Mastoidotomy tympanotomy approach for cochlear implantation

Bilateral Anterior Displaced Sigmoid Sinus in Cochlear Implantation: A Proposed Solution

To assess the safety, time consumption and presumed postoperative complications of posterior repositioning in cases with bilateral anterior displaced sigmoid sinus (ADSS) having cochlear implant surgery. Cases with bilateral ADSS were included. A cortical bone chip was harvested. Sinus plate was drilled thin and removed, ADSS was repositioned posteriorly and secured by the bone chips. The procedure was completed using the standard posterior tympanotomy (PT) technique. Follow up was done both clinically and by computed tomography (CT). Out of 632 cases operated upon in more than 7 years, only 7 cases had Bilateral ADSS (1.1%) of which 5 were females (71.45%). The average age was 8.2 ± 12 (6 children and an adult). No intraoperative bleeding was encountered in any of the 7 cases. The average operative time was 103.6 ± 9.7 min. No minor nor major complications were detected in all 7 cases. To keep the advantages of PT, repositioning of ADSS in bilateral cases can be done safely with a reasonable increase in the average operative time.

Bhopal Technique of Cochlear Implantation: A Surgical Review of 50 Cases

Cochlear Implant is the new age treatment for profound deafness especially in children who are unable to hear since birth. This is a life changing technology where in a surgically implanted device can stimulate the auditory nerve through electrical currents enabling the generation of auditory potential. Various surgical techniques have been described in literature but debate exists over Posterior Tympanotomy and Trans-canal "Veria" technique. We are presenting our experience of 50 cases with modified trans-canal technique "The Bhopal Technique" which combines the best of both. 50 patients with bilateral profound deafness in age group 1-5 years were included in this observational study. These children underwent cochlear implantation by Bhopal Technique. The data was categorised into age, gender, certain surgical parameters like time taken; exposure and complications. In present study. The average time taken for surgery was 77.6 min, with electrode insertion in first attempt in about 43 cases. Round Window exposure was adequate in 37 cases while scala tympani was entered in 49 cases. Average time taken for cochleostomy was 44.6 s. Most common complication was wound hyperemia followed by Perilymph Gusher. Explantation was seen in 1 case. Minor complications included Vertigo and Tinnitus. There was one tympanic membrane perforation at 3 months follow up and response to AVT was excellent in 12 children at 6 month follow up. Bhopal technique is emerging as a promising technique for upcoming cochlear implant surgeons due to its low complication rate, better exposure of surgical landmarks and comparable outcomes to Veria and Posterior tympanotomy techniques.

Anatomy of the Round Window Region With Relation to Selection of Entry Site Into the Scala Tympani

OBJECTIVES/HYPOTHESIS

The aim of cochlear implantation is to safely insert an electrode array into the scala tympani (ST) while avoiding damage to surrounding structures. There is disagreement on the optimal way of entering the ST-the round window (RW) approach versus cochleostomy. Regardless of the chosen approach, it is vital to understand the regional anatomy, which is complex, difficult to conceptualize, and rarely dissected in temporal bone courses. The goal of this study was to examine the anatomy of the RW to gain more in-depth knowledge on the local relationships of the anatomical structures and propose an approach for entering the ST in cochlear implant surgery tailored to the encountered anatomy.

STUDY DESIGN

Cadaveric prevalence study and expert opinion with literature review.

METHODS

Cadaveric temporal bone dissection (n = 13) by the first author assessing the RW anatomy.

RESULTS

The round window membrane (RWM) and the osseous spiral lamina (OSL) are curved structures, each with a horizontal and a vertical part. The two horizontal portions are very closely apposed. The relationship between the OSL and the RWM determines the best site for a cochleostomy, which if required is best placed anteroinferiorly to the RWM. The distance between the oval window inferior margin and the RW membrane is less than 2 to 3 mm. The ST initially extends inferiorly and medially to the RW.

CONCLUSIONS

The findings of our dissection have implications for cochlear implant surgery in aiming to avoid trauma to the OSL and basilar membrane and aid decision making in choosing the safest surgical approach.

LEVEL OF EVIDENCE

5. Laryngoscope, 131:E598-E604, 2021.

Comparison of the Surgical Techniques and Robotic Techniques for Cochlear Implantation in Terms of the Trajectories Toward the Inner Ear

OBJECTIVES

The ideal outcome of cochlear implant surgery involves the insertion of the array inside the scala tympani of the cochlea with the least mechanical trauma. Recently, round window insertion and the direction in which the cochlea is approached have gained attention in this respect. The Angles of Cochlear Approach (ACA) can be defined with a plane in the plane of the basal turn, termed the in-plane angle, and the plane orthogonal to this plane, termed the out-plane angle. The aim of this study was to compare the trajectory angles for different surgical techniques of Veria, suprameatal, pericanal, and multiple posterior tympanotomy (PT) approaches, including an optimal trajectory that is simulated for robotic surgery.

MATERIALS AND METHODS

The trajectories of these surgical techniques were simulated on the same high-resolution computed tomography scan. The simulated trajectory angles were analyzed with dedicated software for medical images, defining the ACA and distances to critical otological structures.

RESULTS

The ACA are the smallest for surgical techniques that pass thought the PT. However, performing a surgical PT can include variability in the ACA, ranging from almost 0° to 20.8° in an out-plane angle, depending on how close a surgeon would approach the facial nerve. The Veria, Suprameatal approach (SMA), and peri-canal approaches have larger ACA and minimal distances to the ossicular chain and the ear canal. The maximum distance to the facial nerve and the widest out-plane angle is observe with a pericanal approach. The optimal PT approach refers to the trajectory without collisions and with the best possible ACA that can be planned.

CONCLUSION

Different surgical approaches yield important differences in the ACA. PT allows better ACA with maximum distances to the critical structures. However, the optimal PT trajectory simulated for robotic keyhole surgery is a further improvement on the trajectories through the facial recess.