The authors thank Gianni Pauciello, Department of Otorhinolaryngology, Head and Neck Surgery, Inselspital, Bern University Hospital, for video production and photography. We also thank Dr. Stefan Henle and the team of the Department of Anesthesiology and Pain Medicine, Inselspital, Bern University Hospital and the team at the Department of Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, Bern, Switzerland.

This study was performed in compliance with institutional guidelines and was approved by the local institutional review board (ID 2020-02561). The patient gave written informed consent for further use of the images and videos. The video shows the processes involved in performing robotic cochlear implantation with the planning software and the robotic system (please refer to the Table of Materials for further details) according to the procedure described by the manufacturer.
1. Patient candidacy screening
NOTE: Use existing preoperative computed tomography images for this step. Currently, robotic cochlear implantation with the system used in this protocol is only available from a single manufacturer (see Table of Materials) for implant systems. Please refer to the instructions for use manual of the planning software for specific details regarding button clicks, software commands, and user inputs.
<ol>
	<li>Use the planning software to load preoperative computed tomography images and to generate the surfaces of the temporal bone, the external auditory canal, the ossicles, the facial nerve, the chorda tympani, and the cochlea.</li>
	<li>Use the planning software to plan a virtual trajectory through the facial recess.</li>
	<li>Confirm a safe distance between the drilling trajectory and the surrounding anatomical structures. To ensure a safe drilling trajectory, the distance of the trajectory to the facial nerve has to be at least 0.4 mm, and the distance to the chorda tympani has to be at least 0.3 mm. Only patients with safe drilling distances are eligible for robotic cochlear implantation.</li>
	<li>Use the planning software to select a suitable electrode array size. In cases with residual hearing, consider including the preoperative audiogram for CI electrode array selection.</li>
</ol>
2. Fiducial screw insertion
<ol>
	<li>Prepare the patient on the OR table and administer general anesthesia as per the conventional cochlear implantation procedure.</li>
	<li>Mark the retroauricular incision for the cochlear implant using a surgical marker. Perform the incision, lift the musculocutaneous flap, and use the curette to expose the mastoid cortical bone.</li>
	<li>Mark the position of the five fiducial screws. Position the first four registration screws retroauricularly at approximately 20-30 mm in a trapezoid pattern. Place the fifth screw, for patient marker attachment, approximately a thumb distance from the first four screws and as inferior as possible. 
	NOTE: Refer to the instructions for an illustration of the screw arrangement.</li>
	<li>Use the pre-drill bit and drill handpiece to pre-drill the holes for the screws, with particular emphasis that the drill is held perpendicular to the bone surface.Insert the screws into the pre-drilled holes. Ensure that the screws are firmly fixed in the bone. 
	&#8203;CAUTION: Always check the stability of the screws. In case of a loose screw, repeat step 2.3. and step 2.4. to reposition the screw.</li>
</ol>
3. Preoperative imaging
<ol>
	<li>Perform computed-tomography (CT) imaging or cone beam CT imaging with a minimum resolution of 0.2 mm x 0.2 mm x 0.2 mm as per the manufacturer&#39;s instructions. Perform imaging under apnea to reduce motion artifacts.</li>
	<li>Export the images via a USB stick and import them into the planning software. Verify the image data quality and visibility of all the screws in the CT data.</li>
</ol>
4. Preoperative planning
NOTE: Perform preoperative planning in parallel with patient preparation (step 5.) to save time. Please refer to the instructions for use manual of the planning software for mesh generation and for specific details regarding button clicks, software commands, and user inputs.
<ol>
	<li>Run the automatic fiducial screw detection in the planning software. Generate the temporal bone surface mesh.</li>
	<li>Generate the external auditory canal surface mesh. Generate the malleus and incus surface meshes.</li>
	<li>Generate the stapes surface mesh.</li>
	<li>Generate the facial nerve surface mesh. 
	CAUTION: Make sure that you segment the facial nerve with a safety margin (e.g., 3 voxels). If desired, let a neuroradiologist verify the labels.</li>
	<li>Generate the chorda tympani surface mesh. Generate the cochlea surface mesh and specify the target position on the cochlea (usually the center of the round window).</li>
	<li>Plan the drill trajectory and approve the plan with the neuroradiologist. Export the plan to a data stick for transfer to the robotic system.</li>
</ol>
5. Patient preparation
<ol>
	<li>Align the patient&#39;s head within the headrest in a way that the neck is supported by the bottom cushion and the patient&#39;s nose is aligned with the center of the head rest&#39;s top frame. Ensure that the patient&#39;s head is sufficiently fixed in the headrest. 
	CAUTION: The correct alignment of the head is essential for the accessibility of the robotic system to the surgical site.</li>
	<li>Place the facial nerve monitoring electrodes. Place the bipolar needle electrodes in the orbicularis oculi and the orbicularis oris for monitoring. Place the self-adhesive pad electrodes on the superficial facial nerve branch for stimulation. Place the monopolar needle electrodes on the chest for stimulation and monitoring.</li>
