Name: electrically evoked stapedius reflex measurements in cochlear implantation and its application in the postoperative fitting process
Uploaded: 2024-06-21T13:40:00.000+00:00
Duration: 7 min
Description: Measuring the electrically evoked stapedius reflex during the fitting of cochlear implants (CIs) provides a reliable estimation of maximum comfort levels, ...

The authors thank the cochlear implant team for pediatric patients and the team of pediatric speech therapists of our department for their support in realizing this work.

The procedure was approved for use in clinical routine in our department. All patients included in the report gave written consent regarding use of data and video production.
1. Intraoperative measurements of the electrically evoked stapedius reflex
NOTE: The measurement of the eSR during cochlear implantation is performed immediately after insertion of the electrode array into the cochlea. After this critical step, stimulation of the auditory nerve is possible as well as checks of the functioning of all internal CI components.
<ol>
	<li>Initial preparation
	<ol>
		<li>Ensure that the surgical drapes are not too thick at the site of the implant coil, which could cause weak coupling of the test coil to the implant.</li>
		<li>Ensure an adequate anesthesia protocol enabling muscle contraction during the time of eSR measurement. Pay special attention to ensure that no drug-induced relaxation is effective at the time of measurement.</li>
		<li>Check patient data, add it to the software of the CI manufacturer (see Table of Materials), and perform in-package tests on the implant as suggested by the manufacturer.</li>
		<li>Check the parameter setting for intraoperative eSR measurements in the software. Set the single burst duration to 500 ms and the minimum pulse width to 30-40 &#181;s. Check the guidelines of the CI manufacturer for the maximum allowed intraoperative stimulation levels.</li>
	</ol>
	</li>
	<li>Measurement preparation
	<ol>
		<li>After insertion of the CI electrode array into the cochlea, place the measurement coil of the CI manufacturer in a sterile packaging provided by the surgical assistant.</li>
		<li>Check the coupling between the measurement coil and the implant using the coupling tool of the software, while the surgeon places the measurement coil on the patient&#39;s skin over the implant housing where the receiver coil is located.</li>
		<li>Perform a telemetric electrical impedance measurement by clicking on the program tab &#39;IFT&#39; of the software to verify the proper functioning of the implant and to measure the electrical impedances of all CI electrodes.</li>
		<li>In case of high impedances on many electrodes, check the CI ground electrode for skin contact and repeat the telemetry test.</li>
		<li>Make sure that the speaker of the facial nerve monitoring system is on. This provides the surgeon with acoustic feedback of the electrical stimulation.</li>
	</ol>
	</li>
	<li>Intraoperative eSR detection
	<ol>
		<li>Start the eSRT program by clicking on the program tab &#39;ESRT&#39; in the software.</li>
		<li>Select an electrode with regular electrical impedance in the ESRT program and start stimulation with moderate stimulation values (10 charge units) while the surgeon observes the stapes tendon under the operating microscope.</li>
		<li>Deliver single stimuli with a burst duration of approximately 500 ms (pulse duration of 30-40 &#181;s) and watch if any movement of the stapedial tendon is observed.</li>
		<li>In case no movement is detected, increase the stimulation intensity by 15% and repeat the stimulation.</li>
		<li>Stop increasing stimulation as soon as movement of the stapedial tendon is visible under the microscope or the maximum-allowed stimulation intensity (according to the manual) is reached.</li>
		<li>Repeat steps 1.3.2-1.3.5 for all electrodes with regular electrical impedance. 
		NOTE: For electrodes with high impedance, the effective current flow may be too small to elicit the eSR. Therefore, no eSR measurement is performed on these electrodes. In many cases, high electrode impedances decrease within the first 10 min after implantation, during eSR measurements. Telemetry measurement can be carried out again to check whether eSR detection is also possible on these electrodes.</li>
	</ol>
	</li>
	<li>Interpretation of results
	<ol>
		<li>Look for the eSR: if detected, it is proven that the CI electrode array is positioned in the cochlea and electrical stimulation is processed along the auditory pathway up to the brainstem.</li>
		<li>In case eSR detection fails, the correct placement of the CI electrode array has not been verified. Verify the correct placement by intraoperative imaging or through electrical auditory brainstem response (eABR) measurements, the latter also demonstrating the processing of the electrical stimulation up to the brainstem.</li>
	</ol>
	</li>
</ol>
2. Postoperative determination of the electrically evoked stapedius reflex threshold levels
<ol>
	<li>Pre-planning of eSRT testing
	<ol>
		<li>Perform the eSR measurement only in patients who are accustomed to electrical stimulation, at least 3-4 weeks after the activation of the CI and daily use since then.</li>
		<li>Review patient records for the middle ear status of both ears and surgical details of CI implantation. Exclude patients without an intact ossicular chain in both middle ears from postoperative eSRT testing.</li>
		<li>Discuss the procedure with the patients and, in the case of children, with their parents or accompanying persons. Plan the measurement according to the patient&#39;s needs and in a comfortable setting. Decide how to carry out the eSRT measurement: during natural sleep (for young children) or while awake. If possible, schedule measurements in very young children during nap time. 
		NOTE: The acoustic impedance measurement, which is performed simultaneously with the electrical stimulation, is sensitive to distortions. Therefore, the patient must stay&#160;calm during the entire procedure for about 10-30 min.</li>
	</ol>
	</li>
	<li>Medical examinations before performing eSRT testing
	<ol>
		<li>Arrange for a medical examination of both ears by an ENT specialist for the assessment of the ear status.</li>
		<li>Perform tympanometry to verify a normal middle ear status with a regular compliance maximum at ambient (zero) pressure (type A tympanogram). 
		NOTE: Negative pressure in the tympanic cavity (type C tympanogram) can strongly influence the detection accuracy of the eSRT. This condition often occurs in children due to a dysfunction of the Eustachian tube and a retracted eardrum. In some cases, this can be treated by the use of decongestant nasal drops. No detection of eSRT is possible with a flat type B tympanogram.</li>
		<li>Determine if and on which ear eSRT measurements are feasible according to ear status (step 2.1.2) and select the ear with better compliance in tympanometry (step 2.2.2) for ESR detection.</li>
	</ol>
	</li>
	<li>Preparation of the patient
	<ol>
		<li>Check the integrity of the patient&#39;s audio processor (e.g., loose contacts, mechanical damage, or dirty microphone openings) to avoid technical problems that prevent reliable stimulation of the cochlear implant, and therefore, accurate measurement of eSRT.</li>
		<li>Perform telemetric electrical impedance measurements of CI electrodes (see step 1.2.3) using equipment and software (program tab IFT) provided by the implant manufacturer. Open and check the last individual CI programming used by the patient in the CI fitting software.</li>
		<li>Wait until the patient has fallen asleep or ensure a comfortable sitting position for measurements taken while awake. With older children, make sure that their feet are comfortably rested (e.g.&#160;using an adjustable chair) and that they are distracted during the measurement (e.g., by reading a book or watching a video [preferably without sound]).</li>
