Idiopathic sudden sensorineural hearing loss and postnatal viral labyrinthitis: a statistical comparison of temporal bone findings

Is Idiopathic Sudden Sensorineural Hearing Loss Seasonal?

OBJECTIVE

To investigate the circannual rhythm (seasonal incidence) of idiopathic sudden sensorineural hearing loss (ISSNHL).

METHODS

Data were retrieved from the medical files of an original cohort of all consecutive patients with ISSNHL in a tertiary medical center between 2012 and 2020. A systematic literature search of "MEDLINE" via "PubMed," "Embase," and "Web of Science" on comparable published cases was performed. A Google Trends analysis of the term [sudden hearing loss] and related terms between 2014 and 2020 was also performed.

RESULTS

Most of the published series (9/12) reported the highest ISSNHL incidence in the spring and the lowest in the winter (8/12). In our local series, the incidence during the winter was significantly lower than that for the other seasons by a factor of 0.69 (95% confidence interval, 0.65-0.77; p = 0.041; r = 0.36). Google Trends data showed no significant correlation between the calendric month and the incidence of ISSNHL in any of the analyzed countries ( p = 0.873, r2 = 0.029).

CONCLUSION

The ISSNHL incidence was lowest during the winter season in our cohort and reported for other cohorts worldwide. Google Trends-based model analysis did not determine any circannual rhythm.

Utilizing Single Cell RNA-Sequencing to Implicate Cell Types and Therapeutic Targets for SSNHL in the Adult Cochlea

OBJECTIVE

To identify genes implicated in sudden sensorineural hearing loss (SSNHL) and localize their expression in the cochlea to further explore potential pathogenic mechanisms and therapeutic targets.

STUDY DESIGN

Systematic literature review and bioinformatics analysis.

DATA SOURCES

The following sources were searched from inception through July 2, 2020: PubMed-NCBI, MEDLINE, Embase, CINAHL, Cochrane Library, ClinicalTrials.gov, OpenGrey, GreyNet, GreyLiterature Report, and European Union Clinical Trials Registry. PubMed-NCBI and MEDLINE were additionally searched for human temporal bone histopathologic studies related to SSNHL.

METHODS

Literature review of candidate SSNHL genes was conducted according to PRISMA guidelines. Existing temporal bone studies from SSNHL patients were analyzed to identify the most commonly affected inner ear structures. Previously published single-cell and single-nucleus RNA-Seq datasets of the adult mouse stria vascularis, as well as postnatal day 7 and 15 mouse cochlear hair cells and supporting cells, were utilized for localization of the SSNHL-related genes curated through literature review.

CONCLUSIONS

We report 92 unique single nucleotide polymorphisms (SNPs) in 76 different genes that have been investigated in relation to SSNHL in the literature. We demonstrate that a subset of these genes are expressed by cell types in the adult mouse stria vascularis and organ of Corti, consistent with findings from temporal bone studies in human subjects with SSNHL. We highlight several potential genetic targets relevant to current and possible future SSNHL treatments.

Association of Acute Upper Respiratory Tract Infections with Sudden Sensorineural Hearing Loss: A Case-Crossover, Nationwide, Population-Based Cohort Study

The etiology of sudden sensorineural hearing loss (SSNHL) has been unclear until now. Understanding its potential etiology is crucial for the development of preventive medicine. In this study, we investigated the association between acute upper respiratory tract infections (URIs) and SSNHL risk. We conducted a case-crossover study by using the longitudinal health insurance database derived from the National Health Insurance Research Database in Taiwan. Individual acute URI between the case and control periods was reviewed. Multivariable conditional logistic regression models were used to estimate the adjusted odds ratios (aORs) of SSNHL risk associated with acute URIs after adjustments for potential confounders. In total, 1131 patients with SSNHL between 2010 and 2013 fulfilled our inclusion criteria and were included. The aOR (95% confidence interval [CI]) for SSNHL was 1.57 (1.20-2.05) in relation to acute URIs one month before the index date. Moreover, the aORs (95% CIs) of the female and young to middle-aged (≤65 years) populations were 1.63 (1.13-2.36) and 1.76 (1.29-2.40), respectively. In addition, the association between SSNHL and acute URIs was decreased over time. The aOR for SSNHL was 1.25 (1.01-1.56) in relation to acute URIs three months before the index date. Acute URIs increase SSNHL risk and are a potential risk factor for SSNHL. The establishment of a feasible health policy for the prevention of acute URIs is crucial for SSNHL prevention, particularly in female, and young to middle-aged populations.

