Ординатура / Офтальмология / Английские материалы / Orbital Tumors Diagnosis and Treatment_Karcioglu_2005

PREOPERATIVE EVALUATION

The preoperative evaluation should begin with a thorough history and physical no matter how obvious the diagnosis appears to be. The original meaning of the Greek word historia, from which we derive the English word history, meant “inquiry.” Detailed systemic and ocular inquiry offer many useful clues for the management of the orbital tumor patient. The family history should specify any cancer, craniofacial syndrome, and other systemic familial disease such as neurofibromatosis. Particular attention should be given to the history of linking diseases as well as to other major health problems. The history of previous hospitalizations, head and neck injuries, and surgeries should be elicited. A list of the patient’s medications and allergies should be obtained.

The patient’s tendency toward bleeding should specifically be elicited. It is very important that the patient be instructed not to take aspirin products, other prostaglandin inhibitors, or anti–red cell and anti-platelet agents 2 weeks prior to surgery (Box 31.1). If there is any doubt regarding the bleeding status, prothrombin time (PT) and partial thromboplastin time (PTT) should be obtained prior to surgery. Younger children with questionable vascular lesions should be typed and crossed for 1 to 2 blood volumes.

The process of obtaining a detailed history and doing a thorough physical examination is an important opportunity to establish a good rapport with the patient and the family, which will strengthen their trust and confidence with the surgeon. It is absolutely essential that the patient’s problem be discussed in detail at every step. One practical way to communicate with the patient is to use computed tomography (CT) and magnetic resonance (MR) to explain the problem shown on the films. Patients can understand the problem much better when they are shown images of a space-occupying lesion in an orbit compressing the eye. The orbit is a particularly good site for this approach because many times the fellow orbit can be shown as a normal comparison. Furthermore, the need for the surgical procedure and the alternative treatments should be discussed, if at all possible, on a model or a detailed diagram of the eye and the orbit. The reasons for surgery, potential benefits, as well as

the complications should be detailed with the patient in a frank manner and the likelihood of complications based on the surgeon’s judgment and experience should be listed.

It is important that the patient and the family, not the surgeon, decide whether to proceed with surgery. In lifeand sight-threatening situations, the physician should make a clear note of his or her plan in the chart. If the advice is disregarded by the patient or family, this should also be documented in the chart. In certain situations, it may even be advisable, with the patient’s agreement, to record the conversation. If the diagnosis is not certain—for example, if an orbital biopsy is required—the need of biopsy diagnosis should be clearly explained. Radiology and pathology reports, as well as visual field and other test results, should also be discussed with the patient.

The surgical complications should be explained to the patient and family, not only for consent purposes, but more important, for the patient’s understanding of potential future problems. They should be told that there is a chance of infection and/or bleeding after surgery. It should also be explained that a persistent or transient visual loss, though a remote possibility, may result. Other postoperative complications include pain, a feeling of pressure, hypoesthesia or hyperesthesia, and scarring on the eyelids and the periorbital skin. It is very useful to obtain preoperative photographs and file them in the patient’s chart. It also must be explained to the patient that the orbital problem may be part of a systemic disease and that better understanding of the orbital pathology may eventually help to arrive at an effective systemic treatment.

It is a sound policy to give information to the patient and the family members regarding the disease and the management plan and let them go home and think about their options. This offers them an opportunity to digest the information, check with other family members and friends, or consult other physicians. It should be clear that they can call and discuss any further concerns with the surgeon and/or with the other members of the team.

Once the history and physical exam, laboratory tests, and imaging procedures are completed, a management plan should be made. The management of a tumor patient should take into account the relation-

BOX 31.1. Partial List of the More Common Aspirin-Containing Products, Which Should Be Discontinued 2 Weeks Prior to Surgery

ship of the orbital manifestations to a systemic disease, the immune status of the patient, the risk of general anesthesia, and the psychological state of the patient. Simpler plans should always be implemented before complicated ones. For example, if a fine-needle aspiration biopsy would offer information about an apical tumor, this procedure should be attempted first, no matter how small the yield, before a transcranial orbitotomy.