		<li>Place the audio processor and its coil in the proper position and check coupling with the patient&#39;s implant.</li>
		<li>Select the most suitable ear according to ear status and tympanometry (step 2.2.3). Place the ear probe of the acoustic impedance meter in the ear canal of the patient using a single-use ear tip. Ensure a proper fit of the probe.</li>
		<li>Fasten the probe cable to reduce acoustic interference: for measurements while awake fix the cable preferably to the patient&#39;s head (e.g., to a headband with two cable clips). This allows the probe cable to follow the movements of the head (Figure 1). 
		NOTE: In the present case, a digital version of an impedance meter based on the works of Stephan8 was used, which was equipped with a standardized ear probe. In general, any impedance meter can be used providing it accepts a trigger input of the implant interface box upon initiating an electrical stimulation burst. In contrast to using the reflex decay mode of a clinical impedance meter to register the electrical stapedius reflex, the visibility of the stapedius reflex is greatly enhanced if the impedance measurement is synchronized to the onset of electrical stimulation.</li>
		<li>Start the software for CI fitting in normal fitting mode as during a standard subjective fitting session. Load the programming of the CI currently in use by the patient.</li>
		<li>Check the setting of the stimulation parameters. Use electrical stimulation bursts of at least 300 - 500&#160;ms duration, followed by a pause of 700 ms. 
		NOTE: The duration of the stimulation burst affects eSRT9.</li>
	</ol>
	</li>
	<li>Procedure for obtaining electrical stapedius reflex thresholds 
	NOTE: Always observe the patient during stimulation to avoid overstimulation or discomfort. The measurement of eSRT levels in infants or multiply handicapped persons should preferably be performed by an audiologist together with a speech therapist who is familiar with behavioral audiometry. The speech therapist is in charge of observing the patient throughout the fitting session and can provide immediate feedback if non-auditory side effects such as facial movements or eye blinking etc. occur. In older children fitting with eSRT can be performed by one CI expert, while for young children, support from a speech therapist is definitely recommended.
	<ol>
		<li>Select an electrode for stimulation in the middle of the electrode array and start stimulation at a moderate loudness level. If an eSR is detected by a change in acoustic impedance in response to the stimulation, reduce the stimulation level.</li>
		<li>Gradually increase the stimulation level in 3% steps of the actual stimulation charge until a change is detected in acoustic impedance. Carefully observe the patient to avoid uncomfortable loudness. 
		NOTE: With higher stimulation charges, the pulse width may be increased, which enhances the probability of triggering the electrical stapedius reflex. Set the pulse duration to a high enough value to prevent this. In a repetitive procedure (i.e., a sweep of stimulation along the electrode array), the electrical stapedius reflex will trigger at slightly lower stimulation levels than through single-channel stimulation with a longer pause in between.</li>
		<li>Carry out the stimulation in phases in which distortions caused by breathing noises, swallowing, and patient movements are minimal. 
		NOTE: The heart rate of a patient may be visible as an artificial change of the acoustic impedance, which can be misinterpreted as a stapedius reflex.</li>
		<li>As soon as the eSR is observed for the first time, increase the stimulation intensity by a further 3% step and then reduce it repeatedly until the eSR is no longer detected. An example of such a stimulation sequence and the recorded acoustic impedance changes interpreted as eSR is shown in Figure 2. 
		NOTE: The morphology of the acoustic impedance change caused by the stapedius reflex may significantly differ in patients with CI compared to normal hearing listeners. Both an increase or a decrease of the acoustic impedance may be observed, as well as a positive deflection of the impedance response followed by a drop to negative impedance values. The morphology itself has no effect on the estimation of the eSRT levels, but it should be verified that the impedance change occurs&#160;strictly correlated with the stimulation.</li>
		<li>Note the lowest stimulation levels in the increasing sequence as well as in the decreasing sequence that cause triggering of the eSR. Repeat this procedure of crossing the eSRT 3x to prove the repeatability of reflex triggering. The median value of the levels noted is defined as eSRT. 
		NOTE: When using this up-down stimulation sequence, the values of eSRT in the ascending sequence may differ slightly from those in the descending sequence as activation of eSR will be influenced by both adaptation as well as facilitation effects of the auditory nerve. Therefore, the repetitive measurement of eSRT is recommended to avoid stimulation bias.</li>
		<li>Repeat steps 2.4.1-2.4.5 for all electrodes of the CI.</li>
	</ol>
	</li>
	<li>Activating the audio processor
	<ol>
		<li>Use the eSRT levels of each electrode determined in step 2.4 to set the maximum comfort levels of the CI programming.</li>
		<li>Compare the eSRT-based comfort levels of the new CI programming with those used in the previous programming and determine the maximum relative change in stimulation values.</li>
		<li>In case of a large increase in stimulation levels, carefully activate the audio processor in microphone mode at a low volume setting according to the relative change, and gradually increase the volume up to a comfortable loudness. In case of a large decrease in these values, if some patients perceive the new programming as too soft immediately after activation, advise those patients to test the new programming at least for 1 day, as patients often become accustomed to the lower stimulation levels without any reduction in word recognition performance despite softer stimulation.</li>
		<li>Store multiple CI programmings with increasing volume on the audio processor. Start with programming with stimulation values to which the patient has already become accustomed and instruct the patient to switch to programming with slightly higher volume after an acclimation phase of 5-7 days as long as the auditory perceptions are not uncomfortable. 
		NOTE: This procedure is mainly used in young children in the initial phase of eSRT fitting to avoid the refusal of the audio processor.</li>
	</ol>
	</li>
</ol>
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/66526/66526fig01.jpg" /> 
Figure 1: A possible fixation option for ipsilateral positioning of the ear probe and the audio processor using a headband. The advantage of this positioning is that the probe follows head movements, which generates less distortion during the eSRT measurement than a fixation of the probe on the patient&#39;s shoulder. Abbreviations: eSR = electrically evoked stapedius reflex; eSRT = eSR thresholds. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/66526/66526fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/66526/66526fig02.jpg" /> 
Figure 2: Compliance change due to ESR in a stimulation sequence using the up-down stimulation procedure (bottom to top starting at low stimulation levels q0). Increasing stimulation levels q0 to q3, decreasing stimulation levels q3 to q0. Single traces correspond to impedance changes observed due to triggering the eSR. Stimuli used: bursts of 300 ms, stimulation starts at time = 0. Abbreviation: eSR = electrically evoked stapedius reflex. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/66526/66526fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Measuring Electrically Evoked Stapedius Reflex for Cochlear Implant Fitting

