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

Abstract

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.

Endoscopic transsphenoidal anterior petrosal approach for locally aggressive tumors involving the internal auditory canal, jugular fossa, and cavernous sinus

“…18,37 Also, it is easier to approach tumors that extensively involve the paramedian regions, such as the clivus, sphenoid sinus, and the nasopharyngeal region, or bilateral petrous apex, from the inside. 10,28,30,35,39 In our cases, most of the tumors extended to the inferolateral part of the petrous apex or the paramedian regions and were considered suitable for the ETAP approach. However, experience with intradural lesions remains limited, and for intracranial tumors without skull base invasion, the transcranial approach remains warranted for safe surgical procedures at present.…”

“…While dissection and resection of the tumor mostly proceeded under the vision of angled endoscopes (30° or 70°), the nasal speculum specially designed for endoscopic transsphenoidal surgery allowed stable maintenance of a wide surgical corridor with maximum preservation of the nasal anatomy, facilitating swift delivery of surgical tools and a clear, bloodless surgical field. 30 To retain a sufficient surgical pathway, the retrocarotid window was enlarged along the petrooccipital fissure, minimizing the risk associated with skeletonization and mobilization of the ICA during the surgical procedure. Our results indicated that the transsphenoidal route was sufficient in a certain number of cases to approach the petrosal areas.…”

“…1A). 30 The role of the nasal speculum in our surgery is to retract the redundant nasal tissues, such as the middle turbinates and nasal septum, during the surgery and prevent narrowing of the approach route by the swollen nasal mucosa. For these purposes, we modified the conventional speculum blades to fit the endonasal transnasal approach, making them slimmer and much thinner than the ones used in microscopic transnasal surgery ( Figs.…”

“…15,16 Since then, over the past 2 decades, introduction of endoscopic technologies into the neurosurgical field has dramatically changed the role of transsphenoidal surgery. Currently, application of this surgical technique has been expanded to the ventral skull base regions, such as the anterior cranial fossa, 19,20 parasellar region, 4,6,38 clival region, 10,28,30,35 and craniovertebral junction. 31,39 Despite success in those paramedian territories, skull base tumors in the lateral regions remain a therapeutic challenge.…”

Endoscopic transnasal resection of the CP angle schwannoma

“…Incision to the nasal septum mucosa First, we dissected the mucosa from the right nasal septum close to the vomer. 3,4 The exact same procedure was performed on the left side. The nasal speculum was applied in each nostril, and the vomer as well as bilateral sphenoid ostium were exposed.…”