SURGICAL PLANNING

AND PREPARATION

Imaging

Imaging has become the gold standard for the diagnosis and management of orbital lesions. All imaging procedures, including ultrasonography, CT, and MRI are helpful, not only to obtain clues for diagnosis, but also for treatment planning in adults and children.1–3 The location, shape, internal characteristics, and relationship of a given lesion to adjacent orbital structures offer considerable clues toward diagnosis. CT and MRI, individually or together, usually provide a wealth of information on orbital lesions. Ultrasonography can be uniquely useful to reveal dynamic changes such as compressibility, multiloculation, and pulsations of cystic lesions; this kind of information

cannot be obtained with other types of imaging. Furthermore, recently developing advanced techniques of imaging, such as color Doppler ultrasonography, diffusion-weighted MRI, cine-MRI, MR spectroscopy, and positron emission tomography (PET), can be useful in special situations to add information regarding the nature and behavior of space-occupying lesions within the orbit.4–6 Because of the significance of imaging procedures for the diagnosis and management of orbital tumors, four chapters of this book are devoted to orbital imaging, offering information from the standpoint of the radiologist and the clinician, as well as covering the most recent advances and their applications to clinical practice (see Chapters 8 through 11).

Anesthesia

The great majority of orbital surgeries in adults and all the procedures in children are performed under general anesthesia. Occasional anterior orbit explorations and/or biopsies in adults can be done with local anesthesia. However, the administration of local anesthetics containing epinephrine 15 to 20 minutes prior to incision into the soft tissues of the surgical field contributes to vasoconstriction and reduces bleeding, particularly within the subcutaneous tissues. At the incision site, 1% lidocaine with epinephrine is usually injected subcutaneously. If the injection is given prior to the induction of general anesthesia, 1% lidocaine should be used because it seems to be the least painful agent. In one study, the order of local anesthetic agents, from least painful to most painful, was 1% lidocaine, 2% chloroprocaine, 1% mepivacaine, 0.5% bupivacaine, and 1% etidocaine.7 If nasal or sinus involvement is anticipated during the orbital exploration, it may be helpful to pack the nose with a half-inch strip of gauze soaked in local anesthetic containing epinephrine or 4% cocaine solution.

Hypotensive anesthesia is useful to reduce intraoperative bleeding; it should be implemented if there are no contraindications.8,9 The problem with this method, however, is that in some patients bleeding occurs postoperatively when the blood pressure returns to a normal level. During extubation at the end of orbital surgery, bucking of the patient should be avoided because it might lead to expulsive orbital bleeding.

GENERAL SURGICAL CONCEPTS

The best position for orbital surgery is reverse Trendelenburg, which reduces the arterial flow to the orbit as well as the venous stasis. The head should be positioned according to the planned orbitotomy. The sterile preparation usually includes the involved orbit. However, if major reconstruction is anticipated

and a symmetrical appearance at the end of the procedure is of concern, both orbits should be prepared. Furthermore, if any tissue borrowing is planned from other sites (e.g., thigh, retroauricular area, fellow eyelid), graft sites should also be prepared and covered with sterile towels. If the use of microscope or endoscope is planned, the surgical team and anesthesiologist should be notified beforehand.

INCISION

Incisions for orbital surgery include the conjunctiva, skin, and bone cuts.

