Multimodal Treatment of Orbital Tumors

Case Selection

The treatment strategy for orbital lesions is primarily determined by the nature of the lesion. An overview of the types of orbital lesions is provided in Table 32.1 . While medical management is best suited for infectious and inflammatory processes involving the orbit, definitive surgical treatment remains the mainstay for many symptomatic orbital tumors and refractory dysthyroid orbitopathy.

The diagnostic workup proceeds logically after clinical examination and primarily consists of imaging in addition to select labs (e.g., CRP, IgG4, thyroid stimulating immunoglobulin) and ancillary testing (e.g., chest or body imaging). Magnetic resonance imaging (MRI) with fat suppression provides excellent definition of orbital soft tissue pathology. ^, Fat suppression eliminates the T1 hyperintensity associated with orbital fat that can obscure intraorbital pathology. Contrast-enhanced MRI provides an augmented view of orbital lesions and helps determine intracranial extension of orbital pathology. Computed tomography (CT) imaging provides excellent definition of regional bone anatomy. ^, An adequate study includes thin cuts through the orbits in multiple planes. Both CT, with its ability to show bony anatomy, and MRI, with excellent soft tissue characterization, have a role in surgical planning, and many complex lesions benefit from both modalities.

Once a thoughtful sequential diagnostic workup has been completed, the location and extent of the pathologic process must be defined and following questions considered:

• Is a tumor present, or do the findings more likely indicate an inflammatory or infectious process?

• Is it likely benign or malignant?

• Is it confined to the muscle cone?

• Does it arise from the optic nerve, or is it medial or lateral to the optic nerve?

• Is the bony integrity of the orbit violated?

• Is the optic canal or any of the foramina or fissures enlarged or hyperostotic?

• Is the process destructive?

• Does the process extend from or enter the cranial cavity?

• Does the process extend from or enter the paranasal sinuses?

Surgical Approaches

Anatomically, orbital tumors can be divided into intraconal, extraconal, and intracanalicular. This distinction is made on the basis of the tumor’s relationship with the muscle cone, with intracanalicular tumors at least partially extending into the optic canal. There are two primary types of surgical approaches to the orbit: transorbital approaches (performed primarily by oculoplastic surgeons—ophthalmologists fellowship-trained in orbital surgery) and extraorbital approaches (often performed by a team that includes a neurosurgeon or head and neck surgeon, as well as an oculoplastic surgeon). ^, This chapter focuses on the intra- and extraorbital approaches not discussed in other sections of this book. Extraorbital approaches typically employed by neurosurgeons include extended bifrontal craniotomy, orbitozygomatic craniotomy, subcranial craniotomy, and unilateral maxillectomy. As a general paradigm, lesions based anteriorly can be approached via transorbital approaches while lesions in the posterior third of the orbit are often managed by extraorbital approaches (open or endoscopic). There are instances in which a combination of approaches may be necessary.

Ultimately, there are four primary transorbital routes: anterior orbitotomy (superior or inferior), medial orbitotomy, lateral orbitotomy, and a combination of medial and lateral orbitotomies. These approaches are discussed here, in addition to endoscopic approaches to the medial orbit.

Approaches to the Anterior Orbit

The anterior approach is typically employed for lesions in the anterior third of the orbit. For superior-based approaches, an incision is typically made through the eyelid crease or a parallel curvilinear fashion superior to it. Such an incision provides excellent access and postoperative cosmesis. A direct sub-brow incision also may be used if eyelid anatomy is unfavorable. For inferior orbital lesions, the transconjunctival approach is favored, where the incision is placed in the conjunctival fornix. The skin and subdermal tissue are retracted after incision, at which point the periosteum (periorbita) is identified. Depending on the location of the lesion, the periorbita may be elevated and incised or the orbital septum may be entered directly. After incision and dissection of the periorbita or septum, the lesion is typically visible, and the remainder of the dissection proceeds according to the lesion. The periorbita can then be closed with interrupted 5-0 absorbable sutures, although the orbital septum should not be closed to avoid eyelid retraction. The skin incision is closed with a running 6- or 7-0 absorbable or permanent suture. Conjunctival forniceal incisions may be closed with running or interrupted 7-0 absorbable suture, or some opt to leave this approximated, without suturing.

For larger lesions located in the anterior superior orbit, a superior osteotomy may be necessary. For this modification, a longer incision is made in the eyebrow, with the surgeon taking care to visualize and preserve the supratrochlear and supraorbital neurovascular bundles. The superior orbital rim can be removed with a sagittal saw or osteotomes, after which the remainder of the dissection proceeds as described earlier. The use of fine osteotomes ultimately results in thinner bone cuts (with minimal resultant bone loss) and improved cosmetic outcomes.

