The pathology of sudden deafness

Prognosis of vestibular dysfunction in idiopathic sudden sensorineural hearing loss with vertigo: a prospective cohort study

BACKGROUND

Approximately 28%-57% of patients with idiopathic sudden sensorineural hearing loss (ISSNHL) have an acute vertigo attack and probable vestibular dysfunction; however, the prognosis of vestibular function in these patients remains unclear.

METHODS

A prospective cohort study of patients with ISSNHL and vertigo was conducted to evaluate the prognosis of vestibular function, especially the roles of peripheral vestibular restoration and central compensation, in patients with ISSNHL and vertigo. Clinical data were recorded at baseline and at 60 days from onset in participants with unilateral ISSNHL with vertigo. Enrolment occurred from May 1, 2019 to May 1, 2022 in the outpatient clinics and inpatient departments of the Eye and ENT Hospital of Fudan University in Shanghai. The primary outcome measure was the recovery rate of vestibular function 60 days after onset as assessed by vestibular function tests, including caloric tests, cervical and ocular vestibular-evoked myogenic potential tests (cVEMP, oVEMP), video head impulse tests (vHIT), and sensory organization tests (SOT). The secondary outcome measure was the recovery of subjective evaluations in vestibular dysfunction (the dizziness handicap inventory [DHI], and the visual analogue scale for vertigo [VAS-V]) and hearing assessments (pure-tone audiometry [PTA]).

RESULTS

Overall, 86 patients were recruited, with an average duration of disease of 11.7 days and follow-up time of 60.7 days. Vestibular function was significantly improved (p < 0.05) after 60 days. The recovery rates were 100% for anterior semicircular canal (ASC), 56% for posterior semicircular canal (PSC), 41% for horizontal semicircular canal (HSC), 28% for saccule, and 23% for utricle. The recovery of vestibular function was not significantly related to changes in DHI (p = 0.245), VAS-V score (p = 0.509), or hearing outcome (p = 0.390).

CONCLUSIONS

Restoration of peripheral vestibular sensory input and central vestibular compensation can occur during the course of ISSNHL with vertigo. The otolith organs are at a higher risk of being affected and have worse recovery than the semicircular canals. Incomplete and in-process restoration of vestibular dysfunction may perturb and delay the establishment of central compensation for balance. Neither hearing outcomes nor subjective vestibular symptoms are related to recovery from vestibular dysfunction.

TRIAL REGISTRATION

ClinicalTrials.gov (identifier NCT03951584).

Advanced Magnetic Resonance Imaging Sheds Light on the Distinct Pathophysiology of Various Types of Acute Sensorineural Hearing Loss

OBJECTIVE

To compare the findings of magnetic resonance imaging (MRI) with advanced protocols in patients with various types of acute sensorineural hearing loss (ASNHL).

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center.

PATIENTS

Two hundred eighty-seven patients with ASNHL.

INTERVENTIONS

All patients underwent MRI scanning, including heavily T2-weighted three-dimensional fluid-attenuated inversion recovery before and 4 hours after the intravenous administration of gadolinium contrast medium (delayed 3D-FLAIR). A hybrid of the reversed image of the positive endolymph signal and the native image of the perilymph signal image was constructed to visualize the endolymphatic space.

RESULTS

The detection rates of abnormal MRI findings vary significantly among different types of ASNHL. A hyperintense signal on delayed 3D-FLAIR was observed in all patients with intralabyrinthine schwannoma or vestibular schwannoma and 20.5% of patients with idiopathic sudden sensorineural hearing loss (ISSNHL) but was rarely observed in definite Ménière's disease (MD, 2.6%). In contrast, endolymphatic hydrops (EH) was frequently observed in patients with definite MD (79.5%) but was observed much less frequently in patients with ISSNHL (11.0%). In patients with cochlear MD and ALHL, detection rates of cochlear EH were similar to those with definite MD, whereas detection rates of vestibular EH were significantly lower than in patients with definite MD.

CONCLUSIONS

The significantly different detection rates of abnormal MRI findings among various types of ASNHL shed light on the distinct pathophysiology of each disorder. A diagnosis based on MRI findings with advanced protocols may help select treatment strategies and provide prognostic information for patients.

Mitochondrial dysfunction in hearing loss: Oxidative stress, autophagy and NLRP3 inflammasome

Sensorineural deafness becomes an inevitable worldwide healthy problem, yet the current curative therapy is limited. Emerging evidences demonstrate mitochondrial dysfunction plays a vital role of in the pathogenesis of deafness. Reactive oxygen species (ROS)-induced mitochondrial dysfunction combined with NLRP3 inflammasome activation is involved in cochlear damage. Autophagy not only clears up undesired proteins and damaged mitochondria (mitophagy), but also eliminate excessive ROS. Appropriate enhancement of autophagy can reduce oxidative stress, inhibit cell apoptosis, and protect auditory cells. In addition, we further discuss the interplays linking ROS generation, NLRP3 inflammasome activation, and autophagy underlying the pathogenesis of deafness, including ototoxic drugs-, noise- and aging-related hearing loss.

Idiopathic Sudden Sensorineural Hearing Loss: Speech Intelligibility Deficits Following Threshold Recovery

OBJECTIVES

This retrospective study tests the hypothesis that patients who have recovered from idiopathic sudden sensorineural hearing loss (SSNHL) show deficits in word recognition tasks that cannot be entirely explained by a loss in audibility.

DESIGN

We reviewed the audiologic profile of 166 patients presenting with a unilateral SSNHL. Hearing loss severity, degree of threshold recovery, residual hearing loss, and word recognition performance were considered as outcome variables. Age, route of treatment, delay between SSNHL onset and treatment, and audiogram configuration were considered as predictor variables.

RESULTS

Severity, residual hearing loss, and recovery were highly variable across patients. While age and onset-treatment delay could not account for the severity, residual hearing loss and recovery in thresholds, configuration of the SSNHL and overall inner ear status as measured by thresholds on the contralateral ear were predictive of threshold recovery. Speech recognition performance was significantly poorer than predicted by the speech intelligibility curve derived from the patient's audiogram.

CONCLUSIONS

SSNHL is associated with (1) changes in thresholds that are consistent with ischemia and (2) speech intelligibility deficits that cannot be entirely explained by a change in hearing sensitivity.

Vestibular prognosis in idiopathic sudden sensorineural hearing loss with vestibular dysfunction treated with oral or intratympanic glucocorticoids: a protocol for randomized controlled trial

Background

Idiopathic sudden sensorineural hearing loss (ISSNHL) is a rapid-onset sensorineural hearing impairment with unclear etiology and unsatisfying treatment effects. Vestibular dysfunction has been considered as a poor indicator in the clinical manifestations and prognosis of ISSNHL, which occurred in approximately 28–57% cases. Glucocorticoids, administered through oral or intratympanic way, are currently regularly and standardly applied for ISSNHL to improve the hearing outcome. However, the vestibular prognosis of ISSNHL after routine treatments remains seldom explored. This study aims to compare the effectiveness of oral and intratympanic glucocorticoids in ISSNHL with vestibular dysfunction in terms of the pattern and trajectory of possible process of vestibular function recovery.

