Journal of Neuro-Ophthalmology, September 2013, Volume 33, Issue 3

New and Emerging Interventional Neuroradiologic Techniques for Neuro-Opthalmologic Disorders

A number of cerebrovascular disorders produce manifestations of neuro-ophthalmologic significance. In many cases, these disorders can be treated using endovascular techniques. The material in this article was obtained from a combination of personal experience and review of the literature using PubMed. A variety of new equipment, materials, and techniques are available to the interventional neuro-radiologist dealing with intracranial vascular lesions such as aneurysms, arteriovenous fistulas, and arteriovenous malformations. Physicians whose patients have intracranial vascular lesions should be aware of the endovascular options available for their patients.

New and Emerging Interventional Neuroradiologic Techniques for Neuro-Opthalmologic Disorders Philippe Gailloud, MD, Neil R. Miller, MD, FACS Background: A number of cerebrovascular disorders produce manifestations of neuro-ophthalmologic significance. In many cases, these disorders can be treated using endovascular techniques. Methods: The material in this article was obtained from a combination of personal experience and review of the literature using PubMed. Results: A variety of new equipment, materials, and techni-ques are available to the interventional neuro-radiologist dealing with intracranial vascular lesions such as aneurysms, arteriovenous fistulas, and arteriovenous malformations. Conclusion: Physicians whose patients have intracranial vascular lesions should be aware of the endovascular options available for their patients. Journal of Neuro-Ophthalmology 2013;33:282-295 doi: 10.1097/WNO.0b013e3182a319e7 © 2013 by North American Neuro-Ophthalmology Society Awide variety of orbital and intracranial disorders of neuro-ophthalmologic significance have the potential to be or are currently being treated by new and emerging interventional neuroradiologic techniques. In this review, some of the most important of these are discussed. PSEUDOTUMOR CEREBRI ASSOCIATED WITH VENOUS SINUS STENOSIS Pseudotumor cerebri (PTC) refers to a condition in which there is increased intracranial pressure (ICP) in the absence of primary cerebral disease on conventional imaging associated with cerebrospinal fluid (CSF) that contains no evidence of an infectious, inflammatory, or malignant process. Although the cause of PTC in some patients is medication, such as lithium, or an underlying systemic condition, such as systemic lupus erythematosus, most patients have no apparent underlying disease. These patients are said to have a form of PTC called "idiopathic intracranial hypertension" (IIH). Patients with PTC (including those with IIH) usually become symptomatic with severe headache and papilledema, with some patients progressing to permanent vision loss. Patients who present with evidence of an optic neuropathy or who experience pro-gressive visual loss despite maximum medical therapy can be extremely difficult to manage and often require surgery (optic nerve sheath fenestration, shunting procedures) and pro-tracted courses of narcotics or other analgesic medications. Venous sinus stenosis may play a role in the pathogenesis of so-called IIH, but the exact mechanism remains a topic of widespread debate. Nevertheless, up to 90% of patients with otherwise typical IIH demonstrate either unilateral or bilateral transverse-sigmoid sinus stenosis, suggesting that stenosis is a potential etiology (1). Venous sinus stenting is possible with the advent of stents that are sufficiently flexible to permit navigation of the intracranial venous sinuses. Multiple publications have docu-mented the efficacy of venous sinus stenting for the treatment of IIH, although there are no clinical trials that have compared this treatment with weight loss alone, medical therapy (e.g., acetazolamide), with or without weight loss, or other types of surgery (e.g., optic nerve sheath fenestration; ventriculoper-itoneal, ventriculoatrial, or lumboperitoneal shunts) (2-13). In any event, these reports, including our own (13), have docu-mented a reduction of ICP with resolution of headache, tin-nitus, and papilledema in at least 80% of treated individuals. However, some patients develop re-stenosis just proximal to the stent and others have persistent headaches that are not related to persistently elevated ICP but rather to a form of migraine as they resolve with anti-migraine medication (11,13). At our institution, we perform computed tomographic venography (CTV) before and after lumbar puncture with removal of sufficient CSF to normalize ICP in patients with Division of Interventional Neuroradiology (PG), Johns Hopkins University, Baltimore, Maryland; and Departments of Ophthalmol-ogy, Neurology and Neurosurgery, Johns Hopkins University School of Medicine (NRM), Baltimore, Maryland. The authors report no conflicts of interest. Address correspondence to Neil R. Miller, MD, FACS, Johns Hopkins University School of Medicine, Baltimore, MD. 282 Gailloud and Miller: J Neuro-Ophthalmol 2013; 33: 282-295 State-of-the-Art Review Section Editors: Grant T. Liu, MD Randy H. Kardon, MD, PhD Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. presumed IIH. If there is venous sinus stenosis and the stenosis disappears after normalization of ICP, we conclude that the increased ICP caused the stenosis, and we treat the patient with standard medical therapy or surgery. However, if, upon normalization of ICP, the stenosis remains, then we consider whether to stent the patient. In some cases, we will use medical therapy (i.e., acetazolamide) first and stent only if there is no clinical improvement; in other cases, particularly those in which an optic neuropathy is already present, we will perform stenting. Our procedure for venous sinus stenting is as follows. At this time, only patients with