Exoscopic surgery of lateral skull base

8.1

Introduction

Literature includes some studies about the use of an exoscope in neurosurgery, either as an exclusive instrument or in combination with the microscope.

The use of the operative exoscope has recently been introduced in head and neck surgery, and there are only a few studies in the literature regarding this kind of exoscopic surgery. Lateral skull-base surgery is traditionally performed mainly using the operative microscope, in some cases with endoscopic assistance.

Some of the limitations of the operative microscope are its large frame and its fixed cumbersome design. It also forces the primary surgeon and his assistants to have fixed positions around the operative field with limited visual angles. Moreover, the operative microscope screens oblige the assistants to follow the surgical procedure with a two-dimensional view because only the surgeon has a stereoscopic vision.

Conversely, endoscopic surgery allows for an ergonomic position of the surgeon with a horizontal gaze and an angled vision “behind the corner.”

Exoscopic surgery is a new surgical technique that has the purpose of using the exoscope to replace the microscope during surgical approaches, it requires the use of a classic two-handed surgery, as it happens in microscopic surgery, while looking at the monitor, where the exoscopic vision is shown.

Exoscopic surgery combines the features of an endoscopic surgical approach as the surgeon works looking at the monitor positioned in front of him/her and the microscopic surgical technique, because the surgeon works with two hands.

However, exoscopic surgery requires adequate training to learn the simultaneous coordination of the hands with the images appearing on the monitor. This technique needs previous training on endoscopic and microscopic surgery because the skills deriving from both techniques are necessary to perform surgery using the exoscope.

Exoscopes are produced by various companies and provide high-resolution imaging and two different kinds of view: two-dimensional (2D) or three-dimensional (3D).

In both the 2D and 3D exoscopes, the images are displayed on 4K high-definition monitors that can enhance anatomical details and make them more realistic.

A 2D exoscope has a 2D vision that is not overcome by the movement of the instrument in the surgical field, as it happens in endoscopic surgery, so it is especially used for video recordings and teaching reasons. On the other hand, the use of a 3D exoscope has 3D vision and allows both residents and fellows to follow the surgical procedure in the same way as the first surgeon.

This chapter is based on our experience with the VITOM 3D exoscope (Karl Storz GmbH, Tuttlingen, Germany) system on lateral skull-base surgical management. We will here describe the use of exoscopic surgery in the surgical treatment of lateral skull-base lesions.

8.2

Exoscopic approaches to lateral skull base

A 3D exoscope can be used as an operative tool to perform surgical procedures in the lateral skull base, replacing the microscope in the majority of cases.

Like every operative tool, the exoscope presents both advantages and disadvantages.