Endoscopic transnasal approach for resection of locally aggressive tumors in the orbit

In recent years, application of endoscopic transnasal surgery (ETS) has been expanded to orbital lesions, and preliminary results have started to be published for medially located soft mass lesions. However, reports on experience with endoscopic intraorbital surgery aimed at resection of invasive skull base tumors remains quite limited. This report presents the authors' experience with ETS for locally aggressive tumors involving the orbit.

ETS was performed for 15 cases of aggressive tumors involving the orbit: 5 meningiomas (meningothelial, n = 3; atypical, n = 1; anaplastic, n = 1), 4 chordomas, 2 chondrosarcomas, and 4 others (metastasis from systemic myxofibrosarcoma, schwannoma, inverted papilloma, and acinic cell carcinoma, n = 1 each). Among these, 9 tumors were located outside the periorbita and 6 inside the periorbita. In 6 intraperiosteal tumors, 5 were intraconal lesions, of which 3 arose in the muscle cone (anaplastic meningioma, optic sheath meningioma, and metastatic myxofibrosarcoma), and 2 meningothelial meningioma had invaded from the sphenoid ridge or the cavernous sinus into the muscle cone through the optic canal and the superior orbital fissure. A case of schwannoma originated around the cavernous sinus and pterygopalatine fossa and extended extraconally into the periorbita. Intraoperatively, ethmoid air cells and the lamina papyracea were removed, and extraperiosteal tumors were safely approached. For intraperiosteal tumors, the periorbita was widely opened, and the tumors were approached through the surgical window between the rectus and oblique muscles.

Gross-total resection was achieved for 12 of the 15 tumors, including 2 intraconal lesions. After surgery, exophthalmos resolved in all 8 patients with this symptom, and diplopia resolved in 5 of 6 patients. Improvement of visual symptoms was reported by 4 of 5 patients with loss of visual acuity or constriction of the visual field. Postoperatively, 1 patient showed mild, transient worsening of existing facial dysesthesia, and another showed transient ptosis and mild hypesthesia of the forehead on the affected side. All those symptoms resolved within 3 months. No patients showed enophthalmos, worsening of diplopia or visual function, or impairment of olfaction after surgery.

ETS appears acceptable as a less-invasive alternative for treating aggressive tumors involving the orbit. For extraperiosteal tumors, gross-total removal can generally be achieved without neurological complications. For intraperiosteal tumors, surgical indications should be carefully discussed, considering the relationship between the tumor and normal anatomy. Wide opening of the periorbital window is advocated to create a sufficient surgical pathway between the extraocular muscles, allowing a balance between functional preservation and successful tumor resection.