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Mittmann P, Ernst A, Seidl R, Lauer G, Gölz L, Mutze S, Windgassen M, Buschmann C. Implications of intracochlear decomposition gas formation in non-putrefied cadavers. Front Surg 2024; 11:1365535. [PMID: 38948482 PMCID: PMC11211390 DOI: 10.3389/fsurg.2024.1365535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 05/23/2024] [Indexed: 07/02/2024] Open
Abstract
Introduction Postmortem computed tomography (pmCT) prior to forensic autopsy has become increasingly important in recent decades, especially in forensic documentation of single injuries, injury patterns, and causes of death. Postmortem decomposition gas formation can also be detected in pmCT scans, which might affect cochlear implant research in postmortem human temporal bones (TBs). Material and methods Fifty non-putrefied hanging fatalities within a 2-year period (January 2017 to December 2019) were included with 100 TBs. Each body underwent whole-body pmCT prior to forensic autopsy. PmCT scans were analyzed with respect to the presence of intracochlear gas despite the lack of putrefaction at autopsy by an experienced fellow neurotologist. Results PmCT revealed gas formation in two individuals despite the lack of head trauma and putrefaction at postmortem examination and autopsy. Both individuals showed enclosed gas in the vestibule and the cochlea on both sides. Discussion Intracochlear gas formation, most likely related to decomposition, may occur despite the lack of putrefaction at postmortem examination and autopsy and can be detected by pmCT. This finding seems to be rather rare in non-traumatic death cases but might affect cochlear pressure research in postmortem human TB.
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Affiliation(s)
| | - Arne Ernst
- Department of ENT, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Rainer Seidl
- Department of ENT, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Gina Lauer
- Department of ENT, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Leonie Gölz
- Department of Radiology and Neuroradiology, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Sven Mutze
- Department of Radiology and Neuroradiology, Unfallkrankenhaus Berlin, Berlin, Germany
| | - Marc Windgassen
- Institute of Legal Medicine and Forensic Sciences, Charité University Medicine Berlin, Berlin, Germany
| | - Claas Buschmann
- Institute of Legal Medicine and Forensic Sciences, University of Kiel, Kiel, Germany
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Fan B, Wang G, Wu W. Comparative analysis of hearing loss caused by steady-state noise and impulse noise. Work 2024:WOR230066. [PMID: 38848149 DOI: 10.3233/wor-230066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2024] Open
Abstract
BACKGROUND Varied noise environments, such as impulse noise and steady-state noise, may induce distinct patterns of hearing impairment among personnel exposed to prolonged noise. However, comparative studies on these effects remain limited. OBJECTIVE This study aims to delineate the different characteristics of hearing loss in workers exposed to steady-state noise and impulse noise. METHODS As of December 2020, 96 workers exposed to steady-state noise and 177 workers exposed to impulse noise were assessed. Hearing loss across various frequencies was measured using pure tone audiometry and distortion product otoacoustic emission (DPOAE) audiometry. RESULTS Both groups of workers exposed to steady-state noise and impulse noise exhibited high frequencies hearing loss. The steady-state noise group displayed significantly greater hearing loss at lower frequencies in the early stages, spanning 1- 5 years of work (P < 0.05). Among individuals exposed to impulse noise for extended periods (over 10 years), the observed hearing loss surpassed that of the steady-state noise group, displaying a statistically significant difference (P < 0.05). CONCLUSION Hearing loss resulting from both steady-state noise and impulse noise predominantly occurs at high frequencies. Early exposure to steady-state noise induces more pronounced hearing loss at speech frequencies compared to impulse noise.
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Affiliation(s)
- Boya Fan
- Department of Otorhinolaryngology Head and Neck Surgery, PLA Strategic Support Force Characteristic Medical Center, Beijing, China
- Department of Otolaryngology Head and Neck Surgery, Peking University Third Hospital, Beijing, China
| | - Gang Wang
- Department of Otorhinolaryngology Head and Neck Surgery, PLA Strategic Support Force Characteristic Medical Center, Beijing, China
| | - Wei Wu
- Department of Otorhinolaryngology Head and Neck Surgery, PLA Strategic Support Force Characteristic Medical Center, Beijing, China
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Bradshaw JJ, Brown MA, Jiang S, Gan RZ. 3D Finite Element Model of Human Ear with 3-Chamber Spiral Cochlea for Blast Wave Transmission from the Ear Canal to Cochlea. Ann Biomed Eng 2023; 51:1106-1118. [PMID: 37036617 DOI: 10.1007/s10439-023-03200-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Accepted: 03/29/2023] [Indexed: 04/11/2023]
Abstract
Blast-induced auditory trauma is a common injury in military service members and veterans that leads to hearing loss. While the inner ear response to blast exposure is difficult to characterize experimentally, computational models have advanced to predict blast wave transmission from the ear canal to the cochlea; however, published models have either straight or spiral cochlea with fluid-filled two chambers. In this paper, we report the recently developed 3D finite element (FE) model of the human ear mimicking the anatomical structure of the 3-chambered cochlea. The model consists of the ear canal, middle ear, and two and a half turns of the cochlea with three chambers separated by the Reissner's membrane (RM) and the basilar membrane (BM). The blast overpressure measured from human temporal bone experiments was applied at the ear canal entrance and the Fluent/Mechanical coupled fluid-structure interaction analysis was conducted in ANSYS software. The FE model-derived results include the pressure in the canal near the tympanic membrane (TM) and the intracochlear pressure at scala vestibuli, the TM displacement, and the stapes footplate (SFP) displacement, which were compared with experimentally measured data in human temporal bones. The validated model was used to predict the biomechanical response of the ear to blast overpressure: distributions of the maximum strain and stress within the TM, the BM displacement variation from the base to apex, and the energy flux or total energy entering the cochlea. The comparison of intracochlear pressure and BM displacement with those from the FE model of 2-chambered cochlea indicated that the 3-chamber cochlea model with the RM and scala media chamber improved our understanding of cochlea mechanics. This most comprehensive FE model of the human ear has shown its capability to predict the middle ear and cochlea responses to blast overpressure which will advance our understanding of auditory blast injury.