progressive optic neuropathy under maximal medical therapy are considered as potential candidates for endovascular therapy. If bilateral stenosis is confirmed by CTV after lumbar puncture (Fig. 1A), the patient is scheduled for endovenous manometry under general anesthesia. A diagnostic cerebral angiogram is performed first to rule out the presence of other vascular anomalies, in par-ticular a dural vascular fistula that could mimic the presenta-tion of IIH. This arterial access will also provide the "roadmap" images necessary for navigation of endovascular devices within the cranial venous system. Venous access is obtained by percutaneous femoral puncture. A long sheath (90 cm long; 6-French Shuttle sheath, Cook, IN) is inserted, and its distal tip brought into the left internal jugular vein, immediately below the skull base. A 3-French microcatheter (Renegade hi-flo; Boston Scientific, Natick, MA) is carefully advanced through the sheath into the cranial venous system. Endovascular navigation is performed using the roadmap tech-nique. The microcatheter is advanced across the torcular and the left transverse sinus into the right internal jugular vein. An exchange-length microwire (300 cm, 0.014 in Luge wire; Boston Scientific), advanced into the left internal jugular vein though the microcatheter, is kept across both transverse sinus stenoses to offer a platform for subsequent stent placement. The microcatheter is connected to a pressure line, and meas-urements are obtained in each segment of dural sinus as it is progressively pulled back into the right internal jugular vein. If a pressure gradient higher than 4 mm Hg is recorded, stenting is performed (Fig. 1B). To date, the right transverse sinus has been targeted in all our patients (15 cases). Our group uses a self-expandable nitinol stent (Precise, Cordis). Our institu-tion review board has approved the off-label application of this carotid stent, and the off-label nature of the treatment is fully disclosed to the patient and recorded on the consent form. Bilateral pressure measurements are repeated after stent deployment. The patient is admitted to our neuroscience crit-ical care unit for overnight observation. Antiplatelet therapy using a combination of aspirin and abciximab, started 5 days before the procedure, is maintained for 6 months, after which abciximab is discontinued. CENTRAL RETINAL ARTERY OCCLUSION Central retinal artery occlusion (CRAO) occurs in 1 per 10,000 ophthalmology out-patient visits (14). The visual prognosis of CRAO is poor with 61% of patients having a final visual acuity (VA) of 20/400 or worse (15). This degree of severe unilateral visual impairment is associated with lim-itations in social functioning, poor mental health (16), and is a risk factor for becoming dependent (17). Most CRAOs are thought to be thrombotic or embolic (18). Standard therapies for CRAO include ocular massage, paracentesis, and other methods of reducing intraocular pressure as well as inhalation of a mixture of 95% oxygen and 5% carbon dioxide (carb-ogen). These treatments have not been shown conclusively to improve VA beyond the natural history of disease (19,20). Systemic and intra-arterial thrombolysis have been success-ful in restoring perfusion to ischemic tissue by fibrin-platelet clot lysis in ischemic stroke and myocardial infarction (21-23). Several small series have reported long-term significant improvement in VA with local intra-arterial or intravenous fibrinolysis, particularly when therapy was begun within 12 hours after the onset of visual loss (24-28). However, to date, there is only one randomized, prospective clinical trial compar-ing intra-arterial fibrinolysis (IAF) with "conventional" therapy. FIG. 1. Bilateral transverse sinus stenosis. A 37-year-old woman with idiopathic intracranial hypertension had worsening papilledema despite maximum medical therapy. A. Computed tomographic venography (CTV) obtained after normalization of the cerebrospinal fluid pressure by lumbar puncture confirms bilateral transverse sinus stenosis (arrows). B. CTV obtained 6 months after stenting the right transverse sinus shows that the treated segment is patent. The patient's papilledema resolved within 4 weeks. Gailloud and Miller: J Neuro-Ophthalmol 2013; 33: 282-295 283 State-of-the-Art Review Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. The European Assessment Group for Lysis in the Eye (EAGLE) trial found no difference in visual outcome in patients treated with "conservative" techniques plus IAF com-pared with patients who received only "conservative" therapy (29). In addition, there were more complications in the IAF-treated group than in the conservatively treated group, and this is one of the reasons that the trial was halted prematurely. It must be noted, however, that in this trial, "conservative" ther-apy consisted of a 5-day course of anticoagulation using hep-arin (this therapy did not include paracentesis). This is not the standard therapy in the United States, and the acute antico-agulation received by both groups of patients may have been an equalizing factor. Although IAF is NOT the standard of care for patients with a CRAO, we have treated a number of patients with IAF with reasonable results and do not believe that the EAGLE trial should necessarily preclude such treat-ment. We believe that a trial of "conservative" therapy with-and without heparinization may be appropriate in some patients, whereas in others, particularly those who are seen within 6 hours after visual loss, intra-arterial fibrinolysis should be considered. Our procedure for intraarterial fibrinolysis is as follows. The patient is brought to the neuroangiography suite as soon as the diagnosis of CRAO has been confirmed. Although most procedures are performed under conscious sedation, elderly patients or patients unable to lie flat may need general anesthesia. Femoral arterial access is