This protocol was approved by the local Ethics Committee in accordance with the Helsinki Declaration (Ruhr-University Bochum: Reg.-No.: 21-7373; Medical University Innsbruck Reg.-No.: 1060/2021). Informed consent was obtained from all participants.
1. Preparation for the surgery
<ol>
	<li>Make sure to obtain audiological testing reports, including pure-tone audiometry, objective testing (e.g., brainstem evoked response audiometry, speech testing), and vestibular diagnostics (e.g., video head impulse test or caloric testing). Obtain radiological imaging reports, including high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) of the skull base, as preparation and indication for surgery. 
	NOTE: MRI is required to secure the presence of the vestibulocochlear nerve and the patency of the cochlea. In the HRCT, anatomic variances (e.g., of the facial nerve) or malformations may be identified.</li>
	<li>Check the required hardware and software for impedance measurements (i.e., IM software, video recording software, MAESTRO).</li>
	<li>Obtain written informed consent from the patient.</li>
	<li>Perform general anesthesia considering the clinical history and risk factors of the patient as per the decision of the anesthesiologist.</li>
	<li>Position the patient&#39;s head in such a way that the mastoid segment of the facial nerve runs approximately horizontally. Achieve this by reclining the head and slightly positioning it to the opposite side.</li>
	<li>Shave the hair in the retro-auricular region (approximately 3 cm) to avoid the penetration of hair into the situs.</li>
	<li>Install facial nerve monitoring. Insert the monitoring needles into the obicularis oris muscle and the orbicularis oculi muscle. Place the reference electrodes on the thorax or shoulder. Make sure to fix the cables in order not to extract them accidentally during surgery.</li>
	<li>Disinfect the surgical site. Use disinfectant (e.g., Octenisept) according to the clinic&#39;s standard.</li>
	<li>Use sterile foil draping to cover the microscope and the patient. Ensure that the cover is as thin as possible in the area of the planned receiver coil position to avoid connection problems between the transmitting and receiving coil. Do not use hair wraps made of cloth as used in many ORs. Utilize self-sticking foil draping and make sure to avoid multi-layering.</li>
</ol>
2. Surgery
<ol>
	<li>Preparing for the implant
	<ol>
		<li>Mark the position of the processor and the skin incision of approximately 8 cm. Ensure enough space between the auricle and the implant housing.</li>
		<li>Inject local anesthesia (e.g., Ultracain 1% -Suprarenin, Sanofi, Paris, France) in an s-shaped area behind the auricle before skin incision.</li>
		<li>Incise the skin up to the temporal fascia using a scalpel. Dissect the periosteum and display the outer ear canal and Henle&#39;s spine. 
		NOTE: The surgical instruments are variable and not decisive for the presented method. Appropriate surgical instruments can be used to perform the surgical steps.</li>
		<li>Set the wound retractors on the opposite of the planned implant side to avoid later interaction (magnetic attraction/electric interference) with the telemetry coil.</li>
		<li>For cochlear implantation, perform antrotomy, mastoidectomy, and posterior tympanotomy8.</li>
		<li>Expose the dura to the middle cranial fossa as a first landmark using a large cutting burr. 
		NOTE: The size of the burr may vary depending on the surgical site.</li>
		<li>Thin out the posterior canal wall of the outer ear canal with the same burr.</li>
		<li>Expose the short incus process in the antrum and identify the lateral semicircular canal. 
		NOTE: Both antrum and semicircular canal are identified visually during the drilling procedure.</li>
		<li>As a next surgical step, expose the chorda facial angle where the chorda tympani leaves the facial nerve. In this step, use a large diamond burr and drill the bone parallel to the expected facial nerve. 
		NOTE: The size of the diamond burr may vary depending on the surgical site.</li>
		<li>Open the facial recess with a small diamond burr. Leave the facial nerve with thin bony coverage.</li>
		<li>Access the middle ear through posterior tympanotomy.</li>
		<li>Enlarge the posterior tympanotomy caudally until the round window niche is visualized.</li>
		<li>Maximize the posterior tympanotomy for great exposure of the middle ear, optimizing the visualization of the insertion process. Remove the bony overhang of the round window niche using a small diamond burr until the round window membrane may be visualized completely. 
