In our cohort of congenital/early-onset SSD (n = 210), the most prevalent cause in children was cochlear nerve deficiency (43.7%; 87 of 199 patients undergoing CT and/or MRI), followed by CMV infection, mumps infection, anomalies of the inner ear, ANSD, and other rare etiologies. In contrast, half of the adult SSD patients presented with idiopathic sensorineural hearing loss, followed by various types of otitis media, cerebellopontine angle tumor and other rare etiologies.

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.

The purpose of this study was to investigate the incidence of endolymphatic hydrops (EH) and the clinical features in patients with atypical Ménière's disease (aMD), by 3 T gadolinium-enhanced magnetic resonance imaging (MRI).Methods: Thirty-three patients who were diagnosed as having aMD participated in this study. Out of the 33 patients, 23 were classified as having cochlear MD (CMD) and the remaining 10 as having vestibular MD (VMD). 3 T MRI was performed 24 hours after intratympanic injection of gadolinium in 24 patients, and 4 hours after intravenous injection of gadolinium in the remaining 9 patients. We investigated the prevalence rate of EH, the relationship between detection of EH and the duration of illness, and the transition rate to classical MD in the study participants. In addition, in the CMD group, the degree of hearing fluctuation was also evaluated.Results and Conclusions: The incidence of EH was 78.3 (18/23) in the CMD group and 40 (4/10) in the VMD group. There was no significant difference in the prevalence of EH in relation to the duration of illness between the two groups. The degree of hearing fluctuation in the patient group with CMD was slightly greater in the patients with EH than in those without EH. It was assumed that patients with other diseases causing episodic vertigo were diagnosed could be misdiagnosed as having VMD, and that 3 T MRI with gadolinium injection could be a good diagnostic tool for confirming the presence of EH.