obtained and a guiding catheter (usually a 5-French system) is brought to the common carotid artery ipsilateral to the affected eye. Biplane angiogra-phy is performed to document the appearance of the cerebral circulation; this baseline angiogram will serve as a reference for comparison with the final angiogram obtained at the end of the procedure. This initial angiogram also provides important information about the craniocervical arterial anatomy, doc-umenting in particular the presence of atheromatous lesions along the endovascular access route (carotid bifurcation, distal internal carotid artery [ICA]), the degree of patency of the ophthalmic artery, and the existence of potential anatomic variants influencing the treatment strategy (e.g., an ophthalmic artery originating from the middle meningeal artery). The guiding catheter is then advanced into the ICA (providing there is no significant atheromatous disease at the bifurcation, in which case the guide would be kept in the common carotid artery), and a microcatheter (usually a 1.7-French system) is advanced to the clinoid segment of the ICA. Several techniques can then be adopted to access the ophthalmic artery, depending on its size and anatomy, the presence of ostial atheromatous disease, and the operator's preference. In our practice, superselective catheterization is performed using an over-the-wire technique, in which the microwire (usually 0.010 inches in diameter) is advanced into the ophthalmic artery and the microcatheter threaded over the wire until it sits in a stable position within the artery, just past its proximal bend. This preferred location is not always attainable, and the microcatheter tip must at times be left at the ostium of the artery. In such cases, the tip of the microcatheter is left abutting the dorsal wall of the ICA just proximal to the ophthalmic artery origin, with the hope that flow preferentially will direct the lytic agent into the targeted artery. The lytic agent (recombinant tissue plasminogen activator [r-tPA], 1 mg/mL) is administered slowly though the microcatheter using hand injections with 3-mL syringes, with a maximum dose of 20mg of r-tPA(Fig. 2).At the end of the procedure, a common carotid angiogram is obtained and compared with the baseline angiogram to detect potential intracranial complications. Patients typically are kept in our neuroscience critical care unit for overnight observation. DIRECT CAROTID-CAVERNOUS SINUS FISTULAS A direct carotid-cavernous sinus fistula (CCF) results from a single tear in the wall of the cavernous segment of the ICA. This produces a direct connection between the artery and one or more of the venous channels within the cavernous sinus. The arteriovenous connection usually is short, tangential, and endothelialized (30-32). It is identical in anatomy and FIG. 2. Endovascular treatment 8 hours after a central retinal artery occlusion. A. Lateral view of a digital subtraction angi-ography shows selective injection of the right ophthalmic artery. Arrow indicates the site of origin of the right ophthalmic artery. This injection was performed through a 1.9F microcatheter (outside diameter of 0.63 mm). Note stagnation of contrast and lack of filling of intraorbital arteries. B. After administration of 10 mg of tissue plasminogen activator, the ophthalmic artery and its branches appear normal. The patient experienced visual recovery within minutes of the thrombolysis. 284 Gailloud and Miller: J Neuro-Ophthalmol 2013; 33: 282-295 State-of-the-Art Review Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. hemodynamics, with traumatic arteriovenous fistulas else-where in the body. The direction of blood flow through a direct CCF may be posterior, into the superior and inferior petrosal sinuses, or anterior, into the orbital veins. Although posteriorly draining fistulas occasionally cause isolated ocular motor cranial nerve pareses, the most severe ocular manifestations occur in patients with anterior redirection of arterial blood through normal orbital venous channels. These manifestations are caused by a combination of diminished arterial flow to the cranial nerves within the cavernous sinus, stasis of both venous and arterial circulation within the eye and orbit, and an increase in episcleral and orbital venous pressure. Typical signs of a direct CCF include an objective and/or subjective bruit, proptosis, chemosis, "arterialization" of conjunctival and episcleral vessels, ophthalmoparesis from neural and/or mechanical mechanisms, increased intraocular pressure, and ischemic retinopathy. Patients in whom the fistula causes arterial drainage into the cerebral veins and sinuses are at risk for intracranial hemorrhage. Accordingly, most direct CCFs require treatment. Endovascular closure is the most common method used to close a direct CCF and most often is accomplished by embolization using a variety of agents, primarily platinum coils and detachable balloons (33-37). These materials usually are introduced into the cavernous sinus through the ICA, but in selected cases, they may be introduced either transvenously through the inferior petrosal sinus, pterygoid plexus, or the superior ophthalmic vein, or directly into the cavernous sinus via a craniotomy, transethmoidal transsphenoidal approach, or even a direct puncture through the superior orbital fissure (38-43). At our institution, we use a variety of techniques for endovascular closure of a direct CCF. Most commonly, the cavernous sinus will be closed with detachable microcoils. The access route can be either transvenous, for example, via the superior ophthalmic vein, the pterygoid plexus, or one of the petrosal sinuses, or transarterial with the microcatheter reaching the cavernous sinus through the carotid wall injury (Fig. 3). When successful, patients experience dramatic improvement in symptoms and signs almost immediately, although it may take months for their