		NOTE: When moving the ossicular chain, a movement of the round window membrane may be seen to clearly identify the round window membrane. Make sure not to touch the membrane with the burr or accidentally open it.</li>
		<li>Before opening the membrane, put some adrenaline (1 mg/mL) in the middle ear and protect it from bone dust with a resorbable sponge (e.g., Spongostan).</li>
	</ol>
	</li>
	<li>Positioning the Implant
	<ol>
		<li>Prepare the implant housing by drilling a bed into the bone in the future position of the receiving coil. Use the implant housing dummy provided by the manufacturer to mark the borders of the implant bed. Avoid slipping of the implant by creating an edge with the rosen burr. Use a diamond burr to smooth the surface. 
		NOTE: The edge of the implant housing prevents the movement of the implant toward the mastoidectomy defect.</li>
		<li>Pack the coil into a sterile sleeve since the coil is placed already at the beginning of the insertion process.</li>
		<li>Position the implant in the drilled implant bed, fix it with sutures, and cover it with the muscle flap.</li>
		<li>Replace the retractors to avoid any magnetic interaction with the stimulating coil.</li>
	</ol>
	</li>
	<li>Implantation and impedance measurement
	<ol>
		<li>Use two computers - one for Maestro and one for IM recordings.</li>
		<li>Start the IM-software.</li>
		<li>Place the telemetry coil above the magnet of the receiving coil. Secure it with a clamp to avoid movements and disconnections.</li>
		<li>Wait for the clinician, engineer, or audiologist to start the software and give feedback about the coupling. Change the position of the receiver coil until a secure connection is achieved.</li>
		<li>Ensure that no bleeding impedes the visualization of the insertion process or enters the perilymph.</li>
		<li>Communicate the visibility of the surgical field on the screens. Make adjustments to the optical focus of the microscope so that the clinician, engineer, or audiologist can follow the insertion process.</li>
		<li>Ensure the facial recess is as dry as possible to avoid early false positive measures.</li>
		<li>Open the round window membrane with a needle.</li>
		<li>Avoid any suction nearby the round window.</li>
		<li>Do not touch the electrode array.</li>
		<li>Communicate the start of insertion to the clinician, engineer, or audiologist so that he/she may adjust the status buttons. Instruct the engineer to mark one status button after the other as the electrode is inserted.</li>
		<li>Insert the first electrode contact into the cochlea. Wait for the feedback of the clinician, engineer, or audiologist and the audio signal to proceed. Apply an audio signal every 10 s to enable a constant and slow insertion speed with an overall insertion time of approximately 2 min.
		<ol>
			<li>For the auditory signal, play a sine wave signal of 500 Hz constant pulsing on and off and repeat it every 10 s using the software Audacity. Do not adjust the timing of the signal and pauses according to the insertion process but keep it constant.</li>
		</ol>
		</li>
		<li>Insert the electrode array slowly to avoid cochlear damage. Advance one electrode contact every 10 s (as guided by the sound signal).</li>
		<li>Inform the clinician, engineer, or audiologist about the progress by clearly communicating the number of contacts inserted so that the clinician, engineer, or audiologist can mark the progress in the software as precisely as possible by pressing the status buttons of the IM tool.</li>
		<li>Instruct the clinician, engineer, or audiologist to mark the number of inserted electrode contacts according to the feedback of the surgeon (Figure 2).</li>
		<li>Continue the measurements until full insertion to observe impedance drops.</li>
		<li>Communicate the surgical steps.</li>
		<li>Store the electrode lead in the mastoid cavity. Make sure to avoid extrusion forces by finding a tension-free position.</li>
	</ol>
	</li>
	<li>End of surgery
	<ol>
		<li>Seal the round window niche with fascia.</li>
		<li>Check the integrity of the implant (impedance telemetry, electrically evoked stapedius reflex thresholds, if applicable, and electrically evoked compound action potentials).</li>
		<li>Close the wound in layers.</li>
		<li>Continue repeated telemetry measurements until the wound is fully closed. Avoid a dislocation of the stimulating coil.</li>
		<li>Check the eardrum and the skin of the outer ear canal for any surgical damage before ending the surgery.</li>
	</ol>
	</li>
</ol>