	<li>Test the correct placement of the electrodes by control stimulation performed according to the instructions for use from the manufacturer of the robotic system.</li>
	<li>Cover the robotic system and navigation platform with a sterile drape.</li>
	<li>Place, align, and fix the patient marker on the fifth screw such that it is visible to the robotic system&#39;s tracking camera. Ensure that the patient marker is attached rigidly and that all the joints are firmly tightened. It is critical to avoid any movement of the patient marker after the registration process. In the case of movement, repeat the registration.</li>
	<li>Perform patient-to-plan registration, which is the process to relate the virtual plan to the actual patient. Use the handpiece with the registration tool and place it onto each fiducial screw (four times). Perform the registration procedure as per the instructions for use from the manufacturer. The screen on the navigation platform indicates which screw to position the tool on.</li>
	<li>After all screw positions are digitized, the registration accuracy is computed. Confirm that the registration accuracy is sufficient to continue by checking the fiducial registration error (FRE). The robotic system does not allow the continuation of the procedure if the fiducial registration error (FRE) is higher than 0.050 mm.</li>
</ol>
6. Middle ear access - Phase 1
<ol>
	<li>Insert the drill bit into the handpiece and attach the irrigation nozzle. Move the robotic arm into the surgical field. The handpiece with the drill slowly approaches the surgical site. Confirm the alignment of the drill bit with the virtual trajectory planned in the planning software.</li>
	<li>Start drilling with the robotic system. The system will drill with a pecking motion until the first safety checkpoint (above the facial recess) is reached. After the first safety checkpoint is reached, move the robotic arm out of the surgical field.</li>
</ol>
7. Intraoperative imaging safety check
<ol>
	<li>Remove the patient marker from the patient. Insert and push the trajectory reference rod inside the drilled tunnel. Drape the patient&#39;s head with sterile draping.</li>
	<li>Perform CT imaging or cone beam CT imaging with the help of the neuroradiology department team.</li>
	<li>Load the CT data into the planning software and confirm together with the neuroradiologist that the trajectory is safe. Refer to the instructions for use of the planning software for further details. Remove the draping and the trajectory reference rod.</li>
</ol>
8. Middle ear access - Phase 2
<ol>
	<li>Reattach the patient marker. Ensure that the patient marker is attached rigidly and that all the joints are firmly tightened.</li>
	<li>Repeat the registration by placing the handpiece with the registration tool onto each of the fiducial screws for position digitization. After all the screw positions are digitized, the registration accuracy is computed. Confirm that the registration accuracy is sufficient to continue.</li>
	<li>Insert the drill bit into the handpiece. Confirm the alignment of the drill bit with the drill tunnel and continue drilling until the first facial nerve stimulation point is reached.</li>
	<li>Insert the facial nerve probe to check the integrity of the facial nerve. Afterward, the robotic system will drill to the next facial nerve stimulation point. In total, five facial nerve stimulation points will be tested.</li>
	<li>Continue drilling until the tympanic cavity is reached.</li>
</ol>
9. Inner ear access
NOTE: Inner ear access is a semi-automatic procedure that can be stopped by the surgeon at any time for visual inspection.
<ol>
	<li>Remove the drill bit from the handpiece of the robotic system and insert the diamond drill bit for inner ear access. Use the trajectory pointer to verify the target upon milling.</li>
	<li>Start the robotic system to mill the bony overhang. The system will automatically stop after breakthrough to ensure that a sufficient aperture for the electrode array is achieved, while aiming to preserve the round window membrane.</li>
	<li>Confirm the inner ear access either via an endoscope or via a microscope through a tympanomeatal flap.</li>
</ol>
10. Implant management and electrode insertion
<ol>
	<li>Remove the patient marker and all five fiducial screws. If not already performed, make a tympanomeatal flap to visualize the cochlear promontory.</li>
	<li>Mark the implant body position using the surgical template and prepare the implant pocket.</li>
	<li>Mill out the lead canal for the excess electrode lead using an otologic drill. Clean the drilled tunnel with suction and irrigation.</li>
	<li>Manually open the round window membrane with a pick. Insert the insertion guide tube into the drilled tunnel. The tube will ensure that the electrode array is protected against blood and bone dust and is directed to the inner ear access.</li>
	<li>Fix the cochlear implant body in the pocket and manually insert the electrode array through the insertion guide tube.</li>
	<li>Mark the electrode lead to indicate full insertion through the insertion guide tube. Use the insertion guide tube as a reference, i.e., by placing it next to the electrode array such that the medial end of the guide tube is aligned with the intended insertion depth, e.g., the outermost contact. Then, mark the array at the lateral end of the guide tube.</li>
	<li>After the final insertion depth is achieved, remove the insertion guide tube. Fix the electrode array with fat and arrange the excess electrode lead as a loop in the mastoid cavity as in conventional cochlear implantation.</li>
</ol>
11. Implant telemetry and wound closure
<ol>
	<li>Perform impedance telemetry and record electrically evoked compound action potentials for nerve response monitoring12.</li>
	<li>Close the wound using disposable stitches.</li>
</ol>

