Effects of Round Window Opening Size and Moisturized Electrodes on Intracochlear Pressure Related to the Insertion of a Cochlear Implant Electrode

Todt, Ingo; Ernst, Arneborg; Mittmann, Philipp

doi:10.1159/000442515

Cited by 25 publications

(35 citation statements)

References 13 publications

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“…These studies investigated the effects of insertion speed (18), insertion technique (i.e. unsupported, supported, or automated) (19), and size of the opening in the round window (32), each revealing generation of large static pressures (~ 200 Pa, or 140 dB SPL) during the insertion. It is interesting that no transient pressures are reported; however this may be due to the use of a plastic model, compared to cadaveric temporal bones in this study.…”

Section: Discussionmentioning

confidence: 99%

“…A prior study suggested that frictional forces between the electrode and the outer wall was responsible for a large proportion of the force encountered during electrode insertion for straight (but perhaps not pre-curved) electrode arrays; however, no hydraulic forces were observed in this prior study, suggesting this is an unlikely source of these transients (17). Third, variability in the size and shape of the opening made in the RW membrane may affect intracochlear pressures, as a small cochleostomy will resist outflow of cochlear fluid displaced by the electrode array more than a large cochleostomy (32). Furthermore, this impedance would result in a relatively slow build-up followed by a transient release of pressure during insertion, repeated over and over until insertion was complete, thus could generate a train of transient events during insertion.…”

Section: Discussionmentioning

confidence: 99%

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Intracochlear Pressure Transients During Cochlear Implant Electrode Insertion

Greene

Mattingly

Hartl

et al. 2016

Otology &Amp; Neurotology

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Hypothesis Cochlear implant (CI) electrode insertion into the round window induces pressure transients in the cochlear fluid comparable to high intensity sound transients. Background Many patients receiving a CI have some remaining functional hearing at low frequencies, thus devices and surgical techniques have been developed to utilize this residual hearing. To maintain functional acoustic hearing, it is important to retain function of any hair cells and auditory nerve fibers innervating the basilar membrane; however, in a subset of patients, residual low frequency hearing is lost following CI insertion. Here, we test the hypothesis that transient intracochlear pressure spikes are generated during CI electrode insertion, which could cause damage and compromise residual hearing. Methods Human cadaveric temporal bones were prepared with an extended facial recess. Pressures in the scala vestibuli (PSV) and tympani (PST) were measured with fiber-optic pressure sensors inserted into the cochlea near the oval and round windows while CI electrodes (five styles from two manufacturers) were inserted into the cochlea via a round window approach. Results PST tended to be larger in magnitude than PSV, consistent with electrode insertion into the scala tympani. CI electrode insertion produced a range of pressure transients in the cochlea that could occur alone or as part of a train of spikes with equivalent peak sound pressure levels in excess of 170dB SPL. Instances of pressure transients varied with electrode styles. Conclusions Results suggest electrode design, insertion mechanism, and surgical technique affect the magnitude and rate of intracochlear pressure transients during CI electrode insertion. Pressure transients showed intensities similar to those elicited by high level sounds and thus could cause damage to the basilar membrane and/or hair cells.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Intracochlear Pressure Transients During Cochlear Implant Electrode Insertion

Greene

Mattingly

Hartl

et al. 2016

Otology &Amp; Neurotology

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“…Experimentally, it has been shown that different steps during the procedure affect the occurrence of pressure. Preinsertional factors are openings of the round window [3], the size of the round window opening [4], and transfluid opening of the round window [5]. The development of atraumatic opening of the round window has led to the development of specific opening tools [6].…”

Section: Introductionmentioning

confidence: 99%

“…The development of atraumatic opening of the round window has led to the development of specific opening tools [6]. Insertional factors have been observed experimentally under force aspects [7] and even under the point of pressure occurrence in terms of speed [8], moisturized insertions [4], and tremor aspects [9]. Different studies have shown the clinical relevance of these findings [10–12].…”

