Exoscope-assisted microlaryngeal surgery

3.1

The introduction of exoscopes in microlaryngeal surgery

The use of the operating microscope in laryngology was first introduced in 1960 by Scalco, Shipman, and Tabb in New Orleans, United States. In their work, they described the applicability of a Zeiss binocular microscope, designed for otologic surgery, with the Lynch suspension laryngoscope to treat small, benign lesions, confined to the true vocal folds. However, it is up to Oskar Kleinsasser to have refined the methodic and to have spread it from 1968 onwards throughout the world. Indeed, the technique, as described by Scalco and colleagues, showed several limits: the magnification was inadequate, the equipment was unwieldy, and the customary laryngoscopes were not suitable for binocular vision. Furthermore, the short focal length of the Zeiss microscope was not adequate for long-shafted laryngeal instruments. In this scenario, Dr. Kleinsasser has developed a laryngoscope larger and tapered, thus allowing to accomplish the binocular vision and bimanual surgery. ^, By the same time, Zeiss had introduced a 400 mm focal lens that permitted an easier use of the long steeled laryngeal instruments for precision surgery of the vocal folds with vastly improved functional results.

Microlaryngeal surgery nowadays (MLS) is a technique that provides for direct examination of the larynx as well as for treatment of benign and malign diseases of the larynx and phonomicrosurgery, using an operating microscope. The use of an operating microscope is preferred over an external surgical approach as it is far less invasive and leads to significantly less intraoperative and postoperative complications such as damage to the blood vessels with consequent significant blood loss, damage to the nerves (particularly CN X) leading to dysphonia and dysphagia, scarring, and postoperative wound infections. MLS also reduces the operating time, the length of hospitalization, and the length of recovery for the patient, thus also bringing economic benefits to the hospital and health benefits to the patient.

MLS is performed under general anesthesia. The operating laryngoscope (Kleinsasser laryngoscope) is used to expose the vocal folds. The patient is laid in a supine position with the head slightly hyperextended, and the operating microscope is positioned behind the patient's head. The laryngoscope is attached to a laryngosuspension apparatus consisting of an adjustable rod anchored to the operating bed. Microlaryngoscopy can be performed with either “cold” instruments or with a CO ₂ laser.

Although the traditional operating microscope is an essential surgical instrument to perform fine and delicate surgeries, like microlaryngeal surgery, technological advancements have introduced the exoscope as a potential substitute. Karl Storz's video telescope operating monitor or “VITOM” was released in 2011. Originally, it was equipped only with 2D platforms, while the VITOM 3D exoscope was launched in 2017.

In 2012, Carlucci et al. first described the use of an exoscope in endoscopic laryngeal surgery. They treated 12 patients with benign and malign pathologies of the vocal folds, using a telescope (VITOM, Karl Storz) equipped with a high-definition endoscopic video system, showing its potential advantages in terms of ease and comfort of the surgeon.

This chapter aims to describe thoroughly the technical characteristics of the exoscopic microlaryngeal surgery, analyzing its feasibility and suitability, with a particular mention to the authors' experience.

3.2

Surgical procedure and setting

The patient is in a supine position with the head extended on the neck and the neck flexed on the chest (Boyce–Jackson position). General anesthesia is carried out through orotracheal intubation and the operating laryngoscope is used to expose the glottic plane, and then attached to a fulcrum-type laryngosuspension apparatus, consisting of an adjustable rod anchored to the operating table. The VITOM 3D operating exoscope mounted on the VERSACRANE holding system is placed behind the patient's head, about 35–45 cm from the operating field ( Fig. 3.1 ).

The vertical column equipped with the monitor (IMAGE1 S platform) and the light source is placed in front of the main surgeon, sitting behind the patient's head, while the scrub nurse stands on the right side of the patient. The assistant surgeon can position himself or herself on the left side of the patient's head. From this position, he or she is able to constantly adjust the framing and the focusing of the image, thanks to the IMAGE1 PILOT control joystick, by looking at the same 3D-HD screen. At the same time, the assistant surgeon can hold the suction or other surgical instruments and can make external counterpressure on the larynx, if needed. Indeed, when it is not possible to visualize the vocal folds up to the anterior commissure, it is possible to optimize such exposure using different maneuvers, such as external laryngeal counterpressure and flexion–flexion position. Other operating room (OR) members, such as students, should position themselves behind the main surgeon to maintain a perpendicular view of the screen. The disposition of the nurse's master table and secondary table, as well as the anesthesia device or other surgical devices in the OR, is not further influenced by the application of this setting and is totally similar to a traditional procedure.

The basic setup of the operating room is shown in Fig. 3.2 .