<ol>
	<li>Wimmer, W., Weder, S., Caversaccio, M., Kompis, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Speech+intelligibility+in+noise+with+a+pinna+effect+imitating+cochlear+implant+processor.">Speech intelligibility in noise with a pinna effect imitating cochlear implant processor.</a> Otology &amp; Neurotology. 37 (1), 19-23 (2016).</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, (2018).</li><li>Klopp-Dutote, N., Lefranc, M., Strunski, V., Page, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Minimally+invasive+fully+ROBOT-assisted+cochlear+implantation+in+humans:+Preliminary+results+in+five+consecutive+patients.">Minimally invasive fully ROBOT-assisted cochlear implantation in humans: Preliminary results in five consecutive patients.</a> Clinical Otolaryngology. 46 (6), 1326-1330 (2021).</li><li>Kluge, M., Rau, T., Lexow, J., Lenarz, T., Majdani, O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Untersuchung+der+Genauigkeit+des+RoboJig+f&#252;r+die+minimal-invasive+Cochlea-Implantat-Chirurgie.">Untersuchung der Genauigkeit des RoboJig f&#252;r die minimal-invasive Cochlea-Implantat-Chirurgie.</a> Laryngo-Rhino-Otologie. 97, 10602 (2018).</li><li>Barriat, S., Peigneux, N., Duran, U., Camby, S., Lefebvre, P. P. <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+a+robot+to+insert+an+electrode+array+of+cochlear+implants+in+the+cochlea:+A+feasibility+study+and+preliminary+results.">The use of a robot to insert an electrode array of cochlear implants in the cochlea: A feasibility study and preliminary results.</a> Audiology and Neurotology. 26 (5), 361-367 (2021).</li><li>. Clinical Trials.gov Available from: <a target="_blank" href="https://clinicaltrials.gov/ct2/show/NCT04577118">https://clinicaltrials.gov/ct2/show/NCT04577118</a> (2022)</li><li>Labadie, R. F., 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=Minimally+invasive+image-guided+cochlear+implantation+surgery:+First+report+of+clinical+implementation.">Minimally invasive image-guided cochlear implantation surgery: First report of clinical implementation.</a> The Laryngoscope. 124 (8), 1915-1922 (2014).</li><li>Caversaccio, M., 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=Robotic+middle+ear+access+for+cochlear+implantation:+First+in+man.">Robotic middle ear access for cochlear implantation: First in man.</a> PLOS One. 14 (8), 0220543 (2019).</li><li>Weber, 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=Instrument+flight+to+the+inner+ear.">Instrument flight to the inner ear.</a> Science Robotics. 2 (4), 4916 (2017).</li><li>Bell, B., 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=In+vitro+accuracy+evaluation+of+image-guided+robot+system+for+direct+cochlear+access.">In vitro accuracy evaluation of image-guided robot system for direct cochlear access.</a> Otology &amp; Neurotology. 34 (7), 1284-1290 (2013).</li><li>Caversaccio, M., 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=Robotic+cochlear+implantation:+Surgical+procedure+and+first+clinical+experience.">Robotic cochlear implantation: Surgical procedure and first clinical experience.</a> Acta Oto-Laryngologica. 137 (4), 447-454 (2017).</li><li>Dillier, N., 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=Measurement+of+the+electrically+evoked+compound+action+potential+via+a+neural+response+telemetry+system.">Measurement of the electrically evoked compound action potential via a neural response telemetry system.</a> The Annals of Otology, Rhinology, and Laryngology. 111, 407-414 (2002).</li><li>Wimmer, 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=Cone+beam+and+micro-computed+tomography+validation+of+manual+array+insertion+for+minimally+invasive+cochlear+implantation.">Cone beam and micro-computed tomography validation of manual array insertion for minimally invasive cochlear implantation.</a> Audiology and Neuro-Otology. 19 (1), 22-30 (2014).</li><li>Wimmer, 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=Electrode+array+insertion+for+minimally+invasive+robotic+cochlear+implantation+with+a+guide+tube.">Electrode array insertion for minimally invasive robotic cochlear implantation with a guide tube.</a> International Journal of Computer Assisted Radiology and Surgery. 11, 80-81 (2016).</li></ol>