SKIN INCISIONS

Skin Incisions of the eyelids and periorbital area should ideally follow the relaxed skin tension lines (RSTLs).10 Prior to the injection with local anesthetics, the incision line should be marked with a finetipped surgical pen such as a Codman® marker (Figure 31.1). The skin incisions can be made with a Bard-Parker 15-C or a 3 mm, 30° sharp, disposable blade (e.g., Super Blade®). The incision should cut only the skin, not the underlying structures; it is helpful to complete the entire length of the incision in one sweep to keep blood from pooling over the incision line. In general, the skin incisions are made perpendicular to the skin surface for the eyebrow. In the eyebrow the cut is made at a 45° angle following the angulation of the hair follicles. The eyelid incisions and the lazy-S incision starting in the mid-eyelid crease are particularly useful to gain access to superior and lateral orbital space. Conjunctival incisions are preferred for an inferior orbital approach, but if one has to go through the skin, a subciliary incision in the lower lid offers easy access to the orbital floor. The most commonly used medial and superior medial skin incisions include modifications of the Lynch incision and the sub-brow incision. Although the classic Lynch

incision leaves considerable scarring, it is still quite useful to provide access to lacrimal drainage system (LDS), the ethmoid sinuses, and the nasal cavity.

CONJUNCTIVAL INCISIONS

In general, conjunctival incisions offer better postoperative cosmetic results. Any quadrant of the orbit can be approached through a segmental conjunctival peritomy overlying the area (Figure 31.1). Through conjunctival incisions, one can easily gain access to the intraconal space. The intraconal space is directly approached through perilimbal incisions of the conjunctiva through the sub-Tenon’s space. For the extraconal space one should use forniceal incisions, which are particularly useful medially and inferiorly.11 Superior and superior lateral fornix incisions are not ordinarily used, to avoid traumatizing the palpebral portion of the lacrimal gland and the ductules. The caruncular incision provides excellent access to the medial and posterior orbit.

BONE INCISIONS (OSTEOTOMIES)

Although many areas in the orbit can be accessed through skin and conjunctival incisions, the extent of the osteotomy to remove portions of the bony orbit should also be very carefully planned. It should be kept in mind that the best exposure of the orbital surgical field is accomplished through well-planned and properly executed removal of the bone.

In orbital tumor surgery, the bone is removed for two primary reasons: first, the removal of the marginal bone improves exposure, such as in lateral orbitotomy. The most common osteotomy is performed for lateral orbitotomy to allow a wide surgical field. Second, the bone is removed to control a neoplastic process in malignant orbital tumors such as adenoid cystic carcinoma.

Surgical Field

FIGURE 31.1. Skin and conjunctival incisions for orbit surgery: black: sub-brow incision in continuity with Lynch incision; orange: lid crease incision; purple: caruncular incision; red: lateral canthal incision; blue: subciliary incision; green: lateral crus incision (swinging lid incision); turquoise: lower lid incision; yellow: perilimbal incision; pink: lazy-S incision. The dotted white circle roughly corresponds to the bony margin of the orbit.

LIGHT AND MAGNIFICATION

During orbital exploration, magnification and lighting are very important. A great majority of cases can be done under 3 to 5 power surgical loupes. However, at times the surgical microscope is invaluable for special purposes, such as fine dissection, with or without carbon dioxide laser, for vascular and canalicular anastomoses, and to identify tumor margins. Because of the depth of the operative field in orbit surgery, it may be preferable to use free-floating operative microscopes with variable objective focal length designed for ear, nose, and throat surgery, rather than the fixed focal microscope designed for ophthalmic surgery.

A headlight combined with surgical loupes provides the best illumination; however ceiling lights of

the operating room, fiberoptic light sources, endoscopes, and the light source of the indirect ophthalmoscope may be needed occasionally.

EXPOSURE FOR EXPLORATION

The orbit is a small cavity inhospitable to the surgeon; it is crowded with vital tissues that are separated by delicate fibrous septae and fat. Orbital exploration usually begins from its anterior aspect, which commits the surgeon to a deep, three-dimensional field with poor visibility. Furthermore, changes in the anatomic relationships between structures because of the orbit’s conal shape add to the difficulty of exploration. Therefore, adequate exposure of the surgical field is of utmost importance. The optimization of the exposure begins with the proper selection of skin and bone incisions and is maintained with accurate positioning of the surgical retractors and placement of traction sutures. Continuous maneuvering employed during orbital exploration to gain optimum exposure often takes more time than the actual biopsy or removal of the tumor.