Approaches to the Medial Orbit (Open)

From a neurosurgical standpoint, medial approaches to the orbit are typically preferred when dealing with meningioma or optic glioma. They are also effective in the management of small tumors, such as cavernous hemangiomas and isolated neurofibromas. The medial peritomy approach gives excellent visualization of the optic nerve at its insertion at the posterior aspect of the globe; thus optic nerve sheath fenestrations and biopsies are often performed via this approach. The medial orbitotomy can be performed via a transconjunctival approach, where a medial peritomy is performed in which relaxing incisions are angled superiorly and inferiorly to expose the insertion of the medial rectus onto the globe. The medial rectus is secured with preplaced 5-0 Vicryl suture which will be used to reapproximate the muscle in closing. It is then transected at its insertion on the globe, and subsequently freed from its intramuscular septum and ligaments and retracted medially. At this point, a medial orbital retractor is employed and a malleable retractor is used to retract the globe laterally. Ideally an operating microscope is employed at this point in the surgery. Dissection through the deeper orbital fat is often necessary before the tumor is identified within the cone. After tumor resection, the medial rectus is then reattached to its insertion site with the preplaced sutures and the conjunctiva is closed with absorbable 7- or 8-0 interrupted sutures. A transcaruncular approach is effective in accessing the extraconal medial space, for repair of medial wall fractures, orbital decompression of the medial wall, or to access tumors in this space. An incision is placed directly through the caruncle, and Stevens scissors are used to palpate the posterior lacrimal crest, with care to avoid the lacrimal drainage system, including the canaliculi and lacrimal sac. Blunt dissection reveals the periorbita, which is opened sharply. Access to the medial orbit back to the apex can then be achieved, with ligation of the anterior and posterior ethmoidal arteries as needed to allow for adequate exposure. Larger tumors may require this approach combined with an endoscopic sinus approach or a lateral orbitotomy to remove bone for better exposure and access medially. Interrupted 7- or 8-0 Vicryl suture can again be used to close the caruncle and conjunctiva.

Approaches to the Lateral Orbit

The lateral orbitotomy is useful for retrobulbar lesions and more posterior lesions. The technique allows the removal of the lateral wall of the orbit, if needed, to visualize lateral, superolateral, and inferolateral tumors; such lesions include cavernous hemangiomas. After induction of general anesthesia, the patient is positioned supine with the head turned contralaterally. A curvilinear incision is made starting in the eyelid crease and extending inferolaterally in a lazy S shape (modified Kronlein incision). The incision follows natural skin tension lines and is lateral to the lateral canthus. As an alternative, an incision is made from the lateral canthus alone and directed posteriorly, with the canthus divided sharply with scissors. This Burke-type incision permits better access to the inferolateral orbit.

After incision and subcutaneous dissection, the periorbita is incised along the orbital rim in a T shape. With blunt dissection, the lateral periorbita is distracted posteriorly to the posterior one-fourth of the orbit to expose the lateral wall of the orbit. The periosteum and temporalis muscle are similarly freed from the bone. To perform the lateral orbital wall osteotomy, initial angled cuts are made along the lateral aspects of the superior and inferior orbital rims. These cuts are directed toward one another to result in a keystone-shaped portion of bone that is removed from the lateral wall. After this initial osteotomy, further posterior visualization is made through removal of bone with a series of rongeurs and drills. Exposure can be extended posteriorly all the way to the orbital apex. Once bone removal has been completed, an incision is made in the periorbita—avoiding the lateral rectus muscle. After entry, the lateral rectus may be retracted superiorly or inferiorly, based on the location of the lesion.

At the completion of the resection, hemostasis is achieved and the integrity of the lateral rectus is verified. The periorbita need not be closed with sutures but merely smoothed into place. The bone is placed back and reconstructed with low-profile craniofacial fixation plates. The periosteum should be closed over these plates to enhance healing and cosmesis. A subcuticular suture is then used to close the skin incision.

Endonasal Endoscopic Approaches to the Medial Orbit

With the introduction of endoscopic sinus surgery in the 1980s, endoscopic techniques and approaches have developed to address various compartments of the cranial base. The endoscope provides excellent illumination, magnification, a panoramic view, and the capacity for angled vision. With increasing understanding of the advantages and limitations of endoscopic skull base surgery, this technique has also been applied to the management of orbital lesions. Endoscopic visualization ultimately has provided surgeons with the possibility to reach medial and inferior orbital structures and the orbital apex with no facial incisions and minimal soft tissue disruption. In addition, endoscopic approaches limit globe retraction. Endoscopic approaches have been used in a variety of situations, ranging from optic canal decompression (in situations of displaced bone fractures) to resection of tumors in the medial orbit.