The authors declare that they have no conflicts of interest. This study was funded by the Department of Otorhinolaryngology, Head and Neck Surgery, at the Inselspital Bern.

Here, an overview of the steps involved in robotic cochlear implantation is presented. An important part is the selection of suitable candidates for the procedure. To ensure that the safety margins during surgery can be maintained, careful candidate screening needs to be performed to ensure eligibility for the procedure. The distance between the virtually planned trajectory and the facial nerve should be at least 0.4 mm. In addition, at least 0.3 mm distance to the chorda tympani needs to be available. To provide more flexibility in trajectory planning after preoperative imaging on the day of surgery, even larger limits can be considered for patient selection.
As the robotic system relies on the fiducial landmark screws to transfer the plan to the patient, they are of central importance for a safe procedure. The surgeon should carefully select the positions of the fiducial screws to ensure that enough space is available for trajectory drilling. A linear arrangement of three screws should be avoided. Also, it needs to be ensured that the screw for the patient marker is positioned such that the marker remains visible throughout the procedure. The instructions for use of the robotic system provide detailed guidelines for screw positioning. When placing the screws, it needs to be ensured that the holes are pre-drilled perpendicularly to the surface of the mastoid bone. Tight fixing of the screws ensures that no movement occurs during the procedure.
For preoperative imaging, patients should be scanned in apnea, as the breathing motion of the patient can cause motion artifacts that may not be immediately identifiable in the images but later on during the registration process can cause errors that impede commencing the procedure. It should be ensured that the person performing the preoperative planning has received extensive training to confidently identify and label the anatomical structures. In particular, the course of the facial nerve, the chorda tympani, and the selection of the target at the cochlea (usually the center of the round window membrane) need to be trained. For facial nerve generation, additional safety through over-segmentation of the nerve should be considered. In case no imaging modality is available directly in the operating room or no mobile imaging system can be transported into the operating room, the patient needs to be transferred to the neuroradiological department for imaging. The additional patient transfer time needs to be considered. Preoperative planning can be performed in parallel with patient transfer and preparation to save time.
The team should extensively train head positioning in the headrest to ensure that the patient marker and screws are visible to the system at later stages. Wrong head positing can result in invisibility of the markers or infeasible kinematics of the robotic arm. At all stages during robotic cochlear implantation, it needs to be ensured that all the screws are tightly fixed, the patient marker is rigidly attached, and the handpiece of the robot is fixed. 
For intraoperative imaging using mobile imaging devices (e.g., mobile cone beam CT), sufficient clearance of the patient's head and the headrest with the sterile draping needs to be ensured. Motion artifacts caused by the scanner touching the sterile drape could worsen the image quality of the intraoperative image and impede decision-making on the safety of the drilled trajectory required for commencing of the drilling.
In an optimal case, the round window membrane is preserved after robotic inner ear access, sealing the inner ear from bone dust and blood that might be introduced by the consecutive steps involved in implant management. As the fiducial screws and patient reference marker are required for inner ear access, it is not recommended to prepare the implant bed before inner ear access to ensure sufficient space for screw placement. In case the round window membrane is not intact after inner ear access, the round window could be temporarily covered as a protective measure until the electrode array insertion is performed.
After access to the inner ear is established, the surgeon may use different techniques to visualize the access. Microscopic inspection through a tympanomeatal flap or direct endoscopic inspection are possible. However, for the later electrode array insertion, we recommend performing a tympanomeatal flap to provide direct access to the electrode array, if required13. The electrode array lead can be marked before insertion to indicate full insertions at the surface of the mastoid bone. We also recommend using the insertion guide tube during insertion to avoid contact with blood and bone dust and to constrain the electrode array to the insertion trajectory14.
The presented procedure applies task-autonomous robotics in the field of otological microsurgery. Potential advantages of the procedure include reproducible, minimally invasive access to the cochlea and, ultimately, targeted, and accurate insertion of electrodes, which could expand the pool of CI patients in the future. The current limitations of the system are the associated additional costs for material and trained staff, the longer surgical duration, and the still manually performed electrode insertion. Currently, robotic cochlear implantation requires more time (about 4 h) than conventional cochlear implantation (about 1.5 h). Therefore, the condition of the patient should be also considered for eligibility.

