Changes of the Action Potential, the Summating Potential and Cochlear Microphonics in Experimental Endolymphatic Hydrops

Kumagami, Hidehaku; Nishida, Hiroaki; Moriuchi, Hiroki

doi:10.1159/000275552

Cited by 35 publications

(15 citation statements)

References 5 publications

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“…Objective assessment of endolymphatic hydrops using electrocochleography was reported in 1977 by Gibson and colleagues, 12 who described an enhanced negative summating potential as indicative of hydrops. This finding was later corroborated in animal studies 13,14 and is a method in wide clinical use today.…”

Section: Introductionmentioning

confidence: 58%

Diagnosis of Patients with Perilymphatic Fistula

Ackley¹,

Ferraro²,

Arenberg³

1994

Semin Hear

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Section: Introductionmentioning

confidence: 58%

Diagnosis of Patients with Perilymphatic Fistula

Ackley¹,

Ferraro²,

Arenberg³

1994

Semin Hear

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“…It is possible that P0 is primarily produced by a combination of CAP response and the DC component of the CM, the summating potential (SP). As mentioned in section 4.3, Flock and Flock (2000) found that static pressure caused a temporary hydrops of SM, and several studies have shown that hydrops of SM can result in increased SP (Kumagami et al, 1981; van Deelen et al, 1987). Salt et al (2009) found that apical injections of viscous HA resulted in increased CM distortion and increased SP, and attributed the observations to a mechanically induced change in transducer operating point.…”

Section: Discussionmentioning

confidence: 85%

Cochlear perfusion with a viscous fluid

Wang

Olson

2016

Hearing Research

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The flow of viscous fluid in the cochlea induces shear forces, which could provide benefit in clinical practice, for example to guide cochlear implant insertion or produce static pressure to the cochlear partition or wall. From a research standpoint, studying the effects of a viscous fluid in the cochlea provides data for better understanding cochlear fluid mechanics. However, cochlear perfusion with a viscous fluid may damage the cochlea. In this work we studied the physiological and anatomical effects of perfusing the cochlea with a viscous fluid. Gerbil cochleae were perfused at a rate of 2.4 μL/min with artificial perilymph (AP) and sodium hyaluronate (Healon, HA) in four different concentrations (0.0625%, 0.125%, 0.25%, 0.5%). The different HA concentrations were applied either sequentially in the same cochlea or individually in different cochleae. The perfusion fluid entered from the round window and was withdrawnfrom basal scala vestibuli, in order to perfuse the entire perilymphatic space. Compound action potentials (CAP) were measured after each perfusion. After perfusion with increasing concentrations of HA in the order of increasing viscosity, the CAP thresholds generally increased. The threshold elevation after AP and 0.0625% HA perfusion was small or almost zero, and the 0.125% HA was a borderline case, while the higher concentrations significantly elevated CAP thresholds. Histology of the cochleae perfused with the 0.0625% HA showed an intact Reissner’s membrane, while in cochleae perfused with 0.125% and 0.25% HA Reissner’s membrane (RM) was torn. Thus, the CAP threshold elevation was likely due to the broken of RM, which likely caused by the shear stress produced by the flow of the viscous fluid. Our results and analysis indicate that the cochlea can sustain, without a significant CAP threshold shift, up to a 1.5 Pa shear stress. Beside these finding, in the 0.125% and 0.25% HA perfusion cases, a temporary CAP threshold shift was observed, perhaps due to the presence and then clearance of viscous fluid within the cochlea, or to a temporary position shift of the Organ of Corti. After 0.5% HA perfusion, a short latency positive peak (P0) appeared in the CAP wavefrom. This P0 might be due to a change in the cochlea’s traveling-wave pattern, or distortion in the cochlear microphonic.

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“…Previously we [Kumagami et al, 1981] reported on AP, CM and SP in relation to the degree of experimental endolymphatic hydrops. In that report, CM responses decreased but AP responses showed relatively good output potential at intensive stimulation as endolymphatic hydrops was intensified.…”

Section: Discussionmentioning

confidence: 99%

Chronological Changes of Electrocochleogram in Experimental Endolymphatic Hydrops

Kumagami¹,

Miyazaki²

1983

ORL

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Chronological changes of the whole nerve action potential (AP), cochlear microphonics (CM) and summating potential (SP) in experimental endolymphatic hydrops in guinea pigs were studied during a period from 1 week to 13 months after the endolymphatic sac obliteration. Endolymphatic hydrops became extensive in month 3 and persisted thereafter. The threshold of AP increased with the lapse of time but good AP output potential was obtained, being maximum in month 3. The threshold of CM increased with the lapse of time. The CM output potential was the highest around week 3 when endolymphatic hydrops was slightly formed, and it decreased thereafter. SP responses at the frequencies of 8, 4, 1 and 0.5 kHz showed the reversed polarity of –SP in month 3 and changed towards potential 0 thereafter. In animals showing super-normal AP output potential, the cilia in the third row of outer hair cells were disarranged. This seems to be involved in recruitment.

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Changes of the Action Potential, the Summating Potential and Cochlear Microphonics in Experimental Endolymphatic Hydrops

Cited by 35 publications

References 5 publications

Diagnosis of Patients with Perilymphatic Fistula

Diagnosis of Patients with Perilymphatic Fistula

Cochlear perfusion with a viscous fluid

Chronological Changes of Electrocochleogram in Experimental Endolymphatic Hydrops

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