Idiopathic sudden sensorineural hearing loss: A review focused on the contribution of vascular pathologies.

Idiopathic sudden sensorineural hearing loss (ISSNHL) is characterized by abruptly appearing hearing loss, sometimes accompanied by vertigo. Vascular pathologies (e.g., cochlear ischemia, or cochlear infarction) are one of the most likely causes of ISSNHL. This review aims to present current understanding of inner ear anatomy, clinical features of ISSNHL, and its treatment strategies. The labyrinthine artery is the only end artery supplying blood to the inner ear, and it has three branches: the anterior vestibular artery, the main cochlear artery, and the vestibulo-cochlear artery (VCA). Occlusion of the VCA can be caused by a variety of factors. The VCA courses through a narrow bone canal. ISSNHL is usually diagnosed after excluding retrocochlear pathologies of sudden sensorineural hearing loss (SSNHL), such as vestibular schwannoma. Therefore, a head MRI or assessing auditory brainstem responses are recommended for patients with SSNHL. Severe SSNHL patients with high CHADS2 scores, an index of stroke risk, have a significantly lower rate of vestibular schwannoma than severe SSNHL patients with low CHADS2 scores, suggesting that severe ISSNHL in individuals at high risk of stroke is caused by vascular impairments. Intralabyrinthine hemorrhage causes SSNHL or vertigo, as in ISSNHL. The diagnosis of intralabyrinthine hemorrhage requires careful interpretation of MRI, and a small percentage of patients diagnosed with ISSNHL may in fact have intralabyrinthine hemorrhage. Many studies have reported an association between ISSNHL and atherosclerosis or cardiovascular risk factors (e.g., diabetes mellitus, hypertension, dyslipidemia and cardiovascular disease), and subsequent risk of stroke in patients with ISSNHL may be elevated compared to controls. Increased hearing level on the healthy ear side, high Framingham risk score, high neutrophil-to-lymphocyte ratio, high platelet-to-lymphocyte ratio, and severe white matter lesions may be poor prognostic factors for patients with ISSNHL. The association between thrombosis-related genes and susceptibility to ISSNHL has been reported in many studies (e.g., coagulation factor 2, coagulation factor 5, plasminogen activator inhibitor-1, platelet-associated genes, a homocysteine metabolism-related enzyme gene, endothelin-1, nitric oxide 3, phosphodiesterase 4D, complement factor H, and protein kinase C-eta). Treatment of ISSNHL with the aim of mitigating the vascular impairment in the inner ear includes systemically administered steroids, intratympanic steroid injections, hyperbaric oxygen therapy, prostaglandin E1, defibrinogenation therapy, and hydrogen inhalation therapy, but there is currently no evidence-based treatment for ISSNHL. Breakthroughs in the unequivocal diagnosis and treatment of ISSNHL due to vascular impairment are crucial to improve quality of life.

Characteristics of pure tone audiogram in patients with untreated sporadic vestibular schwannoma: Analysis of audiometric shape and interaural differences stratified by age and mode of onset.

OBJECTIVE: Asymmetric sensorineural hearing loss (ASHL) is the most common symptom of sporadic vestibular schwannoma (VS). However, there is still no universally accepted MRI protocol for diagnosing VS. This study identified the characteristics of pure tone audiogram (PTA) in patients with VS. METHODS: We conducted a retrospective chart review of patients diagnosed with sporadic unilateral VS. In the analysis, we focused on the shape and interaural differences of PTA, stratified by the mode of onset and patient age. RESULTS: In total, 390 patients met the inclusion criteria. The U-shaped audiogram showed the highest proportion in patients with the onset of sudden sensorineural hearing loss (SSNHL). In patients with SSNHL, U-shaped audiograms were younger than other audiograms, and 86.7 % of patients under 40 had U-shaped audiograms. Patients with VS were more likely to have interaural differences at higher frequencies than at lower frequencies. Patients with SSNHL had a significantly higher percentage of interaural differences at 500-4000 Hz than those with onset other than SSNHL (non-SSNHL patients). In addition, non-SSNHL patients had a significant trend toward a higher percentage of interaural differences at all frequencies with increasing age. CONCLUSION: MRI screening can be considered in patients with SSNHL with U-shaped audiograms under 40 years of age. In ASHL, not SSNHL, MRI screening can be considered for older patients with interaural differences at wider continuous frequencies. Patients with interaural differences at high frequencies had a higher priority than those with interaural differences at low frequencies as indications for MRI screening for VS.

