Minimizing Nasal Trauma in Endoscopic Anterior Cranial Base Surgery: Preservation of Both Middle Turbinates

Objective: To report on the feasibility as well as the benefits of middle turbinate preservation while maintaining sufficient access for endoscopic anterior cranial base surgery.

Background: As the field of endoscopic surgery grows, including surgery of the anterior cranial base, the surgical technique continues to evolve. The endoscopic endonasal approach to olfactory groove meningiomas, for example, classically entails complete resection of the ethmoids and both middle turbinates. Post-operatively the result is a larger nasal cavity with permanent change of the anatomy and natural nasal airflow. The benefits of middle turbinate preservation have been demonstrated in literature for chronic rhinosinusitis and polyposis. We aim to describe the feasibility of similarly preserving the middle turbinate to, theoretically, improve post-operative nasal function, meanwhile maintaining adequate and full exposure for surgical success. The preservation of the middle turbinates ultimately would decrease the postoperative extra-volume of the nasal cavity, and minimize the direct airflow toward the cranial base. Also, it represents extra-vascularized tissue that might be important for future cranial base reconstruction in case of revision surgeries.

Study Design: Cadaveric anatomical study and case presentation.

Methods: Transnasal endoscopic approach and resection of the anterior cranial base was performed in 5 cadaveric specimens. Initially complete bilateral ethmoidectomies, maxillary antrostomies, sphenoidotomies, Draf III frontal sinusotomy were performed maintaining both middle turbinates intact. Then a nasoseptal flap was harvested on the right side and placed in the nasopharynx. Before bilateral exposure of the anterior cranial base, the vertical attachment of the middle turbinates were sectioned with an endoscopic scissors and the turbinates were moved inferiorly toward the nasal cavity floor. The blood supply to the middle turbinates was maintained, as their horizontal attachments were kept intact. Superior septectomy on the left side was performed allowing great exposure of the anterior cranial base. Lastly, the anterior cranial base was resected while both middle turbinates were kept inferiorly. Once the resection and reconstruction were concluded, the middle turbinates were placed in their natural position and sutured to the remnants of the left nasal septum. Similar approach and technique was performed for resection of an olfactory groove meningioma.

Results: In all anatomical dissections and in the representative case, full exposure to the anterior skull base was achieved while preserving the middle turbinates, without compromising surgical access. At 1 month-post-operative nasal endoscopy, both middle turbinates were healed to the septum and a more anatomical nasal cavity was observed. No increased difficulty for post-operative nasal debridement was encountered with the preservation of the middle turbinates.

Conclusion: Access to the anterior cranial base with full anatomical exposure can be achieved via a transnasal endoscopic approach without surgical removal of the middle turbinates. Further review of the functional benefits of such preservation need to be studied.