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Affiliation(s)
- John J Bradshaw
- School of Biomedical Engineering, University of Oklahoma, 173 Felgar Street, Room 101, Norman, OK, 73019, USA
| | - Marcus A Brown
- School of Biomedical Engineering, University of Oklahoma, 173 Felgar Street, Room 101, Norman, OK, 73019, USA
| | - Shangyuan Jiang
- School of Aerospace and Mechanical Engineering, University of Oklahoma, 865 Asp Avenue, Room 200, Norman, OK, 73019, USA
| | - Rong Z Gan
- School of Biomedical Engineering, University of Oklahoma, 173 Felgar Street, Room 101, Norman, OK, 73019, USA.
- School of Aerospace and Mechanical Engineering, University of Oklahoma, 865 Asp Avenue, Room 200, Norman, OK, 73019, USA.
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Argo Iv TF, Wagner CD, Walilko TJ, Bentley TB. Transfer Function for Relative Blast Overpressure Through Porcine and Human Skulls In Situ. Mil Med 2023; 188:e607-e614. [PMID: 34677614 DOI: 10.1093/milmed/usab412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 05/08/2021] [Accepted: 09/27/2021] [Indexed: 11/14/2022] Open
Abstract
INTRODUCTION The overarching objective of the Office of Naval Research sponsored Blast Load Assessment Sense and Test (BLAST) program was to quantify neurofunctional risk from repeated blast exposure. However, human studies have limitations in data collection that can only be addressed by animal models. To utilize a large animal model in this work, researchers developed an approach for scaling blast exposure data from animal to human-equivalent loading. For this study, energy interacting with the brain tissue was selected as a translation metric because of the hypothesized association between observed neurological changes and energy transmitted through the skull. This article describes the methodology used to derive an energy-based transfer function capable of serving as a global correspondence rule for primary blast injury exposure, allowing researchers to derive human-appropriate thresholds from animal data. METHODS AND MATERIALS To generate data for the development of the transfer functions, three disarticulated cadaveric Yucatan minipigs and three postmortem human surrogate heads were exposed to blast overpressure using a large bore, compressed-gas shock tube. Pressure gauges in the free field, on the skull surface, and pressure probes within the brain cavity filled with Sylgard silicone gel recorded the pressure propagation through the skull of each specimen. The frequency components of the freefield and brain cavity measurements from the pig and human surrogates were interrogated in the frequency domain. Doing so quantifies the differences in the amount of energy, in each frequency band, transmitted through both the porcine and the human skull, and the transfer function was calculated to quantify those differences. RESULTS Nonlinear energy transmission was observed for both the porcine and human skulls, indicating that linear scaling would not be appropriate for developing porcine to human transfer functions. This study demonstrated similar responses between species with little to no attenuation at frequencies below 30 Hz. The phase of the pressure transmission to the brain is also similar for both species up to approximately 10 kHz. There were two notable differences between the porcine and human surrogates. First, in the 40-100 Hz range, human subjects have approximately 8 dB more pressure transmitted through the skull relative to porcine subjects. Second, in the 1-10 kHz range, human subjects have up to 10 dB more pressure transmitted into the brain (10 dB more attenuation) relative to the porcine subjects. CONCLUSIONS The fundamental goal of this study was to develop pig-to-human transfer functions to allow researchers to interpret data collected from large animal studies and aid in deriving risk functions for repeated blast exposures. Similarities in porcine and human brain physiology make the minipig experimental model an excellent candidate for blast research. However, differences in the skull geometry have historically made the interpretation of animal data difficult for the purposes of characterizing potential neurological risk in humans. Human equivalent loading conditions are critical so that the thresholds are not over- or underpredicted due to differences in porcine skull geometry. This research provides a solution to this challenge, providing a robust methodology for interpreting animal data for blast research.