Methods/design

A randomized, outcome-assessor- and analyst-blinded, controlled, clinical trial (RCT) will be carried out. Seventy-two patients with ISSNHL complaining of vestibular dysfunction appearing as vertigo or imbalance will be recruited and randomized into either oral or intratympanic glucocorticoid therapy group with a 1:1 allocation ratio. The primary outcomes will be vestibular function outcomes assessed by sensory organization test, caloric test, video head impulse test, cervical vestibular evoked myogenic potential, and ocular vestibular evoked myogenic potential; the secondary outcomes include self-reported vestibular dysfunction symptoms; dizziness-related handicap, visual analogue scale for vertigo and tinnitus; and pure tone audiometry. Assessments of primary outcomes will be performed at baseline and at 4 and 8 weeks post-randomization, while assessments of secondary outcomes will be performed at baseline and 1, 2, 4, and 8 weeks post-randomization.

Discussion

Previous intervention studies of ISSNHL included only hearing outcomes, with little attention paid on the prognosis of vestibular dysfunction. This trial will be the first RCT study focusing on the progress and prognosis of vestibular dysfunction in ISSNHL. The efficacy of two commonly used therapies of glucocorticoids will be compared in both auditory and vestibular function fields, rather than in the hearing outcome alone.

Trial registration

ClinicalTrials.gov NCT03974867. Registered on 23 July 2019

Comparisons among vestibular examinations and symptoms of vertigo in sudden sensorineural hearing loss patients

OBJECTIVES

Vertigo in sudden sensorineural hearing loss (SSNHL) is hypothesized as an extension of the disease caused by the anatomical proximity of the cochlea and vestibule. The present study aimed to demonstrate the association of vestibular function test (VFT) results with SSNHL disease severity and prognosis.

MATERIALS AND METHODS

This study assessed clinical records of 263 SSNHL patients admitted to our hospital, between January 2010 and October 2017. Steroid treatment comprised high-dose intravenous dexamethasone (16 mg/d) or oral methylprednisolone (64 mg/d) for 4 days and tapered oral methylprednisolone for 8 days after discharge. Caloric tests were performed in all patients, and cervical vestibular-evoked myogenic potential (c-VEMP) and ocular VEMP (o-VEMP) tests were performed in 209 and 144 patients, respectively.

RESULTS

Ninety six patients had vertigo, and caloric abnormalities were observed in 119 patients. Initial PTA in patients with vertigo were worse than in those without vertigo (63.0 dB vs 72.7 dB, P = .002). Initial PTA in patients with abnormal o-VEMP was worse than in those with normal o-VEMP (61.4 dB vs 73.0 dB, P = .004). PTA improvement after steroid treatment in patients with vertigo was lower than in those without vertigo (25.0 dB vs 20.9 dB, P = .028). PTA improvement after treatment in patients with abnormal caloric results was lower than in those with normal caloric results (26.0 dB vs 18.4 dB, P = .013).

CONCLUSION

The functions of vestibular organs, particularly the utricle and lateral semicircular canal, are associated with disease severity and hearing outcome in SSNHL patients.

Clinical Practice Guideline: Sudden Hearing Loss (Update)

OBJECTIVE

Sudden hearing loss is a frightening symptom that often prompts an urgent or emergent visit to a health care provider. It is frequently but not universally accompanied by tinnitus and/or vertigo. Sudden sensorineural hearing loss affects 5 to 27 per 100,000 people annually, with about 66,000 new cases per year in the United States. This guideline update provides evidence-based recommendations for the diagnosis, management, and follow-up of patients who present with sudden hearing loss. It focuses on sudden sensorineural hearing loss in adult patients aged ≥18 years and primarily on those with idiopathic sudden sensorineural hearing loss. Prompt recognition and management of sudden sensorineural hearing loss may improve hearing recovery and patient quality of life. The guideline update is intended for all clinicians who diagnose or manage adult patients who present with sudden hearing loss.

PURPOSE

The purpose of this guideline update is to provide clinicians with evidence-based recommendations in evaluating patients with sudden hearing loss and sudden sensorineural hearing loss, with particular emphasis on managing idiopathic sudden sensorineural hearing loss. The guideline update group recognized that patients enter the health care system with sudden hearing loss as a nonspecific primary complaint. Therefore, the initial recommendations of this guideline update address distinguishing sensorineural hearing loss from conductive hearing loss at the time of presentation with hearing loss. They also clarify the need to identify rare, nonidiopathic sudden sensorineural hearing loss to help separate those patients from those with idiopathic sudden sensorineural hearing loss, who are the target population for the therapeutic interventions that make up the bulk of the guideline update. By focusing on opportunities for quality improvement, this guideline should improve diagnostic accuracy, facilitate prompt intervention, decrease variations in management, reduce unnecessary tests and imaging procedures, and improve hearing and rehabilitative outcomes for affected patients.

METHODS

Consistent with the American Academy of Otolaryngology-Head and Neck Surgery Foundation's "Clinical Practice Guideline Development Manual, Third Edition" (Rosenfeld et al. Otolaryngol Head Neck Surg. 2013;148[1]:S1-S55), the guideline update group was convened with representation from the disciplines of otolaryngology-head and neck surgery, otology, neurotology, family medicine, audiology, emergency medicine, neurology, radiology, advanced practice nursing, and consumer advocacy. A systematic review of the literature was performed, and the prior clinical practice guideline on sudden hearing loss was reviewed in detail. Key Action Statements (KASs) were updated with new literature, and evidence profiles were brought up to the current standard. Research needs identified in the original clinical practice guideline and data addressing them were reviewed. Current research needs were identified and delineated.

RESULTS

The guideline update group made strong recommendations for the following: (KAS 1) Clinicians should distinguish sensorineural hearing loss from conductive hearing loss when a patient first presents with sudden hearing loss. (KAS 7) Clinicians should educate patients with sudden sensorineural hearing loss about the natural history of the condition, the benefits and risks of medical interventions, and the limitations of existing evidence regarding efficacy. (KAS 13) Clinicians should counsel patients with sudden sensorineural hearing loss who have residual hearing loss and/or tinnitus about the possible benefits of audiologic rehabilitation and other supportive measures. These strong recommendations were modified from the initial clinical practice guideline for clarity and timing of intervention. The guideline update group made strong recommendations against the following: (KAS 3) Clinicians should not order routine computed tomography of the head in the initial evaluation of a patient with presumptive sudden sensorineural hearing loss. (KAS 5) Clinicians should not obtain routine laboratory tests in patients with sudden sensorineural hearing loss. (KAS 11) Clinicians should not routinely prescribe antivirals, thrombolytics, vasodilators, or vasoactive substances to patients with sudden sensorineural hearing loss. The guideline update group made recommendations for the following: (KAS 2) Clinicians should assess patients with presumptive sudden sensorineural hearing loss through history and physical examination for bilateral sudden hearing loss, recurrent episodes of sudden hearing loss, and/or focal neurologic findings. (KAS 4) In patients with sudden hearing loss, clinicians should obtain, or refer to a clinician who can obtain, audiometry as soon as possible (within 14 days of symptom onset) to confirm the diagnosis of sudden sensorineural hearing loss. (KAS 6) Clinicians should evaluate patients with sudden sensorineural hearing loss for retrocochlear pathology by obtaining magnetic resonance imaging or auditory brainstem response. (KAS 10) Clinicians should offer, or refer to a clinician who can offer, intratympanic steroid therapy when patients have incomplete recovery from sudden sensorineural hearing loss 2 to 6 weeks after onset of symptoms. (KAS 12) Clinicians should obtain follow-up audiometric evaluation for patients with sudden sensorineural hearing loss at the conclusion of treatment and within 6 months of completion of treatment. These recommendations were clarified in terms of timing of intervention and audiometry and method of retrocochlear workup. The guideline update group offered the following KASs as options: (KAS 8) Clinicians may offer corticosteroids as initial therapy to patients with sudden sensorineural hearing loss within 2 weeks of symptom onset. (KAS 9a) Clinicians may offer, or refer to a clinician who can offer, hyperbaric oxygen therapy combined with steroid therapy within 2 weeks of onset of sudden sensorineural hearing loss. (KAS 9b) Clinicians may offer, or refer to a clinician who can offer, hyperbaric oxygen therapy combined with steroid therapy as salvage therapy within 1 month of onset of sudden sensorineural hearing loss.