Proper placement of the patient’s head, positioning of the surgeon and assistants, as well as optimum lighting and magnification are the key elements of success in orbital surgery. Patience is an important virtue in orbital dissection, to maintain a bloodless surgical field and adequate exposure. Because of unanticipated shifting of the orbital fat, the surgeon should be familiar with continuous interruptions of the visibility that make the surgical field look somewhat like a Charlie Chaplin movie, but in color. The fat can be pushed away from the field, put on traction, dissected, and at times even be resected; however, all surgical maneuvers should be done atraumatically, with blunt rather than sharp dissection. The orbital surgeon should maintain a mental correlation between the imaging of the lesion and its actual position within the orbit and should approach the lesion through the appropriate planes of tissue. The importance of the definition of the plane of entry is aptly emphasized in Rootman, Stewart, and Goldberg, Orbital Surgery: a Conceptual Approach: “Instead of entering directly into the pathologically involved tissue planes, the surgeon should begin the dissection in the more easily distracted and pliable normal tissues adjacent to the lesion.”12 This approach allows the distinct advantage of comparing the normal tissues and the abnormal, to permit the ready identification of the pathology.

Most of the dynamic retractions throughout the procedure are done with the use of retractors. A wide range of handheld retractors, including Desmarres, Semm, and Ragnell retractors and malleable ribbon retractors (3/8 to 1 in. width) are used. In addition, rakes (Peck or Follet), muscle hooks (Graf or Jameson), and skin hooks (Joseph or Freer) function well for different levels of tissue retraction. Semipermanent retrac-

tion of the skin and subcutaneous tissues may also be accomplished with nonbarbed fishhooks attached to rubber bands at the wound edges. The advantage of the fishhooks is that they can be moved easily from one location to another; the disadvantage is that no matter how tightly they are clipped to the drapes, they tend to get loose after a while. The hooks and retractors can also be attached to self-retaining stages; however, this apparatus is usually cumbersome to operate and occupies valuable space in the surgical field (Figure 31.2).

Another method of retraction is to use sutures to retract tissues of different kinds. One common application is to use 4-0 silk for eyelids. When the suture is passed at the lid margin, it should be applied parallel to the eyelid margin with a good bite into the tarsus. This is best done with a Brown–Adson tissue forceps, sandwiching the eyelid margin and allowing the needle to be passed into the tarsus between the arms of the forceps. It is also advisable to pass a silk suture under the extraocular muscles to ensure that they can be identified during the later stages of the procedure. In particular, medial and inferior recti muscles should be anchored with sutures during orbital explorations of corresponding sites. If a considerable amount of traction is to be applied to these sutures, it is advisable that they be cuffed or replaced with silicone tubing, which may damage the underlying tissues far less when the traction is applied. Traction sutures can also be applied to the stumps of disinserted extraocular muscles. The best example of this is anchoring the stump of the medial rectus during medial orbitotomy through the conjunctival approach. It is best to run a 5-0 Vicryl or Merseline suture at the stump of the medial rectus muscle and cuff both ends of the suture with silicone tubing to avoid corneal and conjunctival damage during retraction of the globe (Figure 31.3). Corneal protection can also be accomplished by threading ocular conformers with traction sutures.

FIGURE 31.2. Self-retaining retraction apparatus with attached fishhooks. Note the crowding of the surgical field.

FIGURE 31.3. Silicone tubing cuffed over traction suture to protect underlying cornea and conjunctiva.

FIGURE 31.5. Delivery of powdered form of microfibrillar collagen (Avitene®) mixed with thrombin directly into the orbit to control generalized oozing of blood.

