Journal of Otorhinolaryngology, Hearing and Balance Medicine — Open Access Journal

Autophagy is a natural catabolic process of the cell that dismantles the useless or dysfunctional components. Autophagy allows the systematic and the lysosomal-mediated deterioration of cellular organelles. During the embryonic development, autophagy plays a critical role by remodeling the tissue and organs of the body, and the deletion of some of the autophagy related genes results in the defective embryonic development. Inner ear is the most sophisticated organ of the body responsible for the sound perception. In mammalian inner ear, autophagy protects the hair cells (HCs) from drug and noise induced damage. In this review, we particularly discuss how autophagy implicates during the auditory system development in mammals and presents its role in age-related hearing loss. Moreover, we discuss the protecting effects of autophagy after noise and drug induced auditory trauma. Full article

The presence of an ipsilateral cerebellopontine angle (CPA) tumor should be ruled out in patients with asymmetric sensorineural hearing loss (ASNHL). Although many patients with CPA tumors have ipsilateral vestibular hypofunction, some of them do not experience dizziness even with ipsilateral vestibular hypofunction. We analyzed the incidence of CPA tumors among patients with ASNHL without subjective dizziness based on the presence of vestibulopathy. We hypothesized that a patient with silent unilateral vestibular hypofunction (UVH) is more likely to be diagnosed with a CPA tumor. Among 157 subjects who underwent MRI for ASNHL, those who did not have “subjective dizziness” were selected. All subjects underwent hearing and vestibular function tests. UVH was diagnosed if canal paresis ≥ 25%, positive head-shake nystagmus, or gain of head-impulse test < 0.8 were detected. The diameters of the CPA tumors were measured along the petrosal ridge on the axial plane of MRI. Among the enrolled subjects, 44 (28.02%) were diagnosed with a CPA tumor. The 37 patients (84.1%) with a CPA tumor had silent UVH, while only 33 of the 113 patients (29.2%) without a CPA tumor had silent UVH (chi-square test, odds ratio = 12.8, p < 0.001). Silent UVH in patients with ASNHL may be a sign of a CPA tumor. Full article

This study investigates the relationship between the intelligibility and quality of modified speech in noise and in quiet. Speech signals were processed by seven algorithms designed to increase speech intelligibility in noise without altering speech intensity. In three noise maskers, including both stationary and fluctuating noise at two signal-to-noise ratios (SNR), listeners identified keywords from unmodified or modified sentences. The intelligibility performance of each type of speech was measured as the listeners’ word recognition rate in each condition, while the quality was rated as a mean opinion score. In quiet, only the perceptual quality of each type of speech was assessed. The results suggest that when listening in noise, modification performance on improving intelligibility is more important than its potential negative impact on speech quality. However, when listening in quiet or at SNRs in which intelligibility is no longer an issue to listeners, the impact to speech quality due to modification becomes a concern. Full article

Head and neck paraganglioma (HNPGL) are rare, highly vascular; typically slow growing and mostly benign neoplasms arising from paraganglia cells. HNPGL cause morbidity via mass effect on adjacent structures (particularly the cranial nerves), invasion of the skull base and, rarely, catecholamine secretion with associated systemic effects. The last decade has seen significant progress in the understanding of HNPGL genetics, with pertinent implications for diagnostic assessment and management of patients and their relatives. The implicated genes code for three of the five subunits of mitochondrial enzyme succinate dehydrogenase (SDH); recent literature reports that approximately one third of all HNPGL are associated with SDH mutations—a prevalence significantly greater than traditionally thought. There are distinct phenotypical syndromes associated with mutations in each individual SDH subunit (SDHD, SDHB, SDHC, and SDHAF2). This article focuses on the clinical features of HNPGL, the implications of HNPGL genetics, and the current evidence relating to optimal identification, investigation, and management options in HNPGL, which are supported by reference to a personal series of 60 cases. HNPGL require a systematic and thorough assessment to appropriately guide management decisions, and a suggested algorithm is presented in this article. Recent developments are particularly pertinent to surgeons of multiple disciplines, including otolaryngology, neurosurgery, vascular, and general surgery. Full article

The endoplasmic reticulum (ER) plays important roles in coordinating protein biosynthesis and secretion in the cell. Accumulation of misfolded and/or unfolded proteins in the ER causes ER stress and the so-called unfolded protein response (UPR). The UPR alleviates ER stress through blocking protein synthesis and activating expression of chaperone genes, whereas prolonged UPR could induce cell death. Recent research has showed that ER stress and UPR are involved in hearing loss. Accordingly, animal experiments showed that chemical chaperones or ER stress inducers alleviate environment-related hearing loss, whereas ER stress inhibitor has been used to treat certain types of hereditary deafness. Further investigations are needed to fully understand the detailed mechanisms of how ER stress contributes to the loss of auditory function, which will help us to eventually develop ER-stress-related treatment of various types of deafness. Full article

Mutations in GJB2, gene coding for connexin 26 (Cx26), and GJB6, gene coding for connexin 30 (Cx30), are the most common genetic defects causing non-syndromic hereditary hearing loss. We previously reported that overexpression of Cx26 completely rescues the hearing in a mouse model of human GJB6 null mutations. The results suggest that therapeutic agents up-regulating the expression of Cx26 may potentially be a novel treatment for non-syndromic hereditary deafness caused by Cx30 null mutations. Retinoids are a family of vitamin A derivatives that exert broad and profound effects on cochlear protein expression including connexins. They are readily available and already utilized as therapeutic agents for recurrent otitis media and hearing loss due to noise exposure. In this study, we characterized the expression of Cx26 and Cx30 in the postnatal inner ear by different retinoids including retinyl palmitate (RP), the main source of vitamin A in over-the-counter (OTC) supplements, retinyl acetate (RAc) which is an isomer of RP, and all-trans-retinoic acid (ATRA), the most active retinoid derivative. The results revealed ATRA significantly increased cochlear Cx26 expression and improved hearing in Cx30 knockout (KO) mice by 10 dB suggesting its potential benefits as a therapeutic agent. In contrast, RP selectively reduced cochlear Cx30 expression and did not improve hearing thresholds at the dosages we tested. Full article