Endoscopic Transnasal Interseptal Approach for Invasive Clival Tumors: Development of an Approach Method Regarding Maximal Preservation of the Nasal Anatomy

Asian people frequently show small noses, narrow nasal apertures, and congestive mucosa on the turbinates and septum. To reduce the risk of nasal morbidity with increased radicality for skull base tumors in these patients, we developed endoscopic transnasal interseptal approach (ETISA) in transsphenoidal surgery for invasive clival tumors (ICTs). Indication for ETISA is radical resection for tumors occupying deep ventral skull base regions, confined posterior to the level of the middle turbinates. After removing ethmoidal air cells, the middle turbinates are laterally deflected. A linear incision is made vertically on each side of the septal mucosa, which is separated from the bony septum as far as the sphenoid rostrum. The blades of an adjustable speculum are inserted submucosally, and the bony septum is temporarily displaced. The surgical pathway is widely maintained from the entrance to the deep surgical field without sacrificing the nasal mucosa and turbinates. Thirty-two consecutive patients with clival tumors (18 chordomas, 11 chondrosarcomas, 3 others) were treated. Bilateral middle turbinectomy was routinely performed in the initial 3 patients, but in only 4 of the remaining 29 (3 unilaterally, 1 bilaterally). Tumor was sufficiently resected in 29 patients (90.6%; gross total removal n=25, subtotal resection n=4). As complications, 6 patients showed mild and transient worsening of cranial nerve symptoms. Nasal complications arose in 3 patients, persisting >3 months in 2 (5.7%). This approach allows fine bimanual handling and swift delivery of surgical equipment while reasonably preserving the nasal anatomy, which is useful in endoscopic transsphenoidal surgery for ICT.