DIFFERENCES FROM PRIOR GUIDELINE

Incorporation of new evidence profiles to include quality improvement opportunities, confidence in the evidence, and differences of opinion Included 10 clinical practice guidelines, 29 new systematic reviews, and 36 new randomized controlled trials Highlights the urgency of evaluation and initiation of treatment, if treatment is offered, by emphasizing the time from symptom occurrence Clarification of terminology by changing potentially unclear statements; use of the term sudden sensorineural hearing loss to mean idiopathic sudden sensorineural hearing loss to emphasize that >90% of sudden sensorineural hearing loss is idiopathic sudden sensorineural hearing loss and to avoid confusion in nomenclature for the reader Changes to the KASs from the original guideline: KAS 1-When a patient first presents with sudden hearing loss, conductive hearing loss should be distinguished from sensorineural. KAS 2-The utility of history and physical examination when assessing for modifying factors is emphasized. KAS 3-The word "routine" is added to clarify that this statement addresses nontargeted head computerized tomography scan that is often ordered in the emergency room setting for patients presenting with sudden hearing loss. It does not refer to targeted scans, such as temporal bone computerized tomography scan, to assess for temporal bone pathology. KAS 4-The importance of audiometric confirmation of hearing status as soon as possible and within 14 days of symptom onset is emphasized. KAS 5-New studies were added to confirm the lack of benefit of nontargeted laboratory testing in sudden sensorineural hearing loss. KAS 6-Audiometric follow-up is excluded as a reasonable workup for retrocochlear pathology. Magnetic resonance imaging, computerized tomography scan if magnetic resonance imaging cannot be done, and, secondarily, auditory brainstem response evaluation are the modalities recommended. A time frame for such testing is not specified, nor is it specified which clinician should be ordering this workup; however, it is implied that it would be the general or subspecialty otolaryngologist. KAS 7-The importance of shared decision making is highlighted, and salient points are emphasized. KAS 8-The option for corticosteroid intervention within 2 weeks of symptom onset is emphasized. KAS 9-Changed to KAS 9A and 9B. Hyperbaric oxygen therapy remains an option but only when combined with steroid therapy for either initial treatment (9A) or salvage therapy (9B). The timing of initial therapy is within 2 weeks of onset, and that of salvage therapy is within 1 month of onset of sudden sensorineural hearing loss. KAS 10-Intratympanic steroid therapy for salvage is recommended within 2 to 6 weeks following onset of sudden sensorineural hearing loss. The time to treatment is defined and emphasized. KAS 11-Antioxidants were removed from the list of interventions that the clinical practice guideline recommends against using. KAS 12-Follow-up audiometry at conclusion of treatment and also within 6 months posttreatment is added. KAS 13-This statement on audiologic rehabilitation includes patients who have residual hearing loss and/or tinnitus who may benefit from treatment. Addition of an algorithm outlining KASs Enhanced emphasis on patient education and shared decision making with tools provided to assist in same.

Down-regulation of Cav1.3 in auditory pathway promotes age-related hearing loss by enhancing calcium-mediated oxidative stress in male mice

In this study, age related Cav1.3 expression in cochlea and auditory cortex of C57BL/6J male mice was evaluated. It was found that the expression of Cav1.3 in cochlea decreased with aging whereas this phenomenon was not observed in neuron of auditory cortex. The correlation between decreased expression of Cav1.3 and age-related hearing losses was studied in vitro, after Cav1.3 was knocked out, the rate of apoptosis of hair cells increased after being subjected to ROS stresses, accompanied with enhanced senescence. Further, Cav1.3 knock down also interfered with the electrophysiology of hair cells. The effect was further confirmed in vivo, after Cav1.3 knocked down by injection of AAV, hearing impairment was observed in C57BL/6J male mice subjected to senescence and this was accompanied by increased loss of hair cells in cochlea. The effect was further confirmed in 3D organ culture, increased loss of hair cells after Cav1.3 was knocked down under ROS stresses.

Mechanistically, Cav1.3 knock out resulted in decreased intracellular calcium which subsequently reduced the inactivation of ROS from complex I, and finally resulted in increased intracellular ROS and enhanced senescence.

Collectively, these findings confirmed that Cav1.3 could protect cells in auditory pathway from oxidative stresses, and decreased expression of Cav1.3 in auditory pathway could contribute to hearing losses by enhancement of calcium-mediated oxidative stress.

Transient Abnormalities in Masking Tuning Curve in Early Progressive Hearing Loss Mouse Model

Damage to cochlear outer hair cells (OHCs) usually affects frequency selectivity in proportion to hearing threshold increase. However, the current clinical heuristics that attributes poor hearing performance despite near-normal auditory sensitivity to auditory neuropathy or “hidden” synaptopathy overlooks possible underlying OHC impairment. Here, we document the part played by OHCs in influencing suprathreshold auditory performance in the presence of noise in a mouse model of progressive hair cell degeneration, the CD1 strain, at postnatal day 18–30 stages when high-frequency auditory thresholds remained near-normal. Nonetheless, total loss of high-frequency distortion product otoacoustic emissions pointed to nonfunctioning basal OHCs. This “discordant profile” came with a huge low-frequency shift of masking tuning curves that plot the level of interfering sound necessary to mask the response to a probe tone, against interfering frequency. Histology revealed intense OHC hair bundle abnormalities in the basal cochlea uncharacteristically associated with OHC survival and preserved coupling with the tectorial membrane. This pattern dismisses the superficial diagnosis of “hidden” neuropathy while underpinning a disorganization of cochlear frequency mapping with optimistic high-frequency auditory thresholds perhaps because responses to high frequencies are apically shifted. The audiometric advantage of frequency transposition is offset by enhanced masking by low-frequency sounds, a finding essential for guiding rehabilitation.

Auditory Performance and Electrical Stimulation Measures in Cochlear Implant Recipients With Auditory Neuropathy Compared With Severe to Profound Sensorineural Hearing Loss

OBJECTIVES

The aim of the study was to compare auditory and speech outcomes and electrical parameters on average 8 years after cochlear implantation between children with isolated auditory neuropathy (AN) and children with sensorineural hearing loss (SNHL).

DESIGN

The study was conducted at a tertiary, university-affiliated pediatric medical center. The cohort included 16 patients with isolated AN with current age of 5 to 12.2 years who had been using a cochlear implant for at least 3.4 years and 16 control patients with SNHL matched for duration of deafness, age at implantation, type of implant, and unilateral/bilateral implant placement. All participants had had extensive auditory rehabilitation before and after implantation, including the use of conventional hearing aids. Most patients received Cochlear Nucleus devices, and the remainder either Med-El or Advanced Bionics devices. Unaided pure-tone audiograms were evaluated before and after implantation. Implantation outcomes were assessed by auditory and speech recognition tests in quiet and in noise. Data were also collected on the educational setting at 1 year after implantation and at school age. The electrical stimulation measures were evaluated only in the Cochlear Nucleus implant recipients in the two groups. Similar mapping and electrical measurement techniques were used in the two groups. Electrical thresholds, comfortable level, dynamic range, and objective neural response telemetry threshold were measured across the 22-electrode array in each patient. Main outcome measures were between-group differences in the following parameters: (1) Auditory and speech tests. (2) Residual hearing. (3) Electrical stimulation parameters. (4) Correlations of residual hearing at low frequencies with electrical thresholds at the basal, middle, and apical electrodes.

