Volume 4, Issue 1 , Pages 21-24, January 2009
Image-guided endoscopic and microdebrider assisted repair of choanal atresia in a neonate
Article Outline
Summary
Endoscopic transnasal repair of choanal atresia in a 3-week-old infant with CHARGE syndrome under image guidance was employed. Image guidance provided optimal visualization of aberrant bony structures in this small syndromic patient, thus optimizing safety in avoiding damage to vital structures at the skull base. Furthermore, successful endoscopic repair avoided a tracheotomy and expedited extubation. Considering the number of syndromic patients with aberrant skull base and nasal anatomy, image-guided endoscopic repair for choanal atresia may improve safety by avoiding compromise of vital structures at the skull base, particularly in very small neonates. Fiducial marker registration versus laser surface registration is a key consideration in neonates as well as midface deficient patients.
Keywords: Image-guidance, Choanal atresia, Endoscopic repair, Neonate, CHARGE syndrome
Congenital choanal atresia was first described by Roederer in 1755 and occurs in approximately 1 in 7000–8000 births [1], [2]. Several theories have been proposed to explain this condition: failure of bucconasal membrane to recanalize, medial outgrowth of vertical and horizontal processes of the palatine bone, and persistence of the buccopharyngeal membranes [3].
Until 1996 the anatomic classification of choanal atresia was commonly quoted as 90% bony and 10% membranous. Brown et al., however, reviewed 63 computed tomography (CT) scans of choanal atresia and noted a combined incidence of approximately 30% pure bony and 70% mixed bony-membranous with no pure membranous atresia [4]. Bilateral bony choanal atresia in the neonate has been typically considered the most difficult condition to surgically correct [5].
The different surgical options to correct choanal atresia in the neonate include transseptal, transnasal puncture, microscopic transnasal techniques with the use of a diamond burr, transpalatal repair, and endoscopic repair with which Stenkiewicz is credited with the first description [6]. Amongst pediatric otolaryngologists, endoscopic repair is favored slightly over transpalatal repair [7]. Arguments against endoscopic repair include a high rate of failure particularly in patients with CHARGE association while transpalatal repair has been associated with dental malocclusion (crossbite) in up to 50% of patients managed with this approach [8], [9].
With the advent of image-guided assisted endoscopic sinus surgery, anatomical landmarks such as the orbit, skull base, and complicated endonasal congenital abnormalities can be identified during surgery. Schweinfurth described the use of image-guided assisted endoscopic sinus surgery in the repair of a 3-year-old boy with a history of CHARGE syndrome citing optimal location for entering the nasopharynx and enlargement of the choanae without fear of violating surrounding structures as benefits [10]. This case report describes the use of image guidance and powered dissection for choanal atresia in a very small neonate with CHARGE syndrome, thus avoiding a situation that requires a tracheotomy. Unique problems encountered which we associated with the patient's small size are discussed.
1. Report of a case
A 3-week-old Caucasian female weighing 1.78
kg with a history of CHARGE syndrome presented from an outside institution where she was apneic at birth and was intubated. An axial CT scan demonstrated complete bony choanal atresia with a prominent atretic plate extending from the posterior margin of the hard palate posteriorly to the clivus. Surgical planning included a BrainLAB protocol maxillofacial CT (BrainLAB VectorVision ENT, Munich, Germany) with five fiducial markers placed as landmarks around patient's face (Fig. 1).
Figure 1.
Patient with five fiducial markers placed around face used as registering landmarks for the image-guidance system during surgery.
After endotracheal anesthesia was induced, the fiducial markers were registered on the image-guidance system. Due to patient's posterior extension of the hard palate to the sella, the image-guidance probe was used to localize the appropriate location and angle to penetrate the bony atresia plates (Fig. 2a–e). After penetration, a microdebrider was used to enlarge the opening and a pediatric backbiter was used to remove the posterior aspect of the vomer. Urethral sounds were used to dilate the newly created choanae (Fig. 3). Stents were placed and removed after 6 weeks.
Figure 2.
