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Otology
Published in Adnan Darr, Karan Jolly, Jameel Muzaffar, ENT Vivas, 2023
Jameel Muzaffar, Chloe Swords, Adnan Darr, Karan Jolly, Manohar Bance, Sanjiv Bhimrao
History: Brief episodes of vertigo on head movement lasting sec to min, normal in betweenOtology symptoms: Hearing loss, infections, tinnitus, autophony, Tulio's phenomenon to rule out other causesAsk: Falls and impact on quality of life, surgery in pastPMH: Trauma, Vit D levels, previous surgery (perilymph fistula), otosclerosis, Meniere's, migraineFH: Hearing lossRule out central vertebrobasilar insufficiency: (Ds) dysarthria, dysphagia, dysesthesia, diplopia
Anatomy and Physiology of Hearing
Published in R James A England, Eamon Shamil, Rajeev Mathew, Manohar Bance, Pavol Surda, Jemy Jose, Omar Hilmi, Adam J Donne, Scott-Brown's Essential Otorhinolaryngology, 2022
Ananth Vijendren, Peter Valentine
Both the scala vestibuli (SV) and scala tympani (ST) are filled with perilymph, whereas the central scala media (SM) is filled with endolymph. Within the SM is the sensory epithelium of the cochlea, called the organ of Corti. This is a strip of cells coiled in a spiral, resting on the basilar membrane (BM), and overlain by the gelatinous tectorial membrane. Ion transportation within the cochlea is mediated by the stria vascularis, which forms the lateral wall of the SM. It contains the Na+/K+-ATPase, which maintains the high endolymphatic K+ concentration and the +80-mV electrical potential of the cochlea endolymph, relative to the perilymph.
Ear, nose and throat
Published in Nicholas Green, Steven Gaydos, Hutchison Ewan, Edward Nicol, Handbook of Aviation and Space Medicine, 2019
Nicholas Green, Steven Gaydos, Hutchison Ewan, Edward Nicol
Inner ear barotrauma (e.g. from excessive Valsalva manoeuvre) may cause perilymph fistula with sudden onset of vertigo with an accompanying hearing loss and tinnitus; management may be conservative or surgical; flying not usually permitted until resolution.
The role of serum osmolality in Meniere’s disease with acute sensorineural hearing loss
Published in International Journal of Audiology, 2023
Nevertheless, the change in endolymph volume depends on the osmotic pressure gradient between the endolymph and perilymph. The Isosorbide, an osmotic diuretic, is a dehydric alcohol that is formed by subtracting two molecules of water from one of the sorbitol (Kitahara et al. 1982), which may change the plasma osmolality by increasing +4.2 mOSM/kg after treatment with a total dosage of 2.94 L (Kakigi et al. 2006). Once osmotic pressure of the perilymph is greater than that of the endolymph, fluid may transfer from the endolymphatic space to the perilymphatic space, resulting in resolution of the EH and improvement of the hearing (Li, Cheng, and Young 2020). Hence, this study utilised Isosorbide to improve hearing threshold via increasing serum osmolality in EH ears (Figure 1).
Experimental drugs for the prevention or treatment of sensorineural hearing loss
Published in Expert Opinion on Investigational Drugs, 2023
Judith S Kempfle, David H. Jung
The cochlea, a portion of the inner ear, is a snail-shaped, fluid-filled compartment within the petrous portion of the temporal bone. It is divided into three chambers, two of which, the scala tympani, and scala vestibuli, are filled with perilymph (resembling cerebrospinal fluid and low in potassium chloride and high in sodium chloride), and the scala media, which contains endolymph (high in potassium chloride and low in sodium chloride). The scala media also harbors the cochlear duct, which is home to the organ of Corti with the sensory cells (hair cells) of the cochlea (Figure 1). Its unique structure allows frequency tuning along the cochlear axis – high frequencies are perceived at the base, while low frequencies are detected at the apex [10]. Along the organ of Corti, one row of inner hair cells and three rows of outer hair cells are flanked by nonsensory supporting cells and connect to the peripheral neurites of spiral ganglion neurons (SGNs). The cell bodies of the SGNs are located in Rosenthal’s canal, and their central axons project along the modiolus to the brainstem (Figure 1). Approximately 25 000 to 33 000 SGNs are found in the modiolus and connect with 3 500 inner and 12 000 outer hair cells [11].
Drug delivery in cochlear implantation
Published in Acta Oto-Laryngologica, 2021
Anandhan Dhanasingh, Ingeborg Hochmair
From 2014 on, parallel to the above study, another study was taking place at the Martin Luther University Halle-Wittenberg in Germany, conducted by Dr Liebau and his colleagues, to examine how DEX concentrations in the electrode carrier influence drug levels in the perilymph at different time points [33]. The electrode carrier was loaded homogeneously with 0.1%, 1% and 10% concentrations of DEX and the electrode carriers were implanted into the ST of experimental cochleae (n = 45) via cochleostomy. After implantation, DEX concentrations in perilymph and cochlear tissue were measured at several time points over a period of up to seven weeks. Perilymph samples were taken from ST using the method of apical sampling, and DEX concentration was measured using liquid chromatography-mass spectroscopy. The DEX levels in the perilymph for 1% and 10% loaded rods showed an initial burst followed by stable concentrations during the observed period. A higher variance of DEX concentrations was observed during the burst release than in the steady-state phase (Figure 30).