[Endoscopic transethmoidal resection of medial orbital lesions]

To determine the indications, surgical skills, and complications for removal of intraorbital lesions using an endoscopic transethmoidal approach.

A retrospective case series of 12 cases between May 2014 and January 2015 were conducted. Data included visual acuity, exophthalmos, ocular movement, and eyelid function of preoperation and follow-up. The location and size of the lesions were showed and recorded on CT and MRI scans. The cases with imaging diagnosis of cavernous hemangioma, schwannoma or dermoid cyst were included into this study. On the coronal slices the lesions should be located medially to the optic nerve. On the axial slices they should be located in the middle, posterior orbit or apex. The surgical approach began with performance of an endoscopic ethmoidectomy under general anesthesia. A bony window was opened on the lamina papyracea and transethmoidal dissection and removal of an intraorbital lesion was made, with the combination of a mini caruncula incision in 10 cases.

There were 4 male and 8 female patients, with the median age of 44.5 years (ranging from 14.0 to 67.0 years). En bloc tumor resection in 11 cases or piecemeal resection in 1 case was achieved, including 10 cases of hemangioma, and one each schwannoma and dermoid cyst, confirmed by pathologic examination. The tumor size ranged from 11 mm × 11 mm × 10 mm to 24 mm × 23 mm × 16 mm. Three tumors were located medially to the muscle cone, 7 tumors in the cone. One case was located extra-and intracone simulataneously and 1 in the medial rectus muscle. There are 8 tumors within the apex and 4 in the middle and posterior orbit. After 3-11 months follow-up, the best-corrected visual acuity and visual field improved in 3 cases, decreased in 2 case, and vision loss in 1 case. Transient limited ocular movement in 5 cases was recovered within 3 months after surgery. The irreversible limited ocular lateral or medial movement was recorded in 1 case respectively. All complications were recorded in the cases of tumors in the muscle cone.

The endoscopic transethmoidal approach is a useful approach for cavernous hemangiomas, schwannoma or dermoid cyst located medially to the optic nerve in the middle or posterior orbit. It's safer for the tumor located medially to the muscle cone than in the cone. It's an important surgical skill to reduce the complications that intraorbital dissection and exposure of tumors in the cone are assisted with a mini caruncula incision.