Real-Time Telemetric Impedance Measurements During Cochlear Implantation

<ol>
	<li>Dalbert, 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=Hearing+preservation+after+cochlear+implantation+may+improve+long-term+word+perception+in+the+electric-only+condition.">Hearing preservation after cochlear implantation may improve long-term word perception in the electric-only condition.</a> Otology &amp; Neurotology. 37 (9), 1314-1319 (2016).</li><li>Thompson, N. J., 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=Electrode+array+type+and+its+impact+on+impedance+fluctuations+and+loss+of+residual+hearing+in+cochlear+implantation.">Electrode array type and its impact on impedance fluctuations and loss of residual hearing in cochlear implantation.</a> Otology &amp; Neurotology. 41 (2), 186-191 (2020).</li><li>Aebischer, P., Meyer, S., Caversaccio, M., Wimmer, W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Intraoperative+impedance-based+estimation+of+cochlear+implant+electrode+array+insertion+depth.">Intraoperative impedance-based estimation of cochlear implant electrode array insertion depth.</a> IEEE Transactions on Biomedical Engineering. 68 (2), 545-555 (2021).</li><li>Choi, J., 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=Electrode+impedance+fluctuations+as+a+biomarker+for+inner+ear+pathology+after+cochlear+implantation.">Electrode impedance fluctuations as a biomarker for inner ear pathology after cochlear implantation.</a> Otology &amp; Neurotology. 38 (10), 1433-1439 (2017).</li><li>Shaul, C., 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=Electrical+impedance+as+a+biomarker+for+inner+ear+pathology+following+lateral+wall+and+peri-modiolar+cochlear+implantation.">Electrical impedance as a biomarker for inner ear pathology following lateral wall and peri-modiolar cochlear implantation.</a> Otology &amp; Neurotology. 40 (5), e518-e526 (2019).</li><li>Bester, C., 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=Four-point+impedance+as+a+biomarker+for+bleeding+during+cochlear+implantation.">Four-point impedance as a biomarker for bleeding during cochlear implantation.</a> Scientific Reports. 10 (1), 2777 (2020).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> MED-EL. , (2023).</li><li>Lenarz, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cochlear+implant+-+state+of+the+art.">Cochlear implant - state of the art.</a> GMS Current Topics in Otorhinolaryngology, Head and Neck Surgery. 16, Doc04 (2018).</li><li>Gaw&#281;cki, 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=Robot-assisted+electrode+insertion+in+cochlear+implantation+controlled+by+intraoperative+electrocochleography-A+pilot+study.">Robot-assisted electrode insertion in cochlear implantation controlled by intraoperative electrocochleography-A pilot study.</a> Journal of Clinical Medicine. 11 (23), 7045 (2022).</li><li>Jia, H., 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=Molecular+and+cellular+mechanisms+of+loss+of+residual+hearing+after+cochlear+implantation.">Molecular and cellular mechanisms of loss of residual hearing after cochlear implantation.</a> Annals of Otology, Rhinology, and Laryngology. 122 (1), 33-39 (2013).</li><li>Eshraghi, A. A., Van de Water, T. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cochlear+implantation+trauma+and+noise-induced+hearing+loss:+Apoptosis+and+therapeutic+strategies.">Cochlear implantation trauma and noise-induced hearing loss: Apoptosis and therapeutic strategies.</a> The Anatomical Record. Part A, Discoveries in Molecular, Cellular, and Evolutionary Biology. 288 (4), 473-481 (2006).