Successful treatment of a traumatic carotid pseudoaneurysm with the Pipeline stent: Case report and review of the literature.

BACKGROUND: Traumatic intracranial pseudoaneurysms remain one of the most difficult vascular lesions to treat. In the case of traumatic pseudoaneurysms that may not be treated with parent vessel sacrifice, some flow diversion strategy such as stent-assistance or use of a flow diversion device is usually necessary. CASE DESCRIPTION: In this study we describe endovascular parent vessel wall-remodeling/endoluminal reconstruction and traumatic pseudoaneurysm thrombosis through the use of the Pipeline stent and review recent reports concerning indications, safety, and efficacy for alternative pathology.
CONCLUSION: Although currently not routinely employed in the treatment of traumatic pseudoaneurysms, the Pipeline stent may represent a safe and effective treatment alternative achieving complete endoluminal reconstruction of the damaged vessel wall.

INTRODUCTION

Accounting for less than 1% of all aneurysms, traumatic intracranial pseudoaneurysms represent a class of relatively rare lesions.[11224] These aneurysms are the result of blunt or penetrating trauma to the head and, as in our case, may be due to inadvertent surgical injury. Clinical presentations vary depending on the location and size of the aneurysm and whether or not rupture has occurred. Although shrinkage and spontaneous resolution of intracranial pseudoaneurysms has been documented, clinical series have reported rupture rates of up to 60% prior to definitive treatment.[12-142123] Rupture of intracranial pseudoaneurysms is associated with a mortality rate ranging from 31% to 54%.[12-142123] Consequently, prompt definitive surgical intervention has been established as the standard of care. Traditionally, these lesions were treated with open vessel deconstruction of the parent vessel with or without intracranial bypass. Intervention via the endovascular route now allows for minimally invasive parent vessel deconstruction with or without intracranial bypass. In this case, the parent vessel can be preserved and the aneurysm excluded from the circulation with an endoluminal reconstruction strategy using flow diversion. We describe endovascular parent vessel wall-remodeling/endoluminal reconstruction and traumatic pseudoaneurysm thrombosis through the use of the Pipeline stent (ev3 Neurovascular, Irvine, CA).

CASE REPORT

The patient is a 64-year-old female initially admitted with left-sided chronic maxillary, ethmoidal, and sphenoidal sinusitis. She underwent endoscopic left ethmoidectomy, maxillary antrostomy, and sphenoidostomy. During dissection of the sphenoid mucosa, pulsatile bleeding was observed through a punctate hole in the carotid canal, raising concern for injury to the internal carotid artery. Hemostasis was achieved with an Afrin-soaked pledget and pressure. The patient awoke neurologically intact and an immediate postoperative computed tomography angiogram (CTA) showed no evidence of contrast extravasation or pseudoaneurysm [Figure 1a].

Figure 1

(a) Postoperative CT angiogram (CTA) showed no evidence of contrast extravasation or pseudoaneurysm. (b) A CTA repeated one week later, revealed a 2×1.4 mm pseudoaneurysm arising from the left internal carotid artery at the level of the carotid canal dehiscence

A CTA repeated one week later, revealed a 2 × 1.4 mm pseudoaneurysm arising from the left internal carotid artery at the level of the carotid canal dehiscence [Figure 1b]. Angiography confirmed the presence of the pseudoaneurysm, [Figure 2a] and she passed a test balloon occlusion with hypotensive challenge [Figure 2b]. The patient was counseled in regard to both deconstructive treatment options and vessel preservation with the Pipeline stent. Ultimately, the patient was loaded with 600 mg of Plavix and 325 mg of aspirin. At the time of treatment, the pseudoaneurysm had enlarged to 2.8 mm [Figure 3a]. A 4 × 16 mm Pipeline stent was deployed across the pseudoaneurysm and the control angiogram demonstrated contrast stasis within the aneurysmal dome [Figure 3b]. A 4 × 14 mm Pipeline stent was placed within the first stent to reinforce the construct and the final control angiogram revealed further stasis [Figure 3c]. Four-month follow-up angiogram showed complete obliteration of the pseudoaneurysm and successful reconstruction of the left internal carotid lumen [Figure 4]. The patient has remained neurologically intact and has been maintained on daily aspirin 81 mg and Plavix 75 mg. The Plavix was stopped at 6 months and no significant epistaxis was encountered in the postoperative period.

Figure 2

(a) Angiography demonstrating traumatic pseudoaneurysm. (b) Angiogram demonstrates demonstrating balloon occlusion (6×9 mm), which the patient passed with hypotensive challenge

Figure 3

(a) At the time of treatment, the pseudoaneurysm had enlarged to 2.8 mm. (b) A 4×16 mm Pipeline stent was deployed across the pseudoaneurysm and the control angiogram demonstrated contrast stasis within the aneurysmal dome. (c) A 4×14 mm Pipeline stent was placed within the first stent to reinforce the construct and the final control angiogram revealed further stasis

Figure 4

Angiogram at 4-month follow-up showed complete obliteration of the pseudoaneurysm and successful reconstruction of the left internal carotid lumen

DISCUSSION

By definition, intracranial pseudoaneurysms lack a true wall due to the transmural nature of the preceding injury and thus, are only contained by a friable layer of connective tissue.[11] Additionally, these lesions typically lack a true neck and possess a fusiform morphology. As a result, manipulation of traumatic pseudoaneurysms is associated with a high risk of intraoperative rupture, thereby previously rendering parent vessel deconstruction technique as the most commonly employed approach. Open surgical intervention with parent vessel sacrifice with or without bypass was long considered the standard of care. With the advent of endovascular intervention, endovascular occlusion of the parent vessel in a patient with adequate collateral circulation became a less invasive alternative approach and can be performed following a bypass in those with inadequate collateral circulation.

