Onyx-HD 500 Embolization of a Traumatic Internal Carotid Artery Pseudoaneurysm after Transsphenoidal Surgery Akshal S. Patel, Tristram G. Horton, Paul Kalapos, Kevin M. Cockroft From the Department of Neurosurgery, Penn State Hershey Medical Center, Hershey, PA (ASP, TGH, KMC); and the Department of Radiology, Penn State Hershey Medical Center, Hershey, PA (PK).

ABSTRACT BACKGROUND AND PURPOSE: Traumatic intracranial pseudoaneurysms present a challenge for treatment. Traditionally these lesions have required a deconstructive approach consisting of vessel sacrifice since their fragile nature often makes direct microsurgical repair or coil embolization hazardous. As a high-viscosity liquid embolic agent that results in immediate, vessel sparing aneurysm occlusion, Onyx-HD 500 represents a uniquely efficacious tool for this clinical situation. CASE SUMMARY: We report the case of a 56-year-old right-handed gentleman who suffered a vascular injury to the ICA during revision transsphenoidal surgery for a recurrent pituitary macroadenoma. The patient was initially treated with nasal packing, but after recurrent episodes of epistaxis and a CT angiogram demonstrating a large traumatic ICA pseudoaneurysm, the patient was referred for invasive treatment. Given the presumed fragility of the lesion, embolization with Onyx-HD 500 was chosen in order to safely achieve immediate aneurysm occlusion without the need for vessel sacrifice. After an early recurrence due to incomplete initial embolization, the patient went on to complete occlusion without further hemorrhage. CONCLUSION: This case illustrates the utility of a high-viscosity liquid embolic agent in providing immediate protection from rehemorrhage by occluding a large ruptured pseudoaneurysm of the proximal intracranial ICA, while sparing the parent artery.

Keywords: Neurovascular intervention, liquid embolic, reconstructive, epistaxis. Acceptance: Received September 15, 2014, and in revised form November 24, 2014. Accepted for publication January 3, 2015. Correspondence: Address correspondence to Kevin M. Cockroft, MD, MSc, Department of Neurosurgery - EC110, Penn State Hershey Medical Center, PO Box 859, Hershey, PA 17033. USA. E-mail: [email protected]. J Neuroimaging 2015;00:1-4. DOI: 10.1111/jon.12221

Introduction Traumatic intracranial pseudoaneurysms present a challenge for treatment. Traditionally, these lesions have required a deconstructive approach consisting of vessel sacrifice since their fragile nature often makes direct microsurgical repair or coil embolization hazardous. Flow diversion is a potentially appealing alternative, but this therapy does not result in immediate occlusion and requires long-term dual antiplatelet therapy. The liquid embolic agent Onyx-HD 500 represents a unique tool for this clinical situation. We report the case of a traumatic pseudoaneurysm treated to immediate occlusion with Onyx-HD 500.

Case Report The patient is a 56-year-old right-handed gentleman who underwent elective, revision trans-nasal, transsphenoidal debulking of a recurrent pituitary macroadenoma at an outside institution. During this procedure, brisk blood loss was noted requiring urgent nasal packing. The patient was admitted to the intensive care unit and stabilized. He returned to the operating room the next day, for removal of nasal packs; however, upon their removal, arterial hemorrhage was again noted and repacking was required. At this point, the patient underwent a CT angiogram for evaluation of a potential vascular injury. This revealed a large aneurysm arising from the cavernous portion of the right internal carotid artery (Fig 1). The patient was transferred to our tertiary care medical center for treatment. Based on the initial CT angiogram findings, numerous management options were considered. An endovascular approach

was favored over a traditional open surgical procedure due to the aneurysm’s cavernous sinus location. A deconstructive procedure was contemplated, but discounted in favor of a strategy that would preserve the internal carotid artery. Because of the presumed fragile nature of this relatively fresh pseudoaneurysm, the decision was made to attempt direct embolization with Onyx HD-500 rather than platinum coils. Informed consent was obtained from the patient. Under general endotracheal anesthesia via a right femoral artery approach, the patient’s right cervical ICA was catheterized with a 6-French Envoy MPD guide catheter (Cordis Neurovascular, Miami, FL). A biplane, digital subtraction cerebral angiogram was obtained, as well as a rotational angiogram with 3-dimensional reconstructions. Review of the images revealed a large saccular aneurysm arising from the intracavernous internal carotid artery. The aneurysm projected anteriorly and medially. Aneurysm measured approximately 13 × 11 mm in a left anterior oblique projection (Fig 2). The aneurysm was irregular in shape with a relatively narrow neck. Using the rotational images, an appropriate working projection was selected demonstrating the neck of the aneurysm in profile. The patient was loaded with clopidogrel (PLAVIX, Bristol-Myers Squibb/Sanofi Pharmaceuticals Partnership, Bridgewater, NJ) 600 mg delivered through an orogastric tube. In addition, intravenous heparin was administered to prolong the patient’s activated clotting time to greater than 250 seconds. A HyperGlide 5 × 30 mm occlusion balloon (Covidien, Irvine, CA) was positioned in the cavernous internal carotid artery spanning the neck of the aneurysm. The aneurysm itself was


