Delayed intranasal coil extrusion after internal carotid artery pseudoaneurysm embolization

Abstract

Internal carotid artery (ICA) injury is a rare but potentially life-threatening complication of skull base and neck surgery. Although usually manifested by massive intraoperative haemorrhage, impairment of the ICA might go unnoticed and result in formation of a pseudoaneurysm, causing delayed bleeding. Often additional complications are observed such as thrombosis, spasm, embolism or carotico-cavernous fistula formation. The risk of carotid artery injury in aggressive endonasal skull base surgical interventions ranges from 1% to 9%. Digital subtracted angiography remains the gold standard for evaluation of patients with iatrogenic carotid artery injury as it allows for endovascular treatment at the time of the procedure. Endovascular embolization is currently the preferred method for treating ICA pseudoaneurysms and a successful alternative to the surgical approach. Even though endovascular approaches are considered the safer option, delayed complications have been registered, such as endovascular coil extrusion and migration, which increases the risk of further episodes of bleeding. We present our experience with late coil extrusion in a patient who was previously treated with flow diverter stent and coiling for iatrogenic ICA pseudoaneurysm.

Introduction

Internal carotid artery (ICA) injury is a rare but potentially life-threatening complication of head and neck surgery. Although usually manifested by massive intraoperative haemorrhage, impairment of the ICA might remain unnoticed and result in formation of a pseudoaneurysm, causing delayed bleeding. Often additional complications are observed such as thrombosis, spasm, embolism or carotico-cavernous fistula formation. The risk of carotid artery injury in aggressive endonasal skull base surgical interventions ranges from 1% to 9%.¹ Digital subtracted angiography (DSA) remains the gold standard for evaluation of patients with iatrogenic carotid artery injury as it allows endovascular treatment during the procedure.² On the other hand, endovascular embolization is currently the preferred method for treating ICA pseudoaneurysms and a successful alternative to the surgical approach. Even though endovascular approaches are considered to be a favourable option, delayed complications have been registered, such as endovascular coil extrusion and migration, which could increase the risk of further episodes of bleeding.

We present a case report with late coil extrusion in a patient who was previously treated with flow diverter stent and coiling for iatrogenic ICA pseudoaneurysm.

Case report

A 59-year-old male was admitted to our hospital with visual deficit of the right eye three months after endonasal transsphenoidal resection of pituitary adenoma. According to the intraoperative record unexpected arterial bleeding from the right nostril was encountered during the surgery but was successfully overcome with endonasal tamponade. After visual symptoms occurred magnetic resonance imaging was performed and revealed a wide-neck saccular pseudoaneurysm of the cavernous (C5) segment of the right internal carotid artery (Figure 1).

Figure 1.

Magnetic resonance images showing pseudoaneurysm on the right internal carotid artery (C5 segment) after pituitary surgery.

After clinical discussion between neurosurgeons and interventional neuroradiologists it was concluded that endovascular embolization treatment of the aneurysm was appropriate.

The patient underwent full anticoagulation therapy prior to the endovascular treatment: 100 mg acetylsalicylic acid and 75 mg clopidogrel per day were administered for five days before the procedure and the patient was tested for clopidogrel resistance, with no evidence for it. Since the patient had presented with acute haemorrhage, combination of stent assisted coiling along with flow diversion was chosen as the operative strategy in order to rebuild the traumatic portion of the vessel by epithelialization of the stent’s wall and quicker thrombosis of the pseudoaneurysmal lumen.

Under general anaesthesia the pseudoaneurysm was catheterized by Echelon microcatheter and several Target coils (Stryker) were delivered to ensure faster thrombosis inside the aneurysmal lumen. Next, a flow modulation device p64 (Phenox) was deployed to help rebuild the wall of the parent vessel and also to minimize the possibility for recanalization of the aneurysm. Control DSA at the end of the procedure showed satisfactory early results (Figure 2).

Figure 2.

Anteroposterior and lateral views on the first digital subtracted angiography showing the internal carotid artery C5 segment wide-neck pseudoaneurysm and the end of the procedure after performing stent assisted coiling with flow diverter.

One week after the endovascular embolization the patient presented with profuse nasal bleeding requiring blood transfusion and renewal of the nasal packing. Emergency DSA was performed showing slight loosening in the anterior portion of the coil mass, but observation was chosen as the course of action (Figure 3). Although a reduction of the clopidogrel dosage to 75 mg was initiated, episodes of recurring nasal rebleeding were observed. Both the clopidogrel and the acetylsalicylic acid were discontinued. After a control computed tomography scan and DSA showing no evidence of recanalization of the pseudoaneurysm and normal blood flow in the right common carotid artery the patient was discharged 15 days later in a stable condition.

Figure 3.

Control digital subtracted angiography 15 days after the procedure showing loosening of anterior aspects of the coil mass and six months after the procedure, showing the prolapsing coil loops.

The patient remained asymptomatic for six months, when he reported prolapse of the distal tip of the embolization coil wire after sneezing and subsequently removing some of the portion of the coil from his right nostril. An urgent conventional angiogram was performed along with X-ray of the sinuses, which confirmed extrusion of endovascular coils into the nasal cavity (Figure 3). The patient was referred to an otorhinolaryngology department, where, under local anaesthesia the extruded segments were better visualized and trimmed at the level of the nasal mucosa. Given the fact that the pseudoaneurysm was fully thrombosed and the endovascularly deployed flow diverter p64 was successfully isolating the coil mass within the sac, no significant bleeding was observed during and after the latter procedure.