<ol>
	<li>Kosaner, J., Anderson, I., Turan, Z., Deibl, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+use+of+ESRT+in+fitting+children+with+cochlear+implants.">The use of ESRT in fitting children with cochlear implants.</a> J. Int Adv Otol. 5 (1), 62-71 (2009).</li><li>Gordon, K. A., Papsin, B. C., Harrison, R. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Toward+a+battery+of+behavioral+and+objective+measures+to+achieve+optimal+cochlear+implant+stimulation+levels+in+children.">Toward a battery of behavioral and objective measures to achieve optimal cochlear implant stimulation levels in children.</a> Ear hear. 25 (5), 447-463 (2004).</li><li>Stephan, K., Welzl-M&#252;ller, K., Stiglbrunner, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stapedius+reflex+threshold+in+cochlear+implant+patients.">Stapedius reflex threshold in cochlear implant patients.</a> Audiology. 27 (4), 227-233 (1988).</li><li>Stephan, K., Welzl-M&#252;ller, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Post-operative+stapedius+reflex+tests+with+simultaneous+loudness+scaling+in+patients+supplied+with+cochlear+implants.">Post-operative stapedius reflex tests with simultaneous loudness scaling in patients supplied with cochlear implants.</a> Audiology. 39 (1), 13-18 (2000).</li><li>Allum, J. H., Greisiger, R., Probst, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Relationship+of+intraoperative+electrically+evoked+stapedius+reflex+thresholds+to+maximum+comfortable+loudness+levels+of+children+with+cochlear+implants.">Relationship of intraoperative electrically evoked stapedius reflex thresholds to maximum comfortable loudness levels of children with cochlear implants.</a> Int. J. Audiol. 41 (2), 93-99 (2002).</li><li>Kosaner, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Generating+speech+processor+programmes+for+children+using+ESRT+measurements.">Generating speech processor programmes for children using ESRT measurements.</a> CI International. 11, 20-24 (2010).</li><li>Walkowiak, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Evoked+stapedius+reflex+and+compound+action+potential+thresholds+versus+most+comfortable+loudness+level:+assessment+of+their+relation+for+charge-based+fitting+strategies+in+implant+users.">Evoked stapedius reflex and compound action potential thresholds versus most comfortable loudness level: assessment of their relation for charge-based fitting strategies in implant users.</a> ORL J Otorhinolaryngol Relat Spec. 73 (4), 189-195 (2011).</li><li>Stephan, K., Welzl-M&#252;ller, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+stimulus+duration+on+stapedius+reflex+threshold+in+electrical+stimulation+via+cochlear+implant.">Effect of stimulus duration on stapedius reflex threshold in electrical stimulation via cochlear implant.</a> Audiology. 33 (3), 143-151 (1994).</li><li>Stephan, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+fast+response+impedance+meter+for+acoustic+reflex+measurements.">A fast response impedance meter for acoustic reflex measurements.</a> IEEE Trans. Biomed. Eng. 41, 391-393 (1994).</li><li>Litovsky, R. Y., Gordon, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bilateral+cochlear+implants+in+children:+Effects+of+auditory+experience+and+deprivation+on+auditory+perception.">Bilateral cochlear implants in children: Effects of auditory experience and deprivation on auditory perception.</a> Hear. Res. 338, 76-87 (2016).</li><li>Franke-Trieger, A., Mattheus, W., Seebacher, J., Zahnert, T., Neudert, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stapedius+reflex+evoked+in+free+sound+field+in+cochlear+implant+users+compared+to+normal-hearing+listeners.">Stapedius reflex evoked in free sound field in cochlear implant users compared to normal-hearing listeners.</a> Int. J. Audiol. 60 (9), 695-703 (2021).</li><li>Franke-Trieger, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Stapedius+reflex+thresholds+obtained+in+a+free+sound+field+as+an+indicator+for+over-+and+understimulation+in+cochlear+implant+listeners.">Stapedius reflex thresholds obtained in a free sound field as an indicator for over- and understimulation in cochlear implant listeners.</a> Int. J. Audiol. , 1-8 (2023).</li><li>Crawford, M. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Dose-dependent+suppression+of+the+electrically+elicited+stapedius+reflex+by+general+anesthetics+in+children+undergoing+cochlear+implant+surgery.">Dose-dependent suppression of the electrically elicited stapedius reflex by general anesthetics in children undergoing cochlear implant surgery.</a> Anesth Analg. 108 (5), 1480-1487 (2009).</li></ol>

The authors declare no conflict of interest. No funding in financial or any other form was received for the present work. The authors Josef Seebacher, Kurt Stephan, and Joachim Schmutzhard are members of the HEARRING group.

