| Abstract|| |
Aneurysms of the extracranial Internal Carotid Artery (ICA) are rare. Most of the cases seen are due to spontaneous or traumatic dissection of the cervical ICA. Here we report a surgically treated spontaneous extracranial ICA dissecting aneurysm in a ten-year-old girl. The aneurysm was incidentally noticed while performing a routine brain CT for the evaluation of epilepsy. The dissecting aneurysm arising from the extracranial ICA was initially diagnosed by CT, later on confirmed by Doppler and DSA. The imaging features are described with a brief review of literature.
Keywords: Carotid Artery, Internal, Aneurysm/DI, Aneurysm/SU, Seizures/HI, Ultrasonics, Aspiration/CY, Dissection, Tomography, Scanners X-Ray Computed, Magnetic Resonance Imaging, Human, Female, Chile, Case Report,
|How to cite this article:|
Rajagopal K V, Lakhkar B N, Shetty D, Shetty C. Spontaneous giant dissecting aneurysm of extracranial internal carotid artery. Indian J Radiol Imaging 2002;12:517-20
|How to cite this URL:|
Rajagopal K V, Lakhkar B N, Shetty D, Shetty C. Spontaneous giant dissecting aneurysm of extracranial internal carotid artery. Indian J Radiol Imaging [serial online] 2002 [cited 2013 May 19];12:517-20. Available from: http://www.ijri.org/text.asp?2002/12/4/517/28529
| Introduction|| |
Cervical carotid artery dissections account for 10% to 20% of ischemic strokes in young and middle-aged population . They result from penetration of circulating blood into the vessel wall, usually the medial layer. Subintimal dissection results in luminal narrowing, whereas dissection between the media and adventitia results in an aneurysmal dilatation. The aneurysms developed during the arterial dissection consist of blood vessel elements hence they should be called dissecting aneurysms rather than pseudoaneurysms. We report a spontaneous giant dissecting aneurysm arising from the extracranial Internal Carotid Artery (ICA) in a ten-year-old girl.
| Case Report|| |
A ten-year-old female child presented with a history of headache and seizures since 15 days. There was no history of trauma, fever or any source of infection in the recent past. CT scan of the head was performed which was unremarkable. However there was a markedly enhancing mass inferior to the base of the skull on the left side.
Subsequently nonenhanced and enhanced CT of the parapharyngeal region and neck was performed under spiral mode. 5-mm sections were taken from the base of the skull to the C7 vertebral level. A total of 90 ml of contrast was injected at 2.5 ml/s into the antecubital vein with a 30-second scan delay after the start of the contrast bolus. CT showed a large markedly enhancing mass in the left parapharyngeal region extending to the base of the skull. ICA at the level of the mass was narrowed in caliber and eccentrically placed adjacent to the mass. Communication between the mass and the ICA was seen. There was an annular contrast enhancement adjacent to the residual lumen [Figure - 1]. The distal ICA at the skull base was not opacified with contrast suggestive of occlusion of the ICA at the level of the aneurysm. Based on the CT findings the possibility of a dissecting aneurysm of the ICA with an ICA occlusion was diagnosed.
Color Doppler was performed to differentiate between an aneurysm and a very highly vascular neoplasm. Doppler confirmed a large aneurysm with swirling motion of the blood within it [Figure - 2]. This aneurysm was found to arise from the ICA. The ICA was not traceable above the level of the aneurysm.
DSA was performed to know the exact status of the ICA and the aneurysm. DSA showed a large aneurysm arising from the extracranial left ICA, five centimeter beyond the carotid bifurcation. There was gradual tapering of the ICA with occlusion at the level of the aneurysm [Figure - 3],[Figure - 4]. Angiography findings confirmed a dissecting aneurysm of the extracranial ICA. The left anterior cerebral and middle cerebral arteries were adequately supplied from the right ICA through the anterior communicating artery.
The patient underwent surgery. Resection of the aneurysm along with ligation of the left internal carotid artery was performed.
| Discussion|| |
Aneurysms of the extracranial internal carotid artery are uncommon. Houser and Baker  found extracranial ICA aneurysms in 8 (0.16%) of 5000 cervicocephalic angiograms. Extracranial ICA aneurysms can be caused by a wide variety of conditions, including atherosclerosis, trauma, fibromuscular dysplasia, infection, autoimmune connective tissue disease, heritable connective tissue disorders or arterial dissection. In most series the most common cause of intracranial ICA aneurysms has been spontaneous or traumatic arterial dissection. In a review of 22 cases of extracranial ICA aneurysms 50% were caused by spontaneous dissections and the remaining were caused by traumatic dissection of the ICA . In the present case no etiological factors were found for ICA dissection and thus the aneurysm was presumed to be due to spontaneous dissection of the extracranial ICA.
In many large series of extracranial ICA dissection, the age of presentation varied widely between 16-68 years ,,. Our patient was only 10 years old at the time of diagnosis. Misra BK et al , have reported a distal extracranial aneurysm in a 5 year old boy .
It is uncommon for spontaneous ICA dissecting aneurysms to become symptomatic, whereas traumatic ICA dissecting aneurysms more frequently become a nidus for emboli, causing transient cerebral or retinal ischemic attacks . It is rare for an extracranial ICA aneurysm to rupture causing symptoms . Our patient presented with headache and seizures.
Various CT appearances have been described for carotid artery dissections. Dal Pozzo et al have described a picture composed of a narrowed central or eccentric enhancement (residual lumen) surrounded by a hypodensity (mural hematoma),this hypodensity is surrounded by a thin annular contrast enhancement . This typical CT feature has been described as a target appearance. The peripheral annular contrast enhancement could be due to the visualization of enhancing vasa vasorum in the adventitial layer . Zuber et al suggested the use of dynamic CT to demonstrate the mural hematoma when angiographic findings are not conclusive . With the helical CT technique, the acquisition is performed in a very short time and a small volume of contrast material provides a good contrast between the enhanced lumen and the surrounding structures . In our patient CT showed a large aneurysm in the left parapharyngeal region extending to the base of the skull. The communication between the mass and the ICA was demonstrated. The lumen of the ICA, at the level of the mass, was narrowed in caliber and eccentrically placed adjacent to the aneurysm. The peripheral annular contrast enhancement described in previous studies of carotid dissections was also seen in our patient adjacent to the residual lumen [Figure - 1]. The distal ICA at the skull base was not opacified with contrast suggestive of occlusion of the ICA at the level of the aneurysm.
Previous studies have shown usefulness of MR for the diagnosis of carotid dissection. T1 weighted image shows a narrowed eccentric signal void surrounded by a semilunar hyperintensity (mural hematoma). The sensitivity of MR is higher in internal carotid artery dissection than in vertebral artery dissections and in stenotic-type dissections than in occlusive or aneurysmal-type dissections . MRI is useful in the detection and follow-up of dissecting aneurysm. In a follow-up MRI study of 26 dissecting aneurysms with a follow-up interval varying from 10-93 months, Djouhri H et al , revealed that 77% remained unchanged, 15.4 % decreased in size and 7.6 % resolved . MRI can be complimented by ultrasound for follow-up of carotid aneurysms.
Our case represents the occurrence of this rare disease in an uncommon age group and the importance of radiologic modalities in the diagnosis of extracranial ICA dissecting aneurysms.
| References|| |
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K V Rajagopal
Department of Radiodiagnosis & Imaging, Kasturba Hospital, Manipal 576119, Karnataka
[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4]