RESULTS

The children with isolated AN performed equally well to the children with SNHL on auditory and speech recognition tests in both quiet and noise. More children in the AN group than the SNHL group were attending mainstream educational settings at school age, but the difference was not statistically significant. Significant between-group differences were noted in electrical measurements: the AN group was characterized by a lower current charge to reach subjective electrical thresholds, lower comfortable level and dynamic range, and lower telemetric neural response threshold. Based on pure-tone audiograms, the children with AN also had more residual hearing before and after implantation. Highly positive coefficients were found on correlation analysis between T levels across the basal and midcochlear electrodes and low-frequency acoustic thresholds.

CONCLUSIONS

Prelingual children with isolated AN who fail to show expected oral and auditory progress after extensive rehabilitation with conventional hearing aids should be considered for cochlear implantation. Children with isolated AN had similar pattern as children with SNHL on auditory performance tests after cochlear implantation. The lower current charge required to evoke subjective and objective electrical thresholds in children with AN compared with children with SNHL may be attributed to the contribution to electrophonic hearing from the remaining neurons and hair cells. In addition, it is also possible that mechanical stimulation of the basilar membrane, as in acoustic stimulation, is added to the electrical stimulation of the cochlear implant.

Recent advances in cochlear hair cell regeneration-A promising opportunity for the treatment of age-related hearing loss

The objective of this paper is to review current information regarding the treatment of age-related hearing loss by using cochlear hair cell regeneration. Recent advances in the regeneration of the inner ear, including the usefulness of stem cells, are also presented. Based on the current literature, cochlear cell regeneration may well be possible in the short term and cochlear gene therapy may also be useful for the treatment of hearing loss associated with ageing. The present review provide further insight into the pathogenesis of Inner Ear senescence and aged-related hearing loss and facilitate the development of therapeutic strategies to repair hair cells damaged by ageing. More research will be needed in order to translate them into an effective treatment for deafness linked to cochlear senescence in humans.

Predictors of hearing recovery in patients with severe sudden sensorineural hearing loss

Background

Sudden sensorineural hearing loss (SSHL) is a disease, which severely affects the patient’s social and relational life. The underlying pathomechanisms have not been finally clarified yet and outcome is not predictable.

Methods

We conducted a retrospective study in order to identify parameters that influence hearing recovery. The data base contains results of basic otoneurological tests and clinical parameters of 198 patients with idiopathic SSHL of at least 60 dB in at least four frequencies, diagnosed and treated at the University Hospital of Münster, Germany, between 1999 and 2015. Hearing recovery was measured by pure tone audiometry.

Results

Multivariate linear and logistic regression analyses indicate that the chance as well as the magnitude of hearing recovery is higher for patients with normal caloric testing than for patients with pathological caloric testing. However, for the subgroup of patients who attained a hearing recovery, the caloric testing result was not found to influence the magnitude. Instead, the magnitude was noticeably lower for patients within this subgroup who had a previous hearing loss. Furthermore, we found indications that the magnitude is higher for men than for women and that receiving a high-dose steroid therapy is associated with a higher chance and magnitude of a hearing recovery.

Conclusions

We conclude that SSHL associated with disorders of the vestibular system or previous hearing loss represent special sub-entities of SSHL that may be caused by unique pathophysiological mechanisms and are associated with worse outcome. Furthermore, our data support the importance of elevated dosage of steroids in SSHL therapy.

Sudden Sensorioneural Hearing Loss and Autoimmune Systemic Diseases

Introduction  Several authors have demonstrated the relationship between sudden sensorineural hearing loss (SNHL) and systemic autoimmune diseases (SAD). Immune-mediated SNHL can rarely present as unilateral sudden SNHL and manifests itself in the contralateral ear only after years. It presents clinical relevance for being one of the few SNHL that may be reversible given that early and appropriate treatment is applied. Objective  The objective of this study is to describe the clinical presentations and audiological findings from patients with idiopathic sudden SNHL and SAD associated with a probable diagnosis of immune-mediated SNHL. Furthermore, we strive to estimate the prevalence of SAD in patients with sudden SNHL. Methods  This is an observational retrospective cohort. We have selected and studied patients with SAD. Revision of available literature on scientific repositories. Results  We evaluated 339 patients with sudden SNHL. Among them, 13 (3.83%) patients suffered from SAD. Three patients had bilateral involvement, a total of 16 ears. We evaluate and describe various clinical, epidemiological, and audiological aspects of this sample. Conclusion  In our sample of patients with sudden SNHL, the prevalence of SAD was found relevant. The majority had tinnitus and dizziness concomitant hearing loss, unilateral involvement and had experienced profound hearing loss at the time of the installation. In spite of instituted treatment, most cases showed no improvement in audiometric thresholds. Apparently, patients with sudden SNHL and SAD have a more severe initial impairment, higher percentage of bilateral, lower response to treatment, and worse prognosis than patients with sudden SNHL of unknown etiology.

Radiology of the Cochlear Aqueduct

Objectives:

We sought to determine normative data for the radiologic presentation of the cochlear aqueduct (CA), hypothesizing that increasing the scanner's resolution could enhance detection capability.

Methods:

Axial sections of 502 high-resolution computed tomography (CT) images of temporal bones (488 patients) were reviewed. A type 1 CA was visualized on CT scans up to the vestibule, and its portion in the otic capsule segment could be seen as a thin (<1 mm) streak. In type 2, we were able to detect the medial Two thirds of the structure, but we failed to see the whole otic capsule portion. In type 3, only the external aperture of the aqueduct and/or the medial third was seen. We defined undetectable CAs as type 4.

Results:

We obtained CT scans with 0.6-, 1.1-, or 1.3-mm-thick slices through the petrous bones in 9.5%, 58.8%, and 31.7% of cases, respectively. The CA was visible and bilaterally symmetric in 49% of the images, and type 2 was the most commonly detected CA type (36%). The CA was invisible on either side in 21.9% of scans, irrespective of CT resolution, and was asymmetric in 53 of the 502 images. The CA types varied with changes in resolution, although type 3 appeared unchanged independent of alterations in resolution in most cases.

Conclusions:

There was no significant difference in CT detection capability between CA types at different resolutions. Computed tomography failed to demonstrate any CAs ≥1 mm in width in the otic capsule segment.

Lack of Association between Inherited Thrombophilic Risk Factors and Idiopathic Sudden Sensorineural Hearing Loss in Italian Patients

Objectives:

We investigated the presence of congenital thrombophilic risk factors in a population of consecutive Italian patients affected by idiopathic sudden sensorineural hearing loss (SSNHL).

Methods:

We investigated 48 patients with idiopathic SSNHL for the presence of congenital thrombophilic risk factors. The factor V Leiden G1691A, the prothrombin G20210A allele, and methylenetetrahydrofolate reductase (MTHFR) C677T genotypes were investigated. Allele frequencies and genotype distribution of all factors found in patients were compared to those of 48 healthy subjects of the same ethnic background by χ2 and odds-ratio analysis. Odds ratios and 95% confidence intervals were calculated for allele and genotype frequencies of all thrombophilia variants. Statistical significance was accepted with a p value of less than .05. We also performed the following blood tests: hemacytometric analysis including platelet count, prothrombin time, activated partial thromboplastin time, fibrinogen, erythrocyte sedimentation rate, C-reactive protein, protein S, protein C, antithrombin III, and activated protein C resistance.