</li><li>Van De Water, T. R., 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=Caspases,+the+enemy+within,+and+their+role+in+oxidative+stress-induced+apoptosis+of+inner+ear+sensory+cells.">Caspases, the enemy within, and their role in oxidative stress-induced apoptosis of inner ear sensory cells.</a> Otology &amp; Neurotology. 25 (4), 627-632 (2004).</li><li>Roland, P. S., Wright, C. G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surgical+aspects+of+cochlear+implantation:+mechanisms+of+insertional+trauma.">Surgical aspects of cochlear implantation: mechanisms of insertional trauma.</a> Advances in Oto-Rhino-Laryngology. 64, 11-30 (2006).</li><li>Tien, H. -. C., Linthicum, F. H. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Histopathologic+changes+in+the+vestibule+after+cochlear+implantation.">Histopathologic changes in the vestibule after cochlear implantation.</a> Otolaryngology-- Head and Neck Surgery. 127 (4), 260-264 (2002).</li><li>Lenarz, T., 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=Relationship+between+intraoperative+electrocochleography+and+hearing+preservation.">Relationship between intraoperative electrocochleography and hearing preservation.</a> Otology &amp; Neurotology. 43 (1), e72-e78 (2022).</li><li>Bester, C., 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=Electrocochleography+triggered+intervention+successfully+preserves+residual+hearing+during+cochlear+implantation:+Results+of+a+randomised+clinical+trial.">Electrocochleography triggered intervention successfully preserves residual hearing during cochlear implantation: Results of a randomised clinical trial.</a> Hearing Research. 426, 108353 (2022).</li><li>O'Leary, S., 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=Intraoperative+observational+real-time+electrocochleography+as+a+predictor+of+hearing+loss+after+cochlear+implantation:+3+and+12+month+outcomes.">Intraoperative observational real-time electrocochleography as a predictor of hearing loss after cochlear implantation: 3 and 12 month outcomes.</a> Otology &amp; Neurotology. 41 (9), 1222-1229 (2020).</li><li>Dong, Y., Briaire, J. J., Siebrecht, M., Stronks, H. C., Frijns, J. H. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+translocation+of+cochlear+implant+electrode+arrays+by+intracochlear+impedance+measurements.">Detection of translocation of cochlear implant electrode arrays by intracochlear impedance measurements.</a> Ear and Hearing. 42 (5), 1397-1404 (2021).</li><li>Giardina, C. K., Krause, E. S., Koka, K., Fitzpatrick, D. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Impedance+measures+during+in+vitro+cochlear+implantation+predict+array+positioning.">Impedance measures during in vitro cochlear implantation predict array positioning.</a> IEEE Transactions on Biomedical Engineering. 65 (2), 327-335 (2018).</li><li>Sijgers, L., 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=Predicting+cochlear+implant+electrode+placement+using+monopolar,+three-point+and+four-point+impedance+measurements.">Predicting cochlear implant electrode placement using monopolar, three-point and four-point impedance measurements.</a> IEEE Transactions on Biomedical Engineering. 69 (8), 2533-2544 (2022).</li><li>Salkim, E., Zamani, M., Jiang, D., Saeed, S. R., Demosthenous, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Insertion+guidance+based+on+impedance+measurements+of+a+cochlear+electrode+array.">Insertion guidance based on impedance measurements of a cochlear electrode array.</a> Frontiers in Computational Neuroscience. 16, 862126 (2022).</li></ol>

The authors have no conflicts of interest to declare.

