Repeated Atmospheric Pressure Alteration Effect on the Cochlea in Rats: Experimental Animal Study.

OBJECTIVE: This study aimed to evaluate the effects of repeated pressure alterations on cochlear structures in rats in an attempt to understand indirectly the inner ear status of flight crew who are repeatedly exposed to pressure alterations.METHODS: There were 12 adult Wistar albino rats equally divided into 2 groups: Group 1 (controls) and Group 2 (study group). The animals in Group 2 were exposed to repeated pressure changes in a pressure cabin which is regulated by manometers. The animals in Group 1 were placed in the cabin without being exposed to pressure changes. Auditory brainstem response (ABR) testing was performed in all animals at the beginning and at the end of the study. After 12 wk the animals were sacrificed and their cochleas were investigated using scanning electron microscopy (SEM).RESULTS: In the study group, hearing decreases at 2 kHz, 4 kHz, 6 dB at 8 kHz, and 32 kHz were encountered at the end of 3 mo. On SEM evaluation of the control group, the outer hair cells (OHC) and stereocilia were normal throughout the cochlea. In the study group, there were irregularities in lateral surface connections and separations, collapse, and adhesions in the basal segment of the cochlea and partial loss of stereocilia throughout the cochlea.CONCLUSION: Repeated alterations in the atmospheric pressure can lead to damage in the inner ear with subtle or evident hearing loss. Frequent flyers like air workers may be at risk of inner ear damage, which may be considered an occupational health problem.Eroglu S, Dizdar HT, Cevizci R, Cengiz AB, Ogreden S, Bulut E, Ilgezdi S, Dilci A, Ustun S, Sirvanci S, Kaya OT, Bayazit D, Caki BO, Oktay MF, Bayazit Y. Repeated atmospheric pressure alteration effect on the cochlea in rats: experimental animal study. Aerosp Med Hum Perform. 2021; 92(7):550555.

Association of Conductive Hearing Loss with the Structural Changes in the Organ of Corti.

OBJECTIVE: The aim of the study was to evaluate the association of conductive hearing loss (CHL) with the structural changes in the organ of Corti. METHODS: Twenty ears of 10 healthy adult Wistar albino rats were included in the study. The right ears (n = 10) of the animals served as controls (group 1), and no surgical intervention was performed in these ears. A tympanic membrane perforation without annulus removal was performed under operative microscope on the left ears (n = 5) in 5 of 10 animals (group 2). A tympanic membrane perforation with annulus removal was performed under operative microscope on the left ears (n = 5) of the remaining 5 animals (group 3). Auditory brainstem response testing was performed in the animals before the interventions. After 3 months, the animals were sacrificed, their temporal bones were removed, and inner ears were investigated using scanning electron microscopy (SEM). The organ of Corti was evaluated from the cochlear base to apex in the modiolar axis, and the parameters were scored semiquantitatively. RESULTS: In group 1, the pre- and post-intervention hearing thresholds were similar (p > 0.05). In group 2, a hearing decrease of at least 5 dB was encountered in all test frequencies (p > 0.05). In group 3, at the frequency range of 2-32 kHz, there was a significant hearing loss after 3 months (p < 0.01). After 3 months, the hearing thresholds in group 2 and 3 were higher than group 1 (p < 0.01). The hearing threshold in group 3 was higher than group 2 (p < 0.01). On SEM evaluation, the general cell morphology and stereocilia of the outer hair cells were preserved in all segments of the cochlea in group 1 with a mean SEM score of 0.2. There was segmental degeneration in the general cell morphology and outer hair cells in group 2 with a mean SEM score of 2.2. There was widespread degeneration in the general cell morphology and outer hair cells in group 3 with a mean SEM score of 3.2. The SEM scores of group 2 and 3 were significantly higher than group 1 (p < 0.05). The SEM scores of group 3 were significantly higher than group 2 (p < 0.05). CONCLUSION: CHL may be associated with an inner ear damage. The severity of damage appears to be associated with severity and duration of CHL. Early correction of CHL is advocated in order to reverse or prevent progression of the inner ear damage, which will enhance the success rates of hearing restoration surgeries. Subjective differences and compliance of the hearing aid users may be due to the impact of CHL on inner ear structures.

Audiological correlates of tumor parameters in acoustic neuromas.

The objective of this study was undertaken to evaluate a correlation of pure tone audiometry, speech audiometry with tumor size, the presence of intrameatal extension, contralateral pure tone audiometry, and contralateral speech audiometry results at acoustic neuroma (AN) patients. Seventy-six patients with a unilateral-cerebellopontine angel tumor with/without internal acoustic canal (IAC) were included in this study. Data on pure tone audiometry, speech discrimination scores (SDS), speech reception thresholds (SRT), tumour size, and extension to IAC were analyzed retrospectively. As a result, patients with unilateral ANs had an asymmetric sensorineural hearing loss and had an asymmetric finding on the results of speech audiometry was present. We could not find any correlation between the size of the tumor and the hearing levels at each frequency. In addition, there appeared to be no significant correlation between the extension of tumor to the IAC and the audiological findings.

Thermal welding versus cold knife tonsillectomy: a prospective randomized study.

This is a prospective randomized study conducted in a group of children who underwent two methods of tonsillectomy: thermal welding or cold knife tonsillectomy. Parameters, such as postoperative pain scores, intraoperative blood loss, operation time, and postoperative bleeding rates, were analyzed to find out which technique is better. Ninety-one children (aged between 2 years and 13 years) with recurrent tonsillitis, obstructive sleep apnea syndrome, or both were included in the study. According to the type of tonsillectomy procedure, the patients were divided into two groups: cold knife and thermal welding procedure. The two groups were compared on the basis of postoperative pain scores, intraoperative blood loss, operation time, and postoperative bleeding. Fifty-seven patients underwent thermal welding tonsillectomy and 34 had cold knife tonsillectomy. The mean pain score in thermal welding group was significantly lower (p<0.001). There was no remarkable blood loss intraoperatively in the thermal welding procedure. The operation time was not significantly different between two groups. No postoperative bleeding was encountered in the thermal welding group. Compared with the cold knife technique, thermal welding was found to be a relatively new and safe technique for tonsillectomy as it results in significantly less postoperative pain and no remarkable blood loss.