Results:

In our series, we did not find an association between SSNHL and abnormal levels of antithrombin III, protein C, protein S, D-dimer, or fibrinogen; activated protein C resistance; or factor V G1691 A, prothrombin G20210A, or MTHFR C677T mutations.

Conclusions:

At present, the few studies regarding genetic polymorphisms of congenital thrombophilic factors in SSNHL are not conclusive. According to our data, factor V G1691A, prothrombin G20210A, and MTHFR C677T variants should be not considered risk factors for SSNHL. Further large prospective studies are needed to provide currently lacking information and to improve our knowledge in the field before we recommend the determination of genetic polymorphism in SSNHL as routine practice.

A Cell Culture Model of Latent and Lytic Herpes Simplex Virus Type 1 Infection in Spiral Ganglion

PURPOSE OF THE STUDY

Reactivation of latent herpes simplex virus type 1 (HSV-1) in spiral ganglion neurons (SGNs) is supposed to be one of the causes of idiopathic sudden sensorineural hearing loss. This study aims to establish a cell culture model of latent and lytic HSV-1 infection in spiral ganglia.

PROCEDURES

In the presence of acyclovir, primary cultures of SGNs were latently infected with HSV-1 expressing green fluorescent protein. Four days later, these cells were treated with trichostatin A (TSA), a known chemical reactivator of HSV-1. TCID50 was used to measure the titers of virus in cultures on Vero cells. RNA from cultures was detected for the presence of transcripts of ICP27 and latency-associated transcript (LAT) using reverse transcription polymerase chain reaction.

RESULTS

There is no detectable infectious HSV-1 in latently infected cultures, whereas they could be observed in both lytically infected and latently infected/TSA-treated cultures. LAT was the only detectable transcript during latent infection, whereas lytic ICP27 transcript was detected in lytically infected and latently infected/TSA-treated cultures.

CONCLUSION

Cultured SGNs can be both latently and lytically infected with HSV-1. Furthermore, latently infected SGNs can be reactivated using TSA, yielding infectious virus.

Mechanisms of sensorineural cell damage, death and survival in the cochlea

The majority of acquired hearing loss, including presbycusis, is caused by irreversible damage to the sensorineural tissues of the cochlea. This article reviews the intracellular mechanisms that contribute to sensorineural damage in the cochlea, as well as the survival signaling pathways that can provide endogenous protection and tissue rescue. These data have primarily been generated in hearing loss not directly related to age. However, there is evidence that similar mechanisms operate in presbycusis. Moreover, accumulation of damage from other causes can contribute to age-related hearing loss (ARHL). Potential therapeutic interventions to balance opposing but interconnected cell damage and survival pathways, such as antioxidants, anti-apoptotics, and pro-inflammatory cytokine inhibitors, are also discussed.

Glucocorticoid influence on prognosis of idiopathic sudden sensorineural hearing loss

Introduction

Idiopathic Sudden Sensorineural Hearing Loss (ISSHL) is defined when a loss of at least 30 dB occurs in over 3 continuous frequencies, in up to 72 hours, of which etiology is not established, despite adequate investigation. Different types of treatment regimens have been proposed, but only glucocorticoids have shown some evidence of benefit in the literature.

Objective

To analyze whether the type of treatment or time of treatment with glucocorticoids have any influence on hearing recovery in ISSHL.

Methods

Observational retrospective cohort study. One hundred twenty-seven patients with ISSHL, treated at outpatient clinics between the years 2000 and 2010, were studied. We evaluated the prognostic correlation of the type of treatment and time to treatment with glucocorticoids and ISSHL.

Results

The absolute hearing gain and the relative hearing gain was as follows: 23.6 dB and 37.2%. Complete recovery was observed in 15.7% of patients, significant recovery in 27.6% and recovery in 57.5%.

Conclusion

In this study, there was no difference between the use and nonuse of glucocorticoids in hearing improvement. However, when started within seven days after onset, the use of glucocorticoids was a factor of better prognosis.

Association of the 4 g/5 g polymorphism of plasminogen activator inhibitor-1 gene with sudden sensorineural hearing loss. A case control study

Background

The 5 G/5 G genotype of PAI-1 polymorphism is linked to decreased plasminogen activator inhibitor-1 (PAI-1) levels and it has been suggested that lower PAI-1 levels may provide protective effects on inflammation, local microcirculatory disturbance, and fibrotic changes, which are likely associated with development of sudden sensorineural hearing loss (SSNHL).

Methods

The association of the 4 G/5 G PAI-1 polymorphism with the development and clinical outcome of SSNHL is evaluated via a case control study. 103 patients with SSNHL and 113 age and sex-matched controls were enrolled at University of Ferrara, Italy and hearing loss outcome was measured at least 3 months after the onset of hearing loss. DNA was isolated from peripheral blood using the QIAamp kit and the 4 G/5 G polymorphism in the −675 promoter region was genotyped with an allele-specific PCR. Genotype distribution was tested in patients and compared to controls by chi-square and odd-ratio analysis. The codominant and recessive models were used for the multiple logistic regression analyses of the PAI-1 gene allele.

Results

In this population, 5 G/5 G genotype had a two-time lower frequency in SSNHL patients compared to healthy controls (15.5% vs 30.1%) and was associated with decreased odds compared to 4 G/5 G genotype (OR 0.37, 95% CI 0.19-0.75, p = 0.005). In addition, the patients with 5 G/5 G genotype showed a trend of more than 2 times higher ratio of hearing recovery (> 20 dB) after systemic corticosteroid treatment compared to 4 G/5 G genotype (OR 2.3, 95% CI 0.32 - 16.83, p = 0.39), suggesting a better clinical outcome.

Conclusions

The 5 G/5 G genotype of PAI-1 may be associated with a reduced risk of SSNHL in the Italian population.

Clinical Practice Guideline

Objective. Sudden hearing loss (SHL) is a frightening symptom that often prompts an urgent or emergent visit to a physician. This guideline provides evidence-based recommendations for the diagnosis, management, and follow-up of patients who present with SHL. The guideline primarily focuses on sudden sensorineural hearing loss (SSNHL) in adult patients (aged 18 and older). Prompt recognition and management of SSNHL may improve hearing recovery and patient quality of life (QOL). Sudden sensorineural hearing loss affects 5 to 20 per 100,000 population, with about 4000 new cases per year in the United States. This guideline is intended for all clinicians who diagnose or manage adult patients who present with SHL.

Purpose. The purpose of this guideline is to provide clinicians with evidence-based recommendations in evaluating patients with SHL, with particular emphasis on managing SSNHL. The panel recognized that patients enter the health care system with SHL as a nonspecific, primary complaint. Therefore, the initial recommendations of the guideline deal with efficiently distinguishing SSNHL from other causes of SHL at the time of presentation. By focusing on opportunities for quality improvement, the guideline should improve diagnostic accuracy, facilitate prompt intervention, decrease variations in management, reduce unnecessary tests and imaging procedures, and improve hearing and rehabilitative outcomes for affected patients.

