July 2007, Volume 57, Issue 7

Case Reports

Acute stroke secondary to internal carotid artery pseudoaneurysm: MRI findingsand treatment with endovascularcoiling

Mohammad Wasay  ( .The Aga Khan University1, Karachi )
Alper Dai  ( , Gaziantep University, Gaziantep2, Turkey )
Neeraj Dubey  ( Dent Neurologic Institute3, Buffalo, NY, USA, )
Saadat Kamran  ( Hammad Medical Center4, Doha, Qatar )

Abstract

Internal carotid artery pseudoaneurysms are uncommon. We report a young man with history of trivialtrauma who presented with middle cerebral artery stroke.Head CT scan revealed a right parapharyngeal mass. MRI confirmed the diagnosis of internal carotidpseudoaneurysm. Cerebral angiogram showed dissection of internal carotid artery with a large pseudoaneurysm and almost complete occlusion of vessel distal to aneurysm.Vessel was obliterated by fibercoiling and gluing byendovascular technique to diminish risk of furthere mbolization. MRI characteristics of carotid pseudoaneurysms and role of endovascular treatment arediscussed.

Introduction

Internal carotid artery dissection and pseudoaneurysms are uncommon and are associated with high morbidity and mortality.1,2 Thrombosis, embolism and rupture with haemorrhage are common complications.3,4Majority of cases have no history of trauma and may present as parapharyngeal or peri tonsillar mass.5 Spontaneous resolution is uncommon among patients with pseudoaneurysm. Surgical treatment is controversial and isassociated with major complications.6-8  Endovascularcoiling and stenting has been used with success in selected patients.9 We report a young man who presented with right middle cerebral artery embolic stroke due to an internal carotid artery pseudoaneurysm. As the vessel was almost completely occluded, proximal obliteration of vessel wasobtained using fiber coils to diminish the risk of further embolism.

Case Report

A31 year old man with history of minor neck traumasix months ago, presented with acute stroke. Neurological examination revealed slurring of speech, left upper motorneuron facial paresis and left hemiparesis. General physical examination was unremarkable except swollen and protruded right pharyngeal tonsils. There were no redness,inflammation or exudates present involving tonsils. Are tropharyngeal mass was suspected based on clinical examination. Non-contrast head CT scan in axial plane showed a well defined rounded mass involving right paraphyrangeal space representing a large pseudoaneurysm of right internal carotid artery (Figure 1). The etiology of stroke was most likely embolic from partially thrombosed aneurysm. Cerebral angiogram showed dissection of internal carotid artery with a large pseudoaneurysm and almost complete occlusion of vessel distal to aneurysm(Figure 2).Vessel was obliterated by fibercoiling and gluing by

[(1)]

[(2)]

endovascular technique to diminish risk of further embolization. We believe that pseudoaneurysm resulted from a clinically asymptomatic internal carotid arterydissection due to minor trauma as illustrated in history.

Discussion

Stroke is a common complication of carotid artery dissection.1 The mechanism underlying stroke is related to thrombosis, embolism or slow flow due to dissection. Time duration between dissection and stroke could range from immediately post dissection to years. Majority of these patients have history of neck trauma but patients with spontaneous dissection are increasingly recognized. Patients with carotid dissection can be divided into two groups depending on presence or absence of pseudoaneurysm.2 Only a minority of these patients develop pseudoaneurysm.Dissection between tunica media and adventitia is the underlying mechanism for pseudoaneurysm formation.3 Spontaneous resolution is rare in patients with pseudoaneurysm due to carotid and vertebral artery dissection. Diagnosis of possible carotid aneurysm was suggested due to a large paraphyrangeal mass. MRI showeda well-defined mass measuring seven-centimeter superioinferiorly containing multiple layers of thrombus of different ages. These signal characteristics are highly suggestive of thrombosed aneurysm as compared to aparapharyngeal abcess or mass. MRI findings described above may be characteristic for carotid artery pseudoaneurysm. These findings may be helpful indifferentiatial diagnosis of a pharyngeal mass.  The diagnosis could be suggested on routine CT and MRI examination. Recent reports have showed utility of Helical CT angiography and contrast-enhanced MR Angiography inthe diagnosis of carotid dissection and pseudoaneurysm.10 In conclusion, carotid pseudoaneurysm could presentas acute stroke. The diagnosis could be established based onroutine CTand MRI. Endovascular and gluing are effectiveand safe in obliterating pseudoaneurysm. Due to high complication rate of surgery in these cases endovascular treatment may be a good alternative. Alternate endovascular procedures used to treat this condition include, stenting and stent supported coiling of pseudoaneurysm.

References

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2. Friedman WA, Day AL, Quisling RG, Sypert GW, Rhoton AL. Cervicalcarotid dissecting aneurysms. Neurosurgery. 1980;7:207-14.

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8. Catalano PJ, Bederson J, Turk JB, Sen C, Biller HF. New approach foroperative management of vascular lesions of the infratemporal internal carotidartery. Am J Otol. 1994;15:495-501.

9. Delgado F, Bravo-Rodriguez FA, Bautista MD, Chirosa MA, Molina T,Martos JM, et al. Carotid pseudoaneurysms secondary to dissection:endovascular management with bare stent-graft. Cerebrovasc Dis.2005;19:136-8.

10. Phan T, Huston J, Bernstein MA, Riederer SJ, Brown RD. Contrast-enhancedmagnetic resonance angiography of the cervical vessels: experience with 422patients. Stroke. 2001;32:2282-6.

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