Effective cochlear implantation for idiopathic hypertrophic pachymeningitis with bilateral profound hearing loss: A case report.

RATIONALE: Hypertrophic pachymeningitis (HP) is a local or diffuse fibrous thickness of the dura mater of the brain or spinal cord, caused by infection or connective tissue disease. Headache is the most common clinical symptom, followed by various cranial nerve disorders such as visual impairment, diplopia, and hearing loss. HP can be classified into secondary and idiopathic. Here, we report a case of bilateral progressive profound sensorineural hearing loss diagnosed in a patient with idiopathic HP, where a cochlear implant was effectively used. PATIENT CONCERNS: The patient was a 77-year-old woman. Hearing loss gradually progressed bilaterally, and magnetic resonance imaging showed a space-occupying lesion with a continuous contrast enhancement in the bilateral internal auditory canals, and diffused dural thickening from the middle to the posterior cranial fossa. DIAGNOSES: A trans-labyrinthine biopsy was conducted, and a definite diagnosis of idiopathic HP was made. Thickening of the dura mater in the bilateral internal auditory canals was thought to cause profound hearing loss. INTERVENTIONS AND OUTCOMES: A cochlear implant was implemented 4 months after biopsy, and a favorable hearing response was obtained postoperatively. LESSONS: This is the first report of a cochlear implant in a patient with idiopathic HP. Cochlear implantation was considered a good treatment for profound hearing loss due to idiopathic HP, which provides a reference for patients to receive timely and correct treatment.

Bilateral Deafness Due to Relapsing Polychondritis with Semicircular Canal Calcification Treated With Cochlear Implantation: A Case Report.

Relapsing polychondritis (RP) is a rare chronic inflammatory disease characterized by recurrent inflammation of cartilages throughout the body, with treatment-resistant dizziness and hearing loss in 40%-50% of patients with RP. Although rare, severe binaural hearing loss in RP is an indication for cochlear implantation (CI). Therefore, there are only a few reports on CI insertion in cases of RP. This report describes a 68-year-old woman who developed binaural hearing loss due to RP. She was treated with steroids and immunosuppressive drugs; however, her hearing did not improve significantly, and she relied on written communication for conversation. Subsequently, the patient underwent CI in the right ear. The patient showed improvement in speech perception; at 14 months postoperatively, she was able to speak with lipreading, and at 2 years postoperatively, she was able to speak without lipreading. Previous case reports on CI in patients with RP have shown varying degrees of postoperative hearing improvement. Our case demonstrates the effectiveness of CI in improving hearing and speech recognition in patients with RP having semicircular canal calcification. However, previous reports have shown that speech recognition declines 13 years after CI for RP. Therefore, continuous long-term follow-up is necessary.

Association Between Multiple Sclerosis and the Symptoms of Vertigo and Facial Nerve Palsy.

Patients with vertigo and facial nerve palsy as initial symptoms are rarely diagnosed with multiple sclerosis. A 43-year-old woman presented to our department with symptoms of vertigo and right facial nerve palsy (Yanagihara 16-point system [total score, 40] or House- Brackmann grade IV [obvious facial weakness]). On the day of the visit, she presented with right eye abduction, left eye adduction, and complaints of diplopia. Based on magnetic resonance imaging findings, she was diagnosed with clinically isolated syndrome, which is an early manifestation of multiple sclerosis. She was treated with intravenous methylprednisolone. Otolaryngologists often suspect Hunt's syndrome in patients who present with facial nerve palsy combined with vertigo. However, herein, we report our experience with an extremely rare case of a patient with atypical nystagmus symptoms, eye movement disorder, and diplopia secondary to facial palsy and vertigo, who presented with a clinical course different from that of Hunt's syndrome.

Apoptosis of type I spiral ganglion neuron cells in Otof-mutant mice.

