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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 CHADS 2 scores, an index of stroke risk, have a significantly lower rate of vestibular schwannoma than severe SSNHL patients with low CHADS 2 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]