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Bien AG, Jiang S, Gan RZ. Real-time measurement of stapes motion and intracochlear pressure during blast exposure. Hear Res 2023; 429:108702. [PMID: 36669259 DOI: 10.1016/j.heares.2023.108702] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 12/19/2022] [Accepted: 01/12/2023] [Indexed: 01/15/2023]
Abstract
Blast-induced auditory injury is primarily caused by exposure to an overwhelming amount of energy transmitted into the external auditory canal, the middle ear, and then the cochlea. Quantification of this energy requires real-time measurement of stapes footplate (SFP) motion and intracochlear pressure in the scala vestibuli (Psv). To date, SFP and Psv have not been measured simultaneously during blast exposure, but a dual-laser experimental approach for detecting the movement of the SFP was reported by Jiang et al. (2021). In this study, we have incorporated the measurement of Psv with SFP motion and developed a novel approach to quantitatively measure the energy flux entering the cochlea during blast exposure. Five fresh human cadaveric temporal bones (TBs) were used in this study. A mastoidectomy and facial recess approach were performed to identify the SFP, followed by a cochleostomy into the scala vestibuli (SV). The TB was mounted to the "head block", a fixture to simulate a real human skull, with two pressure sensors - one inserted into the SV (Psv) and another in the ear canal near the tympanic membrane (P1). The TB was exposed to the blast overpressure (P0) around 4 psi or 28 kPa. Two laser Doppler vibrometers (LDVs) were used to measure the movements of the SFP and TB (as a reference). The LDVs, P1, and Psv signals were triggered by P0 and recorded simultaneously. The results include peak values for Psv of 100.8 ± 51.6 kPa (mean ± SD) and for SFP displacement of 72.6 ± 56.4 μm, which are consistent with published experimental results and finite element modeling data. Most of the P0 input energy flux into the cochlea occurred within 2 ms and resulted in 10-70 μJ total energy entering the cochlea. Although the middle ear pressure gain was close to that measured under acoustic stimulus conditions, the nonlinear behavior of the middle ear was observed from the elevated cochlear input impedance. For the first time, SFP movement and intracochlear pressure Psv have been successfully measured simultaneously during blast exposure. This study provides a new methodology and experimental data for determining the energy flux entering the cochlea during a blast, which serves as an injury index for quantifying blast-induced auditory damage.
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Affiliation(s)
- Alexander G Bien
- School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK, United States; Department of Otolaryngology-Head & Neck Surgery, University of Oklahoma Medical Center, Oklahoma City, OK, United States
| | - Shangyuan Jiang
- School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK, United States
| | - Rong Z Gan
- School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK, United States.
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Boscoe EF, Banakis Hartl RM, Gubbels SP, Greene NT. Effects of Varying Laser Parameters During Laser Stapedotomy on Intracochlear Pressures. Otolaryngol Head Neck Surg 2023; 168:462-468. [PMID: 35671134 PMCID: PMC10097413 DOI: 10.1177/01945998221104658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 05/13/2022] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Sensorineural hearing loss is a known complication of stapes surgery. We previously showed that laser stapedotomy can result in intracochlear pressures that are comparable to high sound pressure levels. Optimizing laser settings to those that correspond with the lowest pressure changes may mitigate risk for postoperative hearing loss. Here we quantify the effects of various laser parameters on intracochlear pressures and test the hypothesis that intracochlear pressure changes are proportional to the laser energy delivered. STUDY DESIGN Basic and translational science. SETTING Cadaveric dissection and basic science laboratory. METHODS Cadaveric human heads underwent mastoidectomies. Intracochlear pressures were measured via fiber-optic pressure probes placed in scala vestibuli and tympani. Pulses of varied stimulus power and duration from a 980-nm diode laser were applied to the stapes footplate. RESULTS Sustained high-intensity pressures were observed in the cochlea during all laser applications. Observed pressure magnitudes increased monotonically with laser energy and rose linearly for lower stimulus durations and powers, but there was increased variability for laser applications of longer duration (200-300 ms) and/or higher power (8 W). CONCLUSIONS Results confirm that significant pressure changes occur during laser stapedotomy, which we hypothesize may cause injury. Overall energy delivered depends predictably on duration and power, but surgeons should use caution at the highest stimulus levels and longest pulse durations due to the increasing variability in intracochlear pressure under these stimulus conditions. While the risk to hearing from increased intracochlear pressures from laser stapedotomy remains unclear, these results affirm the need to optimize laser settings to avoid unintended injury.