Otof, which encodes otoferlin, knockout mice are considered model mice for auditory neuropathy spectrum disorder, which is characterized by an absent auditory brainstem response (ABR) despite preserved distortion product otoacoustic emission (DPOAE). Although otoferlin-deficient mice lack neurotransmitter release at the inner hair cell (IHC) synapse, it remains unclear how the Otof mutation affects spiral ganglions. Thus, we used Otof-mutant mice carrying the Otoftm1a(KOMP)Wtsi allele (Otoftm1a) and analyzed spiral ganglion neurons (SGNs) in Otoftm1a/tm1a mice by immunolabeling type Ⅰ SGNs (SGN-Ⅰ) and type II SGNs (SGN-II). We also examined apoptotic cells in SGNs. Four-week-old Otoftm1a/tm1a mice had an absent ABR but normal DPOAEs. The number of SGNs was significantly lower in Otoftm1a/tm1a mice on postnatal day 7 (P7), P14, and P28 compared with that of wild-type mice. Moreover, significantly more apoptotic SGNs were observed in Otoftm1a/tm1a mice than in wild-type mice on P7, P14, and P28. SGN-IIs were not significantly reduced in Otoftm1a/tm1a mice on P7, P14, and P28. No apoptotic SGN-IIs were observed under our experimental conditions. In summary, Otoftm1a/tm1a mice showed a reduction in SGNs accompanied by apoptosis of SGN-Ⅰs even before the onset of hearing. We speculate that the reduction in SGNs with apoptosis is a secondary defect caused by a lack of otoferlin in IHCs. Appropriate glutamatergic synaptic inputs may be important for the survival of SGNs.

Intracochlear signal in FIESTA-C and hearings of patients with cerebellopontine angle schwannoma.

BACKGROUND: Hearing loss in patients with cerebellopontine angle (CPA) schwannoma, is thought to be caused by the damage to the cochlea and the cochlear nerve. AIM: This study aimed to examine the relationships between the intracochlear signal in magnetic resonance imaging (MRI) and hearing in patients with CPA schwannoma. MATERIAL AND METHOD: In 79 patients with CPA schwannoma, we retrospectively examined the signal in the cochlea on the affected side was compared with that on the unaffected side to determine signal degradation in fast imaging reagents steady-state acquisition with cycle phases (FIESTA-C) MRI. For hearing evaluation, pure tone audiometry (PTA), speech audiometry, distortion product otoacoustic emissions (DPOAE), and auditory brainstem response (ABR) were used. For each parameter, we examined the differences between the groups with and without signal degradation. RESULTS: In the hearing test results, the I-wave latency of ABR was significantly longer in the group with signal degradation in FIESTA-C (1.84 ± 0.35 msec vs. 2.04 ± 0.37 msec, p = 0.048). There was no statistically significant difference in other tests. CONCLUSION: The MRI signal changes in the cochlear were related to the I-wave latency of ABR and reflected cochlear function. SIGNIFICANCE: We suggested the cochlear signal changes in CPA schwannoma patients related the hearing.

Association between atherosclerosis, hearing recovery, and hearing in the healthy ear in idiopathic sudden sensorineural hearing loss: a retrospective chart analysis.

Atherosclerosis is reported to be a risk factor for the severity of idiopathic sudden sensorineural hearing loss (ISSNHL). We evaluated the hypothesis that atherosclerosis affects the hearing thresholds of both the affected and healthy sides of ISSNHL patients. We conducted multivariate analyses on retrospectively collected data of patients with ISSNHL (N = 762) to evaluate the relationship between known factors linked to atherosclerosis and hearing thresholds on affected and healthy sides and whether these factors are prognostic for hearing recovery. Older ages, vertigo or dizziness, diabetes mellitus, and congestive heart failure were significantly related to higher hearing thresholds on the affected side. Older ages, male, and vascular disease were significantly related to higher hearing thresholds on the healthy side. Vertigo or dizziness, severe hearing loss and hearing loss at high frequencies on the affected side, higher hearing thresholds on the healthy side, regular anticoagulant medication, and delayed steroid treatment were significantly related to lack of recovery. Since several atherosclerosis-related factors are associated with higher hearing thresholds on both affected and healthy sides in ISSNHL and higher hearing thresholds on the healthy side predict poorer prognosis, diagnosis, and predicting prognosis of ISSNHL may benefit from rigorous evaluation of patients' cardiovascular comorbidities and hearing levels on both the healthy and affected sides.

A rare case of external ear canal stenosis caused by COVID-19-related arterial thrombosis.