Vestibular mapping assessment in idiopathic sudden sensorineural hearing loss

OBJECTIVE

The aim of this study was to investigate patterns of semicircular canal (SCC) and otolith organ dysfunction by vestibular mapping, and to determine the clinical implications of treatment outcomes in idiopathic sudden sensorineural hearing loss (ISSNHL).

METHODS

We retrospectively reviewed 135 consecutive patients diagnosed with ISSNHL from January 2016 to December 2020. Patients underwent video-head impulse tests (vHIT) for each SCC, cervical vestibular-evoked myogenic potential test for the saccules, ocular vestibular-evoked myogenic potential test for the utricles, and hearing tests. Hearing outcomes were evaluated according to the American Academy of Otolaryngology-Head and Neck Surgery criteria and factors associated with prognosis were assessed. We also conducted vestibular mapping assessments and hierarchical cluster analysis.

RESULTS

Overall, utricular impairment (76, 56.3%) was the most frequent diagnosis in the 135 ISSNHL patients, followed by saccular impairment (59, 43.7%) and posterior SCC impairment (30, 22.2%). The mean number of affected end organs was 1.37 ± 1.24, with higher numbers in the complete recovery group than in the partial/no recovery groups. In a multivariate analysis, higher initial hearing level and abnormal vHIT results in the posterior SCC were associated with poor prognosis in ISSNHL. In hierarchical cluster analysis, horizontal SCC and anterior SCC showed the highest similarity but were in different clusters than posterior SCC, and the saccule and utricle were in separate clusters from the three SCCs.

CONCLUSIONS

The vestibular end organ showed various patterns of dysfunction in patients with ISSNHL. Of the five vestibular end organs, only abnormal posterior SCC was associated with poor prognosis for hearing recovery.

The Price of Immune Responses and the Role of Vitamin D in the Inner Ear

OBJECTIVE

In this review the authors discuss evidence from the literature concerning vitamin D and temporal bone diseases (benign paroxysmal positional vertigo [BPPV], Menière's disease [MD], vestibular neuritis, idiopathic facial paralysis, idiopathic acute hearing loss). Common features shared by Menière's disease, glaucoma, and the possible influence by vitamin D are briefly discussed.

DATA SOURCES, STUDY SELECTION

Publications from 1970 until recent times have been reviewed according to a keyword search (see above) in PubMed.

CONCLUSIONS

MD, BPPV, vestibular neuritis, idiopathic facial paralysis, idiopathic acute hearing loss may all have several etiological factors, but a common feature of the current theories is that an initial viral infection and a subsequent autoimmune/autoinflammatory reaction might be involved. Additionally, in some of these entities varying degrees of demyelination have been documented. Given the immunomodulatory effect of vitamin D, we postulate that it may play a role in suppressing an eventual postviral autoimmune reaction. This beneficial effect may be enhanced by the antioxidative activity of vitamin D and its potential in stabilizing endothelial cells. The association of vitamin D deficiency with demyelination has already been established in other entities such as multiple sclerosis and experimental autoimmune encephalitis. Mice without vitamin D receptor show degenerative features in inner ear ganglia, hair cells, as well as otoconia. The authors suggest further studies concerning the role of vitamin D deficiency in diseases of the temporal bone. Additionally, the possible presence and degree of demyelination in these entities will have to be elucidated more systematically in the future.

A Trend in Sudden Sensorineural Hearing Loss: Data from a Population-Based Study

This is the first study reporting on the incidence and clinical aspects of sudden sensorineural hearing loss (SSNHL) in South Korea. Using Health Insurance Review and Assessment Service data from 2011 to 2015, the monthly incidence of unilateral SSNHL and incidence according to patients’ sex, age, and month of diagnosis were investigated. The monthly incidence of unilateral SSNHL increased over the 5-year study period, with a mean annual incidence of 17.76 cases/ 100,000 of the population. The incidence increased with age, with most patients presenting in their 60s. There was a slight female preponderance, with a male-to-female ratio of 1: 1.35. Most new patients were diagnosed in October, and the fewest in January. In conclusion, this large-scale study indicates that unilateral SSNHL has a higher incidence among the elderly, women, and in autumn (i.e., along with colder weather).