A cochlear implant (CI) is the standard treatment for severe to profound sensorineural hearing loss1. The surgical procedure for cochlear implantation aims to atraumatically insert the cochlear implant electrode array into the cochlea. For the implantation, surgeons must provide access from the surface of the temporal bone to the cochlea. In conventional procedures, this access is created by removing portions of the mastoid bone through a mastoidectomy and posterior tympanotomy2.
Robot-assisted cochlear implantation aims to perform a minimally invasive access through a small tunnel to the inner ear for electrode array insertion. To date, several systems for robot-assisted cochlear implantation are in development or already available on the market. One such system provides robotic-controlled drilling of the mastoid and electrode insertion and has been recently evaluated in patients3. Another device is a patient-specific guiding system for tunnel drilling and electrode insertion4. Two systems that do not provide the inner ear access tunnel but rather the alignment and motorized insertion of electrode arrays have recently received medical device approval in Europe and the United States5,6. The first clinical implementation of a minimally invasive tunnel procedure using a stereotactic guidance frame was performed by Labadie et al.7. The first robotic system and planning software applied in clinical cases was developed through collaboration between the ARTORG Center for Biomedical Engineering at the University of Bern and the Department of Otolaryngology at Bern University Hospital in Switzerland8,9,10,11. The planning software and system were later commercialized by a spin-off company.
Here, the authors present the protocol involved in performing robotic cochlear implantation with a dedicated robotic cochlear implantation system. The aspects of selecting suitable patients, preoperative planning of the access tunnel, and the complete surgical procedure are covered and discussed. The aim of this article is to present an overview of the procedure and share the authors&#39; experience with the system.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Cochlear implant</td>
			<td>MED-EL, Austria</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>HEARO Consumable Set</td>
			<td>CAScination, Switzerland</td>
			<td>REF 50176</td>
			<td>CE-labelled</td>
		</tr>
		<tr>
			<td>HEARO Instrument Set</td>
			<td>CAScination, Switzerland</td>
			<td>REF 30123</td>
			<td>CE-labelled</td>
		</tr>
		<tr>
			<td>HEARO System Components</td>
			<td>CAScination, Switzerland</td>
			<td></td>
			<td>CE-labelled</td>
		</tr>
		<tr>
			<td>Mobile cone beam CT scanner</td>
			<td>XORAN Xcat</td>
			<td></td>
			<td>if not availalbe, imaging needs to be performed in the neuroradiological department</td>
		</tr>
		<tr>
			<td>OTOPLAN</td>
			<td>CAScination, Switzerland</td>
			<td>REF 20125</td>
			<td>CE-labelled</td>
		</tr>
		<tr>
			<td>Planning laptop</td>
			<td></td>
			<td></td>
			<td>Any computer with enough performance is suitable, software OTOPLAN installed</td>
		</tr>
		<tr>
			<td>USB Stick</td>
			<td></td>
			<td></td>
			<td>A surgical plan that was created with OTOPLAN is transferred to the HEARO system via a USB flash drive.</td>
		</tr>
	</tbody>
</table>

