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Canine Audiology
Published in Stavros Hatzopoulos, Andrea Ciorba, Mark Krumm, Advances in Audiology and Hearing Science, 2020
Kristine E. Sonstrom, Peter M. Scheifele
The division between the outer and middle ear space is the tympanic membrane, behind which are the three auditory ossicles: malleus, incus, and stapes. The middle ear connects to the inner ear via the round window. The inner ear includes the cochlea and vestibular system (semi-circular canals and surrounding structures). The dog’s cochlea has approximately 3¼ turns, as opposed to the human’s cochlea with 2½ turns. This difference becomes important when analyzing the frequency and threshold of hearing in the dog. Thus, we should avoid the use of human references and standards regarding hearing when testing dogs. A further discussion on assessment techniques will follow.
Common otology viva topics
Published in Joseph Manjaly, Peter Kullar, Advanced ENT Training, 2019
Cochlear implant surgery is performed on appropriately assessed and consented patients. A facial nerve monitor must be used. A post-auricular incision is made, a cortical mastoidectomy and posterior tympanotomy are drilled, and the round window niche is exposed. In some implants, a bed is fashioned below temporalis, and the implant package is placed in this bed. The round window membrane is opened or alternatively a cochleostomy is drilled, and the implant is inserted into the cochlea slowly to maximise the chance of preserving any residual acoustic hearing. Electrophysiological testing may be undertaken at the time of surgery or at a later date.
Implantation of an Artificial Tympanum in Cases of Irreversibly Blocked Eustachian Tubes
Published in Waldemar L. Olszewski, CRC Handbook of Microsurgery, 2019
The surgical approach is simple: under local anesthesia a flap is raised from the posterior wall of the auditory meatus. Proceeding to the middle ear the squamous epithelium covering the round window is also raised. The edge of the round window niche is flattened using a diamond burr to get a smooth and even contact surface for the implant close to the round window membrane (Figure 6). Then the implant is inserted, sheathed by using small pieces of temporal fascia, and finally covered by replacing the squamous epithelium. Gel-foam soaked with an antibiotic solution is used for packing the external auditory meatus.
The impact of labyrinthine magnetic resonance signal alterations on the treatment of sudden sensory-neural hearing loss
Published in Acta Oto-Laryngologica, 2023
Edoardo Covelli, Chiara Filippi, Haitham H. Elfarargy, Luigi Volpini, Valerio Margani, Giulia Moltoni, Serena Palizzi, Andrea Romano, Alessandro Bozzao, Maurizio Barbara
For managing SSNHL, we used a course of intratympanic injections of high concentrations of prednisolone for three consecutive days. This therapeutic modality has been proven effective in managing SSNHL in the short and long term, avoiding the side effects of systemic corticosteroids [1]. At the same time, it entails the delivery of high concentrations into the inner ear via the round window membrane. This therapeutic modality was very effective in most cases (83.3%) with idiopathic SSNHL with a significant improvement in the post-treatment average PTA (24.12 ± 20.46 dB). In contrast, the intratympanic prednisolone injection was ineffective in the labyrinthine hemorrhage group, as most cases were slightly or poorly improved (92.8%) with an insignificant change in the post-treatment PTA (92.7 ± 33.48 dB). According to our results, labyrinthine hemorrhage, vertigo, and the anacusis type significantly predict the hearing prognosis.
Do CT values change over time and correlate with hearing in the non-surgical ears of otosclerosis patients?
Published in Acta Oto-Laryngologica, 2022
Wei Chen, Yanqing Fang, Yue Geng, Naier Lin, Yan Sha
In this study, 31/32 (96.9%) of otosclerosis patients showed positive lesions on HRCT images, and the most common focal point of the lesion was located in the area of fissula ante fenestram, which was in line with the results of Wycherly et al. [12] and Min et al. [13]. Other common lesions were located in the round window and the related areas of the inner ear. After comparing the results of the two HRCT examinations, we found that only the change in CT value in AIAM was statistically significant, and its CT value decreased by about 88.5 HU in the second HRCT examination. The specific reason is still unknown, which needs further research. In addition, we accidentally discovered a patient with a diverticulum in the internal auditory canal, which had also been seen in several other reports [14–16]. The reason for this phenomenon was speculated to be the occurrence of cerebrospinal fluid ejection, but the specific formation mechanism of the diverticulum in the internal auditory canal was still unclear. Some scholars speculated that it might be due to the pathological remodeling and vascularization of normal bone tissue which had changed the shear stress of the surrounding bones of the lymphatic vessels. Pathological remodeling could lead to increased pressure in the endolymphatic vessels at the base of the inner ear canal, resulting in the rupture of cerebrospinal fluid and the formation of a hernia or diverticulum.
Change of VOR gain and pure-tone threshold after single low-dose intratympanic gentamicin injection in Meniere’s disease
Published in Acta Oto-Laryngologica, 2020
The reason for failure of initial ITG is important because there could be several substantial factors which may influence on clear dose-response relationship. An Salt et al. reported that gentamicin may enter the inner ear more easily through the oval window than through the round window in guinea pigs study [13]. Also they demonstrated a slow flow of perilymph in the scala tympani towards the apex of the cochlear in previous study [14]. Another factor is anatomical difference around round window and permeability of round window membrane. In one study, 29 of the round windows were judged to be unobstructed, 7 were obstructed partially, and 5 were obstructed completely in 41 cases [15]. A. Walsted suggested that if the internal orifice of cochlear aqueduct is obliterated, drugs delivered into the middle ear concentrate in the inner ear fluids behind the round window membrane after absorption, resulting in a prolonged and damaging ototoxic effect in the cochlea [16]. In our study, 6 out of 16 patients needed further injection after initial ITG. We can expect that patients in multiple injections group might have anatomical obstruction through round window membrane or hindered cochlear aqueduct. In that cases, we can consider the method which can resolve impermeability or anatomical problems, such as exploratory tympanotomy and gentamicin application [17].