Comparative Analysis of the Combined Therapeutic Effects of Lipoprostaglandin E1 on Sudden Idiopathic Sensorineural Hearing Loss

Background and Objectives

Viral and vascular disorders are considered to be a major cause of idiopathic sudden sensorineural hearing loss (ISSNHL). Lipoprostaglandin E₁ (lipo-PGE₁) has vasodilating activity and has been used to treat ISSNHL. The purpose of this study was to determine the specific therapeutic effects of lipo-PGE₁ and compare them to other treatment modalities for ISSNHL.

Subjects and Methods

The study group had 1,052 patients diagnosed with ISSNHL. All were treated with steroid, carbogen inhalation, stellate ganglion block (SGB), or PGE₁. The CP group (steroid, carbogen inhalation, and PGE1 injection; 288 patients) was treated with lipo-PGE₁ and carbogen inhalation, the CS group (steroid, carbogen inhalation, and stellate ganglion block; 232 patients) with steroid, carbogen inhalation, and SGB, the C group (steroid and carbogen inhalation; 284 patients) with steroid and carbogen, and the control group (steroid only; 248 patients) with steroid only. Patients in the groups receiving lipo-PGE₁ received a continuous infusion of 10 µL lipo-PGE₁.

Results

The overall recovery rate after treatment was 52.2%, and recovery rates by group were 67.7% in the CP group, 54.3% in the CS group, 52.1% in the C group, and 32.2% in the control group. Therefore, the therapeutic results in groups treated with lipo-PGE₁ were better than results in other groups. The difference was statistically significant.

Conclusions

The study results suggested that the CP group received effective treatment modalities for ISSNHL. The combined therapy of lipo-PGE₁ with carbogen inhalation in patients with ISSNHL was more beneficial than other treatment modalities.

Sudden sensorineural hearing loss: Is antiviral treatment really necessary?

OBJECTIVES

It was aimed to investigate the necessity of antiviral agents in the ISSHL treatment.

METHODS

In this study, the patients, diagnosed with sudden hearing loss and admitted in the first 7 days of hearing loss were divided into two groups; a combination therapy was administered to one of the groups, and famciclovir was administered to the other group as an antiviral treatment in addition to the combined therapy. Both groups were compared in terms of levels of recovery.

RESULTS

No statistically significant difference was found in the recovery rates between the two groups (p=0.7).

CONCLUSION

In this study, the additional antiviral treatment was found to have no effect on the remission rates in patients with ISSHL treated with combined therapy.

Hyperglycemia as a Potential Prognostic Factor of Idiopathic Sudden Sensorineural Hearing Loss

Objective

Hyperglycemia is not identified as a significant prognostic factor for idiopathic sudden sensorineural hearing loss in any literature. Therefore, we investigated the prognostic value of hyperglycemia in predicting hearing recovery.

Study Design

A retrospective cohort study.

Setting

Tertiary university hospital.

Subjects and Methods

Patients were classified into 3 groups according to their glucose tolerance using the 75-gram oral glucose tolerance test and hemoglobin A1c test as follows: (1) a normal glucose tolerance group, (2) a prediabetes group, which included patients with impaired glucose tolerance and/or impaired fasting glucose levels, and (3) a diabetes mellitus group.

Results

Among 94 patients with idiopathic sudden sensorineural hearing loss, 45 were classified into the normal glucose tolerance group, 28 into the prediabetes group, and 21 into the diabetes mellitus group. The recovery rate of the normal glucose tolerance group was not higher than that of the diabetes mellitus group ( P = .140). However, when the prediabetes and diabetes mellitus groups were collectively defined as the impaired glucose regulation (hyperglycemia) group, the hearing recovery rate of the normal glucose tolerance (normoglycemia) group was significantly better than that of the impaired glucose regulation group ( P = .038).

Conclusion

We suggest that hyperglycemia may be a potential negative prognostic factor for hearing recovery in idiopathic sudden sensorineural hearing loss. Further interventional studies should be followed to determine whether hearing outcomes of the impaired glucose regulation group may be improved to the same extent as those of the normal glucose tolerance group after strict glycemic control.

