Multimodal Treatment of Orbital Tumors

Published on 13/03/2015 by admin

Filed under Neurosurgery

Last modified 22/04/2025

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1153 times

Chapter 50 Multimodal Treatment of Orbital Tumors

Shaan M. Raza, Alfredo QuiÑones-Hinojosa, Prem S. Subramanian

The surgical management of intraorbital tumors requires a thorough understanding of not only orbital anatomy but also the objectives of surgical intervention. The orbital contents abut the skull base, paranasal sinuses, and intracranial compartment or anterior cranial fossa. The orbit is a quadrangular compartment that can be approached through a variety of trajectories along one of its four walls or posteriorly from its apex. From the surgical standpoint, the orbit represents an anatomic compartment that is encountered by several specialties—neurosurgery, ophthalmology and otolaryngology—with their own approaches derived from the pathologic processes they usually encounter.

From the neurosurgical perspective, the orbit is exposed in the surgical management of pathologic processes involving the orbit, in addition to the skull base or intracranial cavity. The neurosurgeon often becomes involved in orbital disease cases when tumors or vascular lesions are present. Orbital tumors are often benign (i.e., meningioma, cavernous hemangioma, and schwannoma) but may be locally invasive or infiltrative. Malignant lesions (i.e., cranial base sarcomas, esthesioneuroblastomas, and squamous cell carcinomas) are even more likely to require a multidisciplinary approach because of their spread across multiple anatomic compartments. Primary orbital tumors are often discrete from normal orbital structures and may engulf, although not necessarily invade, the extraocular muscles and/or optic nerve; secondary tumors extend into the orbit along normal anatomic structures (often nerves) or by bony destruction. As such, the surgical objectives for processes involving the orbit range from the need for negative margins or aggressive resection to purely orbital decompression.

Selecting the most appropriate surgical treatment for orbital disease processes requires an understanding of the various open and endoscopic surgical approaches and their advantages, indications, and limitations. The primary considerations are the location and size of the tumor, including its relationship to crucial orbital structures, the site of origin, the other extraorbital anatomic compartments involved, and histologic diagnosis.

Orbital Anatomy

Orbital Bony Anatomy

The bony orbit not only lies close to other compartments in the facial skeleton but also contains several foramina through which critical neurovascular structures pass1 (Fig. 50-1). The orbital roof is formed by the frontal bone and lesser wing of sphenoid; its superior surface is the floor of the anterior cranial fossa. The roof also lies below the frontal sinus. The orbital plate of the maxillary bone forms most of the orbital floor, in addition to the roof of the maxillary sinus; the palatine and zygomatic bones also contribute to the floor. Medially, the medial wall, also known as the lamina papyracea, forms a thin wall separating the orbit from the ethmoid sinus anteriorly and the sphenoid sinus more posteriorly, a structure through which most endoscopic approaches to the orbit can be directed. It is comprised of four bones: the maxillary, lacrimal, ethmoid, and lesser wing of sphenoid. The medial wall of the orbit also contains the foramina through which the anterior and posterior ethmoidal arteries pass. The lateral orbital wall is covered externally by the temporalis muscle and formed by the frontosphenoid process of the zygomatic bone, in addition to the greater wing of the sphenoid. The apex of the orbit is directed in a medial oblique direction and contains three critical foramina: optic canal, superior orbital fissure, and inferior orbital fissure. The optic canal bridges the intracranial space and orbit inferomedial to the anterior clinoid process while it is bordered laterally by the lesser wing of the sphenoid. The superior orbital fissure is bordered laterally by the greater wing of the sphenoid.

image

FIGURE 50-1 Integrity of the bony orbit and the size and shape of its fissures and foramina can be defined by plain skull radiographs and CT bone windows. The frontal, ethmoidal, and maxillary sinuses are shown diagrammatically. Attention is directed to one of the two roots of the lesser wing of the sphenoid, which lies beneath the anterior clinoid and forms the lateral margin of the optic canal in the medial margin of the superior orbital fissure.

Muscle Cone and Annulus of Zinn

The annulus of Zinn serves as the origin of six of the seven extraocular muscles (Fig. 50-2). Superiorly, the superior rectus arises from the annulus, which at this point is fused with the dura of the optic nerve. The levator palpebrae arises medial and superior to the superior rectus muscle but remains intimately associated with it. More medial and inferior to this are the origins of the medial rectus and superior oblique muscles. Although it is firmly fused to the optic nerve dorsally, the annulus of Zinn loops widely around the nerve laterally and inferiorly, giving rise to the lateral rectus muscle, in addition to the inferior rectus. The space between the insertion sites of these two muscles is known as the oculomotor foramen. Based on this arrangement, there are evident portals of entry of neurovascular structures into the orbit: the optic canal and the superior orbital fissure.

image

FIGURE 50-2 The anulus of Zinn is a fibrous band giving rise to the origins of six of the seven extraocular muscles. This fibrous tissue is in continuity with the dural sheath of the optic nerve. The two heads of the lateral rectus loop around that portion of the superior orbital fissure known as the oculomotor foramen.

