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Ear, Nose, and Paranasal Sinus
Published in Swati Goyal, Neuroradiology, 2020
The external auditory canal (EAC), with lateral one-third cartilaginous and medial two-thirds bony composition, extends from the auricle to the tympanic membrane. The middle ear cavity is within the petrous portion of the temporal bone and consists of the tympanic cavity (containing the ossicles, namely the malleus, incus, and stapes) and the antrum. The mastoid antrum communicates with the epitympanum via aditus ad antrum. The middle ear also contains muscles (tensor tympani and stapedius), the round and oval windows, and the chorda tympani nerve. The inner ear consists of the osseous labyrinth (cochlea, vestibule, and the three semicircular canals, namely the superior, posterior, and lateral canals) and the membranous labyrinth (the cochlear duct, utricle, saccule, semicircular ducts, endolymphatic duct, and endolymphatic sac). The membranous labyrinth contains endolymph, surrounded by perilymph, and is enclosed within the bony labyrinth. The internal auditory canal (IAC) is located in the petrous bone and transmits facial and vestibulocochlear nerves along with the labyrinthine artery. The pars flaccida is the upper delicate part that is associated with Eustachian tube dysfunction and cholesteatoma. The pars tensa is larger and more robust, and associated with perforations.
The Special Sense Organs and Their Disorders
Published in Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss, Understanding Medical Terms, 2020
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss
Idiopathic symptomatic endolymphatic hydrops or Meniere's disease is another disorder of the inner ear that produces hearing impairment, dizziness, and tinnitus (ringing or whistling in the ears). The disease is thought to be caused by an excess of endolymph, the inner ear fluid, and dilation or stretching of the labyrinth. Most patients progress to some baseline hearing loss and to bilateral disease.
Nonconventional Clinical Applications of Otoacoustic Emissions: From Middle Ear Transfer to Cochlear Homeostasis to Access to Cerebrospinal Fluid Pressure
Published in Stavros Hatzopoulos, Andrea Ciorba, Mark Krumm, Advances in Audiology and Hearing Science, 2020
Blandine Lourenço, Fabrice Giraudet, Thierry Mom, Paul Avan
Patent MD consists in attacks during which three symptoms are associated, unilateral (usually fluctuating) neurosensory hearing loss, vertigo, and tinnitus, accompanied by a sensation of aural fullness (Lopez-Escamez et al., 2016). The issue of abnormal hydrostatic pressure of labyrinthine fluids and particularly, endolymph, has been raised as endolymphatic hydrops, defined as volume inflation of the endolymphatic compartment, is a hallmark of the disease that suggests the concept of abnormal pressure homeostasis in the endolymph. However, the relation between pressure and volume may not be straightforward, as the situation is compounded by several findings. One is the postmortem observation of histological hydrops in temporal bones of subjects who, when alive, had never complained of any MD symptom (Merchant et al., 2005). The second, with similar inferences, is the MRI finding of inflated endolymphatic compartments, again, in subjects who experience no clinical sign of the disease in the hydropic ear (Pyykko et al., 2013). In the latter case, a caveat may be that the criteria for deciding that an image undoubtedly shows hydrops are not yet universally acknowledged (Attye et al., 2017).
Magnetic resonance imaging of endolymphatic hydrops in patients with unilateral Meniere’s disease: volume ratio and distribution rate of the endolymphatic space
Published in Acta Oto-Laryngologica, 2021
Hiroshi Inui, Tsuyoshi Sakamoto, Taeko Ito, Tadashi Kitahara
The inner-ear labyrinth comprises two parts: the osseous labyrinth and the membranous labyrinth. The membranous labyrinth, which includes the utriculus, sacculus, ampulla of the semi-circular canals, endolymphatic sac, and cochlear duct, is continuous and filled with endolymph. In 1938, Hallpike and Cairns [1] and Yamakawa [2] revealed that an extended endolymphatic space (ELS), also called endolymphatic hydrops (ELH), is a pathological feature of Meniere’s disease (MD), which is a chronic disease characterized by recurrent vertigo, tinnitus, aural fullness, and fluctuating hearing loss in the affected ear. Currently, ELH in patients with MD is being studied with the use of magnetic resonance imaging (MRI). In 2009, Nakashima et al. employed MRI to grade of ELH in the vestibule and cochlea by calculating the ratio of the area of the ELS to the area of the total fluid space (TFS) [3]. In our previous study, 3D MRI was used to obtain quantitative volumetric measurements of inner-ear components and inner-ear ELH as well as to define the range of normal ELS volumes in healthy volunteers without vertiginous or cochlear symptoms [4]; the average cochlear and vestibular ELS/TFS volume ratios in the healthy volunteers were found to be 10.2% and 17.7%, respectively. In the present study, we sought to measure the distribution rate of endolymphatic fluid in the membranous labyrinth of inner-ear components in patients with MD.
The effect of sport training on otolith function in adults with profound sensorineural hearing loss
Published in Hearing, Balance and Communication, 2021
Homa Zarrinkoob, Arash Bayat, Nasim Kaka
According to our findings, both “non-athletes deaf” and “athletes deaf” people showed some degree of otolithic (saccular or utricular) involvements as revealed by the oVEMP and cVEMP abnormalities. The inner ear vestibule and cochlea have a continuous membranous structure, filled by endolymph fluid. These components also have similar sensory cell ultrastructures and are supplied through “common arterial” blood. Then, inner ear disorders probably influence the cochlea as well as the vestibular system. In children with a profound degree of hearing loss, the incidence of otolithic impairment is rather high, but this issue has not received sufficient attention [2]. Hong et al. [19] reported that 26.9% of adults with profound SNHL indicate abnormal cVEMP responses and suggested that the frequency of saccular damage enhances with the severity of hearing loss. It has been demonstrated that vestibular system lesions may lead to a variety of serious problems, including dizziness, imbalance, falls, blurring of vision, and spatial disorientation [17].
The pharmacological management of vertigo in Meniere disease
Published in Expert Opinion on Pharmacotherapy, 2020
Juan Manuel Espinosa-Sanchez, José A. Lopez-Escamez
The accumulation of endolymph in the membranous labyrinth, leading to an increased pressure in the cochlear duct, is termed endolymphatic hydrops, and it is considered the pathological substrate of the syndrome, but it can be also found in other conditions or even in healthy subjects [6]. In any case, the endolymphatic hydrops would be the common denominator of a series of inflammatory processes in different parts of the cochlea (lateral wall, endolymphatic sac) leading to cochlear damage with autoinflammation or autoimmunity responses resulting from multiple causes (allergy, viral infection, genetic variants) that affect the inner ear homeostasis, lead to the accumulation of endolymph and manifest with a common core phenotype (episodic vertigo with fluctuating auditory symptoms) that defines a clinically heterogeneous syndrome. Classically, when this set of symptoms cannot be attributed to a specifically identified cause, the syndrome is considered idiopathic, and then it is referred to as MD.