An Endoscopic Transcanal Transpromontorial Approach for Vestibular Schwannomas using a Computer-Based Three-Dimensional Imaging System

Summary

Here, we present a transcanal transpromontorial approach for vestibular schwannomas using a computer-based three-dimensional (3D) imaging system combined with a two-dimensional (2D) endoscope. This system provided stereoscopic vision, better depth perception and reduced visual fatigue. This 3D imaging system enabled the application of 3D vision technology in endoscopic lateral skull base surgery.

Abstract

A 2D monocular endoscope has been used in transcanal transpromontory vestibular schwannoma surgery instead of craniotomy. However, the absence of depth perception is the limitation of this approach. With the loss of depth perception, the surgeon will be not able to perform delicate and particularly complicated surgery. A binocular endoscope has been developed to provide stereoscopic vision with better depth perception for complicated anatomic structures and has been applied in some endoscopic surgeries. However, the diameter of the endoscope is a limitation in the performance of transcanal otologic surgeries. A small diameter endoscope facilitates easier surgery in a restricted space. A computer-based 3D imaging system can obtain 3D images in real-time using a small monocular endoscope. In this study, to evaluate the feasibility of a computer-based 3D imaging system for endoscopic lateral skull base surgery, we applied this 3D imaging system in a transcanal transpromontorial approach in two patients with vestibular schwannomas. The surgical procedure was completed without complication in these two cases. There was no mortality, perioperative complications, nor notable postoperative complications. Using this computer-based 3D imaging system, a better depth perception and stereoscopic vision was observed compared to a conventional 2D endoscope. The improvement in depth perception offers superior management of the complicated surgical anatomy.

Introduction

Minimally invasive surgery has become mainstream. Many techniques have been developed, such as the da Vinci robot system and the endoscope. However, the equipment and cost of da Vinci robotic surgery are bulky and very high, respectively. Compared to the conventional craniotomy surgery, the endoscopic transcanal transpromontorial approach for resection of vestibular schwannoma has been developed to decrease the risks of vestibular dysfunction and cerebrospinal fluid leak¹. However, lack of stereoscopic vision is still the main limitation of endoscopic surgery, especially for complicated ear surgeries². Hence, the 3D endo....

Protocol

The protocol follows the guidelines of Chang Gung Memorial Hospital’s Human Research Ethics Committee. Ethical approval for the experiment was obtained from the Institutional Review Board of the hospital (IRB No. 201600593B0).

1. Patient position and skin marking

1. After general anesthesia, place the patient in a supine position on the operating table, with the head gently rotated to the contralateral side and elevated 15–30°.
2. Elevate the head of the bed ap.......

Discussion

Endoscopic ear surgery has become more popular. However, the main limitation is the lack of stereoscopic vision when compared to a microscopic surgery. The use of a 3D endoscope may be difficult in transcanal ear surgery because of the limited space in the external ear canal. In this study, we applied a 3D computer-based processing system with a conventional 2D endoscope in the transcanal transpromontorial approach for vestibular schwannoma resection and evaluated its clinical feasibility for lateral skull base surgery. .......

Materials

Name	Company	Catalog Number	Comments
2D endoscope HOPKINS Straight Forward Telescope 0, with 3, 2.7,1.9 mm diameter	Karl Storz, Germany	7220AA, 7220BA, 7220FA, 7229AA 1232A
3D medical LCD monitor LMD-2451 MT	Sony, Japan	22220055-3 9524 N 22201020-1xx	Image 1 Hub HD
computer-based 3D imaging system	Shinko Optical, Japan	HD-3D-A
Piezosurgery instrument	Mectron, Carasco/Genova, Italy	MP3-a30