Endoscopic Transorbital Approach for Neoplasm and Optic Nerve Decompression

Introduction: The transorbital approach to the anterior skull base has been previously described. Its use for tumor diagnosis and resection, however, has yet to be reported. We present its implementation in two cases: An 84 year-old male was referred to neurosurgery for recurrent left orbital meningioma that had been previously treated with stereotactic radiosurgery twice in the past 9 years. He presented with a 10-month history of progressive vision loss, ptosis, ophthalmoplegia and contralateral facial numbness. The second patient was an 85 year-old female with a 5-month history of left sided cranial nerve 6 palsy, trigeminal neuralgia, and progressive vision loss. Imaging revealed a mass involving the left cavernous sinus, orbital apex, medial orbital wall, ethmoid sinuses, and lateral sphenoid. The aim of this report is to present how the transorbital approach can be successfully used for tumor diagnosis, debulking, and resection.

Methods: For the first patient, the left caruncle was lateralized and the pre-caruncular tissue cut with a Colorado needle. Under endoscopic visualization, the iris scissors were used to bluntly dissect through the avascular plane down to the lamina papyracea. In the second patient, a combined trans-caruncular and trans-nasal approach was used to decompress the optic nerve. In both instances, care was taken to avoid putting pressure on the orbit or violate the peri-orbita. Dissection was continued under endoscopy until the frontoethmoidal suture was identified. The goal is to remain inferior to this suture and identify the anterior ethmoid artery, which can be coagulated. Neuronaviation was used prior to bony resection. The anterior portion of the lamina paprycea was removed, exposing the ethmoid mucosa as well as tumor in both cases. In the first patient, multiple biopsies were taken for the purposes of pathologic identification and decompression. In the second patient, the ethmoidal arteries were divided with the bipolar and the medial rectus muscle was followed back to the optic canal. Tumor was then removed around the optic nerve. The surgical cavities were copiously irrigated with bacitracin-impregnated saline. The pre-caruncular or conjunctival tissues were reapproximated with 6–0 gut suture in an inverted fashion.

Results: The transorbital approach provides direct and quick access to the anterior skull base. As previously described, this port provided a uniformly shorter distance to the pituitary gland, optic chiasm, and ipsilateral cavernous carotid artery. The dissection of the medial orbital wall via an avascular plane in the precaruncular technique appears preferable to the trancaruncular approach. In the former we experienced less blood loss and local tissue manipulation. The patients both tolerated the procedures well, without post-operative orbital edema, proptosis or ecchymosis. The second patient's vision improved from light perception preoperatively to counting fingers at 14-inches post-operatively.

Conclusion: The transorbital approach can be used for anterior skull base tumor resection and may present surgeons with an outpatient operative alternative for unresectable lesions involving the cavernous sinus, for elderly with anesthesia concerns, or in instances of recurrence or irradiated sites with friable tissues.