Results. The panel made strong recommendations that clinicians should (1) distinguish sensorineural hearing loss from conductive hearing loss in a patient presenting with SHL; (2) educate patients with idiopathic sudden sensorineural hearing loss (ISSNHL) about the natural history of the condition, the benefits and risks of medical interventions, and the limitations of existing evidence regarding efficacy; and (3) counsel patients with incomplete recovery of hearing about the possible benefits of amplification and hearing-assistive technology and other supportive measures. The panel made recommendations that clinicians should (1) assess patients with presumptive SSNHL for bilateral SHL, recurrent episodes of SHL, or focal neurologic findings; (2) diagnose presumptive ISSNHL if audiometry confirms a 30-dB hearing loss at 3 consecutive frequencies and an underlying condition cannot be identified by history and physical examination; (3) evaluate patients with ISSNHL for retrocochlear pathology by obtaining magnetic resonance imaging, auditory brainstem response, or audiometric follow-up; (4) offer intratympanic steroid perfusion when patients have incomplete recovery from ISSNHL after failure of initial management; and (5) obtain follow-up audiometric evaluation within 6 months of diagnosis for patients with ISSNHL. The panel offered as options that clinicians may offer (1) corticosteroids as initial therapy to patients with ISSNHL and (2) hyperbaric oxygen therapy within 3 months of diagnosis of ISSNHL. The panel made a recommendation against clinicians routinely prescribing antivirals, thrombolytics, vasodilators, vasoactive substances, or antioxidants to patients with ISSNHL. The panel made strong recommendations against clinicians (1) ordering computerized tomography of the head/brain in the initial evaluation of a patient with presumptive SSNHL and (2) obtaining routine laboratory tests in patients with ISSNHL.

Prognosis of patients with idiopathic sudden hearing loss: role of vestibular assessment

Objective:

To evaluate the correlation between caloric and vestibular evoked myogenic potential test results, initial audiogram data, and early hearing recovery, in patients with idiopathic sudden hearing loss.

Materials and methods:

One hundred and four patients with unilateral idiopathic sudden hearing loss underwent complete neurotological evaluation. Results for vestibular evoked myogenic potential and caloric testing were compared with patients' initial and final audiograms.

Results:

Overall, abnormal vestibular evoked myogenic potential responses occurred in 28.8 per cent of patients, whereas abnormal caloric test results occurred in 50 per cent. A statistically significant relationship was found between the type of inner ear lesion and the incidence of profound hearing loss. Moreover, a negative correlation was found between the extent of the inner ear lesion and the likelihood of early recovery.

Conclusion:

In patients with idiopathic sudden hearing loss, the extent of the inner ear lesion tends to correlate with the severity of cochlear damage. Vestibular assessment may be valuable in predicting the final outcome.

Methylenetetrahydrofolate reductase C677T gene mutation as risk factor for sudden sensorineural hearing loss: association with plasma homocysteine, folate and cholesterol concentrations

Objective:

Impaired cochlear perfusion appears to be the most important event in the development of sudden sensorineural hearing loss. Methylenetetrahydrofolate reductase gene mutations at nucleotide 677 cause reduced methylenetetrahydrofolate reductase enzyme activity, resulting in vascular impairment.

Methods:

Thirty-three patients and 68 control subjects underwent audiological and haematological investigation.

Results:

No statistically significant association was found between sudden sensorineural hearing loss and the methylenetetrahydrofolate reductase C677T gene mutation. Mean homocysteine and cholesterol concentrations were significantly higher in patients than in controls. Mean folate levels were significantly lower in patients than in controls. Amongst patients with sudden sensorineural hearing loss, no significant differences in mean cholesterol, homocysteine or folate concentration were found, comparing patients with methylenetetrahydrofolate reductase C677T mutation genotypes with those without.

Conclusion:

No statistically significant association was found between the methylenetetrahydrofolate reductase C677T gene mutation and sudden sensorineural hearing loss. There was a statistically significant difference between the homocysteine, folate and cholesterol concentrations of sudden sensorineural hearing loss patients, compared with controls. However, there was no statistically significant difference in these levels, comparing patients with and without the methylenetetrahydrofolate reductase C677T mutation.

Semicircular canal versus otolithic involvement in idiopathic sudden hearing loss

Objective:

To evaluate the results of vestibular evoked myogenic potential testing in patients with idiopathic sudden hearing loss, and to correlate these results with the findings of caloric testing, the clinical appearance of vertigo and the influence of age.

Materials and methods:

Eighty-six patients with unilateral idiopathic sudden hearing loss and 35 healthy controls underwent a standard protocol of neurotological evaluation. Vestibular evoked myogenic potential responses were measured and compared with caloric responses.

Results:

On the affected side, 30.2 per cent of patients showed abnormal vestibular evoked myogenic potential responses, while 52.3 per cent had abnormal caloric responses. A statistically significant relationship was found between the results of these two tests. A statistically significant relationship was also found between the type of vestibular lesion and the occurrence of vertigo. Advancing age correlated statistically with more extensive labyrinthic lesions.

Conclusions:

A combination of vestibular evoked myogenic potential and electronystagmography testing indicated the existence of vestibular involvement in many patients with idiopathic sudden hearing loss. Both tests are necessary in order to obtain a more thorough and in-depth knowledge of the pathophysiology of idiopathic sudden hearing loss.

Petromastoid canal and cochlear aqueduct in cochlear implant candidates

Objective: To present temporal bone fine channels in cochlear implantation candidates.

Methods: Review of the axial sections of 108 temporal bone CTs. In type I, the petromastoid canal (PMC) was invisible but appeared as channels in type II and type III, <0.5 and 0.5-1 mm wide, respectively, and in type IV was >1 mm wide. The cochlear aqueduct (CA) was visualized up to the vestibule in type 1, the medial two thirds in type 2, the external aperture and/or the medial third in type 3, and was undetectable in type 4.

Results: The PMC size and shape differed significantly between the young (aged <5 years) and older (aged 5-16 years) children and between the young children and adults. A wide PMC (>2 mm) was found in only children younger than 2 years. Children up to 2 years of age and those aged 2 to 5 years demonstrated similar findings. The CA types differed among the pediatric and adult CI candidates, with the main difference appearing after the age of 16 years. There was no correlation between CA and PMC types.

Conclusions: It is likely that the age-related changes in CA and PMC are attributable to the developmental or age-related changes in skull base growth.

Sudden deafness: is it viral?

A number of theories have been proposed to explain the etiopathogenesis of idiopathic sudden sensorineural hearing loss (ISSHL), including viral infection, vascular occlusion, breaks of labyrinthine membranes, immune-mediated mechanisms and abnormal cellular stress responses within the cochlea. In the present paper, we provide a critical review of the viral hypothesis of ISSHL. The evidence reviewed includes published reports of epidemiological and serological studies, clinical observations and results of antiviral therapy, morphological and histopathological studies, as well as results of animal experiments. The published evidence does not satisfy the majority of the Henle-Koch postulates for viral causation of an infectious disease. Possible explanations as to why these postulates remain unfulfilled are reviewed, and future studies that may provide more insight are described. We also discuss other mechanisms that have been postulated to explain ISSHL. Our review indicates that vascular occlusion, labyrinthine membrane breaks and immune-mediated mechanisms are unlikely to be common causes of ISSHL. Finally, we review our recently proposed theory that abnormal cellular stress responses within the cochlea may be responsible for ISSHL.

Viral etiology for inner ear diseases: proven, unproven, unlikely

This is a revision article that deals with the broad field of inner ear disease caused by viral infections. Some of these entities have been proven to have a viral etiology. Others have strong evidence in favor of a viral causation but still cannot be considered as a viral disease. Finally, other entities are suggestive of a viral etiology but when the whole body of evidence is considered one concludes that a viral etiology is indeed unlikely. We review the literature and add our own experience in this subject. Clearly, the most important evidence about this subject came from the study of temporal bone histopathology. Certainly, we can learn much more if we continue to collect and study temporal bone specimens histopathologically.