complete resolution. In all cases, standard femoral access followed by diagnostic cerebral angiography is obtained to document the anatomy of the lesion and the pres-ence of potential sources of collateral supply if carotid sacrifice has to be contemplated. In addition, a transvenous approach requires venous access, most commonly obtained by puncture of a femoral vein. These procedures are performed at our insti-tution under general anesthesia. Alternate techniques have been used, in which the cavernous sinus is filled with a liquid embolic agent, or in the past, with detachable balloons. In some instan-ces of direct CCF secondary to a ruptured aneurysm, selective coiling of the aneurysm alone is sufficient to close the fistula, whereas in cases where the ICA is extensively damaged, occlu-sion of the cavernous sinus with sacrifice of the carotid artery may have to be performed. In some of these instances, flow-diverting stents provide another endovascular option. DURAL CAROTID-CAVERNOUS SINUS (ARTERIOVENOUS) FISTULAS These lesions are actually congenital arteriovenous fistulas that develop spontaneously, often in the setting of athero-sclerosis, systemic hypertension, connective tissue disease, and during or after childbirth. Dural CCFs consist of a commu-nication between the cavernous sinus and one or more meningeal branches of the ICA, the external carotid artery, or both (44). Fistulas involving branches from both the internal and the external carotid arteries are the most common. Dural CCFs usually have low rates of arterial blood flow. Nevertheless, they can produce significant visual and neurologic deficits similar to those caused by direct CCFs. Although many dural CCFs close spontaneously and others produce only minor visual symptoms and signs and thus do not require treatment, those that produce significant ocular or neurologic manifestations require closure (Fig. 4). Endovascular procedures, including transarterial emboliza-tion, transvenous embolization, or a combination of these FIG. 3. Endovascular treatment of a direct carotid-cavernous sinus fistula. A. Lateral view of digital subtraction angiogram following left common carotid injection reveals carotid-cavernous sinus fistula. An irregularity of the dorsal wall of the left internal carotid artery (ICA) suggests the possibility of an aneurysm (arrow) that has ruptured into the cavernous sinus. B. After coiling, there is complete eradication of the fistula with preservation of normal flow in the left ICA and its branches. Gailloud and Miller: J Neuro-Ophthalmol 2013; 33: 282-295 285 State-of-the-Art Review Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. techniques, usually are the optimum treatment for dural CCFs that produce progressive or significant symptoms and signs, including visual loss, diplopia, an intolerable bruit, severe proptosis, and, most importantly, cortical venous drainage (45). A number of synthetic and natural materials can be used for embolization. Platinum coils are most often used, but other materials include absorbable gelatin (Gelfoam); Silastic; low-viscosity silicone rubber; autogenous clot, muscle or dura; tetradecyl sulfate (a sclerosing agent); polyvinyl alcohol par-ticles (lvalon); ethanol; ethylene vinyl alcohol copolymer (Onyx), oxidized cellulose (Oxycel); various preparations of cyanoacrylate glue; or a combination of these (46). In patients with a fistula fed only by meningeal branches of the external carotid artery, the embolization material is introduced via a microcatheter placed in the external carotid artery and passed into the specific branch or branches that feed the fistula. In this setting, successful closure of the fistula is almost always possible, resulting in rapid resolution of all symptoms and signs. When the fistula is fed by meningeal branches from both the external carotid artery and the ICA, only the branches from the external carotid artery usually are embolized in the hopes that the flow to the fistula will be sufficiently decreased to result in its subsequent closure. The ICA usually is not embolized unless the interventionalist can successfully catheterize the meningohypophyseal trunk or other meningeal feeders from the artery. If the fistula does not close with this technique, it often can be treated subsequently via a transvenous route. In this setting, and in patients whose fistulae are fed only by meningeal branches from the ICA, the favored transvenous approach usually is via the femoral or internal jugular vein into the ipsilateral or rarely the contralateral inferior or superior petrosal sinus and from there into the cavernous sinus (46-52). If this approach fails, a variety of other approaches may be used, most of which involve cannulation of the superior or inferior ophthalmic veins (53-55). The superior ophthalmic vein approach is performed in most cases by surgical exposure of the vessel. All procedures are performed in a neurosurgical operating room under fluoroscopic guidance. With the patient under general anesthesia, a sheath is placed in a common femoral artery to permit intraoperative angiography. Following prepping and draping of the affected eye and orbital regions, the superior ophthalmic vein is accessed via a transcutaneous incision. A segment of it is isolated between 2 sutures, and a microcatheter, the size of which is determined by the diameter of the vein, is placed into an opening in the vein and threaded into the cavernous sinus under fluoroscopic guidance; platinum coils are detached in the cavernous sinus until the fistula is closed as determined by intraoperative angiography. The catheter is withdrawn, the superior ophthal-mic vein is permanently occluded using bipolar cautery and ligatures, and the skin incision is closed (48,49,51,56-60). In some cases, more than one session and more than one approach is needed, and in rare cases, the cavernous sinus can be cannu-lated directly via