Congenital absence of the internal carotid artery

Congenital internal carotid artery hypoplasia: A systematic review

This review evaluates the current evidence for the clinical management of congenital internal carotid artery hypoplasia (CICAH). We summarise clinical presentations diagnostic standards, imaging recommendations, treatment and follow-up. The review was prompted by a case of CICAH in a 50-year-old female who presented to our neurosurgery clinic with an acute episode of vertigo. The patient underwent CT angiogram, which showed an unusually low right carotid bifurcation. The right internal carotid artery (ICA) was hypoplastic, and the A1 segment of the anterior cerebral artery (ACA) was absent. Skull base CT showed an ipsilateral hypoplastic carotid canal. To summarise current evidence for clinical management of CICAH we followed PRISMA guidelines to identify papers meeting our predefined inclusion criteria. We searched three databases using the terms 'ICA' and 'Hypoplasia'. We reviewed 41 papers meeting our criteria. 34 were clinical reports. We performed a data extraction and quality appraisal on these reports. We found that CICAH may be less rare than previously described. Blood pressure control in CICAH is crucial due to the increased risk of stroke and aneurysm formation. Follow-up imaging is strongly recommended. Carotid doppler sonography is a powerful and underutilised diagnostic tool, and carotid canal hypoplasia is not a pathognomic sign. In conclusion, clinicians should be alert to anatomic variations such as CICAH because these produce haemodynamic changes that may have serious clinical consequences. We recommend a central registry of patients with CICAH in order to understand the longer-term natural history of the condition.

Cerebrovascular disorders associated with agenesis of the internal carotid artery: Findings on digital subtraction angiography

Objective

Agenesis of the internal carotid artery (ICA) is a rare vascular condition that is complicated by intracranial aneurysms and rete mirabile. The altered hemodynamics caused by this distinctive cerebrovascular angioarchitecture can cause ischemic or hemorrhagic accidents. Data on clinical and radiographic features have been limited to describing this vascular pattern. We present five cases of agenesis of the internal carotid artery confirmed by digital subtraction angiography (DSA) and further investigate the influence of altered angioarchitecture on the integrity of intracranial morphology.

Methods

Cases of ICA anomalies were screened from the patients who underwent DSA in two hospitals. Clinical manifestation, radiographic features, management, and outcomes were retrospectively reviewed.

Results

Five patients [mean age 44 years (range, 30–65 years)] were included. Two patients presented with subarachnoid hemorrhage, one with cognitive impairment, one with dizziness, and one with intermittent headache. DSA demonstrated that three cases were complicated by intracranial aneurysms, one by dural arteriovenous fistula, and one by rete aneurysm. Three patients underwent endovascular treatment and one underwent bypass surgery. No patient died or experienced cerebrovascular accident during short-term follow-up.

Conclusions

ICA agenesis can be complicated by disorders such as intracranial aneurysm, rete aneurysm, and dural arteriovenous fistula. This suggests that ICA agenesis is associated with a tendency towards disrupted cerebrovascular homeostasis resulting from altered hemodynamics.

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.

A Rare Case of Congenital Internal Carotid Artery Agenesis and Contralateral Internal Carotid Artery Aneurysm

Agenesis of the internal carotid artery (ICA) is a rare congenital entity. This anomaly is typically occult in nature. However, the effects of an incidental discovery secondary to a contralateral ICA aneurysmal rupture can be devastating. The association between agenesis of the ICA and contralateral intracranial aneurysm formation is significantly higher than de novo incidental intracranial aneurysms in the general population. It is important to evaluate the presence of a contralateral intracranial aneurysm in the setting of known agenesis of the ICA. This allows for the performance of prophylactic embolization and characterizes collateral cerebral circulation.

Cerebral Aneurysms with Internal Carotid Artery Agenesis: A Unique Case Similar to Moyamoya Disease and Literature Review

Internal carotid artery (ICA) agenesis/aplasia is occasionally accompanied with cerebral aneurysms caused by hemodynamic stress. If the aneurysms are located around the circle of Willis, they are managed with clipping or coil embolization. Herein, we report a case of ICA agenesis with perforating artery aneurysms treated successfully with revascularization. Moreover, a literature review of ICA agenesis with cerebral aneurysms was performed to compare with the current case. We conducted a literature review using data from PubMed. A secondary search was also performed by reviewing the references of each article previously searched. In our case, the aneurysms shrank and disappeared after direct and indirect bypass surgeries, and indirect bypass developed as in moyamoya disease (MMD). The epidemiological and clinical features of aneurysms accompanied with ICA agenesis were identified via a literature review. Aneurysms with ICA agenesis categorized as type F based on the Lie classification system, or referred to as rete mirabile, are occasionally located in an untreatable site; hence, they cannot be treated with clipping or coil embolization. Moreover, results showed that previous studies did not use revascularization for the treatment of aneurysm. In conclusion, if an aneurysm with ICA agenesis is difficult to approach directly or via an endovascular procedure, revascularization can be a treatment option.

