on day 1, day 3, and day 5 ± 1 between the recovery and non-recovery groups (P = 0.013, P = 0.024, P = 0.005). Spearman's rank correlation analysis indicated weak negative correlations between fibrinogen levels on day 1 and day 3 and hearing improvement, while the level on day 5±1 had a moderate negative correlation. Throughout the follow-up period, no major complications were observed. The study findings suggest that batroxobin therapy not only improves hearing recovery but also maintains plasma fibrinogen at a low and safe level. In addition, sustained low fibrinogen level throughout treatment serves as a predictor for better prognosis in TD-ISSNHL.

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.

Cochlear implantation impairs intracochlear microcirculation and counteracts iNOS induction in guinea pigs

Introduction

Preservation of residual hearing remains a great challenge during cochlear implantation. Cochlear implant (CI) electrode array insertion induces changes in the microvasculature as well as nitric oxide (NO)-dependent vessel dysfunction which have been identified as possible mediators of residual hearing loss after cochlear implantation.

Methods

A total of 24 guinea pigs were randomized to receive either a CI (n = 12) or a sham procedure (sham) by performing a cochleostomy without electrode array insertion (n = 12). The hearing threshold was determined using frequency-specific compound action potentials. To gain visual access to the stria vascularis, a microscopic window was created in the osseous cochlear lateral wall. Cochlear blood flow (CBF) and cochlear microvascular permeability (CMP) were evaluated immediately after treatment, as well as after 1 and 2 h, respectively. Finally, cochleae were resected for subsequent immunohistochemical analysis of the iNOS expression.

Results

The sham control group showed no change in mean CBF after 1 h (104.2 ± 0.7%) and 2 h (100.8 ± 3.6%) compared to baseline. In contrast, cochlear implantation resulted in a significant continuous decrease in CBF after 1 h (78.8 ± 8.1%, p < 0.001) and 2 h (60.6 ± 11.3%, p < 0.001). Additionally, the CI group exhibited a significantly increased CMP (+44.9% compared to baseline, p < 0.0001) and a significant increase in median hearing threshold (20.4 vs. 2.5 dB SPL, p = 0.0009) compared to sham after 2 h. Intriguingly, the CI group showed significantly lower iNOS-expression levels in the organ of Corti (329.5 vs. 54.33 AU, p = 0.0003), stria vascularis (596.7 vs. 48.51 AU, p < 0.0001), interdental cells (564.0 vs. 109.1 AU, p = 0.0003) and limbus fibrocytes (119.4 vs. 18.69 AU, p = 0.0286).

Conclusion

Mechanical and NO-dependent microvascular dysfunction seem to play a pivotal role in residual hearing loss after CI electrode array insertion. This may be facilitated by the implantation associated decrease in iNOS expression. Therefore, stabilization of cochlear microcirculation could be a therapeutic strategy to preserve residual hearing.

Clinical Profiles and Prognoses of Adult Patients with Full-Frequency Sudden Sensorineural Hearing Loss in Combination Therapy

We aimed to characterize the clinical profiles and short-term outcomes of adult patients with full-frequency idiopathic sudden sensorineural hearing loss (ISSNHL) treated uniformly with combination therapy, and to determine the prognostic predictors for the combination therapy. A total of 131 eligible cases hospitalized in our department from January 2018 to June 2021 were retrospectively reviewed. All enrolled cases received a standardized combination therapy employing intravenous methylprednisolone, batroxobin, and Ginkgo biloba extract during the 12 days of hospitalization. The clinical and audiometric profiles were compared between recovered patients and their unrecovered counterparts. The overall recovery rate was 57.3% in the study. Accompanying vertigo (odds ratio = 0.360, p = 0.006) and body mass index (BMI, odds ratio = 1.158, p = 0.016) were two independent predictors of hearing outcomes of the therapy. The male gender and cigarette-smoking history were marginally associated with good hearing prognosis (p = 0.051 and 0.070, respectively). Patients with BMI ≥ 22.4 kg/m² had a better chance of hearing recovery (p = 0.02). Conclusions: Accompanying vertigo and low BMI (<22.4 kg/m²) were independently associated with poor prognosis for full-frequency ISSNHL in combination therapy. Male gender and cigarette-smoking history might be considered positive effects on hearing prognosis.

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.

Cannabinoid Receptor 2 Agonism is Capable of Preventing Lipopolysaccharide Induced Decreases of Cochlear Microcirculation - A Potential Approach for Inner Ear Pathologies

HYPOTHESIS

The ability of JWH-133, an agonist at the cannabinoid receptor 2, to abrogate the effects of lipopolysaccharide on cochlear microcirculation was investigated.

BACKGROUND

Cochlear inflammation and subsequent impairment of microcirculation is part of numerous pathologies affecting inner ear function, including suppurative labyrinthitis, noise trauma, and sudden sensorineural hearing loss. One way of causing cochlear inflammation is exposing the cochlea to lipopolysaccharide, a bacterial endotoxin.