an orbital approach (57,61). Using currently available techniques, successful closure of dural CCFs can be achieved in 80%-100% of patients (52,53,62-65). Complications of endovascular treatment of dural CCFs are uncommon except in patients with connective tissue disorders such as Ehlers-Danlos syndrome (66,67). Nevertheless, signifi-cant complications have been reported, including hemorrhage at the catheter site, in the orbit from perforation of the superior or inferior ophthalmic vein, or even intracranially; damage to orbital structures such as the trochlea when the superior oph-thalmic vein is used for access to the cavernous sinus; local infection; sepsis; ophthalmic artery occlusion; and both transient and permanent neurologic deficits, particularly facial pain and ocular motor cranial nerve pareses, and brainstem infarction FIG. 4. Endovascular treatment of a dural carotid-cavernous (arteriovenous) fistula in an 84-year-old woman with sponta-neous occurrence of right periorbital swelling, redness, and proptosis and recent or old history of trauma. A. Lateral view of digital subtraction angiogram, right common carotid injection, shows a right-sided dural arteriovenous fistula of the cav-ernous sinus that drains into the orbital venous system and inferior petrosal sinus. The lesion is fed by multiple extradural branches of the right internal carotid and external carotid arteries. B. After treatment using a transcutaneous, transvenous approach through the superior ophthalmic vein, there is obliteration of the fistula. 286 Gailloud and Miller: J Neuro-Ophthalmol 2013; 33: 282-295 State-of-the-Art Review Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. FIG. 5. Treatment of a paraophthalmic aneurysm with stent-assisted coiling. A. Digital subtraction angiogram, left common carotid injection, shows a 5-mm right ophthalmic segment saccular aneurysm (arrow). B. Three-dimensional digital sub-traction angiogram shows that the neck of the aneurysm is quite broad and the origin of the ophthalmic artery (arrow) is separate from the aneurysmal sac (arrowhead). C. Unsubtracted lateral view of the region of the aneyrysm as the self-ex-panding stent (4.5 mm by 22 mm) is being deployed. The distal stent markers (arrow) are visible, indicating that this portion of the stent is now applied to the wall of the right internal carotid artery (ICA). The stent extends both proximally and distally well beyond the neck of the aneurysm. A second microcatheter that will be used subsequently to deliver the coils has been placed within the aneurysm (tip indicated by arrowhead). D. Subtracted, right anterior oblique projection shows partial obliteration of the aneurysm after placement of 3 microcoils (arrow). A final control angiogram after 6 microcoils documented total obliteration of the lesion. E. Subtracted right anterior oblique projection, obtained during a 1-year follow-up study, confirms eradiation of the aneurysm with preservation of flow in the right ICA. Gailloud and Miller: J Neuro-Ophthalmol 2013; 33: 282-295 287 State-of-the-Art Review Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. (46,48,51,53,58,62,63,68-71). An analysis of 4 large series of patients with dural CCFs treated endovascularly revealed that of a total of 339 patients, there were complications in 35 (10.3%) (46,52,53,62). Because the embolization techniques used to close dural CCFs can be associated with vision-threatening and even life-threatening complications, physicians performing such procedures should explain to the patient not only the benefits but also the risks of these procedures and must be prepared to deal with them should they occur (70,72). OPHTHALMIC ARTERY SEGMENT ANEURYSMS Aneurysms arising from the ICA at the origin of or just distal to the ophthalmic artery are termed ophthalmic artery segment aneurysms (73). These aneurysms project dorsally or dorsomedially from the surface of the ICA toward the temporal aspect of the ipsilateral optic nerve (73,74). The surgical treatment of ophthalmic artery segment aneurysms is both challenging and complex because of their close proximity to the anterior clinoid process and the optic nerves as well as the need to exclude the lesion from the intracranial circulation while maintaining patency of the parent vessel (73-78). Fortunately, refinements in micro-surgical techniques and greater understanding of regional anatomy have made surgery of these aneurysms less formi-dable (79-81). In addition, endovascular therapy has evolved in the last decade to become an effective alternative to microsurgical clipping of these lesions (82-85). In par-ticular, flow-diverter devices consisting of porous tubular tight mesh have been used with good success (86), as well as with aneurysms in other locations (87). Even when oph-thalmic segment artery (OSA) aneurysms are treated suc-cessfully, procedure-related vision loss remains a significant risk regardless of the modality of treatment, including stents and flow diverters (88-91). At the Johns Hopkins Hospital, we use a consensus-based approach to determine the treatment of patients with OSA aneurysms. All patients with unruptured OSA aneur-ysms are discussed at a weekly conference attended by vascular neurosurgeons, neurologists, neuro-ophthalmolo-gists, and neurointerventionalists. For patients for whom endovascular intervention is recommended, the technique is as follows. All interventional procedures are performed under general anesthesia. Following femoral arterial access, a 6-French guide catheter is advanced over a 0.035 guidewire into a stable position in the ICA. Pre-embolization digital subtraction angiography (DSA), including 3-dimensional FIG. 6. Balloon remodeling technique to treat a ruptured ophthalmic segment aneurysm in a 44-year-old woman who experienced a subarachnoid hemorrhage. A. Lateral projection of digital subtraction angiogram, right common carotid artery injection, shows an ophthalmic segment aneurysm with a wide-neck (arrow) that renders coiling alone challenging. As patients presenting with a sub-arachnoid hemorrhage cannot be adequately prepared for stent-assisted coiling, which typically necessitates antiplatelet premed-ication with aspirin and clopidogrel for 5-7 days, we elected to treat her with the balloon remodeling technique. B. Unsubtracted lateral view shows a coil being deployed into the aneurysmal cavity while the parent artery is protected by inflation of a compliant balloon (4 mm by 7 mm) (arrows) across the aneurysm neck. The balloon, used for the short period during which a coil is advanced into the aneurysm, is deflated in between each coil placement. C. Final control angiogram after placement of 4 coils indicates total obliteration of the aneurysm (arrow). 