Internal Carotid Artery Agenesis in a Trauma Patient with Ipsilateral Neck GSWs

A 38-year-old man presented to the emergency room in the trauma bay for multiple ballistic injuries to the right neck. He was hemodynamically stable, protecting his airway, and neurologically intact. Computed tomography angiography (CTA) revealed absent filling the right internal carotid artery from its origin to the circle of Willis, which was intact, as well as absent petrous carotid canal on the right. The patient was diagnosed with right internal carotid artery (ICA) agenesis and discharged in several days. This report demonstrates the importance of an in-depth knowledge of vascular embryology and anatomy. The patient has agreed to have images and case details published.

Congenital absence of the internal carotid artery with intercavernous anastomosis

Congenitally absent internal carotid artery with intercavernous anastomosis is an exceedingly rare vascular anomaly. We report such a case in a 65-year-old man with chronic symptoms resembling sporadic transient ischemic attacks. While these patients are usually asymptomatic due to compensatory collateralization, they are at increased risk of aneurysm formation, and thus proper identification is important. This report serves as both a case of a very rare anomaly and as a lesson on how to avoid this misdiagnosis by carotid duplex sonography. Additionally, we review the limited number of published cases of congenitally absent internal carotid artery with intercavernous anastomosis.

The clinical presentation and collateral pathway development of congenital absence of the internal carotid artery

OBJECTIVE

The objective of this study was to investigate the clinical presentation, risks, and collateral pathway development of the congenital absence of the internal carotid artery (ICA).

METHODS

Sixty-four patients (10 new patients and 54 patients from the relevant literature) were studied. Data on demographic, clinical, and radiologic features were collected, followed by an analysis of the risks associated with ICA agenesis.

RESULTS

There were 31 male and 33 female patients whose ages ranged from 5 months to 75 years, with a mean age of 31.1 years. The range of clinical symptoms recorded included transient ischemic attack (17 patients), subarachnoid hemorrhage (12 patients), developmental delay (13 patients), asymptomatic (8 patients), and other symptoms (15 patients). All 64 patients presented with absence of unilateral or bilateral ICAs, as measured by cervical computed tomography angiography or magnetic resonance angiography. The carotid canal was absent in all patients on computed tomography of the base of the skull, and abnormal development of collateral circulation pathways was observed. Five patients presented with basilar artery dilation on angiography. Aneurysms were observed in the angiography results from 16 patients. Ten patients presented with variations in the ophthalmic artery origin (the ophthalmic artery originated from the ipsilateral middle meningeal artery in six patients and from the ipsilateral middle cerebral artery in four patients).

CONCLUSIONS

From analysis of our 10 cases of ICA agenesis and our review of the relevant literature, we conclude that young patients with ICA agenesis may present with developmental delay, subarachnoid hemorrhage, or other developmental abnormalities, whereas older patients most commonly present with transient neurologic events. Complications of carotid agenesis are related to specific anatomic subtypes and the resulting collateral circulation development.

Agenesis of the internal carotid artery: a family pathology?

The internal carotid artery agenesis is a rare malformation disorder. We report the case of a 12-year-old boy suffering migraine, who had presented an episode featuring amaurosis fugax, spontaneously regressed. CT angiography images show hypoplasia of the left common carotid artery with loss of opacification of the left internal carotid artery consistent to agenesis. Moreover CT scans through the skull base demonstrate absence of left petrous carotid canal and an hypertrophic left middle cerebral artery originating from an aberrant artery arising from the right cavernous carotid. All diagnostic examinations confirmed the presence of the internal carotid artery agenesis, as Lie's type IV. We started an annual follow up that over the next 7 years did not reveal any change in magnetic resonance angiography images.

Congenital Absence of Internal Carotid Artery with Rare Type of Intercavernous Anastamosis and Ruptured Cerebral Aneurysm

Congenital absence of Internal Carotid Artery (ICA) is a rare anomaly seen in <0.01% of the population. Various collateral circulations develop in these cases to maintain adequate cerebral perfusion. High incidence of aneurysms is reported in these cases. Complete evaluation is required to detect other abnormalities usually seen in these patients. We report a case of congenital absence of right ICA in a 39-year-old female who presented with Subarachnoid Haemorrhage (SAH) and had a Middle Cerebral Artery Aneurysm (MCA). The right MCA got supply from the intercavernous communication from the left internal carotid artery. Skull base Computed Tomogram (CT) confirmed the congenital absence of right ICA. She underwent successful surgical clipping for the aneurysm. The high incidence of aneurysms, collateral circulations, embryological development and postulated mechanisms of this anomaly were discussed. The exact aetiology behind the absence of ICA remains unclear. It is important to differentiate this condition from acquired stenosis/occlusion due to atherosclerosis and carotid dissection. Recognising the anomaly is important and gains even more significance during surgical planning in cases of direct aneurysm clipping, carotid endarterectomy and transphenoidal surgeries.