METHODS

Twenty Dunkin-hartley guinea pigs were divided into four groups of five animals each. Two groups received topic treatment with JWH-133 and two received treatment with placebo. One group that had been treated with JWH-133 and one with placebo were then exposed to lipopolysaccharide or placebo, respectively. Cochlear microcirculation was quantified before, in between and after treatments by in vivo fluorescence microscopy.

RESULTS

Significantly different changes in cochlear blood flow were only seen in the group that was treated with placebo and subsequently lipopolysaccharide. Every other group showed no significant change in cochlear blood flow.

CONCLUSION

JWH-133 is capable of abrogating the effects of lipopolysaccharide on cochlear microcirculation. It may therefore be clinical interest in treating numerous inflammation associated cochlear pathologies.

Butylphthalide enhances recovery from sudden deafness

OBJECTIVES

Cochlear microcirculation disturbance caused by vasculopathy is a common cause of sudden deafness (SD). Reactive oxygen species (ROS) plays an important role in cochlear injury during ischemia-reperfusion. Butylphthalide can improve microcirculation, reduce ROS formation and inhibit apoptosis. The aim of this study was to investigate the therapeutic effect of butylphthalide on patients with SD.

PATIENTS AND METHODS

The hearing gains from 32 ears treated with butylphthalide were compared with that of 32 ears treated with non-butylphthalide. Butylphthalide capsules was administrated orally on an empty stomach for 10 continuous days. There were no significant differences in audiological and clinical data between butylphthalide and non-butylphthalide groups.

RESULTS

The hearing gain of butylphthalide group at 500, 1000, 2000, and 4000 Hz was significantly higher than that of non-butylphthalide group correspondingly (P<0.01). And, the hearing gain at PTA (pure-tone average of 500, 1000, 2000, and 4000 Hz) in butylphthalide group was significantly higher than that of non-butylphthalide group (P<0.01).

CONCLUSION

The recovery of hearing in butylphthalide group was significantly better than that of non-butylphthalide group. It is confirmed that butylphthalide has a definite therapeutic effect on SD.

Lipopolysaccharide decreases cochlear blood flow dose dependently in a guinea pig animal model via TNF signaling

OBJECTIVE

To evaluate the effect of Lipopolysaccharide (LPS), a bacterial endotoxin on cochlear microcirculation, and its mode of action.

METHODS

Twenty-five Dunkin-Hartley guinea pigs were divided into five groups of five animals each. After surgical preparation, cochlear microcirculation was quantified by in vivo fluorescence microscopy. Placebo or LPS (1 mg, 10 µg, and 100 ng) was applied topically, and microcirculation was measured before and twice after application. A fifth group was pretreated with etanercept, a tumor necrosis factor (TNF) antagonist, and afterward the lowest LPS concentrations that yielded significant results (10 µg) were applied.

RESULTS

In the groups that had been treated with 1 mg and 10 µg LPS, a significant drop in cochlear microcirculation was observed after 30 (.791 ± .089 Arbitrary Units (AU), compared to baseline, and .888 ± .071AU) and 60 (.756 ± .101 AU and .817 ± .124 AU, respectively) minutes. The groups that had been treated with 100 ng LPS and that had been pretreated with etanercept showed no significant change in cochlear blood flow compared to placebo.

CONCLUSION

Lipopolysaccharide shows a dose-dependent effect on cochlear microcirculation; this effect can already be observed after 30 min. Pretreatment with etanercept can abrogate this effect, indicating that TNF mediates the effect of LPS on cochlear microcirculation.

Cochlear Capillary Pericytes

Capillary pericytes in the cochlea of mammals are-compared to pericytes in other tissues, like the CNS-relatively poorly researched. To begin with, there is still a considerable debate as to whether the very last precapillary arterioles should-due to their contractile properties-may be considered to be pericytes.However, cochlear capillary pericytes have shifted into the center of attention in the past decade. Most mammals show a considerable number of pericytes in the stria vascularis of the cochlea-up to 1300 in a mouse alone. This high number may be explained by the observation that cochlear capillary pericytes may be differentiated into different subgroups, depending on the immune markers that are expressed by them. Corresponding with these subpopulations, cochlear pericytes fulfill three core functions in the physiology of the cochlea: Formation of the intrastrial blood-fluid barrier-Pericytes monitor the ion, fluid, and nutrient household and aid in the homeostasis thereof. Regulation of cochlear blood flow-By contraction on relaxation, pericytes contribute to the regulation of cochlear blood flow, a paramount function parameter of the cochlea. Immune response-Pericytes actually contribute to the immune response in inflammation of the cochlea. Due to these central roles in the physiology of the cochlea, pericytes actually play a major role in numerous cochlear pathologies, including, but not limited to, sudden sensorineural hearing loss, acoustic trauma, and inflammation of the cochlea.