Virus-induced expression of retinoic acid inducible gene-I and melanoma differentiation-associated gene 5 in the cochlear sensory epithelium

The inner ear has been regarded as an immunoprivileged site because of isolation by the blood-labyrinthine barrier. Several reports have indicated the existence of immune cells in the inner ear, but there are no reports showing immunocompetence of the cochlear tissue. In this report, we examined the potential involvement of retinoic acid inducible gene-I (RIG-I) and melanoma differentiation-associated gene 5 (MDA5), which are critical for initiating antiviral innate immune responses. We found that RIG-I and MDA5 are expressed in the mouse cochlear sensory epithelium, including Hensen's and Claudius' cells. Ex vivo viral infection using Theiler's murine encephalomyelitis virus revealed that the virus replicates in these cells and that protein levels of RIG-I and MDA5 are up-regulated. Furthermore, the critical antiviral transcription factor, interferon (IFN) regulatory factor-3, is activated in the infected cells as judged by its nuclear translocation and the accumulation of type I IFN transcripts. These results strongly suggest that RIG-I and MDA5 participate in innate antiviral responses in cochlear tissue.

Migraine is a risk factor for sudden sensorineural hearing loss: a nationwide population-based study

BACKGROUND

The pathophysiology of idiopathic sudden sensorineural hearing loss (SSNHL) is poorly understood. Few case reports have proposed a possible link between migraine and SSNHL.

OBJECTIVES

This study aimed to explore the risk of idiopathic SSNHL in patients with migraine in a nationwide, population-based cohort study.

METHODS

We identified patients with migraine from the Taiwan National Health Insurance Research Database (NHIRD) between 2000 and 2009. Each migraine patient was matched with four randomly selected subjects without migraine for age, sex, and comorbidities. Both cohorts were followed up until the end of 2009. We compared the incidence rates of SSNHL in the two cohorts and identified the risk factors.

RESULTS

A total of 10,280 migraine patients and 41,120 matched controls were enrolled with a median follow-up of five years. The migraine cohort had a greater risk of developing SSNHL than the matched cohort (81.6 vs. 45.7 per 100,000 person-years, incidence rate ratio (IRR) = 1.8; 95% confidence interval (CI) 1.22-2.61, p = 0.002). The Cox proportional hazards analysis revealed that among migraine subjects, comorbidity with hypertension was associated with a trend of developing SSNHL (hazard ratio (HR) = 1.92, 95% CI 0.97-3.79, p = 0.06).

CONCLUSIONS

This population-based study demonstrates that migraine is associated with an increased risk of idiopathic SSNHL, which, however, is a rare condition.

Neurologic complications of Paget disease of bone

OBJECTIVE

To review the epidemiology, evaluation, and management of the neurologic complications associated with Paget disease of bone (PDB).

METHODS

We reviewed the English-language medical literature using MEDLINE data sources from 1950 to August 2008 and manually searched cross-references from original articles and reviews. Search terms included "Paget* disease of bone" and "neurologic* complications," "cranial nerve," "spinal cord," or "peripheral nerve."

RESULTS

Several neurologic problems in the central and peripheral nervous systems may complicate PDB. Up to 76% of patients may have some form of neurologic involvement. Neurologic complications can occur in patients with a long history of PDB as well as in patients with previously unrecognized disease. The primary mechanisms of nerve damage in PDB involving the spine are ischemic myelitis and compression due to bone hypertrophy. Evaluation includes determining the serum alkaline phosphatase level and imaging by radiography, bone scintigraphy, computed tomographic scanning, and, for lesions of the central nervous system, magnetic resonance imaging. If a soft-tissue mass is found, biopsy should be considered to exclude the presence of sarcoma. Treatment strategies include calcium, vitamin D, bisphosphonates, and possibly surgical intervention for refractory cases.

CONCLUSION

Neurologic sequelae of PDB may be underappreciated. Despite the paucity of data guiding treatment, zoledronic acid is a reasonable first-line therapy. Lack of response to treatment or relapse should prompt diagnostic reevaluation with a heightened suspicion for tumor.

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.

Sudden Sensorineural Hearing Loss: Evidence from Taiwan

OBJECTIVE

This study uses 5-year population data to determine the incidence rate of sudden sensorineural hearing loss (SSNHL) in Taiwan, taking into consideration the age and gender of patients, as well as seasonal variations.

STUDY DESIGN

A retrospective cross-sectional study.

METHOD

The data used is from the Taiwan National Health Insurance Research Database covering the period from 1998 to 2002. A total of 9,267 sample patients were identified from the database by a principal diagnosis of unspecified sudden hearing loss (ICD-9-CM code 3882). The autoregressive integrated moving average (ARIMA) method was also carried out in order to identify any variations in the monthly incidence rates of SSNHL.