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Affiliation(s)
- Elizabeth F. Boscoe
- Department of Otolaryngology–Head and Neck Surgery, University of Colorado, Aurora, Colorado
| | - Renee M. Banakis Hartl
- Department of Otolaryngology–Head and Neck Surgery, University of Colorado, Aurora, Colorado
- Department of Otolaryngology–Head and Neck Surgery, University of Michigan, Ann Arbor, Michigan
| | - Samuel P. Gubbels
- Department of Otolaryngology–Head and Neck Surgery, University of Colorado, Aurora, Colorado
| | - Nathaniel T. Greene
- Department of Otolaryngology–Head and Neck Surgery, University of Colorado, Aurora, Colorado
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Occluded insertion loss from intracochlear pressure measurements during acoustic shock wave exposure. Hear Res 2023; 428:108669. [PMID: 36565603 DOI: 10.1016/j.heares.2022.108669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 12/08/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022]
Abstract
INTRODUCTION Injuries to the peripheral auditory system are among the most common results of high intensity impulsive noise exposure. Hearing protection can mitigate this injury, but careful assessment of the insertion loss they provide is necessary. Insertion loss is typically measured using microphone-based acoustic manikins to measure the decrease in sound pressure level transmitted into the ear canal, which precisely measure the change in air conducted sound, but neglect alternate pathways to the inner ear such as bone conduction. In a previous study we reported intracochlear pressures in cadaveric human specimens to acoustic shock waves, which revealed a substantial bone conducted component (Greene, et al., 2018). Here we evaluate insertion loss to several hearing protection devices (HPDs) in those same specimens using intracochlear pressure measurements. METHODS Human cadaver heads were exposed to impulsive acoustic pressure waves with peak overpressures of 7 and 28 kPa (171 & 183 dB SPL). Ear canal (EAC), middle ear, and intracochlear sound pressure levels were measured bilaterally with fiber-optic pressure sensors. Surface-mounted sensors measured SPL and skull strain near the opening of each EAC and at the forehead. Responses were measured with specimen ears unoccluded, as reported previously, as well as fitted with four types of HPDs. Impulse peak insertion loss (IPIL) and impulse spectrum insertion loss (ISIL) were calculated for each HPD. RESULTS For all HPDs, IPIL generally increases with exposure level, though ISIL tended to be more consistent, and the spectral characteristics across frequency appear to be highly dependent on exposure level. ISIL measured in the ear canal tended to overestimate insertion loss measured in the cochlea, particularly at frequencies > 1 kHz; however, low signal-to-noise in intracochlear pressures limited comparisons. As a proof of concept, 36 low-level unoccluded exposures, were averaged together, and the resulting signal-to-noise ratio was improved by up to 15 dB. CONCLUSIONS Insertion loss measured in the cochlea was lower than in the ear canal, suggesting substantial contributions from transmission pathways in parallel with air conduction (e.g., bone conduction) were present, which will require novel strategies to mitigate. However, high variance was observed, and noise reduction strategies should be utilized in future studies to facilitate more precise insertion loss estimates.
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Brown MA, Bradshaw JJ, Gan RZ. Three-Dimensional Finite Element Modeling of Blast Wave Transmission From the External Ear to a Spiral Cochlea. J Biomech Eng 2022; 144:014503. [PMID: 34318317 PMCID: PMC10782861 DOI: 10.1115/1.4051925] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 07/22/2021] [Indexed: 11/08/2022]
Abstract
Blast-induced injuries affect the health of veterans, in which the auditory system is often damaged, and blast-induced auditory damage to the cochlea is difficult to quantify. A recent study modeled blast overpressure (BOP) transmission throughout the ear utilizing a straight, two-chambered cochlea, but the spiral cochlea's response to blast exposure has yet to be investigated. In this study, we utilized a human ear finite element (FE) model with a spiraled, two-chambered cochlea to simulate the response of the anatomical structural cochlea to BOP exposure. The FE model included an ear canal, middle ear, and two and half turns of two-chambered cochlea and simulated a BOP from the ear canal entrance to the spiral cochlea in a transient analysis utilizing fluid-structure interfaces. The model's middle ear was validated with experimental pressure measurements from the outer and middle ear of human temporal bones. The results showed high stapes footplate (SFP) displacements up to 28.5 μm resulting in high intracochlear pressures and basilar membrane (BM) displacements up to 43.2 μm from a BOP input of 30.7 kPa. The cochlea's spiral shape caused asymmetric pressure distributions as high as 4 kPa across the cochlea's width and higher BM transverse motion than that observed in a similar straight cochlea model. The developed spiral cochlea model provides an advancement from the straight cochlea model to increase the understanding of cochlear mechanics during blast and progresses toward a model able to predict potential hearing loss after blast.
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Affiliation(s)
- Marcus A. Brown
- Biomedical Engineering Laboratory, Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK 73019
| | - John J. Bradshaw
- Biomedical Engineering Laboratory, Stephenson School of Biomedical Engineering, University of Oklahoma, Norman, OK 73019
| | - Rong Z. Gan
- Professor of Biomedical Engineering, Biomedical Engineering Laboratory, School of Aerospace and Mechanical Engineering, University of Oklahoma, Norman, OK 73019
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Mattingly JK, Hartl RMB, Jenkins HA, Tollin DJ, Cass SP, Greene NT. A Comparison of Intracochlear Pressures During Ipsilateral and Contralateral Stimulation With a Bone Conduction Implant. Ear Hear 2021; 41:312-322. [PMID: 31389846 PMCID: PMC8043255 DOI: 10.1097/aud.0000000000000758] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
OBJECTIVES To compare contralateral to ipsilateral stimulation with percutaneous and transcutaneous bone conduction implants. BACKGROUND Bone conduction implants (BCIs) effectively treat conductive and mixed hearing losses. In some cases, such as in single-sided deafness, the BCI is implanted contralateral to the remaining healthy ear in an attempt to restore some of the benefits provided by binaural hearing. While the benefit of contralateral stimulation has been shown in at least some patients, it is not clear what cues or mechanisms contribute to this function. Previous studies have investigated the motion of the ossicular chain, skull, and round window in response to bone vibration. Here, we extend those reports by reporting simultaneous measurements of cochlear promontory velocity and intracochlear pressures during bone conduction stimulation with two common BCI attachments, and directly compare ipsilateral to contralateral stimulation. METHODS Fresh-frozen whole human heads were prepared bilaterally with mastoidectomies. Intracochlear pressure (PIC) in the scala vestibuli (PSV) and tympani (PST) was measured with fiber optic pressure probes concurrently with cochlear promontory velocity (VProm) via laser Doppler vibrometry during stimulation provided with a closed-field loudspeaker or a BCI. Stimuli were pure tones between 120 and 10,240 Hz, and response magnitudes and phases for PIC and VProm were measured for air and bone conducted sound presentation. RESULTS Contralateral stimulation produced lower response magnitudes and longer delays than ipsilateral in all measures, particularly for high-frequency stimulation. Contralateral response magnitudes were lower than ipsilateral response magnitudes by up to 10 to 15 dB above ~2 kHz for a skin-penetrating abutment, which increased to 25 to 30 dB and extended to lower frequencies when applied with a transcutaneous (skin drive) attachment. CONCLUSIONS Transcranial attenuation and delay suggest that ipsilateral stimulation will be dominant for frequencies over ~1 kHz, and that complex phase interactions will occur during bilateral or bimodal stimulation. These effects indicate a mechanism by which bilateral users could gain some bilateral advantage.
