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Endoscopic Orbital Exenteration
Endoscopic-Assisted Orbital Exenteration
Malignant diseases involving the orbit can result in an incalculable amount of human suffering, as their natural course can progress to include bleeding, pain, disfigurement, blindness, and premature death ( Fig. 29.1 ). Orbital exenteration to treat such a malady, whether performed by open surgery or endoscopically, is challenging and is best accomplished through a multidisciplinary approach. The recommendation to exenterate the orbital content is typically based on two critical considerations: (1) will it lengthen life? and/or (2) will it maintain or improve quality of life? The recommendation to exenterate is made more difficult by the lack of controlled studies or even consensus as to when it is absolutely indicated. Regardless of whether orbital exenteration is best performed through a traditional approach or is endoscopically assisted is based on the disease being treated and the experience of the surgeon. Open orbital exenteration is most commonly performed for malignancy arising from within the orbit and its adnexa. Endoscopic-assisted orbital exenteration (EAOE) is typically used for orbital disease arising within the nasal and sinus passages.
A, 61-year-old woman showing the 6-year course of an insufficiently treated collision tumor with basal cell of the eyelid and squamous cell carcinoma of the paranasal sinuses. B, Postcontrast axial and magnetic resonance imaging scan. C, Postcontrast coronal and magnetic resonance imaging scan.
(Image courtesy the Sinus & Nasal Institute of Florida Foundation.)
Traditionally orbital exenteration describes removal of all orbital contents, including the globe, eyelids, conjunctiva, and periorbital structures. However, based on the nature, extent, and location of the disease being treated, the exenteration may be subtotal (eyelids left intact) or extended (removal of adjacent bony structures). At the conclusion of the traditional exenteration, substantial frontal, sphenoid, and/or zygomatic bone is typically left exposed within the exenteration cavity. The average length of time for an exenteration cavity to heal by secondary intention is estimated to be 5 months. In the case of cancer, without immediate reconstruction with split-thickness skin graft, regional tissue transfer, or myocutaneous free flaps, there will be an unacceptable delay in the initiation of postoperative radiation. EAOE, however, represents an alternative approach that permits preservation of the superior and lateral periosteum/periorbita that can greatly facilitate wound healing.
EAOE, introduced by Batra and Lanza in 2005, evolved from experiences with endoscopic dacryocystorhinostomy and endoscopic decompressions of the orbit and the optic nerve. The endoscopic approach offers improvements in visualization and facilitates a more natural transition from the sinonasal portion of the procedure to the orbital exenteration. It allows for better assessment of tissues at the sino-orbital interface if the final decision to exenterate is made intraoperatively. This approach can facilitate postresection mapping to obtain clean margins. EAOE expedites the removal of orbital adnexa, such as the fat, extraocular muscles, lacrimal gland, sac, duct, vessels, and nerves, by using a soft-tissue shaver (microdebrider). Endoscopic resection readily permits eyelid and brow preservation. It is important to note that during EAOE, the globe and distal optic nerve are removed intact, anteriorly through the palpebral fissure. This precludes any risk of contralateral blindness secondary to sympathetic ophthalmia. Despite its advantages, the place of EAOE in our surgical armamentarium is yet to be clearly delineated.
Examining Indications for Endoscopic-Assisted Orbital Exenteration
The indications for EAOE resemble those for traditional exenteration and can include cancer, infections, trauma, inflammatory disorders, and even massive expanding benign tumors. Yet, in most circumstances, there are immediate alternatives to exenteration. However, once the extraocular muscles, intraconal fat ( Fig. 29.2 A ), and/or the globe are involved by destructive disease arising within the paranasal sinuses, aggressive therapy is warranted. However, involvement of the lamina papryacea, lacrimal bone, maxillary bone, or even the periorbita is no longer considered by many treating physicians as absolute indications for orbital exenteration. Accurately determining which of these tissues are directly involved by malignancy can be difficult to ascertain by preoperative imaging even with magnetic resonance imaging (MRI). Surrounding tissue edema secondary to the cancer may be mistaken on imaging for extraocular muscle invasion ( Fig. 29.2 B). Therefore the final determination on critical orbital involvement may be delayed based on intraoperative tissue sampling/pathology results.
In the case of acute invasive fungal sinusitis, orbital exenteration might be delayed until antifungal therapy, reversal of immune dysfunction, and endoscopic sinus surgery can be given a chance to be effective. Topical or injected intraorbital amphotericin B might also be used. Limited treatment without exenteration is more likely to be effective in those patients whose immune deficit can be reversed and/or when mucormycosis is not the infection invading tissue. However, in the case of severe immunosuppression with fulminant mucormycosis tissue invasion, EAOE performed with early signs of involvement is known to be lifesaving.
In the case of sinus malignancy, it is widely accepted that invasion of orbital contents through the periorbita heralds a poorer prognosis for overall and disease-free survival. The standard of care is a combination of surgery with adjuvant radiation therapy with or without chemotherapy. However, whether orbital exenteration improves disease-free survival or overall survival is unclear. This lack of clarity makes the choice to exenterate an orbit for sinus malignancy especially difficult. Moreover, the existing data for sinus malignancy examine traditional orbital exenteration, but similar data are not available for EAOE. Yet early results for endoscopic management of sinus malignancy yield comparable results to open surgery. Endoscopic resection of sinus malignancy alone or in combination with EAOE may be delayed or avoided depending on the malignancy type, extent of involvement, the patient’s choice for neoadjuvant chemotherapy and/or radiation, and patient motivation to preserve the eye.
In one study, induction chemotherapy was successful in down-staging sinus cancer, leading to orbital preservation in 82% of patients. However, nearly 20% did not respond adequately to therapy, potentially jeopardizing those lives to preserve an orbit. In another study, treatment of basal cell carcinoma invading the orbit with an oral hedgehog pathway inhibitor called vismodegib (Erivedge) has prevented blindness and preserved the orbit in select cases. Adding to the controversy is an international collaborative report of 334 patients with ethmoid malignancies who underwent craniofacial resection with and without radiation/chemotherapy. This report indicates that orbital involvement reduces 5 year disease-specific survival from 78.0% to 44.4%. Unfortunately, there is insufficient evidence from even this large study to determine whether orbital exenteration yields a better 5-year survival rate. The survival impact of orbital exenteration, from a series with the most promising results, is 93.4% at 1 year and 53.1% at 5 years. Lastly, orbital invasion by cancer is associated with inferior outcomes even from salvage surgery.
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