The eSR measurement in hearing rehabilitation with CIs has two applications: first, to verify the coupling of stimulation electrodes to the auditory nerve during implantation, and second, to estimate upper stimulation levels in the postoperative programming of the audio processor.
Intraoperative measurements have the purpose of detecting the eSR as an indicator for a neural response and the processing of the electrical stimulation up to the brainstem. The contraction of the stapes tendon in response to electrical stimulation is observed visually, which requires a good view of the stapes and normal anatomical structures.
These values cannot be used for adjusting the stimulation parameters of the implant in the postoperative fitting due to the low correlation of intraoperative eSRT with postoperative loudness perception5. Intraoperative eSR measurements may further be influenced by general anesthesia13&#160;as well as other physiological parameters (e.g., bleeding, malformation, or scar tissue).
For the detection of the eSR, an acoustic impedance measurement device is used to continuously monitor the change in acoustic impedance of the ear during electrical stimulation. To allow easy and reliable detection of the eSR, the impedance measurement should have a trigger function that is activated when the stimulus is delivered via the CI. This allows synchronous recording of eSR in response to the electrical stimulus. Alternatively, the impedance meter can be operated in continuous mode, but this appears less suitable and convenient for the application of the method. The impedance meter and the associated ear probe are typically calibrated according to audiometric standards, with the probe tone frequency of 226 Hz and sound level of 85 dB SPL.&#160;Alternatively higher frequencies can be used as probe tones as well.
The first postoperative eSRT measurement is preferentially performed 1 month after the activation of the CI. The activation session is usually scheduled 4 weeks after cochlear implantation, whereby the primary focus of the CI fitting is to make the patient accustomed to electrical stimulation at moderate stimulation levels and to motivate the patient to accept wearing the audio processor for a whole day of listening. In the next update session, which is normally scheduled 7-10 days later, the stimulation is further increased but not up to maximum comfort levels. From the third fitting session onward, the eSRT method is applicable. The perceived loudness at the eSRT is described as loud or very loud by most patients. Hence, stimulation at uncomfortable loudness levels must be avoided. Therefore, the patient needs to be carefully observed during the eSRT measurement, as eSRT may eventually be elicited but not detected. If no eSRT can be detected in both ears, the measurement must be aborted.
The method of eSRT-based programming of CIs is applicable in children as well as in adults. However, since children are typically unable to give feedback on the sound of electrical stimulation through the CI, the objective eSRT method is preferred to psychoacoustic methods, which rely on subjective feedback from the patient. It is well established by several authors that eSRT is a good estimator for comfort levels needed for programming the audio processor. This channel-specific profile created by the eSRT measurement is unique in each patient and may change over time of implant use. Therefore, the fitting of the CI must be updated at regular intervals.
The eSRT method for fitting CI certainly has one important limitation, which is the requirement of an intact middle ear. Surgical details particularly about the ossicles must be retrieved from the patient&#39;s records. Thus, postoperative eSRT measurements require preservation of the middle ear structures during surgery. In particular, during complex surgeries in case of middle ear malformations or other middle ear pathologies, the ossicular chain could be damaged. In this case, no postoperative eSRT measurement is possible on the operated ear. However, as an alternative, the ear probe can be placed on the contralateral ear and the eSRT measurement performed. In contrast to its detection, the threshold itself at which the stapedius reflex is elicited by electric stimulation does not depend significantly on the ear on which the acoustic impedance measurement is performed.
Typically, the impedance probe is placed ipsilaterally, with stimulation via the CI and reflex detection taking place in the same ear. On the ipsilateral side, the majority of the patients with CIs do not have acoustic hearing, so the probe tone of 226 Hz presented at a sound level of 85 dB SPL is not perceived. As the eSRT measurement on all channels of the CI can take a while, it is more comfortable not to hear the probe tone during the fitting procedure. If patients have acoustic hearing in the contralateral ear, the measurement may be somewhat inconvenient due to the increased listening effort during the presentation of the probe tone.
Prior to any eSRT measurement session, the current middle ear status must be checked. One limitation of eSRT-based CI fitting in children is the frequent occurrence of negative pressure in the tympanic cavity due to tube ventilation dysfunction. In this case, the acoustic impedance measurement for eSR detection is more complex. In these children, the application of nasal drops is often sufficient to relieve the pressure in the tympanic cavity to a sufficient degree that enables a successful impedance measurement in CI fitting.
The measurement of eSRT levels on all electrodes of a CI may take a while. With the equipment used in this work, a complete measurement series on 12 electrodes takes&#160;approximately 10-30 min. During this time, the acoustic impedance measurement must be stable. To ensure this condition for the entire duration of the measurement, proper positioning of the ear probe and passive cooperation by the patient are crucial.
The acoustic impedance measurement may continuously be influenced by noise from breathing and must be carefully observed as this effect may cause artifacts in ESR traces. The electrical stimulation bursts for eliciting the stapedius reflex should be initiated during phases where such distortions are small. Furthermore, the heart rate of a patient may cause a periodic change of the acoustic impedance, which can potentially be misinterpreted as a stapedius reflex.
The protocol described has been used successfully in numerous CI fitting sessions in our department and should encourage other colleagues to consider CI fitting based on eSRT in children and in multiply handicapped patients who cannot give reliable feedback on auditory perception.

Electrically evoked stapedius reflex (eSRT) measurements are a known tool for verifying the coupling between a cochlear implant (CI) and the auditory nerve during surgery and postoperatively for adjusting the stimulation levels of CI programming. Whereas intraoperative measurements of the electrically evoked stapedius reflex (eSR) are quite common in clinical routine, postoperative measurements of the eSRT are still scarcely used in CI fitting because of the additional need for an acoustic impedance measurement device. However, the performance in speech perception of patients fitted with the eSRT method appears to be as good as with the method of loudness scaling1 In the latter procedure, the lower and upper limits of electrical stimulation with a CI are estimated by subjective scaling of the perceived loudness in response to stimulation on each single channel of the CI. Subjective loudness scaling requires the cooperation of the patients, who need to give feedback on their perception of electrical stimulation. Particularly young children, who today can be supplied with a CI at the age of less than one year, are not able to provide feedback on electrical stimulation. In this case, the objective eSR method is superior, and corresponding CI fitting in children allows for proper speech acquisition and cognitive development of the child at an early stage2.
The eSR method dates to the pioneering works of Stephan et al.3 who found a relation between the subjective loudness perception and the stapedius reflex threshold elicited through electrical stimulation. In these studies, a procedure was invented to measure the stapedius reflex in response to electrical stimulation in the ear canal using an acoustic impedance meter4. The correlation between the eSRT and subjective loudness ratings found originally by Stephan et al. was confirmed by other studies over the years2,4,5,6,7. Overall, programming of CIs based on eSRT results in good speech recognition scores in most patients supplied with CIs. 
Today, the measurement of the eSR is a reliable tool to verify the coupling of a CI to the auditory nerve during surgery as well as a reliable estimator for upper stimulation levels in the postoperative fitting process of CIs. This paper presents both: first, a description of the eSR method during surgery for intraoperative verification that stimulation of the auditory nerve via CI is possible and processed up to the brainstem, and second, the application of the eSRT method for fitting of CIs in children and adults.
For the postoperative application of eSR testing, an acoustic impedance meter triggered by the programming interface of the CI is used to measure the eSRT during the fitting session. The entire process of CI fitting in clinical routine using the eSRT method is described. Issues to be considered such as distortions due to breathing noises or artifacts due to patient movements, which may result in distortions of the impedance measurement, are discussed. The protocol described is particularly suitable for CI fitting in children and in multiply handicapped patients.