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Fig 1. Axial (A) and sagittal (B) images CT angiogram demonstrating the pseudoaneurysm (arrows) arising from the right internal carotid artery within the cavernous sinus.

Fig 2. Left anterior oblique angiogram images from initial treatment procedure. Image obtained prior to embolization (A) shows the large irregularly shaped pseudoaneurysm arising from the intracavernous ICA. Image obtained at the completion of the Onyx HD-500 embolization (B) shows obliteration of the aneurysm dome. Note the small area of contrast opacification near the aneurysm base (arrow), which at the time was felt to be overlap from the nearby ophthalmic artery, but in retrospect may have been slight residual filling at the aneurysm neck.

catheterized with an Echelon-10 microcatheter (Covidien, Irvine, CA). Once within the aneurysm, a “seal” test was performed confirming adequate occlusion of the aneurysm neck by the HyperGlide balloon. Upon completion of the “seal test” the microcatheter was flushed with normal saline, followed by dimethylsulfoxide (DMSO). Onyx-HD-500 was then introduced through the microcatheter with the balloon reinflated. Onyx HD-500 delivery was continued for five to six minute cycles consisting of two to three minutes of actual infusion followed by 3 minutes to allow for solidification of the embolic material before balloon deflation. The patient’s electroencephalogram, in addition to upper and lower extremity somatosensory evoked potentials was monitored during the procedure, and no changes were detected during balloon occlusion periods. A total volume of approximately 1.7 mL of Onyx HD-500 was infused into the aneurysm, gradually filling the dome of the aneurysm and sealing the aneurysm neck. Serial follow-up angiograms demonstrated progressive occlusion of the aneurysm with eventual complete occlusion of the aneurysm at the base. There was some evidence of Onyx coating into the parent vessel, but no hemodynamically significant stenosis and no thrombus formation. After waiting approximately 10 minutes from the last injection, the balloon was reinflated, and the microcatheter was removed. Final high


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and low magnification control angiograms were obtained, which demonstrated good occlusion of the aneurysm with normal flow through the adjacent internal carotid artery. There was no evidence of any normal distal arterial occlusions (Fig 3). The patient made an uneventful recovery had his nasal packing removed the next day without evidence of hemorrhage. He was discharged on postprocedure day 2 at his neurological baseline. Unfortunately, after 12 days, the patient returned to the hospital with mild epistaxis. A follow-up cerebral angiogram was performed, which revealed an area of recurrence within the patient’s large intracavernous right ICA pseudoaneurysm (Fig 3A). The recurrence was located along the superior and medial aspect of the previously treated pseudoaneurysm. The area of recurrence measured approximately 8-9 mm in maximal dimension. On retrospective review of the previous completion angiogram, the area of recurrence appeared to correspond to a very slight area of residual aneurysm neck filling. The patient was retreated in a similar fashion as before with the use of Onyx HD-500 to obliterate the recurrence (Fig 3B). He was discharged on postprocedure day 1 without any further complications. At the 3-month follow-up visit, repeat cerebral angiography demonstrated persistent, complete obliteration of the pseudoaneurysm and the patient has had no further episodes of epistaxis.

Fig 3. Left anterior oblique angiographic images from second treatment procedure. Image obtained prior to retreatment (A) shows moderate area of recurrence at the aneurysm base (circle). After retreatment with Onyx HD-500 the aneurysm now appears completely occluded (B). Of note the ophthalmic artery is no longer visible on these studies; however, the patient had no visual complaints or deficits.

