Anterior versus deep tumors

The anterior–posterior position of an orbital mass within the orbit is the most important factor to consider in choosing a surgical approach. Tumors anterior to the equator of the eye are most commonly approached from the front of the orbit using a type of anterior orbitotomy. Tumors posterior to the equator of the eye require more advanced deep surgical approaches. The choice of orbitotomy for deep tumors is related to the relationship of the tumor to the optic nerve.

Relationship to the optic nerve

A fundamental principle of orbital surgery is:

Following this guideline, deep orbital tumors lateral to the optic nerve are approached with a lateral orbitotomy approach. Removal of the lateral orbital wall provides excellent access to these tumors.

Deep tumors medial to the optic nerve are more difficult to reach because there is no bone that can be easily removed to provide good exposure and access. The surgical spaces of the medial orbit can be reached through deep medial orbitotomy approaches, through either the eyelid or the conjunctiva. Access to the apical medial orbit from these anterior orbitotomy approaches is limited. In unusual situations, the medial orbital wall may be removed and limited access to the deep medial orbit can be obtained (Figure 15-2).

Figure 15-2 The choice of orbitotomy approach is based on the position of the mass. (A) Anterior to the equator of the eye: anterior orbitotomy. (B) Posterior to the globe and medial to the nerve: deep medial anterior orbitotomy. (C) Posterior to the globe and lateral to the nerve: lateral orbitotomy. (D) Involving the posterior one third of the orbit: transcranial orbitotomy.

Type of biopsy

The surgical approach may be influenced by the goal of the operation. It is easier to perform an incisional biopsy through a small incision than it is to perform an excisional biopsy. For example, an incisional biopsy of the optic nerve can be performed through either a transconjunctival anterior orbitotomy or a lateral orbitotomy approach. Excision of the entire optic nerve, however, requires a much wider area of exposure, usually provided only by a transcranial orbitotomy approach. You can see that the intent of the operation is a factor in your choice of orbitotomy approach (Box 15-1).

The surgical spaces of the orbit

You will recall that the surgical spaces already discussed in Chapters 2 and 13 are (Figure 15-3):

Figure 15-3 The surgical spaces of the orbit: intraconal space (central surgical space); extraocular muscles; extraconal space (peripheral surgical space); subperiosteal space; Tenon’s space; the extraorbital space (including periocular tissues, brain, nose, sinuses, bone, and surrounding soft tissues). (A) Axial view. (B) Coronal view.

You should already know these spaces. This section is intended as an illustration of how you will begin to think of the spaces of the orbit and their relationship to the orbitotomy approach. Don’t memorize the specific pathologic processes and approaches mentioned here. We will talk about them again later in this chapter. Just start to get an idea of how you are going to choose the orbitotomy approach, based on the position of the pathologic process and what you have already learned in this chapter.

The extraconal space contains the lacrimal gland, the superior oblique muscle and trochlea, and nerves and vessels in the extraconal orbital fat. An enlarged lacrimal gland is often palpable in the upper lid and then is readily accessible through an anterior orbitotomy using the upper lid skin crease approach. Lymphoid tumors are among the most common orbital masses. Because lymphomas tend to occur in the lacrimal gland or elsewhere anteriorly in the extraconal fat, anterior orbitotomy approaches to the extraconal space are commonly used. When a lacrimal gland mass is not palpable (mostly posterior to the globe), a lateral orbitotomy, usually with bone removal, is required. The superior oblique muscle and trochlea are in the medial portion of the extraconal space, but rarely require biopsy. Schwannoma of the frontal nerve may be seen in the superonasal quadrant and can be approached anteriorly, but if the mass extends into the apex, a transcranial approach may be necessary for removal. The anterior portion of the superior ophthalmic vein lies in the extraconal space, but it almost never requires surgical intervention.