<table><tbody><tr><td>Audiointerface</td><td>any&amp;nbsp;</td><td></td><td>Audiointerface with Stereo Line Input is required to Record Acoustic Signal in the Ear Canal for Deriving the Ear Drum Impedance Pattern</td></tr><tr><td>Cable Clips</td><td>any&amp;nbsp;</td><td></td><td>Cable Clips for fixation of the Probe Cable at the Head Band</td></tr><tr><td>Desktop Computer or Notebook</td><td>any&amp;nbsp;</td><td></td><td>Required for Cochlear Implant Programming Software</td></tr><tr><td>Ear Probe</td><td>Bio-Logic</td><td></td><td>Ear Probe for Presenting and Recording Acoustic Signals in the Ear Canal</td></tr><tr><td>Head Band</td><td>any&amp;nbsp;</td><td></td><td>Head Band for fixation of the Ear Probe</td></tr><tr><td>Maestro Software</td><td>Med-El</td><td></td><td>Programming Software for Med-El Cochlear Implants</td></tr><tr><td>MAX Coil</td><td>Med-El</td><td></td><td>Cable connecting Interfacebox and Cochlear Implant via Transcutaneous Inductive Coupling for Telemetry Measurement</td></tr><tr><td>MAX Interface Box</td><td>Med-El</td><td></td><td>Interfacebox to access Cochlear Implant during the Fitting Session</td></tr><tr><td>MAX Programming Cable</td><td>Med-El</td><td></td><td>Cable connecting Interfacebox and Audioprocessor for Adjusting Electrical Stimulation Levels</td></tr><tr><td>Single use Ear Tips</td><td>Sanibel Supply</td><td></td><td>Ear Tips for Ear Probe, Size depending on the Patients Ear</td></tr><tr><td>Sonnet 2 Audioprocessor</td><td>Med-El</td><td></td><td>External Part of the Implant System. Has to be worn by the Patient to Perceive Auditory Sensations</td></tr></tbody></table>

electrically evoked stapedius reflex measurements in cochlear implantation and its application in the postoperative fitting process

Measuring the electrically evoked stapedius reflex during the fitting of cochlear implants (CIs) provides a reliable estimation of maximum comfort levels, resulting in the programming of the CI with high hearing comfort and good speech understanding. Detection of the stapedius reflex and the required stimulation level on each implant channel is already being performed during surgery, whereby intraoperative stapedius reflexes are observed through the surgical microscope. Intraoperative stapedius reflex detection is both an indicator that the auditory nerve is responding to electrical stimulation up to the brainstem and a test for the ability to perform postoperative stapedius reflex measurements. Postoperative stapedius reflex thresholds can be used to estimate upper stimulation levels in the CI fitting process. In particular, in children or patients unable to provide feedback on loudness perception, this method avoids inadequate stimulation with the CI, which can result in poor hearing performance. In addition, overstimulation can be avoided, which could even lead to refusal to use the device.

Generally, the spontaneous acceptance of an eSRT-based fitting is high. In terms of audiological performance, patients with programming based on eSRT do not show significant differences in aided thresholds or word recognition scores compared to experienced patients with programming based on subjective loudness scaling3. However, such results can only be expected when reliable loudness scaling is possible.
In particular, bilateral cochlear implant users appear to benefit from eSRT-based programming. These patients often achieve similar aided hearing thresholds on both ears, as shown in Figure 3. The latter indicates that symmetry in hearing is high when using the eSRT method for fitting both implants.
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/66526/66526fig03.jpg" /> 
Figure 3: Case example of a bilaterally implanted patient. Upper panel: Programmed stimulation levels for the left and right cochlear implants based on the eSRT method. Zero charge indicates inactive electrodes, which are typically deactivated in case of non-auditory side effects or no auditory perceptions on particular electrodes. Lower panel: corresponding aided hearing thresholds in both ears. NOTE: While comfort levels based on eSRT are significantly different in both ears in this patient, the associated aided hearing thresholds show a high degree of symmetry. Abbreviations: eSR = electrically evoked stapedius reflex; eSRT = eSR thresholds. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/66526/66526fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Patients supplied with CIs bilaterally, which were programmed using channel-specific eSRT values as comfort levels, often show scores significantly better than chance levels in binaural listening tests. In particular, children who have grown up with bilateral CIs and have acquired speech by CI reach high scores in speech in noise as well as in sound localization tests10. One requirement for good sound localization is a balanced loudness perception with the CIs, particularly in bilateral users. This criterion seems to be a priori met in bilateral CI users with CI programs based on eSRT. In the case example in Figure 3, the aided hearing thresholds on the left and right sides are almost symmetrical whereas the eSRT-based stimulation levels show a large asymmetry between left and right ears. Regarding sound localization, such patients do not show a bias in their sound localization results. An example of such a patient is shown in Figure 4, who was tested using a clinical sound localization setup consisting of five loudspeakers in the frontal hemisphere.
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/66526/66526fig04.jpg" /> 
Figure 4: Angle-dependent percentages of correct scores of sound localization in a young adult bilateral patient with CI. CI programming was performed from childhood using the eSRT method. Abbreviations: eSR = electrically evoked stapedius reflex; eSRT = eSR thresholds. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/66526/66526fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
Apart from the high percentage of correct localizations of broadband acoustic stimuli 90% or more at angles of 0&#176; and &#177;45&#176; the symmetry was almost perfect, indicating that this patient showed no bias in the sound localization results. Therefore, loudness perception in this patient was well&#160;balanced between the left and the right CIs.
When CIs are programmed using the eSRT method, the behavior of the stapedius reflex mechanism appears to be similar to that of normal hearing listeners. In a recent study by Franke-Trieger et al.11, the stapedius reflex behavior was investigated in a free sound field. Thereby, the stapedius reflex was measured in patients with CIs who were presented with acoustic stimuli at higher sound levels via loudspeakers. In patients who were using CI programming based on the eSRT method, the sound levels at which the stapedius reflex was triggered were similar to those of normal hearing listeners11,12.

