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Disorders of Hearing
Published in Anthony N. Nicholson, The Neurosciences and the Practice of Aviation Medicine, 2017
Linda M. Luxon, Ronald Hinchcliffe
Criteria for the diagnosis of auditory neuropathy or dyssynchrony include normal outer hair cell function (otoacoustic emissions and a normal cochlear microphonic), together with absent or abnormal inner hair cell/neural function (auditory brainstem-evoked responses, with absent stapedial reflexes and absent contralateral suppression of otoacoustic emissions via the efferent pathway). Auditory neuropathy is now recognized as a significant cause of hearing impairment in children, but the prevalence of auditory neuropathy in adults has not been defined. However, it may be associated with congenital and inherited disorders such as the Arnold–Chiari malformation with elongation of the VIII nerve, the ataxia described by Friedreich (1825–1882), trauma, infection such as meningitis, the Ramsay Hunt (1872–1937) syndrome (herpes zoster viral infection of the geniculate ganglion of the facial nerve), vascular disease, neoplasia, temporal bone disorders compressing the VIII nerve, toxic disorders (such as vincristine ototoxicity, alcohol and both lead and mercury poisoning), autoimmune disorders and demyelination.
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.
Optical Cochlear Implants
Published in Francesco S. Pavone, Shy Shoham, Handbook of Neurophotonics, 2020
C. P. Richter, Y. Xu, X. Tan, N. Xia, N. Suematsu
Wells and coworkers published in 2005 that for selected radiation wavelengths in the range between 1,064 nm and 10,000 nm a pulsed laser could be used to stimulate nerves without damaging them (Wells et al., 2005). The wavelengths around 2,100 nm and in the range from 1,844–1,910 nm were especially interesting because lasers exist which emit light at those wavelengths. Inspired by the first results at Vanderbilt, we conducted similar experiments and irradiated the gerbil sciatic nerve with a Ho:YAG laser and could qualitatively validate Wells’ results. In subsequent experiments we showed that stimulation of cranial nerves is possible by stimulating the facial nerve (Teudt et al., 2007), the auditory (Izzo et al., 2006a; Izzo et al., 2006b), and the vestibular system (Dittami et al., 2011; Rajguru et al., 2011). The underlying mechanism for neural stimulation with infrared light has not been fully determined. Today, everybody agrees that spatially and temporally confined heating results in the depolarization of the neuron. It is not fully clear how the heating results in an action potential. Experiments conducted to determine the mechanism for optical stimulation have shown that temperature-sensitive ion channels, the Transient Receptor Potential (TRV) vanilloid channels TRPV1 and TRPV4, are present in the cochlea and contribute to this (Albert et al., 2012; Balaban et al., 2003; Rhee et al., 2008; Suh et al., 2009; Takumida et al., 2005; Zheng et al., 2003), the heating changes in the membrane capacitance are associated with a depolarizing current (Plaksin et al., 2017; Shapiro et al., 2012), and the calcium homeostasis is affected (Dittami et al., 2011; Liu et al., 2014; Lumbreras et al., 2014; Rabbitt et al., 2016; Rajguru et al., 2011). It is not fully clear today how the spatially and temporally confined heating leads to an action potential.
Evaluation of the milling’s response of a new bi-material 3D-printed model of temporal bone used for surgeons’ training
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2020
J. Chauvelot, G. Le Coz, C. Laurent, A. S. Bonnet, A. Moufki, C. Parietti-Winkler
Several types of artificial temporal bones are available for surgeons’ training but the level of satisfaction of surgeons is quite controversial and is evaluated most of the time through subjective qualitative procedures (Suzuki et al. 2018). In this work, a new 3D-printed model of the temporal bone made of two resins representing hard (bone) and soft (facial nerve, dura-mater, etc.) tissues, and whose morphological validation was conducted by Chauvelot et al. (2020) is considered (see Figure 1(a)).
Facial muscle reanimation by transcutaneous electrical stimulation for peripheral facial nerve palsy
Published in Journal of Medical Engineering & Technology, 2019
Eeva Mäkelä, Hanna Venesvirta, Mirja Ilves, Jani Lylykangas, Ville Rantanen, Tuija Ylä-Kotola, Sinikka Suominen, Antti Vehkaoja, Jarmo Verho, Jukka Lekkala, Veikko Surakka, Markus Rautiainen
In the present study, our goal was to study the feasibility of electrical stimulation with surface electrodes for the reanimation of different facial muscles in subjects with a peripheral facial nerve palsy. The frontalis, zygomaticus major, orbicularis oris, and orbicularis oculi muscles were stimulated in an attempt to produce forehead wrinkle, smile, lip pucker, and eye blink, respectively.