The intermuscular septum lies between the anterior portion of the extraocular muscles, separating the intraconal and extraconal spaces. The muscles may become involved in neoplastic or inflammatory processes. The most common condition is thyroid orbitopathy. Painful inflammation of the muscles, myositis, may also occur. Primary neoplasms of the muscles are very rare, but metastatic lesions do occur. Although biopsies are not often performed on the extraocular muscles, the muscles can be approached surgically through anterior orbitotomy incisions if the pathologic lesion is anterior. If the enlargement of the muscle is posterior, you can decide on the best approach for incisional biopsy following the principles described in the previous section. The extraocular muscles are important surgical landmarks to guide your surgical dissection. During lateral orbitotomy approaches, the intraconal space is usually entered between the lacrimal gland and the lateral rectus muscle. We will discuss this dissection technique further in the section “Approach to Deep Lateral Lesions: The Lateral Orbitotomy.”

The subperiosteal space is the potential space between the orbital bones and the periorbita. A hematoma may collect in this space from an adjacent fracture. A collection of pus, a subperiosteal abscess, may collect medially from an adjacent ethmoid sinus infection. For drainage of a subperiosteal abscess, you will usually approach the medial subperiosteal space anteriorly through the skin and conjunctiva with elevation of the periorbita from the orbital rim and dissection posteriorly along the medial orbital wall (frontoethmoidal and transcaruncular anterior orbitotomy). Repair of orbital floor fractures begins with surgical approaches to the subperiosteal space using transconjunctival or transcutaneous lower eyelid anterior orbitotomy techniques. Similarly, you can approach medial wall fractures using the transcaruncular anterior orbitotomy technique.

Tenon’s space lies between the eye and the fibrous capsule, Tenon’s capsule, which surrounds all but the anterior portion of the eye. Probably you have already operated in this space when performing an enucleation or scleral buckle procedure. Although we usually don’t think of it, these operations start with a transconjunctival anterior orbitotomy. Tenon’s space is rarely involved in pathologic processes; one example is the extraocular extension of a choroidal melanoma.

The extraorbital space includes all the tissues surrounding the orbit: bone, brain, sinus, nasal, skin, and conjunctiva. You are already familiar with some of the many problems that originate in these tissues and involve the orbit secondarily. The surgical approach to many of these tissues is obvious, whereas others involve areas of overlap with other surgical specialties for which interdisciplinary cooperation is essential to the success of the operation.

We will talk about the orbital spaces in the context of the orbitotomy procedures again and again throughout this chapter, so start thinking of these spaces in the context of orbitotomy approaches.

Names of orbitotomy approaches

There is no consistent nomenclature or classification of orbitotomy approaches. Most of the names used in this text and by other surgeons are descriptive. You shouldn’t memorize these terms because they can mean different things to different people. Some commonly used descriptive terms and my interpretation of them are:

Room setup

You should have a plan for the setup of the room and any specialized equipment that will be required. If you anticipate using an operating microscope, it should be positioned and adjusted while the patient is being prepared. Any pathology requisitions should be filled out before you start the surgery. You should discuss the plan for operation with the nursing staff before beginning the procedure.

Orbital instruments

Specialized orbital instruments are used (Box 15-2). Retraction of skin is necessary, using small (Storz double-fixation forceps) or large (Joseph) skin hooks and suture retractors (4-0 silk). Retraction of the orbital fat is facilitated with Sewall and malleable ribbon retractors of various lengths. Neurosurgical cottonoids placed under the retractors prevent fat prolapse into the surgical wound. A variety of periosteal elevators should be available, including Freer, Joseph, and Dean elevators. Bone removal equipment including a power saw, drill, and bone rongeurs are necessary if deep orbitotomy procedures with bone removal are anticipated. A microplating system is useful to repair complex orbital bone cuts. A Freer elevator or a long cotton-tipped applicator is a useful orbital dissection tool. Small neurosurgical dissectors can be helpful.