Optic Nerve and Orbital Nerves

The optic nerve, throughout its entire course from the chiasm to sclera, is covered with a pial membrane (providing vascular supply) and associated subarachnoid space (Fig. 50-3). As the optic nerve enters the optic canal, the intracranial dura splits, with the outer leaf forming the orbital periosteum and the inner leaf remaining with the optic nerve. The superior orbital fissure contains the remaining cranial nerves that enter the orbital compartment. The trochlear nerve and the frontal and lacrimal branches of the trigeminal nerve enter through the superior orbital fissure above the extraocular muscles and annulus of Zinn. The remaining nerves—the oculomotor nerve (superior and inferior divisions) and the abducens nerve—pass through the superior orbital fissure and annulus of Zinn.

image

FIGURE 50-3 Partial obliteration of the subarachnoid space of the optic nerve at the anulus of Zinn is shown, and the medial origin of the levator muscle is evident. The ophthalmic artery (OA) enters the orbit through the optic canal. The trochlear (CN IV), frontalis (CN V), and lacrimal (LA) nerves and the ophthalmic vein (OV) enter through the superior orbital fissure and thus lie within the periorbita but outside the muscle cone, whereas the superior division of the oculomotor nerve (Sup. CN III), the abducens nerve (CN VI), the nasociliary nerve (NN), and the inferior division of the oculomotor nerve (Inf. CN III) enter the muscle cone through the oculomotor foramen and lie within the muscle cone.

Because of this arrangement, it is evident that the optic nerve can be approached directly through the medial compartment, between the medial rectus and the levator muscles, without fear of injury to the nerve supply of any extraocular muscle (Fig. 50-4).

image

FIGURE 50-4 The nerve supply to the extraocular muscles is shown entering through the oculomotor foramen. A medial superior approach to the optic nerve between the lateral and the medial rectus muscles provides direct access, with minimal chance of injury to this nerve supply to the extraocular muscles.

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 50-1.2 While medical management is best suited for infectious and inflammatory processes involving the orbit, definitive surgical treatment remains the mainstay for a majority of symptomatic orbital tumors and dysthyroid orbitopathy.

TABLE 50-1 Overview of Orbital Lesions

Category Lesions
Vascular Capillary hemangioma
  Cavernous hemangioma
  Hamartoma
  Hemangiopericytoma
  Lymphangioma
Nerve sheath Neurilemomas
  Neurofibroma (plexiform and solitary)
Osseous and cartilaginous Osteoma
  Osteogenic sarcoma
  Chondroma
  Fibrous dysplasia
  Aneurysmal bone cyst
Neuroepithelial Optic nerve glioma
Meningioma  
Mesenchymal Rhabdomyosarcoma
  Lipoma
  Liposarcoma
Inflammatory Nonvasculitic
  Vasculitic, nongranulomatous
Carcinoma  
Cystic  
Other  

The diagnostic workup proceeds logically after clinical examination and primarily consists of imaging. Magnetic resonance imaging (MRI) with fat suppression provides excellent definition of orbital pathology.3,4 Fat suppression eliminates the T1 bright signal associated with orbital fat that can obscure intraorbital pathology. Contrast-enhanced MRI provides excellent soft tissue resolution and is the best modality to determine intracranial extension of orbital pathology.5,6 Computed tomography (CT) imaging provides excellent definition of orbital pathologic process and regional bone anatomy. An adequate study includes thin cuts through the orbits and shows normal orbital anatomy, including the size and position of the globe, optic nerve, and extraocular muscles. CT is superior to MRI in surgical planning because of its ability to show bony anatomy, but MRI is preferred when optic nerve involvement by the tumor or disease process must be examined.

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?

• 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 extent 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 ophthalmologists) and extraorbital approaches (often performed by a team that includes a neurosurgeon or head and neck surgeon, as well as an ophthalmologist).7,8 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 incision is usually 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 dissection proceeds according to the lesion. The periorbita can then be closed with interrupted 5-0 polygalactin sutures, although the orbital septum should not be closed to avoid eyelid retraction. The skin incision is closed with a running 8-0 nylon suture.