Thrombosis is a characteristic symptom of coronavirus disease 2019 (COVID-19). Here, we present a case of external ear stenosis caused by arterial thrombosis after COVID-19 infection. To the best of our knowledge, this is the first report of external ear stenosis related to COVID-19. A 62-year-old man presented with left hearing loss. The patient had a history of hospitalization for COVID-19 treatment 11 months prior to visiting our hospital. He had been experiencing ear fullness and tinnitus after COVID-19 treatment. Physical examination revealed severe left external ear canal stenosis with a subcutaneous mass. Surgical removal of the subcutaneous mass was performed. Histopathological analysis revealed that a subcutaneous thrombosis caused the external ear canal stenosis. This case describes an unusual case of external ear canal stenosis after COVID-19. Clinical and pathological findings indicate that COVID-19 affected the external ear canal. In addition, histopathological results confirmed the formation of arterial thrombosis in the temporal bone region after COVID-19 treatment. This case shows the broad range of body sites that can be involved with thrombotic events with COVID including the subcutaneous tissue around the outer ear. This observation would be helpful in investigating or explaining the various otological symptoms of COVID-19.

Understanding the Molecular Mechanism of Vestibular Schwannoma for Hearing Preservation Surgery: Otologists' Perspective from Bedside to Bench.

Vestibular schwannoma is a clinically benign schwannoma that arises from the vestibulocochlear nerve that causes sensorineural hearing loss. This tumor is clinically and oncologically regarded as a benign tumor as it does not metastasize or invade surrounding tissues. Despite being a benign tumor, its management is difficult and controversial due to the potential serious complications, such as irreversible sensorineural hearing loss, of current interventions. Therefore, preventing hearing loss due to the natural course of the disease and complications of surgery is a challenging issue for an otologist. Improvements have been reported recently in the treatment of vestibular schwannomas. These include advances in intraoperative monitoring systems for vestibular schwannoma surgery where the risk of hearing loss as a complication is decreased. Precise genomic analysis of the tumor would be helpful in determining the characteristics of the tumor for each patient, leading to a better hearing prognosis. These procedures are expected to help improve the treatment of vestibular schwannomas. This review summarizes recent advances in vestibular schwannoma management and treatment, especially in hearing preservation. In addition, recent advances in the understanding of the molecular mechanisms underlying vestibular schwannomas and how these advances can be applied in clinical practice are outlined and discussed, respectively. Moreover, the future directions from the bedside to the bench side are presented from the perspective of otologists.

The impact of second-hand smoke on ear, nose, and throat diseases and head and neck cancers in Japan: a cross-sectional study using a questionnaire and secondary data from the national health and nutrition survey.

BACKGROUND: The risk of head and neck cancers (HNCs) and ear, nose, and throat (ENT) diseases due to second-hand smoke (SHS) have not been fully assessed. OBJECTIVE: To determine which ENT diseases or HNCs are associated with SHS. MATERIAL AND METHODS: Data from a survey of a cross-sectional sample of ENT patients (n = 1228) on SHS exposure were compared to control-subject data (n = 6598) from a Japan National Health Survey. Multivariate logistic regression and estimated odds ratios (ORs) determined whether SHS-disease associations were related to exposure location and disease occurrence. RESULTS: SHS was significantly associated with acute tonsillitis (OR in workplaces, 2.24 [95% CI, 1.34-3.75]; OR in restaurants, 4.24 [95% CI, 2.50-7.19]; OR in leisure places, 4.72 [95% CI, 2.93-7.62]); recurrent tonsillitis (OR in restaurants, 4.24 [95% CI, 2.52-7.13]; OR in leisure places, 5.29 [95% CI, 3.31-8.46]); facial palsy (OR in home, 2.18 [95% CI, 1.25-3.81]; OR in leisure places, 3.41 [95% CI, 1.97-5.89]); hypopharyngeal cancer (OR in home, 2.51 [95% CI, 1.18-5.36]; OR in workplaces, 2.53 [95% CI, 1.24-5.15]); and laryngeal cancer (OR in home, 2.44 [95% CI, 1.04-5.68]; OR in leisure places, 2.25 [95% CI, 1.00-5.07]). CONCLUSIONS AND SIGNIFICANCE: SHS may contribute to HNCs and ENT diseases, suggesting that merely being in the presence of smokers could increase the risk of head and neck morbidities.

Severe sudden sensorineural hearing loss related to risk of stroke and atherosclerosis.

