Volume 1, Issue 3 , Pages 181-184, September 2006
Image guidance offers additional benefits in the endoscopic solution of extended cranio-facial malformations:
A case report
Article Outline
Summary
Computer-assisted endoscopic surgery (CAES) in combination with a transpalatal approach was applied in a 6-year-old girl with extensive cranio-facial malformation and bilateral nasal and choanal atresia. The GE Healthcare InstaTrak 3500 Plus surgical navigational system was used. The transnasal and choanal atresia was successfully opened and kept patent. The navigational system was able to point and localize orientations between the distorted anatomy, the instrument tip and in depth measurements for intraoperative planning. In extended anatomical malformation of the nasal passages and the surrounding structures, where the anatomical landmarks are missing or definitely altered computer-aided navigation may facilitate the application of additional endoscopic surgery in combination with more radical surgical approaches. Development of special drills and curved suction devices mounted on the receiver and tailored for such anatomical malformations may offer a complete computer-aided endoscopic solution in similar cases.
Keywords: Cranio-facial malformation, Choanal atresia, Computer-aided surgery, Navigation, Image-guidance
1. Introduction
Computer-assisted endoscopic surgery (CAES) has already been successfully utilized in nasal and sinus surgery for more than a decade. A real-time localization of the surgical instruments within the operative field is obtained with different tracking methods and a cross-hair mark serves for visualization on the patient's reconstructed triplanar CT images. Ten years after launching CAES, Metson [1] demonstrated the most important lessons learned from the first 1000 cases. It is already accepted, that the accuracy of instrument localization must be within 2
mm when compared to anatomical landmarks [1], [2]. If needed it can be checked intraoperatively with re-calibration and verification. It seems to be accepted, that navigational systems may be helpful in diffuse inflammatory diseases, revision cases and tumors and where anatomical landmarks are difficult to rely on. The GE Healthcare's InstaTrak device – described by several authors [1], [3], [4], [5], [6] – was used to insure and complete the restoration of the nasal passages in a child with extended facial malformations. Although increasing knowledge is already available, the sophisticated role and exact place of CAES is still required to be outlined.
2. Case report
In a 6-year-old girl with congenital cranio-facial malformation with bilateral naso-choanal atresia CAES was chosen to avoid the external approach. She was born at 41 weeks with the following parameters: APGAR 5, 7, 8; resuscitation was performed, weight: 3750g; length: 56cm. Her examination revealed orbital hypoplasia, missing eyeball on the left, bilateral nasal and choanal atresia with rhinorrhoea, dura mater prolapsed into the nose, nasus bifidus with the left nasal vestibule obstructed, the hard palate deformed and gothic (Fig. 1, Fig. 2, Fig. 3). No neurological or psychological deficiency was detected. After initial difficulties with breast-feeding, she was able to suckle and tracheotomy was avoided. Endoscopy revealed obstructed nasal vestibule on the left. The lateral nasal wall was not developed on either side, with a bony mass significantly narrowing the entrance of the nasal cavity in both sides. The InstaTrak 3500 Plus electromagnetic surgical navigational system (General Electric Healthcare-Surgery Lawrence, MA, USA) was used to assist and help the surgeon during the procedure. The transmitter built in the headset and the receiver placed in one of the surgical instruments are interconnected through the system's computer. The generated electromagnetic field and the automatic headset registration serve as a basis for the accurate localization of the receiver built in the surgical instruments. The position of the latter is then displayed on the triplanar CT pictures as a crosshair signal. System initialization, calibration and verification were performed according to the manufacturer's instructions. Image-guided endoscopic surgery was performed first with the InstaTrak GE navigational system. The nasal mucosa was incised and elevated posterior to the nasal entrance, and the bony mass of the premaxilla was drilled away. The navigational system was able to point and localize orientations between the distorted anatomy, the instrument tip and in depth measurements for intraoperative planning (Fig. 4). The sharp, gothic elevation of the hard palate and the nasal floor prevented the rigid navigational instruments to be guided posteriorly and inferiorly enough to reach the site of the choanal obstruction. Image-guidance offered a safe way to avoid damage of the orbital and cranial prolapse, as well as the intracranial tissue in the region of the sphenoid bone. Because of the long, thick and curved shape of the obstruction a combined transpalatinal and endonasal approach was decided. In the second stage the soft palate was divided by a midline, transpalatal incision and the hard palate was partially drilled away on the right side. The bony mass between the hard palate and the sphenoid bone was readily identified with the InstaTrak. Fine and narrow chisels were inserted endonasally and the lamellar, immature bone was carefully removed in the direction of the nasal floor. Finally, the transpalatal and transnasal tunnels were connected and widened, and a silicone stent was inserted to keep the nasal passage open. Eleven months after surgery the stent remained patent.