Section: Introductionmentioning

confidence: 99%

Postinsertional Cable Movements of Cochlear Implant Electrodes and Their Effects on Intracochlear Pressure

Todt

Karimi

Luger

et al. 2016

BioMed Research International

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Introduction. To achieve a functional atraumatic cochlear implantation, intracochlear pressure changes during the procedure should be minimized. Postinsertional cable movements are assumed to induce intracochlear pressure changes. The aim of this study was to observe intracochlear pressure changes due to postinsertional cable movements. Materials and Methods. Intracochlear pressure changes were recorded in a cochlear model with a micro-pressure sensor positioned in the apical region of the cochlea model to follow the maximum amplitude and pressure gain velocity in intracochlear pressure. A temporal bone mastoid cavity was attached to the model to simulate cable positioning. The compared conditions were (1) touching the unsealed electrode, (2) touching the sealed electrode, (3) cable storage with an unfixed cable, and (4) cable storage with a fixed cable. Results. We found statistically significant differences in the occurrence of maximum amplitude and pressure gain velocity in intracochlear pressure changes under the compared conditions. Comparing the cable storage conditions, a cable fixed mode offers significantly lower maximum pressure amplitude and pressure gain velocity than the nonfixed mode. Conclusion. Postinsertional cable movement led to a significant pressure transfer into the cochlea. Before positioning the electrode cable in the mastoid cavity, fixation of the cable is recommended.

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“…Little is known about possible intracochlear alterations and /or intracochlear pressure changes that occur during the pullback. Intracochlear pressure changes should be kept at a very low level before, during, and after the implantation . The cochlea has a dynamic fluid system, and as such, pressure applied to any part of the cochlea or to the electrode array itself is transferred through the cochlear partitions and can possibly interfere with the cellular structures.…”

Section: Introductionmentioning

confidence: 99%

Intracochlear Pressure Changes After Cochlea Implant Electrode Pullback—Reduction of Intracochlear Trauma

Lauer

Uçta

Decker

et al. 2019

Laryngoscope Investig Oto

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Objective Different aspects should be considered to achieve an atraumatic insertion of cochlear implant electrode arrays as an important surgical goal. Intracochlear pressure changes are known to influence the preservation of residual hearing. By using the intraoperative “pullback technique,” an electrode position closer to the modiolus can be achieved than without the pullback. The aim of the present study was therefore to investigate to what extent the pullback technique can influence intracochlear pressure changes. Methods Insertions of cochlear implant electrodes were performed in an artificial cochlear model with two different perimodiolar arrays. Intracochlear pressure changes were recorded with a micro‐optical pressure sensor positioned in the apical part of the cochlear. After complete insertion of the electrode array, a so‐called pullback of the electrode was performed. Results Statistically significant pressure differences were measured if the electrode array was wet (ie, moisturized) during the pullback. Relative pressure changes in electrodes with smaller total volume are lower than pressure changes in larger electrodes. Conclusion The preservation of residual hearing and, thus, the resulting postoperative audiological outcome has a major impact on the quality of life of the patients and has become of utmost importance. Intracochlear pressure changes during the pullback manoeuver are small in absolute terms, but can even be still reduced statistically significantly by a moistening the electrode before insertion. Using the pullback technique in cases with residual hearing does not affect the probability of preservation of residual hearing but could lead to a better audiological outcome. Level of Evidence NA

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Effects of Round Window Opening Size and Moisturized Electrodes on Intracochlear Pressure Related to the Insertion of a Cochlear Implant Electrode

Cited by 25 publications

References 13 publications

Intracochlear Pressure Transients During Cochlear Implant Electrode Insertion

Intracochlear Pressure Transients During Cochlear Implant Electrode Insertion

Postinsertional Cable Movements of Cochlear Implant Electrodes and Their Effects on Intracochlear Pressure

Intracochlear Pressure Changes After Cochlea Implant Electrode Pullback—Reduction of Intracochlear Trauma

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