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Table of Contents    
Year : 2012  |  Volume : 60  |  Issue : 5  |  Page : 547-549

Agenesis of internal carotid artery with anterior communicating artery aneurysm

Department of Neurosurgery, PGIMER and Dr. RML Hospital, New Delhi, India

Date of Web Publication3-Nov-2012

Correspondence Address:
Shivender Bhaskar
Department of Neurosurgery, PGIMER and Dr. RML Hospital, New Delhi
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0028-3886.103221

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How to cite this article:
Bhaskar S, Singh S, Shivender S, Singh AK. Agenesis of internal carotid artery with anterior communicating artery aneurysm. Neurol India 2012;60:547-9

How to cite this URL:
Bhaskar S, Singh S, Shivender S, Singh AK. Agenesis of internal carotid artery with anterior communicating artery aneurysm. Neurol India [serial online] 2012 [cited 2020 Apr 8];60:547-9. Available from:


Agenesis of internal carotid artery (ICA) occurs in 0.01% of the population with over a 100 cases being reported till date and about 10 cases of bilateral absence of ICA have been reported. [1] Collateral flow is commonly through persistent embryonic vessels or from transcranial collaterals originating from external carotid artery (ECA). The incidence of aneurysms in these patients is very high when compared with the general population.

A 32-year-old man presented with sudden onset severe holocranial headache followed by brief loss of consciousness. Neurological examination was unremarkable except for neck stiffness (World Federation of Neurosurgical Societies (WFNS) Grade-1). Computed tomography (CT) revealed subarachnoid hemorrhage in the anterior inter hemispheric fissure [Figure 1]a. CT angiography [Figure 1]b and digital subtraction angiography (DSA) revealed an anterior communicating artery aneurysm projecting anteriorly, superiorly and to the left [Figure 1]c. Both the anterior cerebral arteries (ACAs) were filling from the right A1 and the left middle cerebral artery (MCA) was filling from the posterior circulation through posterior communicating artery [Figure 1]c.The left common carotid artery (CCA) originated from the aortic arch in a normal fashion but there was absence of the left ICA from the CCA in the neck and the CCA terminated in the ECA [Figure 1]d. He underwent a right pterional craniotomy, transsylvian approach when the agenesis of left ICA was further confirmed. Due to intraoperative rupture of the aneurysm, temporary clip was applied on the right A1for 5 min during which time the mean blood pressure was increased by 20 mm of Hg and the aneurysm clipped. The patient made an uneventful recovery. He did not consent to undergo a DSA and hence only a postoperative CT angiography was done which revealed bilateral patent ACAs and filling of left MCA by posterior cerebral through posterior communicating artery [Figure 2]a and b. He is doing well at 6 months follow-up with no neurological deficits and is on anti-epileptic medication only.
Figure 1: (a) CT head showing subarachnoid bleed (star) in the anterior interhemispheric fissure. (b) CTA (Preop) showing ant comm artery aneurysm (arrow), filling of both ACAs from right ICA (block arrow), and filling of left MCA from posterior circulation via pcomm artery(arrow heads). (c) DSA right ICA injection revealing similar findings. (d) Left CCA (arrow) ending in ECA and (e) Aortogram showing origin of CCAs

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Figure 2: (a) and (b) CTA (Postop) showing clip artifact (arrow) and both ACAs filling normally with left MCA filling via posterior circulation (arrow heads). (c) Postoperative CT showing clip artifact with postop changes

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Lie has defined agenesis as total absence of ICA due to embryological non-development of artery. [2] The terms hypoplasia (incomplete development) and aplasia (lack of development but precursor did exist at one time) are used when a part of the vessel is present and is normal or even enlarged in size proximal to the narrowed segment. The ratio of right, left, and bilateral agenesis is 1:3:1. [1] Embryologically ECA and CCA arise independently from the aortic sac and the ICA from the third aortic arch, this explains the agenesis of ICA with a normal ECA. The agenesis of ICA depends on the abnormal regression of first and third aortic arches. [2] The three associated abnormalities with agenesis of ICA are aneurysms in the circle of Willis, abnormal arterial collateral channels, and dilated vascular channels. The incidence of aneurysms in the general population is 2-4% when compared with 25-43% seen in ICA agenesis with the series by Lee et al. showing incidences as high as 67%. [1],[3] This high incidence is probably due to either a developmental error resulting in both conditions or due to hemodynamic derangements. The collateral channels can be normal anastomotic pathways in the circle of Willis, persistent embryonic vessels like trigeminal artery, or transcranial anastomosis from ECA ('rete mirabile'). [4] Tsuruta et al. proposed the classification of congenital unilateral ICA agenesis based on the collateral channels: Type I-ACA is filled by contralateral ICA and MCA by basilar artery via posterior communicating artery (as seen in this case); Type II-ACA is filled by ipsilateral MCA; and Type III-the side on which the ICA is absent is supplied by contralateral ICA via anastomotic channels. [1] Agenesis of ICA can be asymptomatic or present with headache, epilepsy, cerebral ischemia, focal deficits, or hemorrhage. Other developmental anomalies that have been associated with ICA agenesis include cerebral hemiatrophy, Klippel Trenuanay syndrome, arachnoid cyst, and non-cerebral ones including cardiac septal defects, hemangioma of tongue, nasopharyngioma, angiofibroma with atresia of upper basilar artery, and neurofibromatosis. [1] The management of the aneurysms poses a challenge due to the dependence on a single ICA and collaterals.

 » References Top

1.Lee JH, Oh CW, Lee SH, Han DH. Aplasia of internal carotid artery. Acta Neurochir (Wien) 2003;145:117-25.  Back to cited text no. 1
2.Lie TA. Congenital anomalies of the carotid arteries. Amsterdam: Excerpta Medica; 1968. p. 35-51.  Back to cited text no. 2
3.Kunishio K, Yamamoto Y, Sunami N, Asari S. Agenesis of the left internal carotid artery, common carotid artery and main trunk of the external carotid artery associated with multiple cerebral aneurysms. Surg Neurol 1987;27:177-81.  Back to cited text no. 3
4.Given CA 2nd, Huang-Hellinger F, Baker MD, Chepuri NB, Morris PP. Congenital absence of the internal carotid artery: Case reports and review of the collateral circulation. AJNR Am J Neuroradiol 2001;22:1953-9.  Back to cited text no. 4


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