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 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 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. 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 and the conjunctiva is closed with interrupted sutures. A transcaruncular approach is also effective in accessing extraconal tumors in the medial space. An incision is placed directly through the caruncle, and Stevens scissors are used to palpate the posterior lacrimal crest. 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.

Approaches to the Lateral Orbit

The lateral orbitotomy is useful for retrobulbar lesions and more posterior lesions. The technique removes the lateral wall of the orbit 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, dividing the canthus 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 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 approached for 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 with caution 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 approaches. 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 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. 50-5A 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.

image

FIGURE 50-5 Patient with a metastatic breast cancer lesion at the orbital apex presenting with visual decline and diminished extraocular movements. A, Preoperative T2-weighted image demonstrating compression of the left optic nerve at the orbital apex. B, Preoperative T1-weighted axial image with contrast demonstrating an enhancing lesion at the orbital apex involving the anterior cranial fossa, orbit, and middle cranial fossa. C, Postoperative T2-weighted image demonstrating decompression of left optic nerve. D, Postoperative T1-weighted axial image with contrast demonstrating the debulking of the lesion.

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 (Fig. 50-5C 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.

Key References

Bejjani G.K., Cockerham K.P., Kennerdel J.S., Maroon J.C. A reappraisal of surgery for orbital tumors. Part I: extraorbital approaches. Neurosurg Focus. 2001;10:E2.

Cockerham K.P., Bejjani G.K., Kennerdell J.S., Maroon J.C. Surgery for orbital tumors. Part II: transorbital approaches. Neurosurg Focus. 2001;10:E3.

Darsaut T.E., Lanzino G., Lopes M.B., Newman S. An introductory overview of orbital tumors. Neurosurg Focus. 2001;10:E1.

Haik B.G., Saint Louis L., Bierly J., et al. Magnetic resonance imaging in the evaluation of optic nerve gliomas. Ophthalmology. 1987;94:709-717.

Housepian E.M. Microsurgical anatomy of the orbital apex and principles of transcranial orbital exploration. Clin Neurosurg. 1978;25:556-573.

Jakobiec F.A., Depot M.J., Kennerdell J.S., et al. Combined clinical and computed tomographic diagnosis of orbital glioma and meningioma. Ophthalmology. 1984;91:137-155.

Jakobiec F.A., Yeo J.H., Trokel S.L., et al. Combined clinical and computed tomographic diagnosis of primary lacrimal fossa lesions. Am J Ophthalmol. 1982;94:785-807.

Rhoton A.L.Jr. The orbit. Neurosurgery. 2002;51:S303-S334.

Numbered references appear on Expert Consult.

References

1. Cockerham K.P., Bejjani G.K., Kennerdell J.S., Maroon J.C. Surgery for orbital tumors. Part II: transorbital approaches. Neurosurg Focus. 2001;10:E3.

2. Haik B.G., Saint Louis L., Bierly J., et al. Magnetic resonance imaging in the evaluation of optic nerve gliomas. Ophthalmology. 1987;94:709-717.

3. Housepian E.M. Microsurgical anatomy of the orbital apex and principles of transcranial orbital exploration. Clin Neurosurg. 1978;25:556-573.

4. Jakobiec F.A., Depot M.J., Kennerdell J.S., et al. Combined clinical and computed tomographic diagnosis of orbital glioma and meningioma. Ophthalmology. 1984;91:137-155.

5. Jakobiec F.A., Yeo J.H., Trokel S.L., et al. Combined clinical and computed tomographic diagnosis of primary lacrimal fossa lesions. Am J Ophthalmol. 1982;94:785-807.

6. Bejjani G.K., Cockerham K.P., Kennerdel J.S., Maroon J.C. A reappraisal of surgery for orbital tumors. Part I: extraorbital approaches. Neurosurg Focus. 2001;10:E2.

7. Rhoton A.L.Jr. The orbit. Neurosurgery. 2002;51:S303-S334.

8. Darsaut T.E., Lanzino G., Lopes M.B., Newman S. An introductory overview of orbital tumors. Neurosurg Focus. 2001;10:E1.

Related posts:

Hearing Prosthetics: Surgical Techniques Surgical Management of Cerebrospinal Fluid Leakage after Spinal Surgery Atlantoaxial Instability and Stabilization Lumbar Spinal Arthroplasty: Clinical Experiences of Motion Preservation Arachnoid, Suprasellar, and Rathke’s Cleft Cysts Management of Skull Base Trauma