IV. Navigation-3D-CA-RP-FESS-of the nose, paranasal sinuses, orbit, and the skull base

3D-CA (assisted)-navigation surgery-FESS-of the orbit, nose, paranasal sinuses and the scull base, with the use of computer assisted (CA)-RP (rapid prototyping) models (3D-CA-RP-FESS)
Dg. Rhinosinuitis chronica. Tm. sinus ethmoidalis anterior at posterior et orbitae lateris dextri. Destructio laminae papiraceae lateris dextri. Dislocatio bulbi occuli lateris dextri. Fractura multipl. septi nasi cum deviationem palatinalis lateris dextri (lamina qvadrangularis/perpendicularis) ar III-V.
Op.: Operatio et reconstructio functionalis septi nasi. Operatio sinus paranasales et orbitae lateris dextri per viam 3D-CAS-RP-endoscopicam (3D-CA-RP-FESS)(cum ablationem in tototumoris et pyocelis sinus ethmoidalis et orbitae lat dextri).
Using a special digitalizer (endoscope simulation) model and computer model, the preoperative preparation and simulation of the entire procedure can be done on the computer model of the real patient. Employing 3D digitalizer on the real procedure, the tip of the instrument (simulated endoscope) can be precisely identified in the real operative field and visualized on the computer model. The freedom of endoscope manipulation during the procedure is not reduced because the connection is realized at the sites of instrument handle and endocamera link. The use of computer technology during preoperative preparation and surgery performance allows for all relevant patient data to store during the treatment. CT images, results of other tests and examinations, computer images, 3D spatial models, and both computer and video records of the course of operation and teleoperation are stored in the computer and in CD-R devices for subsequent analysis (www.poliklinika-klapan.com i www.mef.hr/MODERNRHINOLOGY). Also, these are highly useful in education on and practice of different approaches in surgery for surgery residents as well as for specialists in various surgical subspecialties. In this way, the real surgery and telesurgery procedures can be subsequently analyzed and possible shortcomings defined in order to further improve operative treatment. The use of latest computer technologies enables connection between the computer 3D spatial model of the surgical field and video recording of the course of surgery to observe all critical points during the procedure, with the ultimate goal to improve future procedures and to develop such an expert system that will enable computer assisted surgery and telesurgery with due account of all the experience acquired on previous procedures. Also, using the computer recorded co-ordinate shifts of 3D digitalizer during the telesurgery procedure, an animated image of the course of surgery can be created in the form of navigation, i.e. the real patient operative field fly-through, as it was done from the very begining (from 1998) in our telesurgeries.

46-year-old male with chronic sinusitis and the shadow intensity characteristic of a mucocele in the righr orbital space and ethmoids, was examined as the first case. MSCT (Siemens, 64 multislice) of the sinuses in coronal, sagital and axial sections demonstrated a disease of the ethmoidal infundibulum on the right side, with homogenous opacification and/or retention in the region of the right anterior and posterior ethmoidal cells and the orbit, as well as frontal sinus, with sphenoidal and the maxillary sinuses of normal transparency. MSCT scanning of the orbit revealed a tumor like shadow, which partially protruded into the anterior and posterior ethmoidal cells, and partially into the orbit. The medial wall of the orbit, right medial rectus muscle, optic nerve and the eyeball was displaced laterally (exophthalmos). A huge inferior turbinate was noticed on the right. Pronounced also chronic inflammatory changes with signs of ostiomeatal block were observed in the region of surrounded ethmoidal cells and frontal sinus. Patient also complained of difficulty breathing easily, with additional headaches in the right fronto-ethmoidal region, and recurrent sinusitis with postnasal dripping (appropriate nasal discharge/rhinosecretion). Visual function was partially reduced on the right eye, with normal finding on the left eye. Postoperatively, antibiotic therapy with local corticosteroids was prescribed. During the diagnostic process, we used the standard 2D-MSCT-imaging sections, virtual endoscopy of the patient's head model over a few applied travel sections through patient's "virtual" head. Physical RP-models of patient's head showed a clear demarcation (anatomic position) between the diseased and healthy tissues in the projection of the nose, paranasal sinuses and orbit. The patient underwent imageguided-CA-VE-FESS. Three months after the surgery, the patient was symptom-free. Generaly speaking, in this case, RP-approach proved efficient not only for the diagnostic purpose of the localization of the tumor shadow, and its identification within the orbital area, but also during the operation itself.


Figure 1. Basic contours of the pathologic process and the structures surrounding the orbit could not be visualized with certainty, neither was it possible to determine whether there actually were disparate, mutually connected fragments of the right orbilat lamina, or a single bony wall, partially dectructed by pathologic tissue


Fig. 2. AVI-file: partial destruction (middle part) of the bony border between paranasal sinses and the right orbit (orbital lamina), as well as dislocation of the rest of this bony borderline