Discussion Pseudoaneurysms make up less than 1% of all intracranial aneurysms.1 Although rare, pseudoaneurysms involving the intracranial circulation present a significant danger due to their high likelihood of rupture.2 Their development is usually due to iatrogenic, infectious, or traumatic causes.2–9 The resultant pathogenesis leads to an incomplete or noncontiguous saccular out-pouching in the vessel wall. As can be expected, these lesions are highly unstable due to inadequate collagenous support. Urgent treatment is generally recommended to prevent catastrophic hemorrhage. Current treatment modalities include microsurgical approaches or endovascular embolization. Microsurgical approaches may require permanent, parent vessel occlusion or trapping, with successful direct clipping often not being possible due to the friable nature of the aneurysm sac itself. Endovascular therapy presents an attractive alternative;10–13 however, similar to microsurgery, endovascular therapy often requires a deconstructive procedure with parent vessel occlusion. Direct coil embolization can be hazardous for the same reasons as direct microsurgical clipping.14–16 Although rare and perhaps less common than for an intradural pseudoaneurysm, perioperative rupture of a cavernous carotid pseudoanuerysm, may lead to a carotid-cavernous fistula formation with associated ocular morbidity, or a sinonasal connection with fatal epixtaxis.17 No covered stents are approved for intracranial use in the United States and the versions available for peripheral indications are typically difficult to navigate into the cranial circulation and therefore of limited utility. Flow diverter technology is a promising addition to the endovascular armamentarium; however, these devices do not provide immediate aneurysm occlusion. A liquid embolic agent for intracranial aneurysms would therefore appear to be a strong alternative. The present case describes an actively bleeding pseudoaneurysm at the skull base, formed as a result of direct iatrogenic trauma. In this setting, options for a reconstructive procedure that spares the ICA and safely leads to abrupt aneurysm occlusion are limited. As a high density liquid embolic agent, Onyx HD-500 is ideal for this situation. The product is FDA approved for the treatment of broad-based, sidewall, intracranial aneurysms.18,19 The active ingredient is an ethylene-vinyl alcohol copolymer. The material is dissolved in DMSO and

micronized tantalum powder is used to create radiographic opacification. On contact with hydrophilic mediums such as blood, Onyx HD-500 will rapidly polymerize and harden. Delivery of the material into an aneurysm leads to complete volumetric filling of the lesion, resulting in immediate occlusion, which as a liquid, is almost certainly less traumatic than platinum coils. Antiplatelet therapy is required, but unlike the situation with a flow diverter, the lesion can be completely occluded at the conclusion of the procedure, limiting the chances of bleeding or rebleeding. Less viscous versions of the material, Onyx 18 and Onyx 34 are also available and are approved for the presurgical embolization of intracranial arteriovenous malformations. Onyx HD-500, though, with almost fifteen times the viscosity of Onyx 34 (500 centistokes vs. 34 centistokes), is optimally designed to gradually and cohesively fill a large or giant aneurysm. This appears to be the first case report describing the use of Onyx HD-500 to treat this type of large, ruptured pseudoaneurysm. In a PubMed search, we could find no published reports of intracranial pseudoaneurysms treated with OnyxHD500. Medel et al, in 2009 described a single case of a small (7 mm) iatrogenic orbitofrontal artery pseudoaneurysm that was treated with Onyx-18.20 This treatment was a deconstructive procedure leading to occlusion of the parent artery as well. In a small 2012 series, Jadhav et al reported nine intracranial pseudoaneurysms treated with Onyx-34.21 All aneurysms were relatively small (median 5.9 mm) and arose from small distal vessels. Again, procedures were deconstructive, with occlusion of both afferent and efferent limbs of the parent vessels. In the present case, we were able to use the properties of Onyx HD-500 to immediately occlude the aneurysm, while still sparing the parent vessel in truly reconstructive manner.

Conclusion The present case shows the utility of a high-viscosity liquid embolic, Onyx HD-500, in occluding a large ruptured pseudoaneurysm arising from a large, proximal intracranial artery, while sparing the artery itself. Immediate occlusion with protection from rehemorrhage can be achieved, but careful follow-up is essential in order to recognize aneurysm recurrence. This is an important technique for the neurointerventional practitioner to have in his or her armamentarium.

Patel et al: Onyx-HD 500 Embolization of a Traumatic Internal Carotid Artery Pseudoaneurysm


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Onyx-HD 500 Embolization of a Traumatic Internal Carotid Artery Pseudoaneurysm after Transsphenoidal Surgery.

Traumatic intracranial pseudoaneurysms present a challenge for treatment. Traditionally these lesions have required a deconstructive approach consisti...
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