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 particularly suitable for cases with difficult anatomical conditions. Here, the postoperative results in a patient with far advanced otosclerosis are presented. Figure 1 shows a preoperative CT image. The advanced state of otosclerosis has disintegrated the petrous bone, making the cochlea hardly discernible.
The postoperative outcome is illustrated in Figure 2. The small tunnel access can be seen. In this case, surgical planning was used to preoperatively identify an optimal insertion access to the inner ear. The successful insertion of the electrode array can be seen, with an angular insertion depth of about 270&#176;.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/64047/64047fig01.jpg" /> 
Figure 1: Robotic cochlear implantation in a patient with far-advanced otosclerosis. Axial computed tomography slice of the left temporal bone shows the barely discernible cochlea (red ellipse). <a href="https://www.jove.com/files/ftp_upload/64047/64047fig01large.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/64047/64047fig02.jpg" /> 
Figure 2: Robotic cochlear implantation in a patient with far-advanced otosclerosis. Postoperative image showing the drilled tunnel and the inserted electrode array. <a href="https://www.jove.com/files/ftp_upload/64047/64047fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

Watch this Scientific Journal Video about Robotic Cochlear Implantation for Direct Cochlear Access at JoVE.com

Robotic Cochlear Implantation for Direct Cochlear Access

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 ...

robotic-cochlear-implantation-for-direct-cochlear-access

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2.9K Views.  University of Bern. 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.

Video: Robotic Cochlear Implantation for Direct Cochlear Access

Techniques for Processing Eyes Implanted with a Retinal Prosthesis for Localized Histopathological Analysis: Part 2 Epiretinal Implants with Retinal Tacks

Retinal prostheses for the treatment of certain forms of blindness are gaining traction in clinical trials around the world with commercial devices currently entering the market. In order to evaluate the safety of these devices, in preclinical studies, reliable techniques are needed. However, the hard metal components utilised in some retinal implants are not compatible with traditional histological processes, particularly in consideration for the delicate nature of the surrounding tissue. Here we describe techniques for assessing the health of the eye directly adjacent to a retinal implant secured epiretinally with a metal tack.
Retinal prostheses feature electrode arrays in contact with eye tissue. The most commonly used location for implantation is the epiretinal location (posterior chamber of the eye), where the implant is secured to the retina with a metal tack that penetrates all the layers of the eye. Previous methods have not been able to assess the proximal ocular tissue with the tack in situ, due to the inability of traditional histological techniques to cut metal objects. Consequently, it has been difficult to assess localized damage, if present, caused by tack insertion.
Therefore, we developed a technique for visualizing the tissue around a retinal tack and implant. We have modified an established technique, used for processing and visualizing hard bony tissue around a cochlear implant, for the soft delicate tissues of the eye. We orientated and embedded the fixed eye tissue, including the implant and retinal tack, in epoxy resin, to stabilise and protect the structure of the sample. Embedded samples were then ground, polished, stained, and imaged under various magnifications at incremental depths through the sample. This technique allowed the reliable assessment of eye tissue integrity and cytoarchitecture adjacent to the metal tack.

Here we describe histological techniques for visualising ocular tissue directly adjacent to a metal epiretinal tack and retinal prosthesis.

Retinal prostheses for the treatment of certain forms of blindness are gaining traction in clinical trials around the world with commercial devices ...