Electrically Evoked Stapedius Reflex Measurements in Cochlear Implantation and Its Application in the Postoperative Fitting Process

The present protocol describes the measurement of the electrically evoked stapedius reflex (eSR) via cochlear implant (CI). Two applications are discussed: intraoperative detection of eSR for verification of the coupling between the cochlear implant and the auditory nerve and postoperative measurement of eSR thresholds (eSRT) for CI fitting.

Measuring the electrically evoked stapedius reflex during the fitting of cochlear implants (CIs) provides a reliable estimation of maximum comfort levels, ...

electrically-evoked-stapedius-reflex-measurements-cochlear

Nanyang Technological University

Research

JoVE Journal

Medicine

623 Views.  Tirol-Kliniken GmbH. We zijn geïnteresseerd in het verbeteren van de hoorprestaties van cochleaire implantaten door het optimaliseren van aanpasprocedures en ook door middel van geavanceerde spraakcoderingsstrategieën. En een van de specifieke aandachtspunten van ons onderzoek is het ontwikkelen van objectieve methoden voor het aanmeten van zeer jonge kinderen in de leeftijd van één tot 10 jaar, en ook voor patiënten die niet in staat zijn om feedback te geven over elektrisc...

Video: Elektrisch opgewekte Stapedius-reflexmetingen bij cochleaire implantatie en de toepassing ervan in het postoperatieve aanpasproces

A Strategy to Identify de Novo Mutations in Common Disorders such as Autism and Schizophrenia

There are several lines of evidence supporting the role of de novo mutations as a mechanism for common disorders, such as autism and schizophrenia. First, the de novo mutation rate in humans is relatively high, so new mutations are generated at a high frequency in the population. However, de novo mutations have not been reported in most common diseases. Mutations in genes leading to severe diseases where there is a strong negative selection against the phenotype, such as lethality in embryonic stages or reduced reproductive fitness, will not be transmitted to multiple family members, and therefore will not be detected by linkage gene mapping or association studies. The observation of very high concordance in monozygotic twins and very low concordance in dizygotic twins also strongly supports the hypothesis that a significant fraction of cases may result from new mutations. Such is the case for diseases such as autism and schizophrenia. Second, despite reduced reproductive fitness1 and extremely variable environmental factors, the incidence of some diseases is maintained worldwide at a relatively high and constant rate. This is the case for autism and schizophrenia, with an incidence of approximately 1% worldwide. Mutational load can be thought of as a balance between selection for or against a deleterious mutation and its production by de novo mutation. Lower rates of reproduction constitute a negative selection factor that should reduce the number of mutant alleles in the population, ultimately leading to decreased disease prevalence. These selective pressures tend to be of different intensity in different environments. Nonetheless, these severe mental disorders have been maintained at a constant relatively high prevalence in the worldwide population across a wide range of cultures and countries despite a strong negative selection against them2. This is not what one would predict in diseases with reduced reproductive fitness, unless there was a high new mutation rate. Finally, the effects of paternal age: there is a significantly increased risk of the disease with increasing paternal age, which could result from the age related increase in paternal de novo mutations. This is the case for autism and schizophrenia3. The male-to-female ratio of mutation rate is estimated at about 4&#x2013;6:1, presumably due to a higher number of germ-cell divisions with age in males. Therefore, one would predict that de novo mutations would more frequently come from males, particularly older males4. A high rate of new mutations may in part explain why genetic studies have so far failed to identify many genes predisposing to complexes diseases genes, such as autism and schizophrenia, and why diseases have been identified for a mere 3% of genes in the human genome. Identification for de novo mutations as a cause of a disease requires a targeted molecular approach, which includes studying parents and affected subjects. The process for determining if the genetic basis of a disease may result in part from de novo mutations and the molecular approach to establish this link will be illustrated, using autism and schizophrenia as examples.

Molecular genetic strategy for finding de novo mutations causing common disorders such as autism and schizophrenia.

There are several lines of evidence supporting the role of de novo mutations as a mechanism for common disorders, such as autism and schizophrenia. First, ...

Multi-electrode Array Recordings of Human Epileptic Postoperative Cortical Tissue

Epilepsy, affecting about 1% of the population, comprises a group of neurological disorders characterized by the periodic occurrence of seizures, which disrupt normal brain function. Despite treatment with currently available antiepileptic drugs targeting neuronal functions, one third of patients with epilepsy are pharmacoresistant. In this condition, surgical resection of the brain area generating seizures remains the only alternative treatment. Studying human epileptic tissues has contributed to understand new epileptogenic mechanisms during the last 10 years. Indeed, these tissues generate spontaneous interictal epileptic discharges as well as pharmacologically-induced ictal events which can be recorded with classical electrophysiology techniques. Remarkably, multi-electrode arrays (MEAs), which are microfabricated devices embedding an array of spatially arranged microelectrodes, provide the unique opportunity to simultaneously stimulate and record field potentials, as well as action potentials of multiple neurons from different areas of the tissue. Thus MEAs recordings offer an excellent approach to study the spatio-temporal patterns of spontaneous interictal and evoked seizure-like events and the mechanisms underlying seizure onset and propagation. Here we describe how to prepare human cortical slices from surgically resected tissue and to record with MEAs interictal and ictal-like events ex vivo.

We here describe how to perform multi-electrode array recordings of human epileptic cortical tissue. Epileptic tissue resection, slice preparation and multi-electrode array recordings of interictal and ictal events are demonstrated in detail.

Epilepsy, affecting about 1% of the population, comprises a group of neurological disorders characterized by the periodic occurrence of seizures, which ...

