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Manno FAM, Cheung P, Basnet V, Khan MS, Mao Y, Pan L, Ma V, Cho WC, Tian S, An Z, Feng Y, Cai YL, Pienkowski M, Lau C. Subtle alterations of vestibulomotor functioning in conductive hearing loss. Front Neurosci 2023; 17:1057551. [PMID: 37706156 PMCID: PMC10495589 DOI: 10.3389/fnins.2023.1057551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Accepted: 06/08/2023] [Indexed: 09/15/2023] Open
Abstract
Introduction Conductive hearing loss (CHL) attenuates the ability to transmit air conducted sounds to the ear. In humans, severe hearing loss is often accompanied by alterations to other neural systems, such as the vestibular system; however, the inter-relations are not well understood. The overall goal of this study was to assess vestibular-related functioning proxies in a rat CHL model. Methods Male Sprague-Dawley rats (N=134, 250g, 2months old) were used in a CHL model which produced a >20dB threshold shift induced by tympanic membrane puncture. Auditory brainstem response (ABRs) recordings were used to determine threshold depth at different times before and after CHL. ABR threshold depths were assessed both manually and by an automated ABR machine learning algorithm. Vestibular-related functioning proxy assessment was performed using the rotarod, balance beam, elevator vertical motion (EVM) and Ferris-wheel rotation (FWR) assays. Results The Pre-CHL (control) threshold depth was 27.92dB±11.58dB compared to the Post-CHL threshold depth of 50.69dB±13.98dB (mean±SD) across the frequencies tested. The automated ABR machine learning algorithm determined the following threshold depths: Pre-CHL=24.3dB, Post-CHL same day=56dB, Post-CHL 7 days=41.16dB, and Post-CHL 1 month=32.5dB across the frequencies assessed (1, 2, 4, 8, 16, and 32kHz). Rotarod assessment of motor function was not significantly different between pre and post-CHL (~1week) rats for time duration (sec) or speed (RPM), albeit the former had a small effect size difference. Balance beam time to transverse was significantly longer for post-CHL rats, likely indicating a change in motor coordination. Further, failure to cross was only noted for CHL rats. The defection count was significantly reduced for CHL rats compared to control rats following FWR, but not EVM. The total distance traveled during open-field examination after EVM was significantly different between control and CHL rats, but not for FWR. The EVM is associated with linear acceleration (acting in the vertical plane: up-down) stimulating the saccule, while the FWR is associated with angular acceleration (centrifugal rotation about a circular axis) stimulating both otolith organs and semicircular canals; therefore, the difference in results could reflect the specific vestibular-organ functional role. Discussion Less movement (EVM) and increase time to transverse (balance beam) may be associated with anxiety and alterations to defecation patterns (FWR) may result from autonomic disturbances due to the impact of hearing loss. In this regard, vestibulomotor deficits resulting in changes in balance and motion could be attributed to comodulation of auditory and vestibular functioning. Future studies should manipulate vestibular functioning directly in rats with CHL.
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Affiliation(s)
- Francis A. M. Manno
- Department of Physics, East Carolina University, Greenville, NC, United States
- Department of Biomedical Engineering, Center for Imaging Science, Whiting School of Engineering, Johns Hopkins University, Baltimore, MD, United States
- Center for Advanced Nuclear Safety and Sustainable Development, City University of Hong Kong, Kowloon, Hong Kong SAR, China
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong SAR, China
| | - Pikting Cheung
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong SAR, China
| | - Vardhan Basnet
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong SAR, China
| | | | - Yuqi Mao
- Department of Nautical Injury Prevention, Faculty of Navy Medicine, Second Military Medical University, Shanghai, China
| | - Leilei Pan
- Department of Nautical Injury Prevention, Faculty of Navy Medicine, Second Military Medical University, Shanghai, China
| | - Victor Ma
- Department of Clinical Oncology, Queen Elizabeth Hospital, Kowloon, Hong Kong SAR, China
| | - William C. Cho
- Department of Clinical Oncology, Queen Elizabeth Hospital, Kowloon, Hong Kong SAR, China
| | - Shile Tian
- School of Biomedical Engineering, Southern Medical University, Guangzhou, China
| | - Ziqi An
- School of Biomedical Engineering, Southern Medical University, Guangzhou, China
| | - Yanqiu Feng
- School of Biomedical Engineering, Southern Medical University, Guangzhou, China
- Guangdong Provincial Key Laboratory of Medical Image Processing and Guangdong Province Engineering Laboratory for Medical Imaging and Diagnostic Technology, Southern Medical University, Guangzhou, China
- Key Laboratory of Mental Health of the Ministry of Education, Guangdong-Hong Kong-Macao Greater Bay Area Center for Brain Science and Brain-Inspired Intelligence, Guangdong Province Key Laboratory of Psychiatric Disorders, Department of Neurobiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, China
| | - Yi-Ling Cai
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong SAR, China
| | - Martin Pienkowski
- Osborne College of Audiology, Salus University, Elkins Park, PA, United States
| | - Condon Lau
- Center for Advanced Nuclear Safety and Sustainable Development, City University of Hong Kong, Kowloon, Hong Kong SAR, China
- Department of Physics, City University of Hong Kong, Kowloon, Hong Kong SAR, China
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