Bone can also be retracted by sutures. For example, zygomatic arche attached to the temporalis fascia/muscle can be hinged laterally and posteriorly by traction sutures passed through predrilled holes in the bone (Figure 31.4); it is best to use 2-0 Prolene for this purpose because the sharp edges of the holes might cut the finer sutures.

HEMOSTASIS

It should be determined whether any bleeding experienced in the surgical field is due to a ruptured blood vessel or to generalized oozing. This can usually be detected by alternating gentle suction and minimal pressure. If a blood vessel is found to be responsible, it should be isolated, clamped, cauterized, or tied off before the exploration is carried on. If the bleeding is due to generalized oozing, it is beneficial to apply thrombin soaked Gelfoam or surgical cottonoids. Neurosurgical cotton paddies are preferable because they are easier to identify and remove once the oozing has stopped. Powdered Avitene® can also be packed into

FIGURE 31.4. A 2-0 Prolene suture is used to retract the zygomatic arch laterally and maintain its position during lateral orbital exploration.

the surgical field or delivered by syringe (Figure 31.5). Avitene® should be irrigated gently at the end of the procedure.

As mentioned earlier, hemostasis may be initiated by hypotensive anesthesia, as well as by injection of epinephrine-containing local anesthetics. Some authors advise the use of enfluothane (Ethrane®) anesthesia to reduce the intraoperative oozing of blood.13 Intraoperative bleeding can be controlled with bipolar or unipolar coagulators; the fine-needle tip (Colorado tip®) is preferred. Furthermore, vascular ties, clips, and chemical adjuncts can be used to maintain hemostasis (Box 31.2).

BIOPSY

Orbital biopsy is a very important procedure; more than half of tumor-related surgeries are performed just to obtain an adequate tissue sample for diagnosis. For

BOX 31.2. Hemostasis Methods During Orbital Surgery

Hypotensive general anesthesia

Reverse Trendelenburg position on the operating table

Application or injection of chemical vasoconstrictors (epinephrine, cocaine)

Application of strip gauze and/or neurosurgical paddies soaked with chemical vasoconstrictors and/or coagulators (Avitene®)

Thrombin-soaked gelatin sponge (Gelfoam®) Oxidized regenerated cellulose (Surgicel®) Bone wax

Cauteries (bipolar, unipolar, fine-tipped disposable)

Pressure by hand, with or without ice

proper conduct of the orbital biopsy, it is essential to establish a procedure plan. Many biopsy techniques, including FNAB, core biopsy, and excisional biopsy, are available; the biopsy procedure should be selected to fit the case.

Because of the significance of the biopsy in the diagnosis and management of orbital disease, an entire chapter is devoted to the subject. Biopsy procedures, tissue techniques, benefits of special studies, including frozen section biopsy, and sentinel lymph node biopsy, are covered in detail in Chapter 12.

TISSUE REMOVAL/ABLATION

Well-delineated masses (and cysts) can be stabilized with forceps, cryoprobe, and sutures to be removed following blunt dissection around the lesion (Figure 31.6). Unlike well-encapsulated tumors, infiltrating lesions cannot be removed totally but need to be debulked. Debulking with sharp instruments causes a considerable amount of bleeding and may lead to many inaccuracies because of the obstruction of the surgical field by blood. Laser energy, on the other hand, may be a useful surgical adjunct for debulking orbital tumors. Among argon, yttrium-aluminum- garnet, dye, and carbon dioxide (CO2) lasers, which are occasionally used in different applications of ocular plastics surgery, the CO2 laser is the only one with substantial clinical usefulness in orbital tumor sur-

gery. The 10,600 nm output of the CO2 laser is strongly absorbed by tissue water. Because of this high absorption coefficient, the CO2 laser allows great surgical precision, particularly when it is used under magnification. In skillful hands, the CO2 laser is a precise, hemostatic, noncontact, ablation instrument for infiltrating orbital tumors. Some authors claim that it reduces postoperative pain, with improved cosmetic results.14 Because of its precise tissue vaporization effect, it has been a useful surgical adjunct for debulking infiltrating tumors such as hemangioma, lymphangioma, plexiform neurofibroma, and Kaposi sarcoma.15 Plexiform neurofibroma, which is otherwise known as “spaghetti tumor” because of its infiltrating character, is notoriously difficult to remove by conventional surgical means. The CO2 laser has been proven to be a good debulking instrument for this tumor.16 Although the debulking application of the CO2 laser by tissue vaporization is very good, hemostasis of blood vessels larger than 0.5 mm in diameter requires defocusing of the laser beam.