As we discussed in Chapter 1, scissors and forceps for deeper orbital procedures are usually longer than eye instruments for routine procedures. Bayonet-type handles allow comfortable hand position without blocking visualization in deep surgical wounds, especially when an operating microscope is used. Yasargil neurosurgical scissors (which look like long-handled Westcott scissors) with curved or straight blades are good for deep dissections. Westcott scissors are used in anterior orbitotomy procedures. Most eyelid forceps (Paufique forceps) work well for anterior orbital approaches. Myringotomy forceps or any of a variety of small cup biopsy forceps are useful for grasping tissue in deep or tight spaces. The cup forceps or a small “nasal bead” forceps (Hartman–Herzfeld 3 mm cup forceps) is useful for small biopsies of friable tumor tissue. A variety of cautery forceps are helpful, especially microbayonet bipolar forceps (Fischer or Yasargil bipolar forceps) for deep procedures.

Illumination and magnification

You will need excellent illumination to visualize the orbital structures. You can perform anterior orbitotomy procedures with standard operating room lights. You’ll find a fiberoptic headlight helpful for any deeper orbitotomy procedures. The coaxial lighting and view provided by the operating microscope is the only way that both the surgeon and the assistant can see deeper orbital structures at the same time.

Magnification using surgical loupes is standard for anterior orbitotomy procedures. Loupes (2.5 power) from Designs for Vision (Ronkonkoma, NY) are expensive, but great. For deep orbitotomy procedures, you should use the operating microscope for magnification and illumination. The optimal microscope for orbital surgery is mounted on a counter-weighted stand that allows the microscope to be positioned in any direction in three-dimensional space. These stands are commonly used by your neurosurgical colleagues. The gold standard is operating microscopes made by Zeiss. A variety of configurations are available, but opposing microscope heads are ideal for lateral orbitotomy procedures. A 300 mm objective lens provides an adequate distance between the patient and the microscope to move the longer orbital instruments in and out of the operating field without hitting the microscope. An attached video camera and monitor are important for keeping the operating room staff involved.

Body mechanics and posture

This is a good place to remind you to pay attention to your posture and body mechanics as a surgeon. If you are lucky, you will spend many hours a week for many years in the operating room (so far for me, over 20,000 hours!). In your early years as a surgeon, it is easy to abuse your body, often operating in awkward positions, craning your neck to see the field or pass a suture. Over time, operating with the microscope presents its own set of problems, especially for your neck. Combined with your many hours of study, you will find that, if you are not careful, your posture will slump and your neck will start to grow from your chest, not on your shoulders. It is easy to ignore this in your early career, but all you have to do is look at the posture of your senior staff to recognize that the “hanging head” position is an occupational risk. Long cases will start to take a toll on your aging body. So make it a habit to adjust the table and seat height for each case. Set the microscope to be comfortable with your arms and head in a natural position. I recently found I could order a slight tilt (the “dental angle”) on my loupes that prevents me from having to hang my head down all day while operating. Consider stretching breaks during the day. Try to keep fit. It will pay off over time.

Exposure and intraorbital dissection

Adequate surgical exposure begins with well-chosen surgical incisions. You should choose a hidden, or camouflaged, incision as close to the orbital mass as possible. If you choose an incision that will produce a minimal scar, your resistance to making an incision that is long enough to give adequate exposure will be decreased. When the skin and muscle layers of a transcutaneous approach are opened, use 4-0 silk suture retractors to hold the wound edges apart.

Remember that, as you dissect deeper into the orbit, you should make the deep portions of the surgical wound at least as wide, or wider, than the initial skin incision (make the wound A shaped rather than V shaped). Use a hand-over-hand dissection technique with the orbital retractors to move into deeper orbital tissues (Figure 15-4). As with dissections elsewhere, the key to an effective dissection is to gently spread or pull the involved tissues apart. When you get to a point where you cannot pull the layers apart with the Sewall or malleable retractors, ask your assistant to hold the retractors, keeping the tissue on stretch. You can then use additional blunt dissection with the Freer elevator or cotton-tipped applicator. You can use cautious sharp dissection with a Westcott or Yasargil scissors to open the connective tissue planes of the orbit if blunt dissection through a plane of tissue is too difficult. When the plane is open, use the hand-over-hand technique with the retractors until you reach the structure you are looking for. If you get lost, put your finger in the wound and reorient yourself. It is easy to pass by a smaller lesion.