Repeated impedance measurements are a promising approach to gain real-time feedback from the cochlea during the insertion process. They indicate which electrode contacts are positioned inside the perilymph or not. With the here presented novel method for flexible lateral wall electrodes (MED-EL, Innsbruck, Austria)7, impedances may be measured in real-time during cochlear implantation utilizing the inserting electrode array.&#160;However, for reliable measurements, a standardized procedure is cruc...

Preserving residual hearing is an increasing topic of interest in cochlear implantation (CI) surgery, and the indication has changed towards candidates with functional residual hearing. Thus, measurements that may objectify the position of the electrode array and the resulting potential intracochlear damage during surgery are becoming increasingly important. CI-users with successfully preserved hearing have been shown to have superior hearing performance with the implant after surgery, even when stimulated electrically-only1. Some of them may additionally benefit from acoustic stimulation (electro-acoustic stimulation; EAS). Perioperative hearing loss is assumed to result from traumatic insertion. To improve insights into these intraoperative changes and to establish monitoring algorithms, objective measures, and biomarkers are needed. In this context, impedance telemetry may be of interest2,3. Increased impedances have been shown to be associated with hearing loss or vertigo4,5. Further evidence associates blood inclusions during the insertion of the electrode array6. Nevertheless, further investigation is necessary to explore to what extent impedances may be associated with surgical trauma and postoperative performance. For this purpose, repeated intraoperative impedance measurements are a promising approach. On the other hand, impedances deliver additional information about the electrode&#39;s position. High impedances indicate poor conductivity and thus indicate a contact position outside the cochlea, whereas low impedances (impedance drops) may indicate already inserted contacts. Thus, impedances may be used as an objective feedback mechanism for the status of the electrode array insertion. In this video, we present our setup and first experiences with this novel approach of repeated impedance measurements using flexible lateral wall electrodes from the cochlear implant manufacturer MED-EL (Innsbruck, Austria)7.
A study software designed for research purposes is used to perform repeated impedance measurements. In this study, the software is verified according to the MED-EL internal procedures for research-use-only devices. During surgery, only the most recent impedance telemetry data is shown. Figure 1 shows the electronic measurement setup. The Insertion Monitoring (IM) software has buttons to mark the number of electrode contacts currently inserted (red/green highlighting). After starting, the software measures impedances repeatedly in cycles. The IM software shows a table of the measured impedance results and impedances across time in 12 plots. Furthermore, it shows warnings in case of connection problems. A video recording Software (Open Broadcaster Software [OBS]) is used to record (i) the video of electrode insertion (microscope attached, e.g., via HDMI), (ii) a video of the IM software user interface, including all user interactions and (iii) sound. An audio editor software (Audacity) is used to regularly play a sound during the insertion of the electrode array to facilitate a slow insertion.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Audacity</td>
			<td>Open source</td>
			<td>https://www.audacityteam.org/</td>
			<td>Audio editor software</td>
		</tr>
		<tr>
			<td>Coil cable</td>
			<td>Any appropriate brand</td>
			<td></td>
			<td>Implant interface</td>
		</tr>
		<tr>
			<td>Computer</td>
			<td>Any appropriate brand</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Electrode array</td>
			<td>MED-EL</td>
			<td>https://s3.medel.com/pdf/21617.pdf</td>
			<td>Standard, FlexSoft, Flex28</td>
		</tr>
		<tr>
			<td>IM Software</td>
			<td>MED-EL</td>
			<td>https://www.medel.com/</td>
			<td></td>
		</tr>
		<tr>
			<td>Maestro</td>
			<td>MED-EL</td>
			<td>https://www.medel.com/</td>
			<td></td>
		</tr>
		<tr>
			<td>MAX Interface USB</td>
			<td>Any appropriate brand</td>
			<td></td>
			<td>Interface connection</td>
		</tr>
		<tr>
			<td>Octenisept</td>
			<td>SCH&#220;LKE &#38; MAYR GmbH</td>
			<td>N/A</td>
			<td></td>
		</tr>
		<tr>
			<td>Open Broadcaster Software</td>
			<td>Open source</td>
			<td>https://obsproject.com/</td>
			<td>Video recording software</td>
		</tr>
		<tr>
			<td>Spongostan</td>
			<td>&#160;Ethicon</td>
			<td>N/A</td>
			<td>Resorbable sponge</td>
		</tr>
		<tr>
			<td>Ultracain 1%</td>
			<td>&#160;Suprarenin, Sanofi</td>
			<td>N/A</td>
			<td>Local anesthesia</td>
		</tr>
	</tbody>
</table>