After positioning the patient supine, the endoscope is introduced into the ipsilateral nostril. After identification of key landmarks (inferior turbinate, middle turbinate, and nasal septum), the middle turbinate is retracted medially to expose the uncinate process and ethmoid bullae. The middle turbinate is subsequently removed, taking care to avoid injuring the ethmoidal roof. In addition, a posterior septectomy is performed after identification of the sphenoid ostium.

To enter the medial orbital wall, an anterior and posterior ethmoidectomy must be performed. After the nasal steps of the surgery, a unicinacetomy and maxillary antrostomy is performed and the bulla ethmoidalis is entered. The maxillary antrostomy allows definition of the medial wall of the orbit, which lies in the same vertical plane as the maxillary ostium. The inferoanterior wall of the ethmoid bulla is opened, and the anterior ethmoid cells are entered and resected. Recognizing the posterior ethmoid air cells can be entered safely through the horizontal portion of the middle turbinate lamella, the posterior ethmoidectomy proceeds until facing the sphenoid sinus. Throughout the anterior and posterior ethmoidectomy, the surgeon must recognize that the lateral wall of the ethmoid bullae is the lamina papyracea, which is the medial orbital wall.

Prior to the medial orbitotomy, the anterior and posterior ethmoidal arteries must be identified. If the artery is injured prematurely, it may retract into the orbit and cause a dangerous retrobulbar hematoma. After complete resection of the medial orbital wall, the orbital periosteum and underlying periorbital fat tissue are exposed. The fat tissue can be removed and medial rectus identified, after which dissection proceeds according to the tumor.

Ultimately, this technique provides sufficient exposure for particular benign lesions with minimal neurovascular retraction. During dissection, potential complications can be related to globe perforation, optic nerve injury (during canal decompression), and vascular injury (damage to the anterior and posterior ethmoidal arteries).

Conclusions

There are two major types of surgical approaches for the removal of orbital tumors: transorbital and extraorbital. The extraorbital approaches employed typically include extended bifrontal craniotomy, orbitozygomatic craniotomy, and craniofacial approaches (such as unilateral maxillectomy). Transorbital approaches primarily include open approaches (anterior, lateral, and medial orbitotomies) that can be done via cosmetically appealing incisions in the eyelid skin or conjunctiva. With the growing understanding of the advantages and limitations of endoscopy, minimally invasive approaches to the medial orbit can now be done for benign pathology. Ultimately, the selection of surgical approach and goals of surgery are dictated by the location (primarily orbital vs. involvement of the intracranial space and paranasal sinuses) and goals of resection (i.e., need for negative margins with malignancies).

Case Example

The patient is a 50-year-old female, status postmastectomy and postchemotherapy for breast cancer, who presented to our service with vision loss and motility abnormalities in her left eye. The patient was at neurologic baseline until 2 months prior to presentation, when she noted dull color perception in her left eye associated with blurring of vision. Several days after onset of her symptoms, the patient also experienced difficulty in abduction of her left eye, which prompted further workup by her oncologist. MRI ( Fig. 32.5A and B ) demonstrated an extra-axial enhancing mass along the floor of the anterior fossa extending into the left orbit and middle cranial fossa with encasement of the left optic nerve. On initial neuro-ophthalmologic evaluation, the patient’s exam was notable for the following: no light perception in the left eye, a left pupil that was amaurotic, and extraocular movements in the left 95% of abduction, 60% of normal elevation, 60% of normal depression, and 10% of abduction past midline. Furthermore, numbness in the left V2 distribution was noted. On orbital echography, enlargement of the left periophthalmic vein was noted.

The patient was taken to the operating room for tissue diagnosis and decompression. Via an eyebrow incision, a left-sided orbitozygomatic craniotomy was performed. Extradurally, the remaining diseased bone was drilled to decompress the superior orbital fissure and optic canal. Postoperatively, the patient was monitored in the neurocritical care unit and discharged home postoperative day 1. Postoperative MRI demonstrated adequate debulking (see Fig. 32.5C and D ); final pathology indicated metastatic poorly differentiated adenocarcinoma, consistent with the patient’s history of breast cancer.

At 1-month follow-up, the patient exhibited improvement with her extraocular movements, but her vision demonstrated no improvement. In light of the diagnosis of metastatic disease and the low probability of visual improvement, she was referred for radiation therapy.