Neonatal Murine Cochlear Explant Technique as an In Vitro Screening Tool in Hearing Research

While there have been remarkable advances in hearing research over the past few decades, there is still no cure for Sensorineural Hearing Loss (SNHL), a condition that typically involves damage to or loss of the delicate mechanosensory structures of the inner ear. Sophisticated in vitro and ex vivo assays have emerged in recent years, enabling the screening of an increasing number of potentially therapeutic compounds while minimizing resources and accelerating efforts to develop cures for SNHL. Though homogenous cultures of certain cell types continue to play an important role in current research, many scientists now rely on more complex organotypic cultures of murine inner ears, also known as cochlear explants. The preservation of organized cellular structures within the inner ear facilitates the in situ evaluation of various components of the cochlear infrastructure, including inner and outer hair cells, spiral ganglion neurons, neurites, and supporting cells. Here we present the preparation, culture, treatment, and immunostaining of neonatal murine cochlear explants. The careful preparation of these explants facilitates the identification of mechanisms that contribute to SNHL and constitutes a valuable tool for the hearing research community.

Neonatal Murine Cochlear Explant Technique as an In Vitro Screening Tool in Hearing Research

The goal of this protocol is to demonstrate the preparation, culture, treatment, and immunostaining of neonatal murine cochlear explants. The technique can be utilized as an in vitro screening tool in hearing research.

While there have been remarkable advances in hearing research over the past few decades, there is still no cure for Sensorineural Hearing Loss (SNHL), a ...

Cochlear Implantation in the Guinea Pig

Cochlear implants are highly efficient devices that can restore hearing in subjects with profound hearing loss. Due to improved speech perception outcomes, candidacy criteria have been expanded over the last few decades. This includes patients with substantial residual hearing that benefit from electrical and acoustical stimulation of the same ear, which makes hearing preservation during cochlear implantation an important issue. Electrode impedances and the related issue of energy consumption is another major research field, as progress in this area could pave the way for fully implantable auditory prostheses. To address these issues in a systematic way, adequate animal models are essential. Therefore, the goal of this protocol is to provide an animal model of cochlear implantation, which can be used to address various research questions. Due to its large tympanic bulla, which allows easy surgical access to the inner ear, as well as its hearing range which is relatively similar to the hearing range of humans, the guinea pig is a commonly used species in auditory research. Cochlear implantation in the guinea pig is performed via a retroauricular approach. Through the bullostomy a cochleostomy is drilled and the cochlear implant electrode is inserted into the scala tympani. This electrode can then be used for electrical stimulation, determination of electrode impedances and the measurement of compound action potentials of the auditory nerve. In addition to these applications, cochlear implant electrodes can also be used as drug delivery devices, if a topical delivery of pharmaceutical agents to the cells or fluids of the inner ear is intended.

The goal of this protocol is to provide an animal model of cochlear implantation, which can be used to address a multitude of research questions. Potential applications include the evaluation of pharmaceutical interventions or electrical stimulation for beneficial effects on hearing thresholds or electrode impedances.

Cochlear implants are highly efficient devices that can restore hearing in subjects with profound hearing loss. Due to improved speech perception ...

Proton Therapy Delivery and Its Clinical Application in Select Solid Tumor Malignancies

Radiation therapy is a frequently used modality for the treatment of solid cancers. Although the mechanisms of cell kill are similar for all forms of radiation, the in vivo properties of photon and proton beams differ greatly and maybe exploited to optimize clinical outcomes. In particular, proton particles lose energy in a predictable manner as they pass through the body. This property is used clinically to control the depth at which the proton beam is terminated, and to limit radiation dose beyond the target region. This strategy can allow for substantial reductions in radiation dose to normal tissues located just beyond a tumor target. However, the degradation of proton energy in the body remains highly sensitive to tissue density. As a consequence, any changes in tissue density during the course of treatment may significantly alter proton dosimetry. Such changes may occur through alterations in body weight, respiration, or bowel filling/gas, and may result in unfavorable dose deposition. In this manuscript, we provide a detailed method for the delivery of proton therapy using both passive scatter and pencil beam scanning techniques for prostate cancer. Although the described procedure directly pertains to prostate cancer patients, the method may be adapted and applied for the treatment of virtually all solid tumors. Our aim is to equip readers with a better understanding of proton therapy delivery and outcomes in order to facilitate the appropriate integration of this modality during cancer therapy.

The fundamentals of radiation planning and delivery for proton therapy using prostate cancer as a model are presented. The application of these principles to other selected disease sites highlights how proton radiotherapy may enhance clinical outcomes for cancer patients.

Radiation therapy is a frequently used modality for the treatment of solid cancers. Although the mechanisms of cell kill are similar for all forms of ...

Step-by-Step Stapedotomy through Transcanal Exclusive Endoscopic Approach

In recent years there has been an increasing trend in the use of the endoscope to treat a variety of middle ear pathologies, including otosclerosis. Several studies comparing traditional microscopic and endoscopic stapes surgery have reported similar hearing results and an overall low rate of complications. The endoscope has unraveled its full potential in demanding settings of stapes surgery, such as unfavorable anatomy of the oval window niche or revision cases. Reduced manipulation of the chorda tympani and low rate of post-operative dysgeusia are further benefits to mention for endoscopic stapes surgery.
Being a one-handed technique, management of bleeding, positioning, and crimping of the prosthesis may be challenging for novice endoscopic surgeons, so some training in endoscopic ear surgery is recommended before performing endoscopic stapedotomy. The problem of sharing the surgical field between the endoscope and the operating instruments could be easily overcome if proper instruments positioning is understood. One-handed bleeding control in the narrow space of the ear canal may represent an issue during the elevation of the tympano-meatal flap, possibly discouraging the surgeon since the preliminary steps of surgery. Following appropriate technique to raise the flap and the collaboration with the anesthesiology team in keeping the blood pressure low guarantee an adequate bleeding control in most cases.
The aim of this article is to describe the entire surgical procedure of a transcanal exclusive endoscopic stapedotomy, from operating room set up and patient positioning to post-operative care. A step-by-step description of the surgical maneuvers with technical hints is reported, to guide the surgeon across the procedure and allow any ear surgeon to perform stapes surgery endoscopically.

The aim of this article is to provide a step-by-step method for endoscopic stapes surgery from operating room setting and patient positioning to post-operative care. This work would represent a guide for any otologic surgeon who is willing to treat otosclerosis with endoscopic transcanal technique.

In recent years there has been an increasing trend in the use of the endoscope to treat a variety of middle ear pathologies, including otosclerosis. ...