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Affiliation(s)
- Jameson K. Mattingly
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO
| | | | - Herman A. Jenkins
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO
| | - Daniel J. Tollin
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO
| | - Stephen P. Cass
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO
| | - Nathaniel T. Greene
- Department of Otolaryngology, University of Colorado School of Medicine, Aurora, CO
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Noise Damage Accelerates Auditory Aging and Tinnitus: A Canadian Population-Based Study. Otol Neurotol 2021; 41:1316-1326. [PMID: 32810017 DOI: 10.1097/mao.0000000000002848] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Age-related hearing loss (ARHL) is the third most challenging disability in older adults. Noise is a known modifiable risk factor of ARHL, which can drive adverse health effects. Few large-scale studies, however, have shown how chronic noise exposure (CNE) impacts the progression of ARHL and tinnitus. STUDY DESIGN Retrospective large-scale study. SETTING Audiology clinical practice. PATIENTS In this study, 928 individuals aged 30-100 years without (n=497) or with the experience of CNE (n=431) were compared in their hearing assessments and tinnitus. In order to only investigate the impact of CNE on ARHL and tinnitus, people with other risk factors of hearing loss were excluded from the study. INTERVENTION Diagnostic. MAIN OUTCOME MEASURES Noise damage was associated with a greater ARHL per age decades (pure-tone average(PTA)0.5-4kHz alterations 19.6-70.8 dB vs. 8.0-63.2 dB, ≤0.001), an acceleration of developing a significant ARHL at least by two decades (PTA0.5-4kHz 33.4 dB at 50-59yr vs. 28.2 dB at 30-39yr, ≤0.001), and an increased loss of word recognition scores (total average 84.7% vs. 80.0%, ≤0.001). Significant noise-associated growth in the prevalence of tinnitus also was shown, including more than a triple prevalence for constant tinnitus (28.10% vs. 8.85%, ≤0.001) and near to a double prevalence for intermittent tinnitus (19.10% vs. 11.10%, ≤0.001). Noise also resulted in the elevation of the static compliance of the tympanic membrane throughout age (total average 0.61 vs. 0.85 mmho, ≤0.001). CONCLUSIONS Our findings emphasize the significant contribution of CNE in auditory aging and the precipitation of both ARHL and tinnitus.
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Cheng JT, Ghanad I, Remenschneider A, Rosowski J. The onset of nonlinear growth of middle-ear responses to high intensity sounds. Hear Res 2021; 405:108242. [PMID: 33872835 DOI: 10.1016/j.heares.2021.108242] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/20/2021] [Accepted: 03/31/2021] [Indexed: 11/16/2022]
Abstract
The human tympanic membrane (TM) and ossicles are generally considered to act as a linear system as they conduct low and moderate level environmental sounds to the cochlea. At intense stimulus levels (> 120 dB SPL) there is evidence that the TM and ossicles no longer act linearly. The anatomical structures that contribute to the nonlinear responses and their level and frequency dependences are not well defined. We used cadaveric human ears to characterize middle-ear responses to continuous tones between 200 and 20,000 Hz with levels between 60 and 150 dB SPL. The responses of the TM and ossicles are essentially sinusoidal, even at the highest stimulus level, but grow nonlinearly with increased stimulus level. The umbo and the stapes show different nonlinear behaviors: The umbo displacement grows faster than the stimulus level (expansive growth) at frequencies below 2000 Hz, while the stapes exhibits mostly compressive growth (grows slower than the stimulus level) over a wide frequency range. The sound pressure level where the nonlinearity first becomes obvious and the displacement at that level are lower at the stapes than at the umbo. These observations suggest the presence of multiple nonlinear processes within the middle ear. The existence of an expansive growth of umbo displacement that has limited effect on the stapes compressive growth suggests that the ossicular joints reduce the coupling between multiple nonlinear mechanisms within the middle ear. This study provides new data to test and refine middle-ear nonlinear models.
