Complications in Endoscopic Orbital Surgery

Orbital decompression has been performed for more than 100 years and is aimed at decompressing the orbital content by partially removing its bony boundaries. It has evolved from a transfrontal orbital roof approach to the classical external transantral approach. The endoscopic orbital decompression (EOD) was first described by Kennedy et al. in the early 1990s as a surgical treatment for thyroid eye disease (TED), and it used the transnasal corridor to decompress the medial and inferior orbital walls. Since then, indications for EOD have expanded and involve not only TED but also procedures for other orbital diseases including neoplastic, traumatic, vascular, inflammatory, and infectious ones.

Decompression of the optic nerve (ON) is indicated for reducing the pressure at its intracanalicular portion and was first performed through an external approach via craniotomy. Only 20 years ago, the endoscopic approach was described. Its indications involve decompression of acute and subacute optic neuropathy, secondary to trauma, TED, neoplastic causes, fibrous dysplasia, and others.

Although complications in orbital surgery can lead to serious consequences, they are uncommon when surgery is performed by experienced surgeons. The chances of complications and their severity rise considerably depending on the complexity of the disease and proposed orbital procedure. For instance, surgery for intraconal orbital tumors, especially those located lateral to the ON, are of greater risk.

Because endoscopic orbital surgery is a relatively new surgical modality, there is a lack of reports and discussion in the literature of surgical complications specifically related to endoscopic orbital surgery. In didactic terms, complications of endoscopic orbital surgery can be categorized according to the time when they occur (intraoperative vs. postoperative; immediate, early, or late), the anatomic structure that is injured (neural, vascular, muscular, or cerebral), or the region where they manifest (orbital, sinonasal, or intracranial). In this chapter, complications are divided into two categories: immediate/early and late. Immediate/early complications are those easily identifiable in the intraoperative or early postoperative period, consisting mainly of vascular, muscular and neural injuries, and cerebral spinal fluid (CSF) leaks. Late complications, for their turn, consist of mainly orbital and sinonasal complications, such as diplopia, enophtalmos, nasal obstruction, and chronic rhinosinusitis.

Immediate/Early Complications

Vascular Injuries

Vascular injuries occur especially when dealing with intraconal disease. Injury to orbital vessels can lead to catastrophic sequelae, including orbital hematomas and total blindness.

The ophthalmic artery (OA) provides the main blood irrigation to the orbit in most individuals. Fortunately, injury to this vessel is rare owing to its anatomic location, inferolateral to the ON. The ciliary arteries are branches of the OA that form a vascular network surrounding the ON, and their damage may cause important visual impairment. The central retinal artery is one of the first branches of the OA, and injury to this artery causes sudden blindness. Lesions to muscular branches are rare; however, they may occur when working in the posterior orbit. Arterial branches to the medial rectus muscle (MRM) are the most commonly injured.

The anterior and posterior ethmoidal arteries are also at risk of injury during dissection of the ethmoidal cells and the lamina papyracea (LP). The superior limit of bone removal in EOD is traditionally the ethmoidal foramens.

Epistaxis and orbital hematomas can manifest immediately or in the early postoperative period, secondary to inefficient hemostasis or injury to blood vessels, especially during removal of orbital fat ( Fig. 22.1 ). Injuries to minor vessels are usually easily controlled and managed but may cause periorbital hematomas ( Fig. 22.2 ).

Neural Injuries

Neural injuries are infrequent and usually of a lesser degree of morbidity compared with vascular lesions. An exception to this would be ON injuries. Although uncommon, this complication usually leads to total blindness.

Motor nerves may be iatrogenically damaged during surgery. The most commonly affected nerve are branches of the oculomotor nerve that innervate the MRM and the inferior rectus muscle. Because these nerves enter the muscles medially in the posterior orbit, lesions are rare, but when they occur, they can cause diplopia. The long ciliary nerves are also at risk of trauma during surgery. They are usually medial to the ON and have mostly sensory fibers to the sclera.

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