The cause of idiopathic sudden sensorineural hearing loss (idiopathic SSNHL)-diagnosed after excluding other causes of hearing loss, such as SSNHL associated with vestibular schwannoma (VS)-is unknown. The presumed pathogenesis of idiopathic SSNHL includes circulatory disorders (e.g., cochlear infarction). We tested the hypothesis that patients with SSNHL who are at high stroke risk will have a lower rate of VS compared to those with low stroke risk. The rationale is that the primary cause of SSNHL in patients with high stroke risk might be a circulatory disturbance. We conducted a retrospective study in six hospitals. Our sampling of SSNHL patients included those diagnosed with idiopathic SSNHL and VS-associated SSNHL. SSNHL patients who had a head MRI were stratified by severity of hearing loss and evaluated for differences in the detection rate of VS between the high-scoring CHADS2 (CHADS2-H-), an index of stroke risk, and low-scoring CHADS2 (CHADS2-L-) groups. We identified 916 patients who met the inclusion criteria. For severe hearing loss, the CHADS2-H group had a significantly lower rate of VS than the CHADS2-L group (OR 0 [95% CI 0.00-0.612]; P = 0.007). These results indirectly support the hypothesis that a primary cause of severe idiopathic SSNHL in those at high risk of stroke might be a circulatory disorder.

Sudden sensorineural hearing loss in patients with vestibular schwannoma.

Clinical features of sudden sensorineural hearing loss (SSNHL) associated with vestibular schwannoma (VS) are not fully understood. Determining a treatment plan and explaining it to patients requires clinicians to clearly understand the clinical features related to the tumor, including SSNHL. To identify the full range of clinical features of VS-associated SSNHL, especially recovery of hearing following multiple episodes of SSNHL and what factors predict recovery and recurrence. A multicenter retrospective chart review was conducted in seven tertiary care hospitals between April 1, 2011, and March 31, 2020. We collected and analyzed dose of administered steroid, pure-tone audiometry results, and brain MRIs of patients diagnosed with VS-associated SSNHL. Seventy-seven patients were included. They experienced 109 episodes of audiogram-confirmed SSNHL. The highest proportion of complete recoveries occurred in patients with U-shaped audiograms. The recovery rates for the first, second, and third and subsequent episodes of SSNHL were 53.5%, 28.0%, and 9.1%, respectively. Recovery rate decreased significantly with increasing number of SSNHL episodes (P =0 .0011; Cochran-Armitage test). After the first episode of SSNHL, the recurrence-free rate was 69.9% over 1 year and 57.7% over 2 years; the median recurrence time was 32 months. Logarithmic approximation revealed that there is a 25% probability that SSNHL would recur within a year. SSNHL in patients with VS is likely to recur within one year in 25% of cases. Also, recovery rate decreases as a patient experiences increasing episodes of SSNHL.

Thyroid lobe size predicts risk of postoperative temporary recurrent laryngeal nerve paralysis.

OBJECTIVES: In patients who had undergone thyroidectomy in Japan for benign tumor, we determined whether thyroid lobe size correlates with temporary recurrent laryngeal nerve paralysis (T-RLNP). METHODS: We retrospectively collected medical record data on usage of intraoperative neuromonitoring, laterality of thyroidectomy, amount of bleeding during surgery, duration of surgery, and whether the surgeon was a board certified otorhinolaryngologist as determined by the Oto-Rhino-Laryngological Society of Japan. Thyroid size was measured in preoperative axial computed tomography (CT) images. Receiver operating characteristic (ROC) curve analysis was used to determine the thyroid size that predicted a high risk of T-RLNP or permanent recurrent laryngeal nerve paralysis (P-RLNP). RESULTS: Of the 146 eligible patients identified, 9 (6.2%) developed T-RLNP and 2 (1.4%) developed P-RLNP. The amount of bleeding during thyroidectomy was significantly greater in T-RLNP patients than in P-RLNP patients. Thyroid sizes in CT images were significantly larger in T-RLNP patients compared to patients who did not develop RLNP (referred to hereafter as N-RLNP). ROC analysis revealed that 1.3% of thyroid lobes with an area of less than 1000.0 mm2, and 9.9% of thyroid lobes with an area of greater than 1000.0 mm2 were at risk for T-RLNP. CONCLUSION: We presented evidence that thyroid sizes, as measured on preoperative axial CT images, were larger in T-RLNP patients than in N-RLNP patients. Our results indicate a connection between benign thyroid tumor stretch injuries and T-RLNP. LEVEL OF EVIDENCE: IV.