Transcanal Cochlear Implantation Under Monitored Anesthesia Care

Common challenges in cochlear implant surgery performed under local anaesthesia and how to overcome them: the experience of UK surgeons

BACKGROUND

Cochlear implantation performed under local anaesthesia is an increasingly accepted technique worldwide, though the literature to date includes only single-surgeon and single-centre experiences. This study explored the national experience of UK surgeons using this challenging surgical technique, with the goal of providing consensus recommendations.

METHODS

A qualitative analysis was conducted of semi-structured interviews with 10 UK-based cochlear implantation surgeons, focusing on common challenges, how to overcome them and candidate selection.

RESULTS

Cochlear implantation under local anaesthesia can potentially be offered to all eligible adult patients with favourable anatomy. A posterior tympanotomy and round window approach is recommended. Common challenges and recommendations are explored thematically: managing patient, surgeon and staff expectations; optimising communication; patient comfort and position; minimising pain and vertigo; and safe use of sedation.

CONCLUSION

This is the first study of national experience of cochlear implantation performed under local anaesthesia. Key themes, including refinements to surgical technique and optimising patient comfort and communication, have been explored in depth.

Cochlear implantation under local anesthetic: A systematic review and meta-analysis

OBJECTIVES

As the population ages and implantation criteria are relaxed, more patients with complex comorbidities are becoming eligible for cochlear implantation (CI). These patients have higher risks associated with general anesthesia. This systematic review assesses outcomes and complications following CI under local anesthetic to examine utility for patients deemed not suitable or at high risk for general anesthesia.

METHODS

A systematic review and meta-analysis performed according to the 2020 PRISMA guidelines. Databases searched were MEDLINE, PubMed, EMBASE, CINAHL, Web of Science Core Collection, Cochrane Database of Systematic Reviews, and Cochrane Central Register of Controlled Trials and ClinicalTrials.gov. There were no limitations on year of publication or language.

RESULTS

Then, 132 unique were identified. After screening abstracts and full texts for eligibility criteria a total of 18 articles were included. In the nine studies where audiological data were reported, all patients demonstrated improvement in audiological outcomes following implantation under local anesthetic (LA). Only minor complications of transient vertigo, wound infection, facial nerve paralysis, confusion, and tinnitus were reported but all were transient. Meta-analysis showed surgical time was significantly shorter under LA.

CONCLUSIONS

CI under LA is safe for patients with comorbidities which preclude them from general anesthesia, with minimal complications and an improved cost-effectiveness profile. However, larger scale, robust trials are required to assess this further.

Cochlear Implantation Under Local Anesthesia With Conscious Sedation in the Elderly: First 100 Cases

OBJECTIVE

To report the outcomes on a large series of elderly patients who underwent cochlear implantation (CI) surgery under local anesthesia with conscious sedation (LA-CS).

METHODS

Retrospective chart review on 100 consecutive elderly patients (> 65 years) who underwent CI with LA-CS at a tertiary care center between August 2013 and January 2020. An age-matched control group of 50 patients who underwent CI with general anesthesia (GA) are used for comparison. Outcomes measured included time in the operating room, time in the postanesthesia care unit (PACU), and rate of adverse events.

RESULTS

Cochlear implant surgery under LA-CS was successfully performed in 99 (99%) patients. One patient requiring conversion to GA intraoperatively. No patients in the LA-CS group experienced cardiopulmonary adverse events; however, three patients (6%) in the GA group experienced minor events including atrial fibrillation and/or demand ischemia. Overnight observation in the hospital due to postoperative medical concerns or prolonged wake-up from anesthesia was required in one patient (1%) from the LA-CS cohort and 12 patients (24%) from the GA cohort. Perioperative adverse events exclusive to the LA-CS group included severe intraoperative vertigo (8%), temporary facial nerve paresis (3%), and wound infection (1%). The average amount of time spent in the operating room was 37 minutes less for procedures performed under LA-CS compared to GA (P < .05). The average amount of time in recovery was similar for both groups (P > .05).

CONCLUSION

Cochlear implant surgery under LA-CS offers many benefits and is a safe, feasible, and cost-effective alternative to GA when performed by experienced CI surgeons.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:E946-E951, 2021.

