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Vestibular and Related Oculomotor Disorders
Published in Anthony N. Nicholson, The Neurosciences and the Practice of Aviation Medicine, 2017
Nicholas J. Cutfield, Adolfo M. Bronstein
For patients who report loud sound-induced disequilibrium, oscillopsia or vertigo, the eyes should be examined for torsional nystagmus while applying a continuous loud sound (100 dB) or with a Valsalva manoeuvre. A low-amplitude torsional nystagmus can be difficult to see clinically (opening the eyelids wide to view the scleral vessels can help) and is more reliably recorded with video-oculography. However, high-resolution tomography of the temporal bones is the most important investigation. Additionally, recording muscle activity induced by applying loud clicks (vestibular-evoked myogenic potential) is easier to induce due to enhanced bone transmission (Colebatch et al., 1998). Similarly, the audiogram will typically show an ‘air–bone gap’ at 1 kHz and below due to enhanced transmission of sound with the ‘bone’ stimulus, a kind of conductive hyperacusis.
Head and neck
Published in David A Lisle, Imaging for Students, 2012
The temporal bone is an extremely complex structure that contains the external auditory canal, middle and inner ear structures, and transmits the seventh cranial (facial) nerve (CN7). Middle ear structures include the tympanic membrane, aerated bony chambers, and three ossicles (malleus, incus, stapes) responsible for transmission of sound vibrations to the inner ear. Inner ear structures include the cochlea (responsible for hearing), vestibule and semicircular canals (responsible for balance), facial nerve canal and internal auditory canal (IAC). IAC transmits the facial nerve and the vestibular and cochlear components of the eighth cranial (vestibulocochlear) nerve (CN8). CN7 and CN8 exit the brainstem and pass laterally across a cerebrospinal fluid (CSF)-filled space known as the cerebellopontine angle (CPA) to enter the IAC.
Human physiology, hazards and health risks
Published in Stephen Battersby, Clay's Handbook of Environmental Health, 2016
David J. Baker, Naima Bradley, Alec Dobney, Virginia Murray, Jill R. Meara, John O’Hagan, Neil P. McColl, Caryn L. Cox
Sound energy is transmitted from the tympanic membrane through the middle ear cavity to the inner ear – cochlea, which is a spiral passage in the temporal bone, which also contains the semicircular canals (these contain the sensory organs for equilibrium and movement).
Effect of ossicular chain deformity on reverse stimulation considering the overflow characteristics of third windows
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Houguang Liu, Lin Xue, Jianhua Yang, Gang Cheng, Lei Zhou, Xinsheng Huang
To simulate the structural abnormalities of the ossicular chain, we used our previously reported FE model including the ear canal and middle ear (Zhou et al. 2016). In brief, the geometric model of the ear canal and middle ear are based on a series of histological section images collected from a human temporal bone (male, 60 years old, right ear). The volume of the air in the ear canal is 952.18 mm3, and the average length is about 26.32 mm. The volume of the malleus, incus, and stapes are 13.53, 15.54, and 2.95 mm3, respectively. The corresponding mass can be calculated from the measured dimensions. The definition of fluid-structure interaction surface, boundary conditions, and material properties of components in the model are consistent with those reported by Zhou et al. (2016). Figure 2 indicates the FE model of the ear canal and the middle ear. Coupled structural–acoustic analysis of the FE model was conducted using Abaqus (Dassault Systèmes, Johnston, RI, USA).
Numerical analysis of the effects of ossicular chain malformations on bone conduction stimulation
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Yu Zhao, Wen Liu, Houguang Liu, Jianhua Yang, Lei Zhou, Xinsheng Huang
The human ear FE model was developed based on a fresh human temporal bone, which comprises an ear canal, a middle ear and a spiral cochlea, as shown in Figure 2. This study was approved by the Ethics Committee of Affiliated Hospital of Xuzhou Medical University. The middle ear portion of the model comprises the middle ear cavity, the tympanic membrane (TM), ossicular chain, ligaments, and tendons. The cochlea is filled with lymph fluid and includes the scala vestibuli, scala tympani, helicotrema, basilar membrane (BM), bony spiral plate, and RW membrane. In addition, the bony wall was built as a layer shell elements at the outer layer of the cavities (the ear canal and the middle ear cavity) and the cochlea, which was in contact with the air and the lymph fluid in this model. The BM was connected with the bony wall via the bony spiral plate.
The biomechanical characteristics of human vestibular aqueduct: a numerical-based model construction and simulation
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Qingjie Guan, Dong Sun, Ming Zhao, Yingxi Liu, Shen Yu, Jianing Zhang, Rui Li, Kaili Sun, Xiuzhen Sun, Xu Bie
The inner ear is embedded deeply in temporal bone, making its elaborate structure hard to be accessed by routine approaches. Although the CT image can demonstrate the labyrinth in detail, it only predicts the lesion extent by measuring external opening of VA because the VA is far more tiny than the labyrinth (Takagi and Sando 1989; Koesling et al. 2006; Maiolo et al. 2013; Santos et al. 2017). Taking the advantage of histological and pathological knowledge accumulated in the past decades, the precise structure of VA can be read in the histological sections (Arnold and Lang 2001). However, the complicated manipulation during the section preparation is prone to change the original shapes of samples, making the histological images unreliable for the three dimensional re-construction, especially for the elaborate structure of VA. Thus, the 3D numerical model based on the high resolution CT or MRI images seems to be the only means to get an accurate 3D model of VA.