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.

For repeated impedance measurements during cochlear implantation, a standardized procedure is mandatory to achieve the highest possible reproducibility. The major aspects that have been considered to play an important role are the video quality as well as the insertion angle. Both may impede the visualization of the electrode contacts entering the round window and thus, the interpretation of the video for future analyses. Further, the placement of the receiver coil is crucial to prevent interruptions during insertion and...

Watch this Scientific Journal Video about Performing Repeated Intraoperative Impedance Telemetry Measurements during Cochlear Implantation at JoVE.com

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.

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 ...

performing-repeated-intraoperative-impedance-telemetry-measurements

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1.0K Views.  Ruhr-University Bochum, St. Elisabeth-Hospital Bochum. 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.

Video: Author Spotlight: Advancements in Impedance Monitoring for Cochlear Implant Surgery

Intrauterine Telemetry to Measure Mouse Contractile Pressure In Vivo

A complex integration of molecular and electrical signals is needed to transform a quiescent uterus into a contractile organ at the end of pregnancy. Despite the discovery of key regulators of uterine contractility, this process is still not fully understood. Transgenic mice provide an ideal model in which to study parturition. Previously, the only method to study uterine contractility in the mouse was ex vivo isometric tension recordings, which are suboptimal for several reasons. The uterus must be removed from its physiological environment, a limited time course of investigation is possible, and the mice must be sacrificed. The recent development of radiometric telemetry has allowed for longitudinal, real-time measurements of in vivo intrauterine pressure in mice. Here, the implantation of an intrauterine telemeter to measure pressure changes in the mouse uterus from mid-pregnancy until delivery is described. By comparing differences in pressures between wild type and transgenic mice, the physiological impact of a gene of interest can be elucidated. This technique should expedite the development of therapeutics used to treat myometrial disorders during pregnancy, including preterm labor.

Intrauterine Telemetry to Measure Mouse Contractile Pressure In Vivo

This manuscript provides a protocol for implanting telemeters in the mouse for the purpose of measuring intrauterine pressures during pregnancy.

A complex integration of molecular and electrical signals is needed to transform a quiescent uterus into a contractile organ at the end of pregnancy. ...

Long-term Blood Pressure Measurement in Freely Moving Mice Using Telemetry

During the development of new vasoactive agents, arterial blood pressure monitoring is crucial for evaluating the efficacy of the new proposed drugs. Indeed, research focusing on the discovery of new potential therapeutic targets using genetically altered mice requires a reliable, long-term assessment of the systemic arterial pressure variation. Currently, the gold standard for obtaining long-term measurements of blood pressure in ambulatory mice uses implantable radio-transmitters, which require&#160;artery cannulation. This technique eliminates the need for tethering, restraining, or anesthetizing the animals which introduce stress and artifacts during data sampling. However, arterial blood pressure monitoring in mice via catheterization can be rather challenging due to the small size of the arteries. Here we present a step-by-step guide to illustrate the crucial key passages for a successful subcutaneous implantation of radio-transmitters and carotid artery cannulation in mice. We also include examples of long-term blood pressure activity taken from freely moving mice after a period of post-surgery recovery. Following this procedure will allow reliable direct blood pressure recordings from multiple animals simultaneously.

The goal of this protocol is to assess systemic blood pressure in conscious freely moving mice using implantable radio-telemetry devices.