The Mouse Round-window Approach for Ototoxic Agent Delivery: A Rapid and Reliable Technique for Inducing Cochlear Cell Degeneration

Investigators have utilized a wide array of animal models and investigative techniques to study the mammalian auditory system. Much of the basic research involving the cochlea and its associated neural pathways entails exposure of model cochleae to a variety of ototoxic agents. This allows investigators to study the effects of targeted damage to cochlear structures, and in some cases, the self-repair or regeneration of those structures. Various techniques exist for delivery of ototoxic agents to the cochlea. When selecting a particular technique, investigators must consider a number of factors, including the induction of inadvertent systemic toxicity, the amount of cochlear damage produced by the surgical procedure itself, the type of lesion desired, animal survivability, and reproducibility/reliability of results. Currently established techniques include parenteral injection, intra-peritoneal injection, trans-tympanic injection, endolymphatic sac injection, and cochleostomy with perilymphatic perfusion. Each of these methods has been successfully utilized and is well described in the literature; yet, each has various shortcomings. Here, we present a technique for topical application of ototoxic agents directly to the round window niche. This technique is non-invasive to inner ear structures, produces rapid onset of reliably targeted lesions, avoids systemic toxicity, and allows for an intra-animal control (the contra-lateral ear). Results stemming from this approach have helped deeper understanding of auditory pathophysiology, cochlear cell degeneration, and regenerative capacity in response to an acute injury. Future investigations may use this method to conduct interventional studies involving gene therapy and stem cell transplantation to combat hearing loss.

Various methods exist for introducing ototoxic agents to the cochleae of animal models. Presented is a surgical protocol for delivery of ototoxic agents to the round window niche. The procedure is reliable, creates targeted intra-cochlear lesions, and avoids mechanical damage to the microarchitecture. Examination of cochlear self-repair/regeneration is possible.

Investigators have utilized a wide array of animal models and investigative techniques to study the mammalian auditory system. Much of the basic research ...

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 ...

Intrathecal Application of a Fluorescent Dye for the Identification of Cerebrospinal Fluid Leaks in Cochlear Malformation

In cases of cerebrospinal fluid (CSF) leaks, reliable detection of their origins is needed to seal the leak sufficiently and prevent complications, such as meningitis. A method is presented here using intrathecal administered fluorescein in a clinical case of bilateral congenital ear malformation. A fluorescent dye is administered intrathecally to achieve intraoperative visualization of CSF leaks. The dye is applied 20 min before surgery, and concentration of 5% is used. Per every 10 kg of body weight, 0.1 mL of the fluid is applied intrathecally. The fluorescein is visualized using a fully digital microscope. The origin of the fluid leak is identified in the stapes footplate. During primary surgery, it is sealed, and cochlea implantation is performed for hearing restoration. In this specific case, 6 weeks later, the implant was explanted due to acute meningitis, and the electrode array was left as a spacer. Postoperatively, in the aural smear, &#946;-transferrin was detected. During a revision mastoidectomy, dislocated coverage of the leak was found. The stapes was removed and oval window sealed. Five days after revision surgery, no &#946;-transferrin was detected in the aural smear. During the revision of cochlea implantation 6 months later, intact coverage of the oval niche was observed. Thus, intrathecal fluorescein application proves to be a reliable tool for the detection of CSF leaks. It facilitates the orientation in malformations and complicated or unknown surgical situs. In the literature, its use is described for CSF fistulas in endonasal surgery but is rarely described in skull base and mastoid surgeries. The method has been used successfully in several cases with CSF leaks, and the results confirm the feasibility of safely accessing the origin of the leak.

Intrathecally applied fluorescein is used to achieve intraoperative visualization of CSF leaks. This protocol describes a lumbar puncture, the application of 5% fluorescein, and intraoperative visualization using a fully digital microscope.

In cases of cerebrospinal fluid (CSF) leaks, reliable detection of their origins is needed to seal the leak sufficiently and prevent complications, such ...

Implantation of Human-Sized Coronary Stents into Rat Abdominal Aorta Using a Trans-Femoral Access

Percutaneous coronary intervention (PCI), combined with the deployment of a coronary stent, represents the gold standard in interventional treatment of coronary artery disease. In-stent restenosis (ISR) is determined by an excessive proliferation of neointimal tissue within the stent and limits the long-term success of stents. A variety of animal models have been used to elucidate pathophysiological processes underlying in-stent restenosis (ISR), with the porcine coronary and the rabbit iliac artery models being the most frequently used. Murine models provide the advantages of high throughput, ease of handling and housing, reproducibility, and a broad availability of molecular markers. The apolipoprotein E deficient (apoE-/- ) mouse model has been widely used to study cardiovascular diseases. However, stents must be miniaturized to be implanted into mice, involving important changes of their mechanical and (potentially) biological properties. The use of apoE-/- rats can overcome these shortcomings as apoE-/- rats allow for the evaluation of human-sized coronary stents while at the same time providing an atherogenic phenotype. This makes them an excellent and reliable model to investigate ISR after stent implantation. Here, we describe, in detail, the implantation of commercially available human coronary stents into the abdominal aorta of rats with an apoE-/- background using a trans-femoral access.