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Affiliation(s)
- Jeffrey Tao Cheng
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, United States; Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, 243 Charles Street, Boston, MA 02114, United States; Graduate Program in Speech and Hearing Bioscience and Technology, Division of Medical Studies, Harvard University, Boston, MA 02115, United States.
| | - Iman Ghanad
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, United States
| | - Aaron Remenschneider
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, United States; Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, 243 Charles Street, Boston, MA 02114, United States; Department of Otolaryngology, UMass Medical Center, 281 Lincoln Street, Worcester, MA 01605, United States
| | - John Rosowski
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, United States; Department of Otolaryngology-Head and Neck Surgery, Harvard Medical School, 243 Charles Street, Boston, MA 02114, United States; Graduate Program in Speech and Hearing Bioscience and Technology, Division of Medical Studies, Harvard University, Boston, MA 02115, United States
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Ucta C, Mittmann P, Ernst A, Seidl R, Lauer G. Minimizing Intracochlear Pressure: Influence of the Insertion Sheath. Audiol Neurootol 2021; 26:281-286. [PMID: 33647910 DOI: 10.1159/000512466] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 10/21/2020] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE Atraumatic cochlear implantation (CI) and insertion of the electrode in particular are major goals of recent CI surgery. Perimodiolar electrode arrays need a stylet or exosheath for insertion. The sheath can influence the intracochlear pressure changes during insertion of the electrode. The aim of this study was to modify the insertion sheath to optimize intracochlear pressure changes. METHODS In an artifical cochlear model, 7 different modified insertion sheaths were used. The intracochlear pressure was measured with a micro-optical sensor in the apical part of the model cochlea. RESULTS Significant lower intracochlear pressure changes were observed when the apical part of the insertion sheath was either shortened or tapered. Modification of the stopper does influence the intracochlear pressure significantly. CONCLUSION Modification of the insertion sheath leads to lower intracochlear pressure gain. The differences and impact on intracochlear pressure changes found in this study underline the importance of even subtle modifications of the electrode insertion technique.
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Affiliation(s)
- Ceyhun Ucta
- Department of Otolaryngology at ukb, Charité Med School Berlin, Hospital of the University of Berlin, Berlin, Germany
| | - Philipp Mittmann
- Department of Otolaryngology at ukb, Charité Med School Berlin, Hospital of the University of Berlin, Berlin, Germany
| | - Arneborg Ernst
- Department of Otolaryngology at ukb, Charité Med School Berlin, Hospital of the University of Berlin, Berlin, Germany
| | - Rainer Seidl
- Department of Otolaryngology at ukb, Charité Med School Berlin, Hospital of the University of Berlin, Berlin, Germany
| | - Gina Lauer
- Department of Otolaryngology at ukb, Charité Med School Berlin, Hospital of the University of Berlin, Berlin, Germany,
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13
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Dual-laser measurement of human stapes footplate motion under blast exposure. Hear Res 2021; 403:108177. [PMID: 33524791 DOI: 10.1016/j.heares.2021.108177] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 12/24/2020] [Accepted: 01/18/2021] [Indexed: 11/21/2022]
Abstract
Hearing damage is one of the most frequently observed injuries in Service members and Veterans even though hearing protection devices (HPDs, e.g. earplugs) have been implemented to prevent blast-induced hearing loss. However, the formation and prevention mechanism of the blast-induced hearing damage remains unclear due to the difficulty for conducting biomechanical measurements in ears during blast exposure. Recently, an approach reported by Jiang et al. (2019) used two laser Doppler vibrometers (LDVs) to measure the motion of the tympanic membrane (TM) in human temporal bones during blast exposure. Using the dual laser setup, we further developed the technology to detect the movement of the stapes footplate (SFP) in ears with and without HPDs while under blast exposure. Eight fresh human cadaveric temporal bones (TBs) were involved in this study. The TB was mounted in a "head block" after performing a facial recess surgery to access the SFP, and a pressure sensor was inserted near the TM in the ear canal to measure the pressure reaching the TM (P1). The TB was exposed to a blast overpressure measuring around 7 psi or 48 kPa at the entrance of the ear canal (P0). Two LDVs were used to measure the vibrations of the SFP and TB (as a reference). The exact motion of the SFP was determined by subtracting the TB motion from the SFP data. Results included a measured peak-to-peak SFP displacement of 68.7 ± 31.6 μm (mean ± SD) from all eight TBs without HPDs. In five of the TBs, the insertion of a foam earplug reduced the SFP displacement from 48.3 ± 6.3 μm to 21.8 ± 10.4 μm. The time-frequency analysis of the SFP velocity signals indicated that most of the energy spectrum was concentrated at frequencies below 4 kHz within the first 2 ms after blast and the energy was reduced after the insertion of HPDs. This study describes a new methodology to quantitatively characterize the response of the middle ear and the energy entering the cochlea during blast exposure. The experimental data are critical for determining the injury of the peripheral auditory system and elucidating the damage formation and prevention mechanism in an ear exposed to blast.