Performing Intracochlear Electrocochleography During Cochlear Implantation

Electrocochleography (ECochG) measures inner ear potentials generated in response to acoustic stimulation of the ear. These potentials reflect the residual function of the cochlea. In cochlear implant candidates with residual hearing, the implant electrode can directly measure ECochG responses during the implantation process. Various authors have described the ability to monitor the inner ear function by continuous ECochG measurements during the surgery. The measurement of ECochG signals during surgery is not trivial. There are no interpretable signals in up to 20% of cases. For a successful recording, a standardized procedure is recommended to achieve the highest measurement reliability and avoid possible pitfalls. Therefore, seamless collaboration between the CI surgeon and CI technician is key. This video consists of an overview of the system setup and a stepwise procedure of performing intracochlear ECochG measurements during CI surgery. It shows the surgeon's and the CI technician's roles in the process, and how a smooth collaboration between the two is made possible.

Electrocochleography (ECochG) measures inner ear potentials generated in response to acoustic stimulation. In cochlear implant (CI) candidates, such inner ear potentials can be measured directly with the implant electrodes. In this video, we systematically explain how to perform ECochG recordings during CI surgery.

Electrocochleography (ECochG) measures inner ear potentials generated in response to acoustic stimulation of the ear. These potentials reflect the ...

A State-of-the-Art Method for Preserving Residual Hearing During Cochlear Implant Surgery

The developments in surgical techniques and cochlear implant (CI) electrode design have expanded the indications for CI treatment. Currently, patients with high-frequency hearing loss may benefit from CIs when low-frequency residual hearing can be preserved, as this enables combined electric-acoustic stimulation (EAS). The possible benefits of EAS include, for example, improved sound quality, music perception, and speech intelligibility in noise.
The risks of inner ear trauma and a deterioration or even complete loss of residual hearing vary according to the surgical technique and the type of electrode array used. Short, lateral-wall electrodes with shallower angular insertion depths have demonstrated higher rates of hearing preservation than longer electrodes. The very slow insertion of the electrode array through the round window of the cochlea contributes to insertion atraumaticity and, thus, may lead to favorable hearing preservation results. However, residual hearing can be lost even after an atraumatic insertion. 
Electrocochleography (ECochG) can be used to monitor inner ear hair cell function during the insertion of the electrode. Several investigators have demonstrated that the ECochG responses during surgery may predict postoperative hearing preservation results. 
In a recent study, we correlated the patients' subjective hearing perception with simultaneously recorded intracochlear ECochG responses during the insertion. This is the first report evaluating the association between intraoperative ECochG responses and hearing perception in a subject undergoing cochlear implantation under local anesthesia without sedation. The combination of intraoperative ECochG responses with the patient's real-time feedback to sound stimuli has excellent sensitivity for the intraoperative monitoring of cochlear function. This paper presents a state-of-the-art method for the preservation of residual hearing during CI surgery. We describe this treatment procedure with the special consideration of performing the surgery under local anesthesia, which makes it feasible for monitoring the patient's hearing during the insertion of the electrode array.

The preservation of cochlear structures and possible residual hearing is one important factor to consider during cochlear implant surgery. Here, we present a state-of-the-art method for preserving residual hearing during cochlear implant surgery under local anesthesia.

The developments in surgical techniques and cochlear implant (CI) electrode design have expanded the indications for CI treatment. Currently, patients ...

Real-Time Telemetric Impedance Measurements During Cochlear Implantation

Performing Repeated Intraoperative Impedance Telemetry Measurements during Cochlear Implantation

Impedance measurements are routinely performed during cochlear implantation (CI) after finalized electrode insertion. They may allow conclusions on the electrode's and implant's function. In the postoperative setting, the analysis of impedance changes enables the identification of scarring or inflammation processes around the electrode. Recent studies report associations between impedance telemetry and the site of stimulation. Consequently, repeated impedance measurements during cochlear implant electrode insertion may enable objective feedback on whether the electrode is positioned inside the perilymph or outside the inner ear. With the presented novel method, impedances can be measured in real-time during cochlear implantation. This protocol systematically explains how to perform repeated impedance recordings during CI surgery. These repeated measurements are challenging since they depend on multiple intraoperative methodological factors starting with the draping of the patient. Thus, for successful recordings, a standardized procedure is mandatory. In this article, we comprehensively illustrate the system setup and procedure of performing intraoperative measurements during CI surgery.

Author Spotlight: Advancements in Impedance Monitoring for Cochlear Implant Surgery

Here we present a protocol to conduct repeated impedance telemetry measurements during cochlear implantation (CI). They may allow conclusions on the electrode's and implant's function. Repeated impedance measurements enable objective feedback on whether the electrode is positioned inside the perilymph or outside the inner ear.

Impedance measurements are routinely performed during cochlear implantation (CI) after finalized electrode insertion. They may allow conclusions on the ...

Hearing Preservation with Long Electrodes in Electric-Acoustic Stimulation

Enhanced Cochlear Coverage and Hearing Preservation in High-Frequency Hearing Loss via Electric Acoustic Stimulation with Longer Electrode

Electric-acoustic stimulation (EAS) is a promising treatment to improve hearing ability in patients with high-frequency hearing loss (HL). In EAS surgeries, shorter electrodes have been preferred to avoid the presence of an electrode covering the residual hearing region. However, our earlier studies showed that EAS with longer electrodes (28 mm) could preserve acoustic hearing. Additionally, we reported that the hearing preservation (HP) scores were independent of the length of the inserted electrodes, consistent with the systematic review. As most EAS patients gradually lose residual hearing over time due to the natural course of HL, in these cases, providing broader cochlear coverage using longer electrodes was beneficial toward better place-pitch matching. In addition to preparing for the deterioration in&#160;hearing in&#160;the future, EAS with longer electrodes could offer various types of map strategies. Herein, we show the pre-, intra-, and post-procedures for EAS surgery. Appropriate preoperative evaluation, less invasive surgery, flexible lateral-wall electrodes, and steroid administration resulted in good HP following EAS with longer electrodes.

Author Spotlight: Optimizing EAS with Long Electrodes for Enhanced Cochlear Coverage and Hearing Preservation

Electric acoustic stimulation (EAS) with longer electrodes can offer broader cochlear coverage and various types of maps in cases of high-frequency hearing loss. Combining less invasive surgery, flexible lateral-wall electrodes, and steroid administration permits deeper insertion with little or no surgical trauma, resulting in good preservation of hearing.

Electrically Evoked Stapedius Reflex Measurements in Cochlear Implantation and Its Application in the Postoperative Fitting Process

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