Recently, parent vessel preservation through endovascular intervention has gained increasing popularity, as coil, stent, and liquid embolic agent technology continue to evolve. The majority of existing literature regarding endovascular vessel preservation of traumatic pseudoaneurysms is comprised of case reports and series, each of which state various rates of success and aneurysm recurrence. Yuen et al. reported coil compaction and regrowth of a traumatic pericallosal pseudoaneurysm that required clip ligation.[26] Fulkerson et al. presented three pediatric patients successfully treated for proximal traumatic intracranial aneurysms with either coiling or stent-assisted coiling.[10] Two of these patients developed coil compaction and recurrence requiring additional coiling procedures. Cohen et al. in one of the largest series, presented a 4 year experience of 13 traumatic pseudoaneurysms treated via the endovascular route.[4] One patient underwent coiling with complete obliteration and no recurrence found on periodic follow-up CTA, while three patients were treated via stent-assisted coiling. One of these patients was found to have aneurysm recanalization on the 6-month angiogram and was definitively treated with endovascular coil occlusion of the carotid and superficial temporal artery-middle cerebral artery bypass. In 2012, Lim et al. reported complete obliteration of a traumatic pseudoaneurysm and preservation of flow through the carotid artery using a stent-in-stent-assisted coil embolization.[15] At the one-year follow-up angiogram, the pseudoaneurysm was found to be entirely occluded. Medel et al. reported successful embolization of a traumatic orbitofrontal artery pseudoaneurysm with Onyx, a liquid embolic agent.[17] No recurrence was found at the four-month follow-up angiogram. In our experience, the treatment of pseudoaneurysms (particularly traumatic pseudoaneurysms) without parent vessel sacrifice or some flow diversion strategy (such as stent-assistance or use of a flow diversion device) should be used cautiously. We have seen patients with traumatic cavernous carotid injuries following transsphenoidal surgery treated with coils alone, experience coil extrusion through the nose and massive epistaxis.

The Pipeline stent is a flow diversion and vessel remodeling device composed of cobalt chromium and platinum tungsten arranged in a 48-strand braided design. The stent reduces blood flow into the aneurysm, thus promoting thrombosis, while also providing a scaffold for endothelialization and reconstruction of the vessel wall. Due to these properties, the Pipeline stent has developed into a treatment option for aneurysms difficult to treat via clipping or coiling, such as, giant and fusiform aneurysms and those located at the skull base.

Chitale et al. reported the treatment of 42 aneurysms with the pipeline embolization device (PED) (41 anterior circulation, 1 vertebrobasilar junction) and experienced a symptomatic complication rate of 13.9%.[3] Szikora et al. reported the treatment of treatment of 19 wide-necked aneurysms with complete occlusion in 18 of 19 aneurysms at 6 month follow-up, and a transient complication rate related to stenting in 5.2% of cases.[22] Colby et al. reported a successful deployment rate of 97% and an immediate flow disruption rate of 97% and 3% rate of major stroke.[5] Others have reported similar occlusion and complication rates with the use of PED in the treatment of intracranial aneurysms.[279161920] A systematic review of the literature demonstrated a complication or poor outcome rate of 11.5% with PED for intracranial aneurysms.[18]

Flow-diversion devices have also been utilized in the treatment of spontaneous dissecting aneurysms. Yeung et al. reported successful obliteration of four dissecting vertebral artery aneurysms with flow diversion.[25] Ducruet et al. reported the use of the PED to treat a ruptured dissecting vertebral artery aneurysm with preservation of flow through a covered posterior inferior cerebellar artery.[8] This strategy also preserved endovascular access for the treatment of severe posterior circulation vasospasm. De Barros Faria et al. reported the use of PED to treat 23 dissecting aneurysms of which 91% were in the posterior circulation. Total occlusion increased from 69.5% to 87.5% at 3 month follow up with smaller lesions achieving higher occlusion rates.[6]

Traumatic intracranial pseudoaneurysms remain one of the most difficult vascular lesions to treat by either open or endovascular techniques. Although the PED has been shown to successfully obliterate complex aneurysms, there is a lack of literature regarding the use of this device in the treatment of traumatic pseudoaneurysms. Our case reports the novel use of the PED for successful obliteration of a traumatic pseudoaneurysm resulting from intraoperative injury during endoscopic sinus surgery. Complete exclusion of the pseudoaneurysm at 4-month follow up angiogram supports the possible durability of PED repair achieving endoluminal reconstruction of the damaged vessel. A limitation of the PED is that decreased flow into aneurysms may not provide immediate thrombosis, and it may take a number of weeks for complete occlusion. This may leave a patient at risk for rupture during this interim. Future investigations into the utility of the PED in the treatment of traumatic pseudoaneurysms are necessary in order to define the feasibility, durability, and complications associated with this treatment option.

CONCLUSION

Traumatic pseudoaneurysms remain rare, but challenging lesions treated via the open or endovascular route traditionally with parent vessel deconstruction. The PED has been shown to be effective in the treatment of simple and complex aneurysms. Although currently not routinely employed in the treatment of traumatic pseudoaneurysms, the PED may represent a safe and effective treatment alternative achieving complete endoluminal reconstruction of the damaged vessel wall.