Late and sudden recovery of sudden deafness or vestibular neuronitis

INTRODUCTION

Vestibular neuronitis (VN) and sudden deafness (SD) are well-defined entities. The abrupt appearance of symptoms in both disorders represents an important element for the diagnosis. In cases of VN, symptoms regress gradually over time as the peripheral function recovers, or the central nervous system compensates for the balance deficit. In cases of SD, the recovery occurs in about half the cases and is generally progressive. The chances to recover normal levels of hearing are better if the recovery occurs early after the onset of the deficit. The goal of the paper is to present new insights of these disorders based on four unusual cases and on an evaluation of the delay for the function's recovery.

MATERIAL AND METHODS

1) We report two cases of VN and two of SD whose the recovery was late and sudden; 2) The recovery time after a SD was retrospectively analysed using the chart of 36 patients seen<or=24 hours after the onset of the deficit, who recovered hearing, and who had undergone at least one audiogram per month up to 6 months after the deficit, whether treated or not.

RESULTS

Twenty-eight patients recovered hearing within 6 months following the deficit. In eight patients, an audiogram was performed months later and showed a normalization of hearing. In these patients, the exact time of the recovery remained unknown.

CONCLUSION

A few patients may recover their inner ear function more than 6 months after the deficit. The recovery of function after SD or VN does not always follow the generally accepted pattern, as it can be late and sudden. These observations raise new questions to the hypothetical etiologies of SD and VN.

Partial withdrawal of deeply inserted cochlear electrodes: observations of two patients

Three patients implanted in our department received the preformed Clarion S-Series cochlear implant with the electrode Positioning System (EPS). The EPS is a device designed to bring the electrode array closer to the modiolus and deeper into the cochlea. Two of these patients still complained because they were perceiving too low pitch sounds, and because of the presence of echoes and poor discrimination after 3 years of implant use and many tuning sessions. We hypothesized that the electrode array was too deeply inserted and could be stimulating overlapping populations of neurons in the low frequency range. The EPS was removed through a transcanal tympanotomy under local anesthesia and the array was pulled 2-3 mm out of the cochlea. The angle of electrode insertion into the cochlea and the patients' performances on consonant identification tests were evaluated before and after the removal surgery and over the long term, 3 years after the surgery. Immediately after the removal surgery the angle of insertion of the electrode array decreased from 720 degrees to 485 degrees in one case and from 675 degrees to 485 degrees in the other. Both patients reported subjective improvements after the removal which were confirmed by tests of performance at the long term by one of the patients. These observations show that (1) the electrode array can be moved without deterioration of performances even several years after being implanted; revision surgery may be beneficial in some cases, (2) neighboring electrodes might stimulate overlapping populations of neurons, inducing a deterioration of performances; for anatomical reasons, this is most likely to occur in the apex of the cochlea and (3) tuning of the external processor should be a customized procedure.

The Treatment of Idiopathic Sudden Sensorineural Hearing Loss Using Pulse Therapy: A Prospective, Randomized, Double-Blind Clinical Trial

OBJECTIVES

The etiology and treatment of idiopathic sudden sensorineural hearing loss (ISSHL) is still unclear. The anti-inflammatory effect of corticosteroids is thought to play an important part in the recovery from ISSHL. We aimed to determine whether a more powerful anti-inflammatory technique using pulse therapy is effective in the treatment of ISSHL.

METHODS

In a randomized, prospective, double-blind, multicenter clinical trial, we recruited 81 patients with ISSHL. Patients were randomly allocated to pulse therapy (300 mg dexamethasone for 3 consecutive days followed by 4 days of placebo) or control treatment (prednisone 70 mg per day tapered in steps of 10 mg per day to 0 mg). The primary outcome was hearing recovery as measured by pure-tone audiometry and speech audiometry after 12 months. Secondary outcomes were subjective parameters such as hearing recovery, tinnitus, vertigo, and a pressure sensation in the ear.

RESULTS

The overall improvement in pure-tone thresholds and speech discrimination scores was not significantly better in patients who were given dexamethasone than those who were given standard prednisone. Hearing improved from 71 dB HL to 36 dB HL in the dexamethasone group and from 75 dB HL to 42 dB HL in the prednisone group. Speech discrimination scores of 100% were achieved by 64% of dexamethasone-treated patients and by 57% of the prednisone group.

CONCLUSION

Pulse therapy is equally effective and safe as standard-dose prednisone. Pulse therapy suppresses both humoral and cellular immune responses and therefore has a wider anti-inflammatory effect.

Impact of methionine synthase gene and methylenetetrahydrofolate reductase gene polymorphisms on the risk of sudden sensorineural hearing loss

Idiopathic sudden sensorineural hearing loss (SSNHL) represents a frequently encountered otological disease of unknown etiology. In recent years, several inherited risk factors have been found in the pathogenesis of vascular diseases. In the present study, we determined whether specific polymorphism or the combination of polymorphisms in folate-dependent homocysteine metabolism genes can act as predisposing inherited vascular risk factors in the development of SSNHL. We conducted a prospective case-control study using DNA samples extracted from 81 patients diagnosed as suffering from SSNHL and 264 healthy control subjects. Three functional polymorphisms were analyzed by polymerase chain reaction amplification, restriction enzyme digestion, and DNA fragment separation by electrophoresis: methylenetetrahydrofolate reductase (MTHFR) C677T, MTHFR A1298C, and methionine synthase (MTR) A2756G polymorphisms. The prevalence of the homozygous genotype of MTR 2756GG in the SSNHL patients (9%) was significantly higher than in the control group (4%) (p = 0.011). The allelic frequency of the G allele of the MTR A2756G polymorphism among SSNHL patients (12.5%) was also significantly higher than in the control group (5%) (p = 0.033). The prevalence of patients possessing two polymorphisms (31%) and three polymorphisms (17%) in the SSNHL group was significantly higher than in the control group (23 and 9%, respectively; p = 0.019). The frequency of patients with a very high rank risk (double homozygous) was significantly higher in the SSNHL group, MTHFR 677TT/MTR 2675GG--7%, than the frequency of patients in the control group, MTHFR 677TT/MTR 2675GG--3% (p = 0.030). Certain polymorphisms in genes encoding enzymes in the folate-dependent homocysteine metabolism are associated with SSNHL. In our case-control study, a significant association between MTR 2756GG genotype and SSNHL was found which may represent an inherited vascular risk factor in the pathogenesis of SSNHL.

Serum heat shock protein 70 and its correlation with clinical characteristics in patients with sudden sensorineural hearing loss

OBJECTIVES

Previous studies have reported that in cochlear cells, heat shock protein (HSP)70 is expressed after ototoxic stimuli. We performed this study to investigate the possibility of HSP70 being found in circulation and to observe its possible clinical role in patients with sudden sensorineural hearing loss (SSNHL).

METHODS

A total of 67 patients with SSNHL and age-sex matched normal controls were included in this study. Their serum HSP70 levels were measured with highly sensitive enzyme-linked immunoadsorbent assay (ELISA) test and confirmed with Western blot immunoassay. Clinical variables including initial and final audiometric findings and accompanying symptoms were analyzed to find the possible clinical value of serum HSP70 level in the patients with SSNHL.