288 Gailloud and Miller: J Neuro-Ophthalmol 2013; 33: 282-295 State-of-the-Art Review Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. imaging, is then performed (Fig. 5A, B). Under roadmap guidance, a microcatheter is placed within the aneurysmal sac. Patients with an unfavorable sac-neck ratio in whom placement of a stent (e.g., Enterprise, Cordis Neurovascular; Neuroform, Boston Scientific; Pipeline, Covidien) (Fig. 5C) is anticipated are placed on a regimen of aspirin and clopi-dogrel at least 3 days before the procedure. Aneurysm coiling is performed using various brands of detachable microcoils. All patients are heparinized during treatment using activated clotting time monitoring. Control angiography is performed to monitor progress (Fig. 5D) and at the end of the procedure to ensure obliteration of the aneurysm and patency of the parent vessel and the rest of the intracranial circulation (Fig. 5E). Patients are admitted to the Intensive Care Unit for over-night observation; heparinization is continued for 24 hours. The balloon remodeling technique can be used as an alternative to stent placement in wide-necked ophthalmic segment and other aneurysms. In this technique, the balloon is positioned across the aneurysm neck and transiently inflated during each microcoil placement (Fig. 6). This is particularly useful in patients with ruptured aneurysms, in whom prepa-ration with antiplatelet therapy is not advisable (a loading dose of aspirin and clopidogrel can be given at the time of a stent procedure but in our practice, it is only given after the stent has been deployed). The aneurysm cavity is filled with micro-coils of various sizes and configurations until a satisfactory result has been achieved. Patients typically are observed over-night in the neuroscience critical care unit and a second night in a regular floor bed. Aspirin usually is continued indefinitely in all patients, regardless of the technique used to treat the aneurysm, and, in patients in whom a stent has been placed, are treated with clopidogrel for 6 months, at which time a fol-low- up angiogram usually is obtained. A recent review of 101 ophthalmic artery segment aneurysms treated at our institution, using a consensus-based approach, demonstrated that regardless of the treatment modality, there is a significant risk of vision loss (91). Twenty-nine patients (33%) had what appeared to be either a new visual deficit or a worse visual deficit after treatment, and no patient with pre-existing visual loss expe-rienced visual improvement postoperatively. Factors associ-ated with postoperative vision loss were greater aneurysm size, pretreatment aneurysm rupture, pre-existing visual loss, and aneurysm re-treatment. Specifically, giant aneur-ysms, 7 (32%) of 22 large aneurysms, and 15 (19.5%) of 77 small aneurysms occurred in the group of patients that experienced visual deficits. Nineteen (21%) of 92 unruptured aneurysms were in this group. Five (83%) of 6 patients with pre-existing visual symptoms experienced worsening of their vision posttreatment. Vision loss postcoiling may result from emboli to the optic nerve or retina, an increase in mass effect from excessive coil packing, a water-hammer effect from inadequate coil packing, or coil-related peri-aneurysmal inflammation that may or may not respond to systemic cor-ticosteroids (83,91-93). CAVERNOUS SINUS ANEURYSMS (UNRUPTURED) Aneurysms arising from the cavernous portion of the ICA may produce a variety of neurological deficits, primarily those related to vision, including diplopia from single or multiple ocular motor nerve pareses, decreased VA from compressive or ischemic optic neuropathy, corneal and facial anesthesia or hypesthesia from involvement of the trigeminal nerve, and facial pain (94). Like other intracranial aneurysms, these FIG. 7. Treatment of a cavernous aneurysm with a flow diverter. A. Digital subtraction angiogram, lateral view, shows a large saccular aneurysm of the cavernous segment of the left internal carotid artery (ICA). B. The aneurysm was treated by placing 3 overlapping flow-diverting stents (Pipeline, eV3) in the artery as shown on a DynaCT scan (lateral view). C. Digital sub-traction angiogram, lateral view, left common carotid injection 6 months after treatment indicates obliteration of the aneurysm with preservation of the left ICA and its branches (Courtesy of Dr. Mohammad Ali Aziz-Sultan, University of Miami, Florida). Gailloud and Miller: J Neuro-Ophthalmol 2013; 33: 282-295 289 State-of-the-Art Review Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. aneurysms can rupture, but this is a rare event and when it occurs, usually does not produce a subarachnoid or intrace-rebral hemorrhage because of the cavernous location of the aneurysm (95,96). Rupture of a cavernous sinus aneurysm (CCA) usually causes a CCF or, rarely, epistaxis (96,97). Although most intracranial (intradural) aneurysms can be treated surgically or with endovascular techniques that isolate them from the parent vessel without occluding that vessel, this is more difficult with CCAs (97). In the