2025 Proffered Presentations
S110: CONTRALATERAL MONONOSTRIL ENDOSCOPIC APPROACH USING THE CHOPSTICK TECHNIQUE: A MINIMALLY INVASIVE CONCEPT TO ACCESS THE FAR LATERAL SKULL BASE
Arianna Fava, MD; Caspar Chu, MD; Nobuyuki Watanabe, MD; Norio Ichimasu, MD; Jerold Justo, MD; Jonathan Chaney, MD; Rosaria Abbritti, MD; Thibault Passeri, MD; Anne Laure Bernat, MD; Sébastien Froelich, MD, PhD; Hôpital Lariboisière, Paris
Background: Endoscopic endonasal approach has been a revolution in skull base surgery providing a natural and direct line of sight to deep seated skull base lesions. Although it is considered less invasive compared to transcranial routes, most often, it includes significant resection of normal nasal structures to gain more working space to lateral targets. Thus, the approach is often distant from minimally invasive and patients’ expectations. Accordingly, the authors are presenting a minimally invasive one nostril concept using angled endoscopes, malleable rotative suction, and dedicated instruments maneuvered with the “chopsticks technique”. The goal of this study was to evaluate the amount of lateral exposure obtained with this technique and for various scope angulation.
Methods: Three cadaveric specimens were used. A contralateral mononostril endoscopic transsphenoidal approach using the chopstick technique was performed. A vertical septal incision was performed in front of the rostrum. The septum was mobilized and the sphenoid sinus was widely opened. The contralateral vidian nerve and pterygosphenoidal fissure were identified, and the paraclival and lacerum internal carotid artery (ICA) were exposed. With endoscopes from 0- to 30- and 70-degrees, further drilling of the sphenoid body, occipital, and petrous bone was performed to expose lateral targets: IAC, posterior surface of the petrous ICA, meckel’s cave, jugular foramen, jugular tubercle, and hypoglossal canal. Finally, to enhance the lateral exposure, a small sublabial trans maxillary corridor (SLTMC) was created to provide a more oblique trajectory to the curved drill. CT scans were performed before and after each step of the dissection: 0°, 30°, 70°, and after addition of the SLTMC. The exposure of lateral targets and the drilled bone volume obtained after each step were compared. A clinical case is presented.
Results: Using a 0° scope, exposure was limited to the volume located immediately posterior to the contralateral paraclival ICA. With a 30° scope, removal of the medial part of petrous apex and medial part of jugular tubercle was possible. With a 70° scope, petrous apex and jugular tubercle could be drilled till the IAC was reached, and to expose the jugular foramen and hypoglossal canal. Finally, with an additional SLTMC the anterior wall of petrous apex could be removed to expose the posterior wall of the petrous ICA. Comparing the volumes of bone drilling using different scope angulation, we found a progressive increase of bony removal of 36% from 0- to 30-degrees, 37% from 30- to 70-degrees, and 3% with a biportal approach. In the presented chondrosarcoma case, bone destruction by this soft tumor facilitated exposure of deeper lateral targets avoiding the need for additional SLTMC.
Conclusions: The contralateral mononostril transsphenoidal approach using the chopstick technique represents a novel minimally invasive concept applied to endoscopic endonasal surgery with the aim to reduce the surgical footprint, allowing to reach far lateral skull base targets by drilling the sphenoidal, petrous, and occipital bone with progressively higher angulation without any damage to the nasal cavity. Angled endoscopes, malleable and rotative suction, angled drills, and chopstick technique are key for the technique.