The OTOA gene (Locus: DFNB22) is reported to be one of the causative genes for non-syndromic autosomal recessive hearing loss. The copy number variations (CNVs) identified in this gene are also known to cause hearing loss, but have not been identified in Japanese patients with hearing loss. Furthermore, the clinical features of OTOA-associated hearing loss have not yet been clarified. In this study, we performed CNV analyses of a large Japanese hearing loss cohort, and identified CNVs in 234 of 2262 (10.3%, 234/2262) patients with autosomal recessive hearing loss. Among the identified CNVs, OTOA gene-related CNVs were the second most frequent (0.6%, 14/2262). Among the 14 cases, 2 individuals carried OTOA homozygous deletions, 4 carried heterozygous deletions with single nucleotide variants (SNVs) in another allele. Additionally, 1 individual with homozygous SNVs in the OTOA gene was also identified. Finally, we identified 7 probands with OTOA-associated hearing loss, so that its prevalence in Japanese patients with autosomal recessive hearing loss was calculated to be 0.3% (7/2262). As novel clinical features identified in this study, the audiometric configurations of patients with OTOA-associated hearing loss were found to be mid-frequency. This is the first study focused on the detailed clinical features of hearing loss caused by this gene mutation and/or gene deletion.

Ear surgery in many ways lagged behind other surgical fields because of the delicate anatomical structures within the ear which leave surgeons with little room for error. Thus, while surgical instruments have long been available, their use in the ear would most often do more damage than good. This state of affairs remained the status quo well into the first half of the 20th century. However, the introduction of powered surgical instruments, specifically the electric drill used in conventional microscopic ear surgery (MES) and the ultrasonic aspirator, the Sonopet^® Omni, in transcanal endoscopic ear surgery (TEES) marked major turning points. Yet, these breakthroughs have also raised concerns about whether the use of these powered surgical instruments within the confines of the ear generated so much noise and vibrations that patients could suffer sensorineural hearing loss as a result of the surgery itself. This paper reviews the intersection between the noise and vibrations generated during surgery; the history of surgical instruments, particularly powered surgical instruments, used in ear surgeries and the two main types of surgical procedures to determine whether these powered surgical instruments may pose a threat to postoperative hearing.