Endoscopic view of right-sided nasal cavity (a) and atretic plate (b). Preoperative sagittal view demonstrating posterior extension of hard palate to skull base (c). Intraoperative sagittal view of probe being used to create connection from nasal cavity to pharynx (d). Intraoperative sagittal view of probe abutting the skull base (e). Without image-guidance, this could be mistaken for the bony atretic plate.
Figure 3.
(a) Microdebrider used to enlarge choanal opening. (b) Right nasal choana prior to stenting.
The choanae remained patent at 4 months. Subsequently, the left choana has restenosed but the right remains open. The patient does not suffer from airway obstruction nor failure to thrive. Tracheotomy was avoided.
2. Discussion
A survey of the American Society of Pediatric Otolaryngology (ASPO) members revealed endoscopic technique (85%) favored over transpalatal (60%) repair of choanal atresia [7]. Endoscopic transnasal repair of choanal atresia allows the surgeon direct visualization while performing delicate maneuvers such as removing the posterior nasal septum and lateral bony narrowing. This combined with the potential for maxillofacial disturbance, palatal fistula, and increased operative time of the transpalatal approach likely accounts for the endoscopic preference.
The endoscopic transnasal approach, however, is not without its complications. Small neonates with choanal atresia have unique anatomical configurations with the carotid artery, optic nerve, and skull base in close proximity. Morbid and potentially fatal injuries to these structures are more likely in smaller patients even using endoscopic technique. In our patient, the mucosal covered sella could have easily been mistaken for the bony atretic plate and disrupted without image guidance (Fig. 2e). Employing an image guidance system facilitated optimal location for safely entering the nasopharynx and avoiding injury to the skull base in this neonate weighing less than 2kg [10].
Our institution uses an image-guidance system which employs a laser to register surface features for navigation. In neonates, the lack of prominent midface structures render this registration system unusable. Setting up the image guidance system properly is essential, in particular, the order in which the registration is executed. Fiducial markers are absolutely necessary and it is critical they are placed prior to obtaining navigational surgical scans (Fig. 1). Registration markers on a dental splint has been used in a 2-year-old with bilateral choanal atresia associated with Treacher Collins syndrome [11]. Multiple registration markers are available internationally, but one that employs fiducial markers rather than laser registration may be more appropriate, particularly in small neonates with aberrant midface anatomy. Although not a necessity, the use of the microdebrider was extremely helpful because it was able to fit into the small nasal cavity and provide adequate strength and accuracy to enlarge the bony choanae under direct visualization. A recent case report describes the use of the KTP laser in a neonate with bilateral choanal atresia as safe adjunct to the endoscopic technique [12]. Other pediatric sinus instruments were too bulky to maneuver with the exception of the pediatric backbiter. Otologic instruments were also useful in this situation.
Without image-guided assistance, alternative modalities for our patient include a transpalatal approach for choanal atresia repair versus a tracheotomy. The atresia plate with an extremely small nasopharynx in a very small neonate made this consideration a difficult and potentially unsafe option. Neonatal tracheotomy is not without its own complications, but was reserved in case safe repair was not possible using an endoscope under image guidance.
Although our patient did develop restenosis on one side, a tracheotomy was avoided and one patent choana provided an adequate airway. Factors contributing to restonosis after transnasal endoscopic surgery for choanal atresia include gastroesophageal reflux disease (GERD), age younger than 10 days at the time of the procedures, and insufficient postoperative endoscopic revision [13].
3. Conclusion
The use of fiducial markers to register bony landmarks on an image-guidance system may expand the number of patients offered image-guided surgery for choanal atresia repair. Furthermore, neonates with congenital anomalies, other than CHARGE syndrome, with anatomical variance near the skull base may stand to benefit most form the use of image guidance systems that use fiducial markers. Likewise, powered instruments for dissection and debridement may also allow for this procedure to be offered to smaller neonates and patients with previously deemed “unfavorable” anatomy. Parents of neonates may be offered this procedure instead of a tracheotomy.
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PII: S1871-4048(08)00034-8
doi:10.1016/j.pedex.2008.05.002
© 2008 Elsevier Ireland Ltd. All rights reserved.
Volume 4, Issue 1 , Pages 21-24, January 2009
