Objectives: This study aimed to investigate the efficacy of simultaneous steroid and hyperbaric oxygen therapy (HBOT) in patients with severe to profound idiopathic sudden sensorineural hearing loss (ISSNHL), which has a poor prognosis. Methods: Sixty patients diagnosed with severe to profound ISSNHL (≥70 dB HL) were randomly divided into two groups in a prospective controlled trial: an oral steroid + intratympanic steroid injection (ITSI) group (control group) and an oral steroid + ITSI + HBOT group (study group). Pure-tone audiometry (PTA) results and word discrimination scores (WDS) were compared between the two groups before treatment and 10 days and 1, 2, and 3 months after treatment. Hearing improvement was assessed using the modified American Academy of Otolaryngology-Head and Neck Surgery criteria. Analyses were by both intention to treat and per protocol. Results: A total of 58 patients completed the 3-month follow-up, and 2 patients in the study group were excluded due to follow-up loss in the per-protocol analysis. In the intention-to-treat and per-protocol analyses, the study group showed significantly better hearing levels than did the control group at 500 Hz (p < 0.05) 1 month after treatment and at 1 kHz (p < 0.05) 3 months after treatment. However, the average PTA values and PTA at 2, 4, and 8 kHz showed no significant difference. WDS improvement was significantly higher in the study group compared to the control group 3 months after treatment by both per-protocol (66.4 ± 13.3 and 56.7 ± 19.1%, respectively; p = 0.029) and intention-to-treat analyses (65.9 ± 14.1 and 56.7 ± 19.1%, respectively; p = 0.035). The sum of complete and partial hearing recovery for the study group was significantly higher than that for the control group by per-protocol analysis (60.7 vs. 33.3%; p = 0.037) and intention-to-treat analysis (60.0 vs. 33.3%; p = 0.038). Conclusion: These results demonstrate that the addition of HBOT to steroid combination therapy does not improve the average PTA values in severe to profound ISSNHL; however, it was associated with a better outcome at 500 Hz 1 month after treatment and, at 1 kHz, WDS 3 months after treatment. The sum of complete and partial hearing recovery was significantly higher for the study group than for the control group.

Cochlear hair cells convert sound into electrical signals that are relayed via the spiral ganglion neurons to the central auditory pathway. Hair cells are vulnerable to damage caused by excessive noise, aging, and ototoxic agents. Non-mammals can regenerate lost hair cells by mitotic regeneration and direct transdifferentiation of surrounding supporting cells. However, in mature mammals, damaged hair cells are not replaced, resulting in permanent hearing loss. Recent studies have uncovered mechanisms by which sensory organs in non-mammals and the neonatal mammalian cochlea regenerate hair cells, and outlined possible mechanisms why this ability declines rapidly with age in mammals. Here, we review similarities and differences between avian, zebrafish, and mammalian hair cell regeneration. Moreover, we discuss advances and limitations of hair cell regeneration in the mature cochlea and their potential applications to human hearing loss.

Objective: Our objective was to evaluate the surgical restrictions, audiologic benefits and satisfaction from using an active transcutaneous bone conduction device (BCD), Bonebridge^® (BB) in patients with mixed/conductive hearing loss (MCHL) or single-sided deafness (SSD). Design: A retrospective review from all patients who underwent BB surgery at the Pusan National University Hospital from 2015 to 2017 for SSD or MCHL was performed. Study sample: Twenty-two patients with SSD and five with MCHL had a BB implanted and analysed. Results: Complete transmastoid implantation of the device was possible for all patients with an intact canal wall (ICW), using lifts if necessary. The overall functional hearing gain (FHG) in SSD and MCHL was 31.4 and 37.6 dB, respectively. The mean percentage of speech recognition in a quiet was 81% (vs. 11% unaided) for MCHL group and 82% (vs. 29% unaided) for SSD group. Mean speech recognition scores in noise improved significantly under various signal-to-noise ratio (SNR) for both groups. Questionnaires showed overall improvement, and there was no significant difference between the two groups. Conclusions: The BB provides improved functional gain, and there were no limitations during surgery despite the large device. Both MCHL and SSD group had benefit and improved quality of life with BB.

Adipose-derived stromal cells (ADSCs) can repair auricular cartilage defects. Furthermore, stem cell secretome may also be a promising biological therapeutic option, which is equal to or even superior to the stem cell. We explored the therapeutic efficacies of ADSCs and their secretome in terms of rabbit auricular cartilage regeneration. ADSCs and their secretome were placed into surgically created auricular cartilage defects. After 4 and 8 weeks, the resected auricles were histopathologically and immunohistochemically examined. We used real-time PCR to determine the levels of genes expressing collagen type II, transforming growth factor-β1 (TGF-β1), and insulin-like growth factor-1 (IGF-1). ADSCs significantly improved auricular cartilage regeneration at 4 and 8 weeks, compared to the secretome and PBS groups, as revealed by gross examination, histopathologically and immunohistochemically. ADSCs upregulated the expression of collagen type II, TGF-β1, and IGF-1 more so than did the secretome or PBS. The expression levels of collagen type II and IGF-1 were significantly higher at 8 weeks than at 4 weeks after ADSC injection. Although ADSCs thus significantly enhanced new cartilage formation, their secretome did not. Therefore, ADSCs may be more effective than their secretome in the repair of auricular cartilage defect.