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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
Electrocochleography: Measures electrical activity from cochlea and CN VIII Gold standard for outer hair cell functionUtilised in endolymphatic hydropsRecording of electrical potentials generated within cochlea and auditory nerve in response to wideband click stimuliProbe on promontry (transtympanic), against tympanic membrane or in canal, click or tone burst stimuli introduced and electrical potentials recordedVariables measured: Cochlear microphonic (CM): AC microphonic potential, seen as cochlea is stimulatedSummation potential (SP): DC potential, current generated in hair cellsCompound action potential (CAP): Averaged activity of action potentials of CN VIII
Common otology viva topics
Published in Joseph Manjaly, Peter Kullar, Advanced ENT Training, 2019
Pure tone audiometry is the most useful diagnostic test. An MRI scan of the head and internal auditory meati (IAM) is standard practice to rule out a lesion of the IAM/CPA or a white matter lesion e.g. MS. Increasingly, MRI with IV gadolinium is being used to look for objective evidence of hydrops. Vestibular assessment including calorics may also be useful to establish the degree of existing peripheral vestibulopathy and help guide further management. Electrocochleography (ECochG) can be performed but is primarily a research tool. A delayed cVEMP response may also be found.
Acute vertigo
Published in S. Musheer Hussain, Paul White, Kim W Ah-See, Patrick Spielmann, Mary-Louise Montague, ENT Head & Neck Emergencies, 2018
Rahul Kanegaonkar, Max Whittaker
Fluctuating but progressive low-frequency sensorineural hearing loss is characteristic of this condition, although all frequencies are eventually affected. As such, serial pure tone audiograms are a useful adjunct in diagnosis, as well as patient monitoring. Caloric testing will reveal a peripheral vestibular deficit as the disease process progresses. Electrocochleography has been used to demonstrate an increase in the ratio between the amplitudes of the summating and action potentials suggestive of Ménière’s disease. An MRI of the internal auditory meati is required to exclude central pathology (e.g. a vestibular schwannoma).
EAS-Combined electric and acoustic stimulation
Published in Acta Oto-Laryngologica, 2021
Anandhan Dhanasingh, Ingeborg Hochmair
To address the above points, we will canvass through a brief history of MED-EL’s electric acoustic stimulation (EAS) journey beginnings in the late ’90s, followed by its early research works that supported the development of the first EAS™ system. This article covers the key clinical studies that evaluated the safety and effectiveness of unified EAS™ audio processors from the first generation until the most recent generation so far, along with patients’ overall hearing performance with the system. This article will also address some EAS-relevant topics, such as the effective hearing preservation (HP) classification system in general, and how it may be mathematically calculated in a uniform manner. The article will walk us through the topic advancements, including identification of patient-specific LF cut-off region, effective preservation of residual hearing, long electrode arrays in EAS, and electrocochleography to monitor inner ear function during the electrode insertion process. Advancements in genetic testing to predict HP results will be discussed, as well as the current EAS indication criteria, and studies that supported MED-EL in obtaining its EAS™ device approval by the notified bodies in the USA, EU and Japan. Also, this article will give a short overview of the annually held Hearing and Structure Preservation (HSP) workshop.
Potential insertion complications with cochlear implant electrodes
Published in Cochlear Implants International, 2020
Akira Ishiyama, Frank Risi, Paul Boyd
Apart from direct visual or imaging confirmation of electrode position, there are also several objective measures that may provide some information relevant to electrode positioning. In particular, there has been considerable recent interest in the potential of electrocochleography (ECoG) recordings using the intracochlear contacts of a CI electrode array as a means of monitoring residual acoustic hearing during insertion of the electrode (Bester et al., 2017; O’Connell et al., 2017b) or predicting electrode location or scalar translocation (Koka et al., 2018). Other evoked response measures, such as neural response telemetry (compound action potential) or electrically evoked auditory brainstem responses, can also confirm proximity to surviving neural elements (Jeong et al., 2015; Telmesani and Said, 2015).
Comparing the sensitivity and specificity of cervical vestibular-evoked myogenic potentials and electrocochleography in the diagnosis of Ménière’s disease
Published in International Journal of Audiology, 2019
Faten Saeed Obeidat, Steven Lewis Bell
Electrocochleography (ECochG) has been widely used as an objective clinical tool for the diagnosis of cochlear hydrops. The ECochG response is composed of three basic potentials: the action potential (AP), the summating potential (SP), and the cochlear microphonic (CM) (Ferraro and Durrant 2006; Wuyts et al. 1997). The AP, which is also referred to as the whole nerve or compound AP, is the summation of the APs of the spiral ganglion and auditory cochlear nerve. The CM is an alternating current voltage, which is generated predominantly by the outer hair cells in the cochlea. The SP is a constant direct current component, which is thought to reflect the displacement of the basilar membrane (BM) toward the scala tympani in response to the asymmetrical vibration of the BM at high intensities (Wuyts et al. 1997). Currently, the CM is thought to be useful in the differential diagnosis of inner ear and auditory nerve diseases. Typically the magnitude of AP is measured relative to that of SP. SP amplitude is thought to increase in ears with hydrops due to the distention of the BM towards the scala tympani. It is thought that elevation of SP amplitude compared with AP amplitude may be a positive indicator of EHs in patients with suspected MD. For details on the history of ECochG, see Eggermont (2017).