Left internal carotid artery agenesis with trans-sellar collateral and a right aortic arch: Case report

Combined lie's type D and type A agenesis of the left internal carotid artery diagnosed by magnetic resonance angiography

PURPOSE

To report an unusual case of combined Lie's types A and D of internal carotid artery (ICA) agenesis, diagnosed by magnetic resonance angiography (MRA).

METHODS

A 60-year-old woman with dizziness underwent cranial magnetic resonance imaging (MRI) and MRA of the intracranial region for the evaluation of brain and vascular lesions. The magnetic resonance machine was a 3.0-T scanner.

RESULTS

MRI showed no abnormalities, except for multiple small white matter lesions. MRA showed that the left ICA was absent, except for the supraclinoid segment, and an anastomotic vessel was present between the paraclinoid segments of the bilateral ICAs, indicating Lie's type D ICA agenesis. The left posterior communicating artery (PCoA) was also present. Thus, there were also features of type A ICA agenesis. The anastomotic vessels between the bilateral ICAs and ipsilateral PCoA were relatively small in caliber.

CONCLUSION

Lie's type D ICA agenesis usually does not communicate with the anterior and posterior circulations. We encountered a case of combined type D and type A ICA agenesis. To our knowledge, no similar case has been reported in the English literature. This is the second case of type D ICA agenesis with patent ipsilateral PCoA. We speculate that in case of type A ICA agenesis, when the development of the PCoA is insufficient to support collateral blood flow, an anastomotic vessel between bilateral ICAs may develop.

Congenital unilateral absence of the internal carotid artery associated with aneurysms of different arteries: a review

There are four hundred and sixty- six cases of absent unilateral (398) and bilateral (68) internal carotid artery (ICA) published in online books, abstracts and original articles from 2020. to 2021. Of the 398 cases of absent unilateral ICA, 95 were associated with aneurysm. The analysis of these cases includes age, nationality and gender, location of aneurysm(s), description, and scheme of carotid-vertebrobasilar angioarchitecture mode in the brain base, as well as hypothesis on embryonic background of accompanying vascular variations and abnormalities. Calculated ratio between number of absent unilateral ICA cases and number of absent bilateral ICA cases is 5.8:1. The ratio between the total number of cases of absent unilateral ICA and those associated with aneurysms is 4.2:1. The association between the posterior communicating-middle cerebral anastomosis and intercavernous (trans-sellar or intercarotid) channel with absence of both anterior cerebral and anterior communicating arteries is common. More than half of the cases with aneurysms are located at the anterior segment vessels of the cerebral arterial circle. This review is based on the description and explanation of embryology and morphology of absent unilateral ICA with aneurysms, which would be significant contribution to published literature on this topic, especially due to the fact that nothing similar has been published since 1957.

Imaging Classification of Internal Carotid Artery Hypoplasia Based on Distal Ophthalmic Segment Occlusion

BACKGROUND

Internal carotid artery (ICA) hypoplasia (ICAH) is rare. The classification of ICAH is largely unclear. The aim of the study is to propose a new imaging classification for ICAH based on the occlusion of the distal ophthalmic segment and discuss the clinical and radiological differences between the different types.

MATERIALS AND METHODS

This was a retrospective study of patients with congenital ICAH diagnosed at the Department of Neurology of the China-Japan Friendship Hospital between June 2011 and June 2016. The patients underwent temporal bone computed tomography (CT), brain CT, cranial magnetic resonance imaging, transcranial Doppler, and head and neck CT angiography.

RESULTS

A total of 20 ICAH patients were divided into the distal occlusion (12 cases; 60%) and nondistal occlusion (8 cases; 40%) types based on whether the distal ophthalmic segment was occluded. The frequencies of collateral circulation from the circle of Willis (P = .01) and dilated cerebrovascular lesions (P = .001) in the distal occlusion type was higher than in the nondistal occlusion type. Five (25%) patients developed adverse cerebrovascular events during followup: 3 ischemic cases were of the nondistal occlusion type, and 2 cases with subarachnoid hemorrhage were of the distal occlusion type.

CONCLUSIONS

A novel classification of ICAH was revealed based on the occlusion of the distal ophthalmic segment. The 2 types may show differences in collateral circulation patterns, coexisting cerebrovascular abnormalities, and potential clinical outcomes.

Right Aortic Arch Associated with Left Internal Carotid Artery Agenesis

We report the rare case of a right aortic arch associated with agenesis of the left internal carotid artery. A 75-year-old woman with a medical history of tetralogy of Fallot presented with dizziness. Magnetic resonance angiography revealed agenesis of the left internal carotid artery in addition to a previously diagnosed right aortic arch. The left common carotid artery was present, but it was thin. Computed tomography showed the absence of the left carotid canal. The left anterior cerebral artery was fed via the anterior communicating artery. The left middle cerebral artery was fed via a thickened posterior communicating artery originating from the left posterior cerebral artery. Although a right aortic arch and agenesis of the internal carotid artery are both very rare, association of the two conditions may occur. Both anomalies depend on the abnormal regression of the dorsal aorta during embryonic development. In such a situation, the presence of other anomalies in the cardiac or central nervous system should be taken into consideration.

Congenital absence of internal carotid artery with intercavernous anastomosis: Case report and systematic review of the literature

The absence of an internal carotid artery is a rare congenital anomaly. In the absence of the internal carotid artery, collateral circulations develop through the circle of Willis, persistent embryonic arteries or transcranial collaterals of the external carotid artery. Six pathways of collateral circulation have been described. Intercavernous anastomosis is between cavernous segments of the bilateral internal carotid arteries and is rarely seen. Patients with an absence of the internal carotid artery can be completely asymptomatic. However, these patients can present with subarachnoid hemorrhage or stroke accompanying cerebral aneurysm or abnormal collateral. We combined our case with 33 previous publications to form a retrospective series including 35 cases of unilateral internal carotid artery agenesis with intercavernous anastomosis.

Congenital absence of internal carotid artery with intercavernous anastomosis: Case report and systematic review of the literature

The absence of an internal carotid artery is a rare congenital anomaly. In the absence of the internal carotid artery, collateral circulations develop through the circle of Willis, persistent embryonic arteries or transcranial collaterals of the external carotid artery. Six pathways of collateral circulation have been described. Intercavernous anastomosis is between cavernous segments of the bilateral internal carotid arteries and is rarely seen. Patients with an absence of the internal carotid artery can be completely asymptomatic. However, these patients can present with subarachnoid hemorrhage or stroke accompanying cerebral aneurysm or abnormal collateral. We combined our case with 33 previous publications to form a retrospective series including 35 cases of unilateral internal carotid artery agenesis with intercavernous anastomosis.