Potential corneal injury with the CO2 laser should be kept in mind, and wavelength-specific eye protection should be placed over the patient’s eyes and should be mandatory for all members of the surgical team.

CORRELATION OF SURGICAL PROCEDURES WITH ANATOMY

FIGURE 31.6. Use of the cryoprobe as a stabilizer during the removal of a cavernous hemangioma. The lower frame depicts a new design of a straight (“Finger probe”) instrument which provides a larger zone of cryoadhesion at the tip (Courtesy of Dr. Paul Finger, New York City, NY.)

The orbit is a pear-shaped bony chamber with an anterior opening measuring approximately 40 and 35 mm in horizontal and vertical diameters, respectively (Figures 31.7 and 31.8). Its volume expands approximately 1 cm posterior to the bony rim and then gradually decreases toward the apex, which consists of the optic canal at its narrowest diameter. In the axial plane, the medial wall measures approximately 45 to 50 mm from the anterior lacrimal crest to the entrance of the optic canal (Figure 31.9). In the same plane, each lateral walls forms a 45° angle to the medial walls and measures approximately 40 mm from the center of the lateral orbital rim to the opening of the superior orbital fissure. The surgeon should be familiar with the relationship of the superior and inferior orbital fissures to the superior, lateral, and inferior orbital rims. In particular, the superior aspect of the superior orbital fissure (SOF) and the inferior aspect of the inferior orbital fissure (IOF) are helpful landmarks that should not be violated during orbital exploration. The anatomic relationships between tissue structures vary because of the orbit’s conal shape. This relative positional variability plus poor visibility of the field make surgical intervention difficult, particularly in the midand posterior orbit. A thorough knowledge of the anatomy eases this difficulty. Many elaborately

A

B

FIGURE 31.7. Parameters of orbital anatomy. (A) The vertical diameter (white arrow) is about 35 mm; the horizontal diameter (black arrow) is about 45 mm; the red lines represent the relative axis position of each orbit to the other of 90°. (B) The position of the anterior (red arrow) and posterior (white arrow) of ethmoidal foramina FB, frontal bone; ZB, zygomatic bone; EB, ethmoidal bone; LF, lacrimal fossa [bounded by anterior lacrimal crest (black arrow) and posterior lacrimal crest (double white arrows)], SOF, superior orbital fissure; IOF, interior orbital fissure.

written and illustrated textbooks and review articles exist on orbital anatomy and surgery. This chapter is not meant to be either an anatomy or surgery atlas. Only anatomic points that are pertinent to orbital tumor surgery are reviewed here; otherwise the reader is referred to detailed anatomy texts.12,17,18

There are three main reasons for surgery in a tumor-containing orbit: biopsy, partial excision (debulking), and total removal of the tumor. When total excision with clear margins by means of an orbitotomy is not possible because of tumor infiltration into both the globe and the soft and bony tissues of the orbit, special procedures, including enucleation, exenteration, and orbitectomy are undertaken.19,20 Traditionally, the orbit is divided into several compartments as anterior versus posterior, extraconal versus intraconal, and superior, inferior, medial, and lateral. The surgical approach is planned according to these spaces.21 In tumor surgery, however, the invasive and expanding nature of the pathology may force the surgeon to operate in several spaces at once.22–24

