ABO blood group and cochlear function: evidence from a large sample size study

OBJECTIVE

The present study investigated the effect of blood group on cochlear function in a large participant sample across different age groups. The study hypothesis was that participants with blood group O would show relatively reduced cochlear function as reflected in otoacoustic emission (OAE) measures.

DESIGN

Data were collected from transient evoked otoacoustic emission (TEOAE), distortion product otoacoustic emission (DPOAE), DPOAE input/output (I/O) function, and spontaneous otoacoustic emission (SOAE) recordings.

STUDY SAMPLE

Four hundred and sixty-three normal hearing adults aged 20-59 years among the four ABO blood groups participated in the study.

RESULTS

TEOAE and DPOAE amplitudes did not reveal significant differences for participants with blood group O compared with participants with non-O blood groups. No significant differences in I/O function categories were found among participants with different blood groups. SOAE prevalence was also not significantly different across blood groups. However, previously reported age and gender differences for OAE variables were confirmed.

CONCLUSIONS

Participants with blood group O were not found to have significantly reduced cochlear function, based on OAE measures. Results from the current study do not support the hypothesis that normal hearing individuals with different ABO blood groups differ in level of cochlear function.

Maternal exposure to zinc oxide nanoparticles causes cochlear dysfunction in the offspring

Introduction: Zinc oxide nanoparticles (ZnO NPs) have been engineered and are largely used in material science and industry. This large and increasing use justifies a careful study about the toxicity of this material for human subjects. The concerns regard also the reproductive toxicity and the fetotoxicity. Materials and methods: The effect of the exposure to ZnO NPs on the cochlear function was studied in a group of pregnant CD1 mice and in their offspring. This study is part of a larger toxicological study about the toxicity of ZnO NPs during pregnancy. Four groups were analyzed and compared, exposed and non-exposed dams and their offspring. The cochlear function was quantitatively assessed by means of Distortion Product Otoacoustic Emissions (DPOAEs). Results and discussion: A large statistically significant difference was found between the non-exposed dams offspring and the exposed dams offspring (p = 1.6 · 10-3), whose DPOAE levels were significantly lower than those of non-exposed dams offspring and comparable to those of the adults. The DPOAE levels of the exposed and non-exposed dams were very low and not significantly different. This occurrence is related to the fact that these mice encounter a rapid aging process. Conclusion: Our findings show that maternal exposure to ZnO NPs does not reflect in overt toxicity on fetal development nor impair offspring birth, however it may damage the nervous tissue of the inner ear in the offspring. Other studies should confirm this result and identify the mechanisms through which ZnO NPs may affect ear development.

Cochlear Function in Individuals with and without Spontaneous Otoacoustic Emissions

PURPOSE

This study investigated the status of spontaneous otoacoustic emissions (SOAEs) on cochlear function in a cohort of male/female participants with a wide age range. It examined whether there was a correlation between the presence of SOAEs and measurements of transient evoked otoacoustic emissions (TEOAEs), distortion product otoacoustic emissions (DPOAEs), SOAEs and extended high-frequency (EHF) hearing thresholds.

METHODS

463 participants (222 male, 241 female; age range 20-59 years) with pure-tone thresholds ≤25 dB HL for octave frequencies of 500-8000 Hz were included in the study, divided into three age groups (20-29, 30-39, and 40-59 years). Evaluations included EHF (9000-16,000 Hz) hearing thresholds and TEOAE, DPOAE and SOAE measures.

RESULTS

Multiple regression models showed that participants with SOAEs had larger expected amplitudes and signal-to-noise ratios (SNRs) for TEOAE and DPOAE responses than participants without SOAEs, holding gender and age variables constant. Spearman correlation tests identified deterioration in TEOAE and DPOAE amplitudes and SNRs, and EHF hearing thresholds with age in participants without SOAEs. Among participants with SOAEs, no significant decreases in TEOAE and DPOAE measures were shown in participants with older age. Nonetheless, as expected, EHF hearing thresholds did become worse with age, with or without SOAEs.

CONCLUSIONS

Participants with identifiable SOAEs had greater TEOAE and DPOAE amplitudes and SNRs than participants without SOAEs. SOAEs appear to be a useful marker of cochlear health in adults.

Effects of primary arterial hypertension on cochlear function

BACKGROUND

Hypertension (HT) is one of the most common chronic diseases. The existing literature on HT and hearing contains conflicting results, and no consensus has been reached yet.

OBJECTIVES

This study aimed to investigate cochlear function in hypertensive and normotensive groups.

METHODS

This study was conducted on 34 patients with primary HT and 17 healthy adults. The Cochlear function was assessed with conventional audiometry (0.125-8 kHz), ultra-high frequency audiometry (10-16 kHz), the transient evoked otoacoustic emission (TEOAE) test, and the distortion product otoacoustic emission (DPOAE) test.

RESULTS

Hearing thresholds at 8, 10, 12.5, 14, and 16 kHz were significantly poorer in the HT group than in the control group (p < .05). There was no significant difference in the mean conventional thresholds between the groups. Compared to the control group, the patient group exhibited statistically significant lower amplitudes of TEOAE and DPOAE.