Fig. 1.
3D CT scan showing bony constriction of the pyriform aperture.
Fig. 2.
(a) Left orbital hypoplasia on MRI. (b) CT scan demonstrates the missing nasal cavity with the dura mater prolapsed in the nose.
Fig. 3.
(a and b) The bony obstruction is continuous until the choanae. The sphenoid sinus and the choanae are filled with bony tissue.
Fig. 4.
The InstaTrak 3500 Plus navigational system was able to delineate the bony obstruction in three planes.
3. Discussion
Endoscopic nasal and paranasal sinus surgery (ESS) in children – performed in a conservative manner – is usually indicated in chronic rhinosinusitis, when medical therapy, adenoidectomy and systemic antibiotics have all failed, or when anatomic abnormalities predispose to chronic rhinosinusitis by obstructing normal sinonasal drainage pathways. ESS proved to be effective in pediatric sinonasal polyposis and in orbital complications of sinonasal diseases [7]. Periorbital cellulitis and abscess secondary to acute rhinosinusitis is relatively common in pediatric patients [8], which often needs surgical drainage. The increasing knowledge and experience with computer-assited navigational systems in pediatric nasal and paranasal sinus surgery [9], [10] has widened the indications and facilitates the accomplishment of ESS in children. It has already been demonstrated, that unilateral and bilateral choanal atresia can be surgically managed with computer-aided surgery [11], [12]. Image guidance was successfully applied in endoscopic transnasal drainage of periorbital abscesses [13]. CAES proved to be useful also in removal of tumors, in tumor biopsy and in minimally invasive maxillary, frontal and sphenoidal surgery in children [14].
In our case, the transnasal bony obstruction was planned to be solved by an endoscopic procedure, where navigational help could insure the orientation within the transnasal bony mass and the safe avoidance of the dura and the orbit. The extended bony transnasal and choanal atresia with the additional abnormalities along the skull base and the absence of the normal anatomical reference points would have made a standard endoscopic intervention too dangerous. The rigid navigational and endoscopic instrumentation prevented the endonasal approach from the completion of the curved and thick choanal portion, and an additional transpalatal approach was decided. It is also believed that by a transpalatal approach alone the transnasal obstruction could not be solved.
4. Conclusion
In extended anatomical malformation of the nasal passages and the surrounding structures, where the anatomical landmarks are missing or definitely altered computer-aided navigation might facilitate the application of additional endoscopic surgery in combination with more radical surgical approaches. Development of special drills and/or curved suction devices mounted with receiver-tip and tailored for such corresponding situations might offer complete computer-aided endoscopic solution in similar cases. According to our findings, this indication of CAES may be added to the already known ones, as the distorted and challenging anatomy around the frontal and/or sphenoid sinuses, and the extended or revision cases with tumors and diffuse inflammation. In this case image-guidance may be helpful, increases safety even for experienced surgeons.
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PII: S1871-4048(06)00046-3
doi:10.1016/j.pedex.2006.04.002
© 2006 Elsevier Ireland Ltd. All rights reserved.
Volume 1, Issue 3 , Pages 181-184, September 2006