Cochlear implantation under local anesthesia: a possible alternative for elderly patients

Introduction

As average life-expectancy increases, a sufficient hearing rehabilitation for elderly patients with severe-to-profound sensorineural hearing loss becomes more important. Cochlear implantation is a relatively safe surgical procedure also for elderly patients, the higher risk is caused by general anesthesia. We report on four patients who underwent cochlear implantation under local anesthesia.

Methods

After detailed preoperative examinations (audiological tests, imaging, genetic tests, evaluation of motivation and compliance of the patient), four patient with severe-to-profound hearing loss were selected for cochlear implantation under local anesthesia. For the electrode insertion, we used the posterior suprameatal approach technique. Pre- and postoperative pure tone audiometry and speech-perception tests were conducted to prove the success of the procedure.

Results

The mentioned technique was applied; the average length of the operation was 52 min. The intraoperative measurements showed normal impedance and normal neuronal response telemetry, all the patients had sound experience during the intraoperative examination of the engineer. No complications were observed. The postoperative audiological tests showed a significant increase in the hearing perception.

Conclusion

Cochlear implantation under local anesthesia is a safe and fast procedure for elderly patients. The intraoperative sound experience can give an extra motivation in the postoperative rehabilitation. Our results prove that by carefully selected elderly patients cochlear implantation can assure a significant increase in speech perception. We can establish that the new posterior suprameatal approach technique combined with local anesthesia presents a viable future option for those patients who were inoperable beforehand because of high risks of general anesthesia.

Conscious sedation and local anesthesia for patients undergoing neurotologic and complex otologic procedures

OBJECTIVE

Is conscious sedation an effective, safe, and efficient anesthetic choice in patients undergoing select neurotologic and otologic procedures?

STUDY DESIGN

Retrospective case review.

SETTING

Tertiary referral center.

PATIENTS

Six patients underwent eight neurotologic procedures including cerebrospinal fluid leak and encephalocele repair, and primary and revision cochlear implant surgery. Patients were deemed poor candidates for general anesthesia secondary to medical comorbidities. These were compared to 11 control patients who underwent same procedures under general anesthesia with intubation.

INTERVENTION

Dexmedetomidine infusion was utilized as the primary agent for conscious sedation in this high-risk patient population because, unlike other commonly used sedatives, it preserves normal respirations while providing adequate analgesia.

MAIN OUTCOME MEASURES

Preoperative Physiological and Operative Severity Score for the enUmeration of Mortality and Morbidity (P-POSSUM) scores were calculated for the study group. We measured total anesthesia, and perioperative and recovery times. Cost of anesthetic agents was considered and any adverse effects were noted. Patient satisfaction with the operative experience was assessed with telephone surveys.

RESULTS

P-POSSUM scores were high for the study group. Postoperative anesthesia was shorter for the study patients undergoing conscious sedation. Difference in cost of anesthetic agents was negligible. The adverse effects were few and as expected for the type of procedure. Patients reported satisfaction and comfort with their operative experience.

CONCLUSION

Select neurotologic and otologic procedures can be safely, effectively, and efficiently performed under conscious sedation with dexmedetomidine infusion as the primary anesthetic choice for patients who are deemed poor medical candidates for general endotracheal anesthesia.

Accuracy of linear drilling in temporal bone using drill press system for minimally invasive cochlear implantation

PURPOSE

A minimally invasive approach for cochlear implantation involves drilling a narrow linear path through the temporal bone from the skull surface directly to the cochlea for insertion of the electrode array without the need for an invasive mastoidectomy. Potential drill positioning errors must be accounted for to predict the effectiveness and safety of the procedure. The drilling accuracy of a system used for this procedure was evaluated in bone surrogate material under a range of clinically relevant parameters. Additional experiments were performed to isolate the error at various points along the path to better understand why deflections occur.

METHODS

An experimental setup to precisely position the drill press over a target was used. Custom bone surrogate test blocks were manufactured to resemble the mastoid region of the temporal bone. The drilling error was measured by creating divots in plastic sheets before and after drilling and using a microscope to localize the divots.