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14
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3D Finite Element Modeling of Blast Wave Transmission from the External Ear to Cochlea. Ann Biomed Eng 2020; 49:757-768. [PMID: 32926269 DOI: 10.1007/s10439-020-02612-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 09/02/2020] [Indexed: 10/23/2022]
Abstract
As an organ that is sensitive to pressure changes, the ear is often damaged when a person is subjected to blast exposures resulting in hearing loss due to tissue damage in the middle ear and cochlea. While observation of middle ear damage is non-invasive, examining the damage to the cochlea is difficult to quantify. Previous works have modeled the cochlear response often when subjected to an acoustic pressure input, but the inner ear mechanics have rarely been studied when the ear is exposed to a blast wave. In this study we aim to develop a finite element (FE) model of the entire ear, particularly the cochlea, for predicting the blast wave transmission from the ear canal to cochlea. We utilized a FE model of the ear, which includes the ear canal, middle ear, and uncoiled two-chambered cochlea, to simulate the cochlear response to blast overpressure (BOP) at the entrance of the ear canal with ANSYS Mechanical and Fluent in a fluid-structure interface coupled analysis in the time domain. This model was developed based on previous middle and inner ear models, and the cochlea was remeshed to improve BOP simulation performance. The FE model was validated using experimentally measured blast pressure transduction from the ear canal to the middle ear and cochlea in human cadaveric temporal bones. Results from the FE model showed significant displacements of the tympanic membrane, middle ear ossicles, and basilar membrane (BM). The stapes footplate displacement was observed to be as high as 60 µm, far exceeding the displacement during normal acoustic stimulation, when the 30 kPa (4.35 psi, 183 dB (SPL), Sound Pressure Level) of BOP was applied at the ear canal entrance. The large stapes movement caused pressures in the cochlea to exceed the physiological pressure level [< 10 Pa, 120 dB (SPL)] at a peak of 49.9 kPa, and the BM displacement was on the order of microns with a maximum displacement of 26.4 µm. The FE model of the entire human ear developed in this study provides a computational tool for prediction of blast wave transmission from the ear canal to cochlea and the future applications for assisting the prevention, diagnosis, and treatment of blast-induced hearing loss.
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15
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Yu Y, Huang J, Tang X, Allison J, Sandlin D, Ding D, Pang Y, Zhang C, Chen T, Yin N, Chen L, Mustain W, Zhou W, Zhu H. Exposure to blast shock waves via the ear canal induces deficits in vestibular afferent function in rats. J Otol 2020; 15:77-85. [PMID: 32884557 PMCID: PMC7451608 DOI: 10.1016/j.joto.2020.01.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 01/09/2020] [Accepted: 01/15/2020] [Indexed: 12/11/2022] Open
Abstract
The ears are air-filled structures that are directly impacted during blast exposure. In addition to hearing loss and tinnitus, blast victims often complain of vertigo, dizziness and unsteady posture, suggesting that blast exposure induces damage to the vestibular end organs in the inner ear. However, the underlying mechanisms remain to be elucidated. In this report, single vestibular afferent activity and the vestibulo-ocular reflex (VOR) were investigated before and after exposure to blast shock waves (∼20 PSI) delivered into the left external ear canals of anesthetized rats. Single vestibular afferent activity was recorded from the superior branch of the left vestibular nerves of the blast-treated and control rats one day after blast exposure. Blast exposure reduced the spontaneous discharge rates of the otolith and canal afferents. Blast exposure also reduced the sensitivity of irregular canal afferents to sinusoidal head rotation at 0.5-2Hz. Blast exposure, however, resulted in few changes in the VOR responses to sinusoidal head rotation and translation. To the best of our knowledge, this is the first study that reports blast exposure-induced damage to vestibular afferents in an animal model. These results provide insights that may be helpful in developing biomarkers for early diagnosis of blast-induced vestibular deficits in military and civilian populations.
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Affiliation(s)
- Yue Yu
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - Jun Huang
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - Xuehui Tang
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - Jerome Allison
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - David Sandlin
- Program in Neuroscience, University of Mississippi Medical Center, Jackson, MS, USA
| | - Dalian Ding
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, USA
| | - Yi Pang
- Department of Pediatric, University of Mississippi Medical Center, Jackson, MS, USA
| | - Chunming Zhang
- Department of Otolaryngology, First Affiliated Hospital, Shanxi Medical University, Taiyuan Shanxi, 030001, China
| | - Tianwen Chen
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - Nathan Yin
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - Lan Chen
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - William Mustain
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA
| | - Wu Zhou
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Neurology, University of Mississippi Medical Center, Jackson, MS, USA
| | - Hong Zhu
- Departmant of Otolaryngology and Communicative Sciences, University of Mississippi Medical Center, Jackson, MS, USA.,Department of Neurobiology and Anatomical Sciences, University of Mississippi Medical Center, Jackson, MS, USA
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16
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Jokel C, Yankaskas K, Robinette MB. Noise of military weapons, ground vehicles, planes and ships. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2019; 146:3832. [PMID: 31795677 DOI: 10.1121/1.5134069] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Noisy equipment and processes are found throughout military operations, exposing service members to risks of hearing damage due to hazardous noise levels. This article provides an overview of the military noise environment for the non-expert and provides a general characterization of the noise by source type and operational category. The focus of the article is primarily related to the Army, but the same, or similar, equipment is used by the Navy, Marine Corps, and Air Force. Damage risk criteria used by the Army Public Health Command are discussed. In addition, the important role of hearing protection to mitigate the hazards of noise exposure is provided.