In the months afterwards the patient experienced several episodes of prickling sensation in his nasopharynx, which were proven to be due to subsequent migration of the coils treated with the same technique by the otorhinolaryngology team. Multiple X-rays were obtained showing the path of migration and the reduction of the volume of the remaining coil mass (Figure 4). No bleeding, thrombosis or respiratory complications were observed.

Figure 4.

Later control X-ray images, 14 months after the first extrusion, showing the coil’s intranasal migration.

Discussion

Traumatic pseudoaneurysm occurs as a result of injury to the arterial wall. The pathologic mechanism consists of partial resolution of periarterial haematoma development of fibrinous wall, leading to a perfused sac formation. Due to the influence of continuous pulsatile arterial forces the latter expands to a globular shape.³ Pseudoaneurysms can also be observed as part of the impending Carotid Blowout Syndrome, especially in irradiated head and neck cancer patients.^4,5 The wall of the pseudoaneurysm, in contrast to a true aneurysm, lacks the media and intima layers and therefore is more fragile. The latter leads to an increased rupture risk.

Surgical and technical approaches in these cases vary among institutions, with some authors advocating reconstructive and even deconstructive techniques. Extracranial to intracranial cerebral artery bypass is considered a complex procedure carrying significant risk; parent artery occlusion alone may be favourable if the patient could tolerate it. Protocols including temporary balloon test occlusion with clinical neurological evaluation, neurophysiological monitoring and angiographic and cerebral haemodynamic perfusion assessment followed by permanent occlusion are considered as the traditional, and in some cases the bearable, approach of elimination of ICA pseudoaneurysm.⁶ Technically speaking the treatment goals and techniques have many similarities to the treatment of supraclinoid blister-like aneurysms of the ICA, where permanent parent vessel takedown has been reported to be the therapy of choice.⁶

The expansion of new endovascular techniques, for example, balloon occlusion, flow diversion, stent-assisted coiling or coiling alone, has transformed the treatment of these complex lesions dramatically. Recently endovascular reconstruction approaches have become the standard treatment, whereas deconstructive methods and bypass procedures are now considered as a backup plan.

An endovascular approach aiming at full occlusion of the lumen of the pseudoaneurysm and preserving the blood flow in the parent artery is currently the preferred method for treating pseudoaneurysms. Detachable balloons, coiling, stent placement and their combinations are all possible techniques for achieving better results.^3,7,8 In traumatic iatrogenic pseudoaneurysms combination of Onyx and balloon assisted coiling has proven to be successful.¹ Jafari et al. have confirmed in the case of a pseudoaneurysm in a child that stent placement alongside coiling could be a useful method of choice.⁹ To our knowledge, to date, combination of flow diverter stent and coil embolization has not been described in cases of traumatic iatrogenic pseudoaneurysms.

The most frequently reported complications of coil embolization of such pseudoaneurysms are related to thromboembolic events or coil extrusion. Any coil movement in balloon assisted embolization is usually evident right after the balloon deflation. If proper packing of the coil loops is not achieved, soft or ultra-soft coils, used in the final packing of the lumen, may displace even months after the procedure.⁸ Both low-density packing and overpacking, as well as coil size and the shape of the aneurysm, might generate instability in the coil mass. Choosing the flow modulation device p64 gives us the benefit of constructing the lumen of the parent vessel by providing faster endothelialization within six months, as opposed to the conventional braided stents that endothelialize for one year or more. In patients with previous bleeding incidents coil embolization along with flow diversion could be a new safer option in order to accelerate the pseudoaneurysmal lumen thrombosis.

Coil migration after endovascular embolization has been reported in the upper and the lower respiratory tract, including paranasal sinuses, and could result in hypoxia and even respiratory arrest if not quickly removed.^5,10 The inherent instability of the pseudoaneurysmal wall and the resolution of the intramural haematoma with subsequent loosening and eventual migration of the embolization coils might account for the possible mechanism of coil extrusion.^1,3 In our case this hypothesis is validated by a series of radiographs revealing progressive loosening of the anterior portion of the initial coil mass.

Dedmon et al. have published a case of coil herniation into the nasal cavity two months after embolization of a cavernous ICA aneurysm.¹ Jafari et al. present in their case report a coil extrusion associated with an extracranial ICA pseudoaneurysm after a tonsillectomy in an otherwise healthy child.⁹ Singh et al. have reported a similar case of coil extrusion after embolization of a traumatic aneurysm without previous surgical intervention.³ In all those cases the extruded coil loop was treated by trimming at the level of the defect while the embedded portions were left in place.

Conclusion

Formation of carotid artery pseudoaneurysm is a rare but dreadful potentially life-threatening complication of head and neck surgery. Currently endovascular treatment is the preferred approach since it has a relatively lower morbidity and mortality rate. Due to the histologic characteristics of the pseudoaneurysmal wall complications such as extrusion of endovascular coils are reported more often than in embolized true aneurysm. Using flow diversion along with coil embolization could provide us with the opportunity of rebuilding the traumatic portion of the vessel while reducing the risk of recanalization. However, in this case scenario extra-luminal coil extrusion is still possible as described above. In our opinion flow diversion is the best endovascular treatment option for pseudoaneurysm.

Declaration of conflicting interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The authors received no financial support for the research, authorship, and/or publication of this article.