The most significant innovation in orbital surgery

during the past decades has been the development of preoperative orbital imaging with CT and MR. The imaging not only confirms the presence of a spaceoccupying lesion but also shows its location relative to other orbital structures and helps immensely in surgical planning. The surgical plan for an orbital tumor is based primarily on the location of the tumor, and the incisions are done accordingly. The best exposure in the orbit is accomplished by wide bone removal; however, extensive osteotomies are known to be associated with more complications, longer procedure time, and slower postoperative recovery. Conventional planning dictates a surgical approach through the orbital wall closest to the mass lesion. Since, however, at times, more than one wall needs to be used, orientation to orbital wall anatomy is important to the surgeon. The anatomy of orbital walls and the related surgical procedures are discussed together in the following section. Capital and lowercase letters in parentheses correspond to structures shown in Figures 31.7, 31.8, and 31.9.

SURGICAL PROCEDURES

Lateral Wall and Lateral Orbitotomy

The orbital rim tapers laterally to form the thickest of all orbital walls. Although a small extension of the frontal bone is included in the superior aspect of the lateral wall of the orbit, for all practical purposes, this wall is composed of the zygomatic (ZB) and sphenoid bones. The frontosphenoid suture and superior and inferior orbital fissures limit the superior and inferior borders of the lateral orbital wall, respectively. Posteriorly, the greater wing of the sphenoid bone (gSB) separates the orbit from the middle cranial fossa.

An important superior orbital landmark, the Whitnall ligament, is the suspensory component of the levator aponeurosis. This ligament is attached to the tubercle of Whitnall, located approximately 10 mm inferior to the frontozygomatic fissure and 5 mm posterior to the lateral rim. The posterior head of the lateral canthal tendon and Lockwood’s ligaments are also attached to this site. The junction between the frontal and zygomatic bones, the zygomaticofrontal (FZF) suture, is usually identified at the superior one third of the lateral orbital rim. The location of this junction to which the periosteum is firmly attached is variable, and, on occasion, it is difficult to identify during surgery.

Posteriorly, the lateral wall is bordered with the superior orbital fissure, situated between the greater and lesser (lSB) wings of the sphenoid bone. This foramen transmits the third, fourth, and sixth cranial nerves and the ophthalmic branch of the fifth cranial nerve, the superior orbital vein, and sympathetic nerves. Space-occupying lesions compressing these

structures or originating from them present with signs and symptoms of ocular motor palsies related to these cranial nerves.

The lateral orbitotomy is considered the best approach to gain access to the midand posterior orbit. Kronlein’s original technique, which was described in the late 1800s, has been modified on numerous occasions, by Berke, Reese, Wright, and others.20,25–28 In practice, all who utilize lateral orbitotomy come up with minor modifications until the technique suits them well.29

Numerous skin approaches to lateral orbitotomy exist: superotemporal lazy S in the eyebrow, superonasal lazy S in the lid crease, lateral canthal incision, inferotemporal lid incision for the “swinging” eyelid approach, and scalp incision for coronal approach (Figure 31.1). Most of these skin incisions allow access to the bony and soft tissue structures of the lateral, superiolateral, and inferolateral orbit. Therefore, the incision preference of the surgeon is based on minimizing the amount of postoperative scarring and the operative time, as well as staying away from important eyelid structures.

Although bone removal is occasionally performed in orbitotomies of other types, in lateral orbitotomy

bone excision is a routine part of the procedure. It is important to realize that maximum exposure in the field of surgery targeted by the surgeon is governed by the amount of bone excision rather than the skin incision. This concept is succinctly expressed by Rootman, Stewart, and Goldberg: “Careful preoperative evaluation should determine whether or not the lesion will require more than the standard bone removal because virtually all of the anterior walls can be removed from the region, lateral to the superior orbital notch (SON) and posteriorly as far as the superior orbital fissure (SOF).”12 If additional access is needed inferiorly, a portion of the inferior rim and the floor as far medially as the inferior orbital fissure can be excised (Figure 31.10).