past, the treat-ment of CCAs required occlusion of the ipsilateral ICA with its attendant risks of stroke, blindness, or both (98,99). Endovascular techniques such as stenting alone using a pipe-line or similar device (Fig. 7), stenting and coiling (Fig. 8), and balloon remodeling can be used successfully to occlude the aneurysm, with the precise technique used depending on the anatomy of the lesion, including its shape, size, and the manifestations it is producing. At our institution, the protocol for endovascular treatment of CCAs is as follows. Procedures are performed under general anesthesia. Patients are placed on antiplatelet therapy (aspirin and clopidogrel) at least 5 days before the procedure, as a preparation for possible stent placement and/or balloon remodeling. Femoral arterial access is obtained (6-French system) and intravenous heparin administered (aiming for ACT value between 250 and 300 sec). A baseline cerebral angiogram is performed. In addition, three-dimensional DSA images are used to measure the size of both the aneurysm and its parent artery, to choose appropriately size microcoils and/or stent, and also to determine the best angiographic projections for the procedure. A 6-French guiding catheter is advanced into the ICA under roadmap guidance, and a microcatheter placed into the aneurysmal cavity. Various types of micro-catheters are available; the most commonly used ones vary in size between 1.9 and 2.3 French. If the use of a stent followed by coiling is contemplated (wide-necked aneurysms), the stent can be deployed while the microcatheter is already in place within the aneurysmal cavity ("jailing technique" most com-monly used at our institution) or, alternatively, the microcath-eter can be advanced into the aneurysm with the stent already deployed (the latter technique having the potential disadvan-tage, in our opinion, of moving the stent if accessing the aneurysm is not straightforward). The balloon remodeling technique can be used as an alternative to stent placement in wide-necked cavernous aneurysms in the same way as for intradural aneurysms (see above). In our practice and regard-less of the technique used to occlude the aneurysm, patients are observed overnight in the neuroscience critical care unit, and a second night in a regular floor bed. Aspirin is usually continued indefinitely in all patients who undergo emboliza-tion of an aneurysm, and, in addition, patients in whom a stent FIG. 8. Treatment of a cavernous aneurysm with stent-assisted coiling. A. Three-dimensional digital subtraction angiogram, common carotid injection, shows a wide-necked saccular aneurysm (arrow) arising from the cavernous segment of the right internal carotid artery (ICA). B. Lateral unsubtracted view during endovascular therapy of the aneurysm shows that a self-expandable stent has been placed in the cavernous portion of the ICA with the stent positioned well proximal and distal to the aneurysm neck (arrows) and the aneurysm is packed with coils. Flow is preserved in the ICA and its branches. C. Lateral subtracted view, right common carotid injection, obtained 6 months after treatment shows complete obliteration of the aneurysm (arrow) with preservation of flow in the ICA and its branches (Courtesy of Dr. Monica Pearl, Division of Interventional Neuroradiology, Johns Hopkins Hospital). 290 Gailloud and Miller: J Neuro-Ophthalmol 2013; 33: 282-295 State-of-the-Art Review Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. is placed are treated with clopidogrel for 6 months. A follow-up angiogram usually is obtained 6 months after treatment. OCCIPITAL LOBE ARTERIOVENOUS MALFORMATION Arteriovenous malformations (AVMs) are the most common form of intracranial vascular hamartoma. The incidence in unselected populations is about 1 in 100,000 per year (100). AVMs occur slightly more often in men than in women, with a ratio of about 1.4:1. The majority of intracranial AVMs occur as an isolated sporadic phenomenon; however, familial cases have been described. As AVMs are congenital, they can become symptomatic at any age (101). In the majority of patients (70%), they do not produce symptoms until the second or third decade of life and frequently present during puberty. The data on arteriovenous malformation (AVM) hemorrhage during pregnancy are controversial and inconclu-sive, and there is no evidence that cesarean section is better than vaginal delivery (102). There is no consistent correlation between the location, size, and structural peculiarities of intracranial AVMs and their clinical manifestations (103); however, most occipital AVMs produce signs of intracerebral or subarachnoid hem-orrhage, seizures, or visual manifestations, all of which may be associated with headaches that often are similar to or identical with migraine with or without visual aura (104,105). In most large series, hemorrhage is a more common presenting manifestation than seizures or isolated neurologic symptoms and signs, regardless of the age of the patient, but the actual percentages vary considerably. AVMs account for 1%-2% of strokes, 9% of subarachnoid hem-orrhages, 4% of primary intracerebral hemorrhages, 1% of unprovoked seizures, and 0.3% of isolated headaches. The long-term annual fatality rate is probably 1%-1.5%, with an annual rate of initial bleed of about 2% (100). FIG. 9. Endovascular treatment of an occipital arteriovenous malformation (AVM) in a 48-year-old woman with severe headaches and a left superior homonymous quadrantanopia. Axial (A) and coronal (B) T1 magnetic resonance imaging shows changes consistent with a right occipitotemporal AVM. C. Lateral view of digital subtraction angiogram, right vertebral artery injection, shows a large AVM fed by multiple branches from the right posterior cerebral artery and principally draining into the right transverse sinus via the right vein of Labbé. D. Subtracted angiogram, right external carotid