Exoscope-assisted laser laryngeal surgery

4.2.1.1

Surgical setting

The idea of overcoming the limitations of the operative microscope and fully replicate a transoral laser microsurgery (TOLMS) setting, coupling the free-beam CO ₂ laser micromanipulator with the new exoscopic system, radically changed the system of visualization and led to novel difficulties and shortcomings. In fact, the technologies employed were not conceived to be assembled in a transoral microsurgical setting. To make them work efficiently as a whole, several adaptations were needed, especially in terms of stability, paring, and movement.

As an exoscopic system of vision, the VITOM 3D-HD (Karl Storz SE & Co. KG, Tuttlingen, Germany) was employed. Since it was conceived to enhance visualization quality in micro and open surgical procedures, the VITOM 3D-HD was equipped with a thin and lightweight holding system called VERSACRANE LIGHT. While being very compact and wieldy to hold the VITOM in position, the VERSACRANE did not have sufficient stability when the first tests with the laser micromanipulator were carried out. In particular, many vibrations affecting the frame resulted in unstable vision during laser positioning and movements, probably due to the extra weight of the manipulator that the holding system was not designed to support. This issue revealed the necessity to substitute the VERSACRANE with a new holder, specifically conceived to firmly support the weight of the VITOM and micromanipulator simultaneously in a transoral laser microsurgical setting. Thus, a customized support arm ( Fig. 4.1 ) was created in collaboration with the IIT, designed to be mounted on a Zeiss microscope stative, removing the optic system. The holder arm was provided with a handle to allow macroscopic movements and positioning, knobs to lock all joints in place once the definitive position of the support structure was reached, and a specific regulatory wheel for precise adjustments of the framing angle. A specific adaptor plate (model TH004 Micromanipulator Interface VITOM, installation of CO ₂ laser micromanipulators on VITOM 3; Karl Storz SE & Co. KG, Tuttlingen, Germany) was designed by IIT engineers and fixed to the holder arm to allow for coupling with the micromanipulator, so that the micromanipulator could be stably fixed in a position aligned with the line of sight of the VITOM 3D-HD.

With this prototype of the exoscope-assisted transoral laser microsurgical setting, the essential requisites for precise alignment between the line of sight of the exoscope through the laryngoscope and laser micromanipulator workspace were achieved. Moreover, the ideal operating distance between the laser scanner and surgical target was precisely established to optimize the “char-free” cutting properties of the laser. The methods followed for these adjustments are thoroughly described in a previous publication.

Besides helping the first surgeon in traditional TOLM with external counterpressure on the larynx and cooperating to a surgical maneuver with suction or other surgical tools, with the exoscopic system the assistant surgeon can constantly follow the procedure on the 3D surgical screen and, if needed, zoom in on a particular target, regulate focus, and slightly move the framing to follow the first surgeon's maneuvers using the IMAGE1 PILOT control device, directly fixed on the left side of the operating bed (see also Chapter 1 ).

The preliminary results with this novel prototype in alternative to the traditional TOLMS, were obtained in 17 nonconsecutive oncological cases.

4.2.1.2

Adaptability to fiber laser procedures

An additional advantage of this setting can be employed by removing the CO2 laser micromanipulator from its adaptor plate on the VITOM holder arm and using a fiber laser with different wavelength with less precise and char-free cut, but a better control of hemostasis, in relation to the site and type of resection. This offers the simultaneous availability to employ 3D angled telescopes for different indications or different surgical steps of the same procedure.

In our experience, a flexible fiber tulium/diode laser was utilized when the disease involved one of the supraglottic subsites in the presence of extensions to the medial hypopharyngeal wall or to the base of the tongue. During the preparation of this setting, a good suggestion is to move the exoscope slightly away from the laryngoscope/mouth-gag compared to the CO ₂ laser setup, thereby offering a wider operative field and avoiding competition between surgical instruments, which is not easily feasible with the standard operative microscope.