RESULTS

We find that for the period under examination, gender-specific incidence rates per 100,000 of the population were 8.85 for males, and 7.79 for females, and that there was an increase in age-specific SSNHL incidence with age. The ARIMA test for seasonality was found to be significant for the whole sample. Of all the seasons in Taiwan, the highest SSNHL incidence rates were found in autumn.

CONCLUSIONS

Our finding of significant variations in the monthly incidence of SSNHL provides valuable information for otolaryngologists and public health officials, creating an awareness of periods of a potential increased risk of SSNHL.

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.

Oscillucusis and sudden deafness in a migraine patient

Migraine is a complex disease that includes neurologic, gastrointestinal and autonomic symptoms, although headache is most common feature. In a portion of cases headache is preceded by focal neurologic symptoms termed auras. Auditory symptoms only rarely occur as part of an aura. We describe a patient whose 13-year migraine history that included the abnormal perception an oscillation of the intensity of ambient sounds (oscillucusis). During a migraine attack immediately after oscillucusis, the patient developed acute and permanent sudden deafness. Clinical and neurologic examinations revealed only profound hearing loss in her left ear. Audiometric testing confirmed the sensorineural nature of the hearing loss. The clinical aspects and physiopathology of auditory symptoms in this case and in patients with migraine is reviewed.

Idiopathic sudden sensorineural hearing loss: temporal bone histopathologic study

We microscopically examined the temporal bones of 12 ears with idiopathic sudden sensorineural hearing loss (iSSNHL), 10 ears with presbycusis, 11 ears with normal hearing, and 8 unaffected contralateral ears of patients with iSSNHL. The degeneration of the spiral ligament, vascular stria, hair cells, dendrites, and apical spiral ganglion cells was greater in ears with iSSNHL than in the other groups. The apical ganglion cells were significantly more affected than the basal ganglion cells, and the spiral ganglion cell loss increased as a function of duration of iSSNHL. Cochlear ossification was found in 1 ear with iSSNHL, and hydrops in 2. These findings suggest a viral rather than a vascular or ruptured inner ear membrane origin for iSSNHL.

Alpha-Interferon for the treatment of idiopathic sudden sensorineural hearing loss

We have employed alpha-interferon (IFN-alpha), an anti-viral agent, in the treatment of severe idiopathic sudden sensorineural hearing loss (ISSHL). Forty-two patients were studied and had an average hearing ability of > or = 70 dB before treatment. We also examined 2'-5' oligoadenylate synthetase (2,5A-S) activity, one of the parameters indicating anti-viral activity of IFN, to investigate the relationship between the suppression of viral proliferation and prognosis and explain the pathogenesis of ISSHL. Complete recovery was found in 27 patients (64.3%) after IFN therapy. Increased 2,5A-S activity was observed on the 3rd day of IFN therapy in 24 of the 27 patients who completely recovered. No severe adverse events were reported after IFN therapy. Findings suggest that IFN therapy may be effective and safe in the treatment of ISSHL and calls for further investigation.

Late sequelae of cochlear infection

Inflammatory reactions within the inner ear are deleterious to cochlear function and can result in server hearing loss that does not recover. This study investigated a guinea pig model of long-term cytomegalovirus infection. At high doses active inflammation was still present after 35 days. At lower doses some ears showed partial resolution while others were still inflamed. Hearing was totally lost in all cases of persistent inflammation. There was some residual hearing in the cases that had resolved. Cochlear structures including the organ of Corti, stria vascularis, and spiral ganglion were partially degenerated. Fibrotic matrix within scala tympani was ossified in many cases. These changes are consistent with those described for human cochleas following putative viral infections.

Respiratory tract viruses in otosclerotic lesions. An immunohistochemical study

A series of viral antigens, including adenovirus, influenza A and B, parainfluenza types 1 and 3, measles, mumps, respiratory syncytial (RSV) and Epstein Barr (EBV) viruses was studied in a prospective series of stapes specimens from 24 consecutive patients operated on for otosclerosis. The stapes specimens were processed for light microscopy and immunohistochemistry. With the exception of one case of positive specific reactivity for anti-RSV antibody in one multinuclear osteoclastic cell, no specific reactivity was seen in the specimens. This was the case both in active (n = 8) and inactive (n = 16) otosclerotic lesions. The possibility of unspecific staining reactions is discussed.