RESULTS

Serum HSP70 levels were significantly higher in the patients with SSNHL than those of normal controls by ELISA test (P < .01), and their presence were confirmed as strong bands in the Western blot assay. There was significant correlation between serum HSP70 levels and the recovery of HL in the patients with SSNHL (P < .01).

CONCLUSION

This is the first report showing elevated serum HSP70 levels in the patients with SSNHL compared with normal controls. We suggest that serum HSP70 levels might have a clinical role for predicting prognosis of HL in the patients with SSNHL.

Methylenetetrahydrofolate reductase gene mutations as risk factors for sudden hearing loss

Sudden hearing loss (SHL) can be caused by vascular disorders favoring impaired cochlear perfusion. Several inherited prothrombotic risk factors have been considered in the pathogenesis of vascular impairment, and the possible role of genetic alterations has recently been suggested. Methylenetetrahydrofolate reductase (MTHFR) gene mutations at nucleotides 677 and 1298 cause reduced MTHFR enzyme activity, which leads to increased homocysteine and reduced serum folate levels that are known to be involved in vascular impairment. We studied the relationship between SHL and MTHFR C677T and A1298C gene polymorphisms in 67 patients with SHL and 134 controls. Wild-type MTHFR CC677/AA1298 was significantly more frequent in the controls (P = .05), and gene mutations were significantly more frequent in the patients (P = .001; P = .001 for trend). Fifty-three patients (79.1%) and 56 controls (41.8%) (P = .012) had a double mutation (homozygosis 677TT or 1298CC; compound heterozygosis for both polymorphisms). Homocysteine levels were significantly higher and serum folate levels significantly lower in the patients than in the controls (P < .0001). These data suggest that MTHFR gene polymorphisms may be involved in the pathogenesis of SHL.

Idiopathic Sudden Sensorineural Hearing Loss Is Not an Otologic Emergency

OBJECTIVE

To investigate whether delay in treatment has any influence on the audiometric outcome at Day 30 in idiopathic sudden sensorineural hearing loss.

STUDY DESIGN

Prospective study.

SETTING

Otorhinolaryngologic emergency center in Paris, France.

PATIENTS

Three hundred forty-seven consecutive cases of sudden sensorineural hearing loss were examined. A neurologic or retrocochlear cause was revealed in 17 cases. Four additional cases were lost for follow-up. Three hundred twenty-six cases of "idiopathic" sensorineural hearing loss seen within 7 days of onset were enrolled and classified by type according to five audiogram shapes: low tone (Type A), flat (Type B), high tone (Type C), cup-shaped (Type D) or total or subtotal (Type E). Because of loss for follow-up, the hearing outcome at 1 month could be evaluated in only 249 cases.

INTERVENTION

All 326 patients were given 1 mg/kg per day corticosteroids intravenously for 6 days and 500 ml mannitol 10% in the subgroup presenting ascending audiometric shape.

MAIN OUTCOME MEASURES

The following parameters were used. The first parameter was hearing recovery (initial PTA-PTA at Day 6 or Day 30). It was considered as complete if final PTA was below 25 dB. The second parameter was incidence of hearing recovery based on the following formula: (initial PTA-PTA on a given test day)/(initial PTA) x 100%. Using regression analysis and ANOVA, the audiometric outcome was analyzed at Day 6 and Day 30 as a function of the day of onset of treatment and of the audiometric type.

RESULTS

Whatever the audiometric type, there was no significant difference in final outcome whether the treatment was started within the first 24 hours or within the first week.

CONCLUSIONS

Delay in initiating treatment does not appear to influence the final degree of hearing loss. Idiopathic sudden sensorineural hearing loss cannot be considered as an otologic emergency.

Pathology and Pathophysiology of Idiopathic Sudden Sensorineural Hearing Loss

BACKGROUND

The cause and pathogenesis of idiopathic sudden sensorineural hearing loss remain unknown. Proposed theories include vascular occlusion, membrane breaks, and viral cochleitis.

AIMS

To describe the temporal bone histopathology in 17 ears (aged 45-94 yr) with idiopathic sudden sensorineural hearing loss in our temporal bone collection and to discuss the implications of the histopathologic findings with respect to the pathophysiology of idiopathic sudden sensorineural hearing loss.

METHODS

Standard light microscopy using hematoxylin and eosin-stained sections was used to assess the otologic abnormalities.

RESULTS

Hearing had recovered in two ears and no histologic correlates were found for the hearing loss in both ears. In the remaining 15 ears, the predominant abnormalities were as follows: 1) loss of hair cells and supporting cells of the organ of Corti (with or without atrophy of the tectorial membrane, stria vascularis, spiral limbus, and cochlear neurons) (13 ears); 2) loss of the tectorial membrane, supporting cells, and stria vascularis (1 ear); and 3) loss of cochlear neurons only (1 ear). Evidence of a possible vascular cause for the idiopathic sudden sensorineural hearing loss was observed in only one ear. No membrane breaks were observed in any ear. Only 1 of the 17 temporal bones was acquired acutely during idiopathic sudden sensorineural hearing loss, and this ear did not demonstrate any leukocytic invasion, hypervascularity, or hemorrhage within the labyrinth, as might be expected with a viral cochleitis.

DISCUSSION

The temporal bone findings do not support the concept of membrane breaks, perilymphatic fistulae, or vascular occlusion as common causes for idiopathic sudden sensorineural hearing loss. The finding in our one case acquired acutely during idiopathic sudden sensorineural hearing loss as well as other clinical and experimental observations do not strongly support the theory of viral cochleitis.

CONCLUSION

We put forth the hypothesis that idiopathic sudden sensorineural hearing loss may be the result of pathologic activation of cellular stress pathways involving nuclear factor-kappaB within the cochlea.

Surdités brusques idiopathiques

Idiopathic Sudden Sensorineural Hearing Loss (ISSHL) remains one of the major unsolved otologic emergencies. It is characterized by the onset of an unilateral sensorineural hearing loss developing within 24 hours, and averaging on pure tone audiogram at least 30 dB HL for three subsequent octave steps, with no marked vestibular symptoms and no identifiable cause. ISSHL is a syndrome covering several heterogeneous entities resulting from different pathogenetic mechanisms. At this time, the audiogram is the unique tool which may help clinicians to identify these entities and provide a classification based on 5 types of hearing loss. Numerous experimental and clinical studies have investigated the mechanisms by which infectious, ischemic, mechanic or immunologic insults may induce cochlear dysfunction. However, extrapolation to humans and rationale therapeutic approaches to ISSHL remain uncertain. SSHL being a diagnosis of exclusion, retrocochlear and neurologic etiologies should be eliminated. No argument allows to consider ISSHL a therapeutic emergency. More precisely, the experimental data presently available on cochlear physiology suggests that a treatment could have some chance to be effective if undertaken within minutes following the onset of ISSHL, a condition never encountered in daily practice. Conversely, it is not justifiable to impute the absence of hearing recovery to a delay in therapy. The various therapeutic strategies currently recommended are highly empirical and should be questionned in terms of cost-effectiveness, the most common being high-dose corticosteroids. New investigation tests are required for improving our approach to ISSHL.

Intratympanic steroids for sensorineural hearing loss

Corticosteroids are standard treatment for a number of inflammatory and immune-mediated inner ear diseases. In recent years there has been growing interest in intratympanic administration of steroids as a means of achieving high inner ear drug concentration and low risk of systemic side effects. Idiopathic sudden sensorineural hearing loss seems to be the condition with the greatest potential for both study and clinical use of intratympanic steroid treatment. Despite promising preliminary observations, there re-main many unanswered questions about this treatment modality.