RESULTS

The drilling error was within the tolerance needed to avoid vital structures and ensure accurate placement of the electrode; however, some parameter sets yielded errors that may impact the effectiveness of the procedure when combined with other error sources. The error increases when the lateral stage of the path terminates in an air cell and when the guide bushings are positioned further from the skull surface. At contact points due to air cells along the trajectory, higher errors were found for impact angles of [Formula: see text] and higher as well as longer cantilevered drill lengths.

CONCLUSION

The results of these experiments can be used to define more accurate and safe drill trajectories for this minimally invasive surgical procedure.

Clinical validation of percutaneous cochlear implant surgery: initial report

OBJECTIVE

Percutaneous cochlear implant surgery consists of a single drill path from the lateral mastoid cortex to the cochlea via the facial recess. We sought to clinically validate this technique in patients undergoing traditional cochlear implant surgery.

STUDY DESIGN

Prospective clinical trial.

METHODS

After institutional regulatory board-approved protocols, five ears were studied via the following steps. 1) In the clinic under local anesthesia, bone-implanted anchors were placed surrounding each mastoid. 2) Temporal-bone computed tomography (CT) scans were obtained. 3) On the CT scans, paths were planned from the lateral mastoid cortex, through the facial recess, to the basal turn of the cochlea both "manually" and "automatically" using computer software. 4) Customized microstereotactic frames were rapid-prototyped to serve as drill guides constraining the drill to follow the appropriate path. 5) During cochlear implant surgery, after drilling of the facial recess, drill guides were mounted on the bone-implanted anchors. 6) Accuracy of paths was assessed via intraoperative photodocumentation.

RESULTS

All surgical paths successfully traversed the facial recess and hit the basal turn of the cochlea. Distance in millimeters (average +/- SD) from the midpoint of the drill to the facial nerve was 1.18 +/- 0.68 for the "manual" path and 1.24 +/- 0.44 mm for the "automatic" path and for the chorda tympani 0.986 +/- 0.48 for the "manual" path and 1.22 +/- 0.62 for the "automatic" path.

CONCLUSIONS

Percutaneous cochlear implant access using customized drill guides based on preoperative CT scans and image-guided surgery technology can be safely accomplished.

Percutaneous cochlear access using bone-mounted, customized drill guides: demonstration of concept in vitro

HYPOTHESIS

Percutaneous cochlear access can be performed using bone-mounted drill guides that are custom made on the basis of preintervention computed tomographic scans.

BACKGROUND

We have previously demonstrated the ability to use image guidance based on fiducial markers to obtain percutaneous cochlear access in vitro. A simpler approach that has far less room for application error is to constrict the path of the drill to pass in a predetermined trajectory using a drill guide.

METHODS

Cadaveric temporal bone specimens (n = 8) were affixed with three bone-implanted fiducial markers. The temporal bone computed tomographic scans were obtained and used in planning a straight trajectory from the mastoid surface to the cochlea without violating the boundaries of the facial recess, namely, the chorda tympani, the incus buttress, and the facial nerve. These surgical plans were used to manufacture a customized drill guide by means of rapid prototyping (MicroTargeting Platform; FHC Inc.; Bowdoinham, ME, U.S.A.) that mounts onto anchor pins previously used to mount fiducial markers. The specimens then underwent traditional mastoidectomy with facial recess. The drill guide was mounted, and a 1-mm drill bit was passed through the guide across the mastoid and the facial recess. The course of the drill bit and its relationship to the boundaries of the facial recess were photographed and measured.

RESULTS

Eight cadaveric specimens were subjected to the study protocol. In seven of eight specimens, the drill bit trajectory was accurate; it passed from the lateral cortex to the lateral wall of the cochlea without compromise of any critical structures. In one specimen, the access to the middle ear was achieved, but the incus was hit by the drill. The average shortest distance +/- standard deviation from the edge of the drill bit to the boundaries of the facial recess was 0.78 +/- 0.56 mm (chorda tympani), 2.00 +/- 1.06 mm (incus buttress), and 1.27 +/- 0.54 mm (facial nerve).

CONCLUSION

Our study demonstrates the ability to obtain percutaneous cochlear access in vitro using customized drill guides manufactured on the basis of preintervention radiographic studies.