Figure 15-4 Hand-over-hand dissection technique to visualize deeper orbital tissues.

No doubt there will be times when you are very close, but you cannot see what you are looking for. Palpation can be very helpful for showing you where you are in relation to where you want to be. Once you have identified the mass, gently place dampened neurosurgical cottonoids (1 inch by 3 inches) into the wound using a bayonet forceps. Reposition the retractor over the cottonoid to push the fat behind the retractor and to prevent the orbital fat from prolapsing around the retractor. You may remember the analogous general surgical technique of packing the bowel off with a lap sponge to allow exposure of the abdominal surgical wound. Repeat this using three or four cottonoids to expose the wound (Figure 15-5). With the cottonoids in place, you can remove or reposition the retractors without the surgical wound collapsing on itself.

Figure 15-5 Neurosurgical cottonoids. (A) Lateral canthotomy approach to fenestrate the optic nerve. Small canthotomy incision. (B) Neurosurgical cottonoids under malleable and Sewall retractors are essential to prevent the orbital fat from prolapsing around the retractors. Note that the optic nerve is faintly visible in the depth of wound.

You will need to follow surgical landmarks to find the area of the orbit that you are interested in. For example, to find the optic nerve during an intraconal dissection:

You will learn to use the visible or palpable landmarks to navigate through the orbital tissues.

If you find that exposure is poor, inspect the wound. There may be a band of periorbita or other tough tissue resisting your retraction. Don’t be afraid to lengthen your incision if visualization is poor or you are struggling with lack of room. Consider an alternative or additional orbitotomy approach if you cannot safely obtain the goal of the orbitotomy with the original plan (see “Combined Orbitotomies” below).

Learn to use orbital retractors safely. Remember to have your assistant release the pressure on orbital tissues intermittently to maintain blood flow to the orbital tissues. With cottonoids in the wound, you can relax the retractors without “losing your place.” Avoid toeing in on the orbital retractors to prevent damage to the orbital tissues. Suture retractors or self-retaining retractors, such as the Jaffe lid speculum, are safe for retraction of the skin and muscle, but self-retaining retractors should not be used deep in the orbit.

As we discussed in Chapter 1, you cannot underestimate the help that an experienced assistant can give you, especially in a deep orbitotomy. The anticipation and facilitation of the assistant provide you with a third and fourth hand. This is necessary because it is not possible for the surgeon alone to retract the deep wound open and perform a dissection or biopsy. If you are dissecting out an orbital mass:

This is a basic and important technique for you to know and use for all surgical dissections. If you don’t understand this, ask an experienced surgical colleague to explain it to you. You must understand this technique to function effectively as a surgeon (Figure 15-6). When I am having trouble with an orbital dissection, I remind myself of this basic concept. Probably the tissues are not being pulled apart by either me or my assistant.

Figure 15-6 Orbital dissection technique. (A) Globe and medial rectus are removed. (B) As the assistant “pulls the orbital fat away from the mass” with an orbital retractor, the surgeon “pulls the mass away from the fat” with the nondominant hand. (C) The surgeon then frees any tissue on stretch between the mass and the fat with the dominant hand using a dissecting tool such as a Freer elevator.

Hemostasis

Related posts:

The Diagnosis and Management of Misdirected Eyelashes The Art of the Surgical Technique Aesthetic Surgery of the Face Evaluation and Treatment of the Patient with Ptosis Diagnosis of Malignant and Benign Lid Lesions Made Easy The Diagnostic Approach to the Patient with Proptosis

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