obvious at rest but cause intermittent proptosis when the patient strains (Valsalva maneuver), bends, or exerts physical effort. At rest, these patients may have enophthalmos because of fat atrophy and orbital expansion associated with the DVVM. Occasionally, a deep lesion will present with some surface bruising related to a hemorrhage that has tracked forward. Combined lesions will have some combination of the above findings, and complex lesions will extend outside the orbit to involve the venous system of the face and intracranial areas. Facial lesions might have some surface discoloration and may become problematic from a cosmetic point of view.

Our indications for treating selected patients with DVVMs of the orbit are intermittent or unrelenting pain, progressive expansion, and cosmesis. Only one of our patients has presented with reduced vision in addition to discomfort and esotropia. Symptoms of distensible lesions are summarized in Table 1.

INVESTIGATION OF DVVMs

Initial investigation is with computed tomographic (CT) scanning or magnetic resonance imaging (MRI), both of which are usually done with and without contrast enhancement. The CT scanning is performed with the patient lying flat on the table at rest for the axial imaging plane and then somewhat strained with the head hanging over the back of the table to attain the coronal plane. This positioning effectively produces a Valsalva maneuver and the lesions are usually distended and more conspicuous on the coronal images (Fig. 6). For MRI, the patient remains flat and quiet throughout with the various imaging planes being provided computationally. Thus, when MRI is used, it is important to ask the patient to strain during at least one of the acquisitions in order to ‘‘bring out’’ the lesion (Fig. 7). The CT and MRI will delineate the primary focus of the orbital lesion and should reveal any involvement beyond the orbit into the face, skull base, paranasal sinuses, and intracranial areas. Dynamic ultrasound and the use of Doppler may aid in confirming the hemodynamics of the DVVMs.

Figure 4 Direct injection lateral view with multiple channels and saccular areas extending beyond the orbit into the anterior cranial fossa and pterygopalatine region. (Borrowed with permission from Ref. 2.)

Venography is also used for investigation. Indirect venography is done by accessing the venous system via a vein, usually in the frontal scalp, and directing contrast injection toward the orbit by placing a tourniquet around the head

Figure 3 (Facing page) Enchanced CT scan (A) reveals the presence of a venous malformation affecting the left superior orbit. The patient underwent excision of his lesion via left lateral orbitotomy. A direct intralesional lateral view venogram performed intraoperatively revealed an ectatic area draining straight back through the superior ophthalmic vein to the cavernous sinus (B, C). With pressure applied at the superior orbital fissure, control of outflow is confirmed venographically before injection of the cyanoacrylate mixture. The glue cast is seen in situ following embolization (D) and following excision (D-inset). An intraoperative fluoroscopic anterior–posterior view

(E) confirmed the presence of the glue cast within the superior orbital venous malformation, correlating well with CT findings. The excised cast itself is demonstrated on x-ray (F). The histology of thin-walled vessels after the casting material has been removed is shown in (G). (Fig. 3A–E borrowed with permission from Ref. 2.)

Figure 5 The left lower lids show some fullness when the patient strains. (Borrowed with permission from Ref. 2.)

below the orbits or by asking the patient to compress the angular veins. As noted, visualization is somewhat limited by this technique because of anomalous connections. Direct puncture with contrast injection into the lesion is the best

Table 1 Symptoms of Distensible Lesions

Figure 6 Axial (A) and coronal (B) CT scans demonstrate an inferior orbital DVVM, which is more conspicuous on the coronal view.

technique to understand their features and most importantly, their connections to the normal venous system. For access to superficial lesions, using a small butterfly needle is relatively straightforward and can be done in the angiography suite prior to making a decision to proceed to the operating room for treatment. For combined and complex lesions with superficial components, access into the superficial component allows visualization of deeper lesions by demonstrating connecting channels. Lesions that are deep will usually require surgical exposure to allow controlled access for venography. For such deep lesions, the intention to treat is established preoperatively with a relatively high level of certainty that the venographic findings will be appropriate for subsequent

Figure 7 Axial MRI (A) shows that the lesion in the superior orbit is more distended with Valsalva maneuver (B).

controlled injection of glue mixture prior to surgical removal of the DVVM and that there is a low risk of shared circulation to normal structures. For these, a mobile C-arm angiography unit with digital subtraction and road mapping capability is available for our use in the operating room.

OPTIONS FOR TREATMENT WITH EMPHASIS

ON NEW TECHNIQUE

Surgical treatment of DVVMs of the orbit is difficult, since varices are tortuous tangles of fragile, thin walled, malformed vessels with a tendency to rupture and bleed easily during surgery. There are also multiple and complex relationships

with venous drainage pathways within the orbit and out into the face, pterygopalatine fossa, paranasal sinuses, bones, and intracranial space. The exact margins of the lesion are difficult to see and separate from surrounding structures at surgery. Surgery requires meticulous control of bleeding, identification, cauterization, clipping, or obstruction of outflow and inflow channels.

Several strategies have been used to treat DVVMs of the orbit. These include intralesional thrombosis using thermoelectric desiccation (4) and retrograde venous catheterization and embolization with platinum microcoils (5,6). We had concerns pursuing these techniques based on numerous direct puncture venographic studies, which showed that many of the lesions have complex anatomy consisting of, or draining through, multiple thin walled channels that would be at significant risk for rupture by either antegrade or retrograde catheterization.

Our goal was to find a technique that would reduce vascularity and define the margins of the lesion for easier surgical excision. We felt that controlled injection via direct puncture of a liquid embolic agent could accomplish this. There is a long experience of using cyanoacrylate (glue) for devascularizing brain arteriovenous malformations. Neurosurgeons have noted that resecting what remains of a brain arteriovenous malformation after glue embolization is not impeded by the presence of glue. The glue-casted part of the nidus can be handled and retracted for resection like a tumor mass, allowing for removal with little blood loss.

For treatment of selected DVVMs of the orbit, the procedure is done in the operating room with a mobile digital C-arm angiography unit. Puncture into the lesion allows for venography to identify the extent and drainage pathway. For lesions with intracranial communication (i.e., into the cavernous sinus), surgical exposure allows for control of the venous outflow (and glue) by appropriately placed pressure (either direct or indirect). When potential dangerous communications are seen to be controlled by repeat venography, injection of the cyanoacrylate glue mixture is performed under live subtracted fluoroscopy to form a cast of the lesion.