CONCLUSION

This study demonstrated significantly poorer high-frequency hearing and lower otoacoustic emission amplitudes for adults with HT. Impairment in hearing thresholds associated with HT begins at ultra-high frequencies in the cochlea. HT may be a potential risk factor for the development of hearing loss; therefore, individuals with HT should be screened for auditory function.

The Effect of Endoscopic Endonasal Transsphenoidal Skull Base Surgery on Cochlear Function

Endoscopic transsphenoidal skull base surgery (ETSS) has become a standard approach in the treatment of sellar and clival lesions, such as pituitary adenoma and chordoma. Due to the close proximity of the clivus and the sella turcica to the inner ear, it is thought that bone drilling in the surgery may have effects on hearing. The aim of this study was to assess the effect of bone drilling in ETSS procedure on cochlear function. This study was performed on 18 patients who underwent ETSS procedure between December 2016 and May 2017. The study was designed as a prospective study. All of the data were prospectively collected. These included demographic data, date of surgery, type of surgery, preoperative pure-tone audiometry, and preoperative and postoperative distortion product otoacoustic emission (DPOAE) measurements. Of the DPOAE measurements of the patients who were operated for pituitary adenoma, there was a statistically significant difference between the signal-to-noise ratio (SNR) measurements at 0.5, 1, 2 and 4 kHz ( p  < 0.05). Additionally, there were no significant differences in preoperative and postoperative SNR measurements of six patients who were selected for clivus chordoma. When the preoperative and postoperative tonal audiometric tests of the patients were compared, no statistically significant difference was found ( p  > 0.05). In conclusion, it is found that bone drilling in ETSS procedure has a negative effect on cochlear function in the early period. This is the first study to evaluate the degree of noise-induced cochlear damage in patients who were gone under ETSS procedure.

Effect of Bone Marrow-Derived Mesenchymal Stem Cells on Cochlear Function in an Experimental Rat Model

Mesenchymal stem cell (MSC) therapy is an emerging treatment modality for various human diseases. Although induced pluripotent stem cells have been explored for the restoration of hearing, the potential of MSCs as a therapeutic strategy for various cochlear insults is not precisely known. MSCs possess anti-inflammatory, anti-apoptotic and neuroprotective properties, making them an attractive target for the treatment of inner ear disorders such as hair cell damage in response to inflammation. Most of the previous studies have used immunosuppression or the complex surgical techniques to deliver stem cells into the cochlea. However, no information is available regarding the biocompatibility and safety of MSCs in the inner ear in immunocompetent cochlea. The aim of the present study was to determine the effect of non-surgical administration of rodent bone marrow derived MSCs (BM-MSCs) through transtympanic delivery on the cochlear function and to assess any adverse effects on the auditory system employing a rat model without immunosuppression. We observed that the transtympanic administration of BM-MSCs has no significant effect on the hearing thresholds as determined by auditory brainstem response and distortion product otoacoustic emissions. Histopathological examination revealed no recruitment of inflammatory leukocytes and edema in the cochlea of BM-MSCs administrated rats. The results of this study suggest that transtympanic administration of BM-MSCs is safe and can be explored in providing otoprotection against cochlear insults. Anat Rec, 303:487-493, 2020. © 2019 American Association for Anatomy.

The Genetic Architecture of Hearing Impairment in Mice: Evidence for Frequency-Specific Genetic Determinants

Genome-wide association studies (GWAS) have been successfully applied in humans for the study of many complex phenotypes. However, identification of the genetic determinants of hearing in adults has been hampered, in part, by the relative inability to control for environmental factors that might affect hearing throughout the lifetime, as well as a large degree of phenotypic heterogeneity. These and other factors have limited the number of large-scale studies performed in humans that have identified candidate genes that contribute to the etiology of this complex trait. To address these limitations, we performed a GWAS analysis using a set of inbred mouse strains from the Hybrid Mouse Diversity Panel. Among 99 strains characterized, we observed approximately two-fold to five-fold variation in hearing at six different frequencies, which are differentiated biologically from each other by the location in the cochlea where each frequency is registered. Among all frequencies tested, we identified a total of nine significant loci, several of which contained promising candidate genes for follow-up study. Taken together, our results indicate the existence of both genes that affect global cochlear function, as well as anatomical- and frequency-specific genes, and further demonstrate the complex nature of mammalian hearing variation.

Evaluation of hearing and cochlear function by audiometric testing in patients with hyperemesis gravidarum

Introduction

The aim of this study was to investigate cochlear functions in patients with hyperemesis gravidarum (HG).

Methods

Twenty-nine HG patients (58 ears) and 31 healthy control subjects (62 ears) were included. Audiometry testings at 250 and 500 Hz and 1, 2, 4, 8, 10, 12, 14, 16 kHz were performed to the patients and controls.

Results

Mean age of patients with HG was 26,5 ± 4,4 years and the mean age of control group was 28,0 ± 4,2 years. At the time of the tests mean gestational age of the HG group and controls were 9 and 11 weeks respectively. No differences were observed between the groups in tympanic membrane status, orother otolaringological evaluations. No significant differences were observed in audiometric tests at any frequencies between the groups (p values for all > 0.05).

Conclusion

There was not a difference between pregnant cases with HG and cases with normal pregnancy in terms of audimetric tests. Cochlear functions are not affectedremarkably in women with HG.