Before the skin incision is made, a 4-0 silk traction suture is placed under the lateral rectus muscle to tag the muscle during the procedure. The author feels most comfortable with the lazy-S incision through the lid crease as the routine approach for lateral orbitotomy. Prior to injection, the incision is drawn with a microsurgical marker and made in one sweep for its entire length. The subcutaneous tissues and muscle may be cut with a fine-tip (Colorado® tip) unipolar cautery, or, if one is concerned about the heat effect on the underlying

FIGURE 31.9. Corresponding planes of anatomic specimen and axial CT scan at midglobe level. Superior orbital fissure (white arrow); optic canal (black arrow). ES, ethmoidal sinus; gSB, greater wing of sphenoid bone; LG, lacrimal gland; LF, lacrimal fossa; SS, sphenoid sinus; ZB, zygomatic bone.

lesion, the subcutaneous tissues can be dissected bluntly with a curved hemostat or Stevens scissors.

The skin incision starts from the middle of the eyelid crease and extends laterally over the frontozygomatic process about 4 mm superior to the lateral canthal tendon. The incision should not go more than 30 mm or so beyond the frontozygomatic suture (Figure 31.11). It is helpful to identify the frontozygomatic process prior to the marking the skin incision. Subcutaneous tissues are bluntly dissected or gently cauterized over the temporalis muscle fascia to minimize the damage to the branches of the seventh nerve. The blunt dissection may be facilitated if two (superior and inferior) 4-0 silk traction sutures are placed into the subcutaneous tissues to retract the open wound and expose the lateral orbital rim. These sutures should be placed into the subcutaneous tissue with a wide, horizontal bite to avoid the “cheese-wiring” of the skin during traction. The extent of immobilization of the overlying tissues should be customized according to the planned extent of the osteotomy. When the orbital rim has been visualized, the periosteum is incised with a curvilinear cut approximately 2 mm posterior to the lateral orbital rim and extended superiorly and inferiorly as much as is necessary. A horizontal relaxing incision is made in the middle, and then the

periosteum of the zygoma is separated from the bone with a sharp periosteal elevator. The periosteum is stripped over the zygomatic arch in all directions; however, the temporalis muscle attachment from the bone is not completely severed inferiorly with this technique.

Once the orbital rim has been exposed as bare bone, the osteotomy sites are marked with the unipolar cautery and then the vertical bony incisions are made with an oscillating saw, under irrigation to avoid extensive heating. Suction is applied to the area of bone incisions to collect small fragments of bone and bone marrow, which could disseminate and cause inflammation later. The bone incisions are usually made at the superior lateral margin of the orbit a few millimeters above the zygomaticofrontal suture and inferiorly through the zygomatic bone just above the junction of the inferior orbital rim. The extent of the osteotomy should be tailored to the size, location, and the nature of the tumor. Therefore, more extensive osteotomies can be designed to include superior, inferior, and posterior orbital bones (Figure 31.10). When the horizontal bone incisions are completed, their anterior edges are extended into the orbit and the horizontal incisions are connected with a vertical one, following the contour of the lateral orbital wall (Figure 31.11). The vertical cut is best created by gently tapping on a sharp, curved osteotome with a mallet about 15 to 20 mm posterior to lateral rim. Even a very shallow horizontal cut connecting the superior and inferior bony incisions leads to a clean break, controls the posterior extent of the osteotomy much better, and usually avoids the additional removal of the bones with rongeur or burrs. If one chooses to burr additional bone, it should be remembered that on the other side of the bone in this area lies the middle cranial fossa.

Most surgeons prefer to drill holes on either side of the bone incisions prior to the osteotomies because it is much easier to drill while the bone is stable. Par-

FIGURE 31.10. Depiction of the extent of bony removal on frontal and lateral views of the human skull. The black lines delineate the margins of bone removal for conventional lateral orbitotomy. SOF, superior orbital fissure; IOF, inferior orbital fissure.