This protocol describes the implantation of human coronary stents into the abdominal aorta of rats with an apoE-/- background using a trans-femoral access. Compared with other animal models, murine models carry the advantages of high throughput, reproducibility, ease of handling and housing, and a broad availability of molecular markers.

Percutaneous coronary intervention (PCI), combined with the deployment of a coronary stent, represents the gold standard in interventional treatment of ...

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 ...

The Miniature Pig: A Large Animal Model for Cochlear Implant Research

Cochlear implants (CI) are the most effective method to treat people with severe-to-profound sensorineural hearing loss. Although CIs are used worldwide, no standard model exists for investigating the electrophysiology and histopathology in patients or animal models with a CI or for evaluating new models of electrode arrays. A large animal model with cochlea characteristics similar to those of humans may provide a research and evaluation platform for advanced and modified arrays before their use in humans. 
To this end, we established standard CI methods with Bama mini-pigs, whose inner ear anatomy is highly similar to that of humans. Arrays designed for human use were implanted into the mini pig cochlea through a round window membrane, and a surgical approach followed that was similar to that used for human CI recipients. Array insertion was followed by evoked compound action potential (ECAP) measurements to evaluate the function of the auditory nerve. This study describes the preparation of the animal, surgical steps, array insertion, and intraoperative electrophysiological measurements. 
The results indicated that the same CI used for humans could be easily implanted in mini-pigs via a standardized surgical approach and yielded similar electrophysiological outcomes as measured in human CI recipients. Mini-pigs could be a valuable animal model to provide initial evidence of the safety and potential performance of novel electrode arrays and surgical approaches before applying them to human beings.

Miniature pigs (mini-pigs) are an ideal large animal model for research into cochlear implants. Cochlear implantation surgery in mini-pigs can be utilized to provide initial evidence of the safety and potential performance of novel electrode arrays and surgical approaches in a living system similar to human beings.

Cochlear implants (CI) are the most effective method to treat people with severe-to-profound sensorineural hearing loss. Although CIs are used worldwide, ...

Systematic Hearing Performance Evaluation Process for Adolescents with Cochlear Implantation at Early Ages

Cochlear implant (CI) provision is the most effective clinical treatment to restore hearing performance in individuals with profound sensorineural hearing loss (SNHL). It has been successful in providing improved speech perception outcomes, especially in quiet environments. However, speech perception performance within complex environments, lexical tone recognition, and music perception have been shown to only improve with newer fine structure coding strategies or related techniques. Therefore, the methods used to assess hearing performance in noisy environments, lexical tone recognition, and music perception are of vital importance. These assessments must reflect the postoperative outcomes and also provide guidance for the programming, rehabilitation, and application of new coding strategies. In this study, hearing performance in simple and complex situations was evaluated before and after upgrading to a fine structure strategy. The participants were a cohort of Mandarin-speaking adolescents, who were experienced CI users. The comprehensive clinical workflow involved assessments of speech in quiet conditions, speech in noisy conditions, lexical tone recognition, and music perception. This battery of tests is explained in detail, from the coding strategy to the test methods, including the test process, environment, device, material, and order. The details that require special attention are discussed, such as the position of the participants, the angle of the loudspeaker, the intensity of the sound, the noise type, the practice test, and the way of answering questions. Each test step, method, and material for speech, lexical tone, and music perception is presented in detail. Finally, the clinical results are discussed.

This paper describes a battery of tests used to clinically assess the hearing performance of adolescent, Mandarin-speaking, experienced cochlear implant users upgraded to a new fine structure coding strategy. The battery of tests include speech in quiet conditions, speech in noisy conditions, lexical tone, and music perception.

Cochlear implant (CI) provision is the most effective clinical treatment to restore hearing performance in individuals with profound sensorineural hearing ...

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 ...