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Affiliation(s)
- Charles Jokel
- Army Public Health Center, 8977 Sibert Road, Aberdeen Proving Ground, Maryland 21010-5403, USA
| | - Kurt Yankaskas
- Office of Naval Research, 875 N Randolph Street, Arlington, Virginia 22203, USA
| | - Martin B Robinette
- Army Public Health Center, 8977 Sibert Road, Aberdeen Proving Ground, Maryland 21010-5403, USA
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17
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Rosowski JJ, Remenschneider AK, Tao Cheng J. Limitations of present models of blast-induced sound power conduction through the external and middle ear. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2019; 146:3978. [PMID: 31795712 PMCID: PMC6881194 DOI: 10.1121/1.5132288] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
The use of models to predict the effect of blast-like impulses on hearing function is an ongoing topic of investigation relevant to hearing protection and hearing-loss prevention in the modern military. The first steps in the hearing process are the collection of sound power from the environment and its conduction through the external and middle ear into the inner ear. Present efforts to quantify the conduction of high-intensity sound power through the auditory periphery depend heavily on modeling. This paper reviews and elaborates on several existing models of the conduction of high-level sound from the environment into the inner ear and discusses the shortcomings of these models. A case is made that any attempt to more accurately define the workings of the middle ear during high-level sound stimulation needs to be based on additional data, some of which has been recently gathered.
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Affiliation(s)
- John J Rosowski
- Eaton-Peabody Laboratory and Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, Massachusetts 02114, USA
| | - Aaron K Remenschneider
- Eaton-Peabody Laboratory and Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, Massachusetts 02114, USA
| | - Jeffrey Tao Cheng
- Eaton-Peabody Laboratory and Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, Massachusetts 02114, USA
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18
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Bugay V, Bozdemir E, Vigil FA, Chun SH, Holstein DM, Elliott WR, Sprague CJ, Cavazos JE, Zamora DO, Rule G, Shapiro MS, Lechleiter JD, Brenner R. A Mouse Model of Repetitive Blast Traumatic Brain Injury Reveals Post-Trauma Seizures and Increased Neuronal Excitability. J Neurotrauma 2019; 37:248-261. [PMID: 31025597 DOI: 10.1089/neu.2018.6333] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Repetitive blast traumatic brain injury (TBI) affects numerous soldiers on the battlefield. Mild TBI has been shown to have long-lasting effects with repeated injury. We have investigated effects on neuronal excitability after repetitive, mild TBI in a mouse model of blast-induced brain injury. We exposed mice to mild blast trauma of an average peak overpressure of 14.6 psi, repeated across three consecutive days. While a single exposure did not reveal trauma as indicated by the glial fibrillary acidic protein indicator, three repetitive blasts did show significant increases. As well, mice had an increased indicator of inflammation (Iba-1) and increased tau, tau phosphorylation, and altered cytokine levels in the spleen. Video-electroencephalographic monitoring 48 h after the final blast exposure demonstrated seizures in 50% (12/24) of the mice, most of which were non-convulsive seizures. Long-term monitoring revealed that spontaneous seizures developed in at least 46% (6/13) of the mice. Patch clamp recording of dentate gyrus hippocampus neurons 48 h post-blast TBI demonstrated a shortened latency to the first spike and hyperpolarization of action potential threshold. We also found that evoked excitatory postsynaptic current amplitudes were significantly increased. These findings indicate that mild, repetitive blast exposures cause increases in neuronal excitability and seizures and eventual epilepsy development in some animals. The non-convulsive nature of the seizures suggests that subclinical seizures may occur in individuals experiencing even mild blast events, if repeated.
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Affiliation(s)
- Vladislav Bugay
- Cell and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas
| | - Eda Bozdemir
- Department of Cell Systems and Anatomy, University of Texas Health San Antonio, San Antonio, Texas
| | - Fabio A Vigil
- Cell and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas
| | - Sang H Chun
- Department of Cell Systems and Anatomy, University of Texas Health San Antonio, San Antonio, Texas
| | - Deborah M Holstein
- Department of Cell Systems and Anatomy, University of Texas Health San Antonio, San Antonio, Texas
| | - William R Elliott
- Sensory Trauma, United States Army Institute of Surgical Research, Fort Sam Houston San Antonio, Texas
| | - Cassie J Sprague
- Sensory Trauma, United States Army Institute of Surgical Research, Fort Sam Houston San Antonio, Texas
| | - Jose E Cavazos
- Cell and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas.,Department of Neurology, University of Texas Health San Antonio, San Antonio, Texas
| | - David O Zamora
- Sensory Trauma, United States Army Institute of Surgical Research, Fort Sam Houston San Antonio, Texas
| | | | - Mark S Shapiro
- Cell and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas
| | - James D Lechleiter
- Department of Cell Systems and Anatomy, University of Texas Health San Antonio, San Antonio, Texas
| | - Robert Brenner
- Cell and Integrative Physiology, University of Texas Health San Antonio, San Antonio, Texas
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19
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Dual-laser measurement and finite element modeling of human tympanic membrane motion under blast exposure. Hear Res 2019; 378:43-52. [DOI: 10.1016/j.heares.2018.12.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 12/10/2018] [Accepted: 12/12/2018] [Indexed: 11/23/2022]
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