During the development of new vasoactive agents, arterial blood pressure monitoring is crucial for evaluating the efficacy of the new proposed drugs. ...

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 ...

Improved Registration of 3D CT Angiography with X-ray Fluoroscopy for Image Fusion During Transcatheter Aortic Valve Implantation

The fusion of 3D anatomical models derived from high-fidelity pre-interventional computed tomography angiography (CTA), and x-ray (XR) fluoroscopy to facilitate anatomical guidance is of huge interest for complex cardiac interventions like TAVI procedures with cerebral protection. Co-registration of CTA and XR has been introduced either based on additional intraoperative non-/contrast-enhanced cone-beam computed tomography (CBCT) or two separate aortograms. With the related increase of radiation exposure and/or contrast agent (CA) dose, a potential additional risk for the patient is introduced. Here, we propose a modified co-registration approach making use of arteriograms of the iliofemoral arteries, routinely performed during the femoral puncture and sheath introduction. On-the-fly refinement of the co-registration during the on-going procedure enables accurate co-registration without any additional angiograms, thus reducing CA, XR dose and procedure time, while simultaneously improving operator confidence and procedure safety.

The aim of this study was to improve the co-registration for image fusion (IF) of pre-interventional CT data with real-time x-ray (XR) fluoroscopy during transfemoral transcatheter aortic valve implantation (TAVI).

The fusion of 3D anatomical models derived from high-fidelity pre-interventional computed tomography angiography (CTA), and x-ray (XR) fluoroscopy to ...

Intraoperative Ultrasound in Spinal Surgery

Since the 1980s, there have been several reports for the use of intraoperative ultrasound as a useful adjunct in spinal surgery. However, with the advent of newer cutting-edge imaging modalities, the use of intraoperative ultrasound in spine surgery has largely fallen out of favor. Despite this, intraoperative ultrasound continues to provide several advantages over other intraoperative techniques such as magnetic resonance imaging and computed tomography including being more cost-effective, efficient, and easy to operate and interpret. Additionally, it remains the only method for the real-time visualization of soft tissue and pathologies. This paper focuses on the advantages of using intraoperative ultrasound, especially in cases of intradural lesions and lesions ventral to the thecal sac when approaching posteriorly.

Here, we present a protocol on the use of intraoperative ultrasound in spinal surgery, particularly in cases of intradural lesions and lesions in the ventral spinal canal when using a posterior approach.

Since the 1980s, there have been several reports for the use of intraoperative ultrasound as a useful adjunct in spinal surgery. However, with the advent ...

Repeated Orotracheal Intubation in Mice

The literature describes several methods for mouse intubation that either require visualization of the glottis through the oral cavity or incision in the ventral neck for direct confirmation of cannula placement in the trachea. The relative difficulty or the tissue trauma induced to the subject by such procedures can be an impediment to an investigator&#8217;s ability to perform longitudinal studies. This article illustrates a technique in which physical manipulation of the mouse following the use of a depilatory to remove hair from the ventral neck permits transcutaneous visualization of the trachea for orotracheal intubation regardless of degree of skin pigmentation. This method is innocuous to the subject and easily achieved with a limited understanding of murine anatomy. This refined approach facilitates repeated intubation, which may be necessary for monitoring progression of disease or instillation of treatments. Using this method may result in a reduction of the number of animals and technical skill required to measure lung function in mouse models of respiratory disease.

The goal of this article is to describe a refined method of intubation of the laboratory mouse. The method is noninvasive and, therefore, ideal for studies that require serial monitoring of respiratory function and/or instillation of treatments into the lung.

The literature describes several methods for mouse intubation that either require visualization of the glottis through the oral cavity or incision in the ...

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 ...