artery injection, reveals a smaller posterior nidal compartment with separate venous drainage toward the superior sagittal sinus. The decision was made to treat the anterior compartment with endovascular techniques and the posterior one with radiosurgery. E. Lateral subtracted view after 3 endovascular sessions shows that the right posterior cerebral branches have been embolized using a liquid embolic agent (NBCA glue). There is no residual opacification of the nidus from this vessel. Neuro-ophthalmological evaluation postembolization showed the visual field defect to be stable. F. Axial computed tomographic image, obtained after embolization, shows the distribution of the radio-opaque NBCA glue within the AVM nidus. Gailloud and Miller: J Neuro-Ophthalmol 2013; 33: 282-295 291 State-of-the-Art Review Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. As noted above, most AVMs in the occipital region present with visual symptoms; however, the precise location of most AVMs, unlike tumors, has no close correspondence with the resulting neurologic symptoms and signs. This may be the result of circulatory disturbances in neighboring areas of the brain due to steal by the AVM from normal vascular channels. In addition, the manifestations of occipital AVMs may result from spread of seizure discharge or from the destructive effects of intracranial hemorrhage or increased ICP. Transient attacks of unformed photopsias in the right or left homonymous field of vision may occur by themselves or as an aura of a seizure. Transient homonymous hemi-anopia is a related phenomenon (98,100). Occipital lobe AVMs may be discovered in 1 of 4 settings: 1) after an intracranial hemorrhage, 2) after a seizure, 3) in the course of an investigation of progressive or acute focal or generalized neurologic dysfunction, including an isolated homonymous field defect, and 4) fortuitously during an evaluation for an unrelated abnormality. Risk factors for bleeding identified in various retrospective series include patient-related factors (e.g., hypertension, previous hemorrhage), and angioarchitectural features (e.g., intra-nidal aneurysm, deep venous drainage, high feeding artery pressure, deep/periventricular location, flow-related aneu-rysm, venous stenosis, slow filling of feeding arteries, and nidus size) (100,103). Depending on their manifestations, size, feeding vessels, and drainage, occipital lobe AVMs may be observed without intervention, resected, embolized, treated with stereotactic radiosurgery, embolized and then resected, or embolized and then treated with radiosurgery (Fig. 9) (106,107). A number of synthetic and natural agents are available for embolization, including Gelfoam (absorbable gelatin) powder and sponge, collagen (Avitene), Silastic, steel or fiber platinum coil, elec-trolytically detachable coils (Gugliemi detachable coils), low-viscosity silicone rubber, autogenous clot, muscle or dura, tetradecyl sulfate (a sclerosing agent), polyene threads, poly-vinyl alcohol (Ivalon), absolute ethanol, oxidized cellulose (Oxycel), isobutyl-2-cyanoacrylate (bucrylate), and n-butyl-cyanoacrylate. These latter 2 agents are liquid adhesive ma-terials of low viscosity that polymerize rapidly upon contact with blood. In addition, embolization using latex or silicone detachable and calibrated-leak balloons also may be used in appropriate cases. At our institution, all patients with occipital lobe AVMs undergo a neuro-ophthalmologic assessment before treatment, and all are advised of the potential for development of a new homonymous field defect or worsening of a previous incom-plete defect. They are also advised as to the visual implications of such a defect, particularly if it is complete (e.g., inability to drive). Embolization of an occipital lobe AVMis performed as follows. Depending on the patient's age and size, 4-, 5-, or 6-French systems are used. The posterior cerebral artery (PCA) is generally accessed via one of the vertebral arteries, except when it originates predominantly from the ICA (fetal origin of the PCA). Additional supply from the middle cerebral artery must be considered in larger lesions. Embolization of cerebral AVMs with liquid embolic agents in a multimodality context is our preferred approach. This means that embolization is usually not performed with a curative goal in mind but as a preparation to either surgery or radiosurgery. We believe that this multi-modality approach offers the best chances of successful therapy with the lowest possible complication rate. However, in favor-able instances, cure can be achieved by endovascular means alone. Various interventional techniques can be applied to the embolization of cerebral AVMs. Procedures are performed under general anesthesia, and our patients are heparinized (ACT 250-300 sec), with the exception of ruptured AVMs treated acutely. Thanks to the recent improvements in catheter and wire technology, we believe that flow-guided and over-the-wire systems are equally safe in most situations, and the latter option generally is used in our practice. A liquid embolic agent, in our practice NBCA glue, is injected within the AVM nidus or, if this optimal position cannot be achieved, as close as possible to the nidus, after detailed angiographic analysis of the feeding artery anatomy to exclude the presence of normal arterial branches (Fig. 9). Procedures are staged to prevent posttreatment cerebral edema and hemorrhages secondary to the normal perfusion breakthrough phenomenon (108). We use a maximum embolization goal of 30%-50% of the nidus per session. Intranidal high-flow arteriovenous shunts and/or intra/juxtanidal aneurysms are generally tar-geted during the initial sessions. The microcatheter and the guiding catheter are withdrawn simultaneously after each glue injection, and new systems are used for each superselective embolization. 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