Robotic Cochlear Implantation for Direct Cochlear Access

Robot-assisted systems offer great potential for gentler and more precise cochlear implantation. In this article, we provide a comprehensive overview of the clinical workflow for robotic cochlear implantation using a robotic system specifically developed for a minimally invasive, direct cochlear access. The clinical workflow involves experts from various disciplines and requires training to ensure a smooth and safe procedure. The protocol briefly summarizes the history of robotic cochlear implantation. The clinical sequence is explained in detail, beginning with the assessment of patient eligibility and covering surgical preparation, preoperative planning with the special planning software, drilling of the middle ear access, intraoperative imaging to confirm the trajectory, milling of the inner ear access, insertion of the electrode array, and implant management. The steps that require special attention are discussed. As an example, the postoperative outcome of robotic cochlear implantation in a patient with advanced otosclerosis is presented. Finally, the procedure is discussed in the context of the authors' experience.

Robotic cochlear implantation is a procedure for minimally invasive inner ear access. Compared to conventional surgery, robotic cochlear implantation involves additional steps that need to be carried out in the operating room. In this article we give a description of the procedure and highlight the important aspects of robotic cochlear implantation.

Robot-assisted systems offer great potential for gentler and more precise cochlear implantation. In this article, we provide a comprehensive overview of ...

Establishment of a Simple and Effective Rat Model for Intraoperative Parathyroid Gland Imaging

Parathyroid gland (PG) identification is a critical unmet need in thyroidectomy. The identification of the PG is challenging in thyroid surgery as it is similar in color to the thyroid gland. The lack of effective animal models in preclinical research is a severe limitation for the development of PG identification techniques. This protocol allows for the establishment of a simple and effective rat model for PG identification. In this model, black iron oxide nanoparticles (IONPs) are injected locally in the thyroid gland and rapidly diffuse within the thyroid gland but not the PG. A negatively stained PG and a positively stained thyroid gland can be easily identified by the naked eye without requiring external microscopes. The position of the PG can be identified by increasing the color contrast between the thyroid gland and the PG, based on the color of the black IONPs. This rat model is low-cost and convenient for PG identification, and the IONPs are a novel PG contrast agent.

To date, the development of parathyroid gland (PG) identification methods is limited by the lack of animal models in preclinical research. Here, we establish a simple and effective rat model for intraoperative PG imaging and evaluate its effectiveness by using iron oxide nanoparticles as a novel PG contrast agent.

Parathyroid gland (PG) identification is a critical unmet need in thyroidectomy. The identification of the PG is challenging in thyroid surgery as it is ...

Orthopedic Robot-Assisted Femoral Neck System in the Treatment of Femoral Neck Fracture

Cannulated screw fixation is the main therapy for femoral neck fractures, especially in young patients. The traditional surgical procedure uses C-arm fluoroscopy to place the screw freehand and requires several guide wire adjustments, which increases the operation time and radiation exposure. Repeated drilling can also cause damage to the blood supply and bone quality of the femoral neck, which can be followed by complications such as screw loosening, nonunion, and femoral head necrosis. In order to make fixation more precise and reduce the incidence of complications, our team applied robot-assisted orthopedic surgery for screw placement using the femoral neck system to modify the traditional procedure. This protocol introduces how to import a patient's X-ray information into the system, how to perform screw path planning in software, and how the robotic arm assists in screw placement. Using this method, the surgeons can place the screw successfully the first time, improve the accuracy of the procedure, and avoid radiation exposure. The whole protocol includes the diagnosis of femoral neck fracture; the collection of intraoperative X-ray images; screw path planning in the software; precise placement of the screw under the assistance of the robotic arm by the surgeon; and verification of the implant placement.

This article introduces a method of robot-assisted orthopedic surgery for screw placement during the treatment of femoral neck fracture using the femoral neck system, which allows for more accurate screw placement, improved surgical efficiency, and fewer complications.

Cannulated screw fixation is the main therapy for femoral neck fractures, especially in young patients. The traditional surgical procedure uses C-arm ...