A rare case report of bilateral internal carotid artery hypoplasia in postpartum female: Clinical spectrum and role of various modalities in diagnosis

Congenital hypoplasia of bilateral internal carotid arteries (ICAs) is an extremely rare anomaly with less than 25 reported cases in literature till date. We present a case of a 30-year-old primigravida, who developed seizures and subsequently loss of consciousness just few minutes after the delivery of a healthy male child. To the best of our knowledge, this is the first case with bilateral ICA hypoplasia presenting in postpartum female who developed infarct in bilateral frontal region and subarachnoid hemorrhage (SAH). On a postpartum three-dimensional (3D) computed tomography (CT) angiography, bilateral ICA hypoplasia was confirmed and the manifestations of infarcts were probably the consequence of altered hemodynamics of pregnancy. In conclusion, a patient in her late pregnancy and postpartum period, having nonspecific cerebral symptoms or having suffered a cerebrovascular accident, should not only be evaluated for pregnancy or puerperium-related complications but also whenever possible a baseline screening with Doppler study of neck vessels and a noncontrast magnetic resonance imaging (MRI) angiography of neck and cerebral vessels should be performed to rule out congenital anomalies.

Congenital Agenesis of Right Internal Carotid Artery: A Report of Two Cases

Congenital unilateral agenesis of the internal carotid artery (ICA) is a rare anomaly. Due to proper sufficient collateral circulation via the circle of Willis most cases are asymptomatic, but patients can also present with ischemic or hemorrhagic cerebrovascular insults. The absence of the bony carotid canal is essential to differentiate this anomaly from chronic ICA occlusion. Awareness of this situation by clinicians and radiologists is essential because these patients have an increased incidence of various intracranial pathologies. We report two cases of this rare developmental congenital abnormality occurring in two young patients and describe the presentation, diagnosis, determined developmental causes, imaging findings, and complications.

Carotid endarterectomy in an asymptomatic patient with contralateral agenesis of the internal carotid artery

A 64-year-old man was referred to the vascular surgery department with an incidental finding of right internal carotid artery stenosis during thyroid ultrasound imaging. Carotid artery color duplex revealed an ulcerated type III plaque producing stenosis of the right internal carotid artery of 70% and agenesis of the left internal carotid artery. Further imaging with computed tomography angiography confirmed the initial findings and excluded cerebral vascular malformations and ischemic cerebral infarcts. The patient was treated with endarterectomy of the right internal carotid artery with elective shunting and synthetic patch closure.

Agenesis of internal carotid artery associated with isolated growth hormone deficiency: a case report and literature review

BACKGROUND

Agenesis of the internal carotid artery (ICA) is a rare congenital abnormality, sporadically reported to be associated with a combined congenital hypopituitarism. Nevertheless, only a few cases have been extensively described, and none of these have been characterized by an isolated growth hormone (GH) deficiency.

CASE PRESENTATION

Here, we describe a 17-year old boy referred to our hospital for fatigue, decreased muscle strength and severe headache reported after the cessation of rhGH treatment for a GH deficiency diagnosed at the age of 2 years and 3 months. Magnetic resonance imaging (MRI) showed an adenohypophyseal hypoplasia with a lack of posterior pituitary hyperintensity, whereas MRI angiography indicated the absence of a normal flow void in the left ICA. Endocrinological tests confirmed the GH deficiency (GH peak after growth-hormone-releasing hormone (GHRH) + arginine: 2.42 ng/mL) with a very low IGF-I value (31 ng/mL) and normal function of other pituitary axes.

CONCLUSION

To the best of our knowledge this is the first confirmed case of an isolated GH deficiency in a patient with ICA agenesis. The presence of an isolated pituitary deficit is unlike to be considered only as an effect of hemodynamic mechanism, suggesting a role for genetic factor(s) as a common cause of these two rare birth defects. Further studies could clarify this issue and the underlying mechanisms to better understand the etiopathogenetic characteristics of this disorder.

Internal Carotid Artery Hypoplasia: Role of Color-Coded Carotid Duplex Sonography

OBJECTIVES

The purpose of this study was to determine the role of color-coded carotid duplex sonography for diagnosis of internal carotid artery hypoplasia.

METHODS

We retrospectively reviewed 25,000 color-coded carotid duplex sonograms in our neurosonographic database to establish more diagnostic criteria for internal carotid artery hypoplasia.

RESULTS

A definitive diagnosis of internal carotid artery hypoplasia was made in 9 patients. Diagnostic findings on color-coded carotid duplex imaging include a long segmental small-caliber lumen (52% diameter) with markedly decreased flow (13% flow volume) in the affected internal carotid artery relative to the contralateral side but without intraluminal lesions. Indirect findings included markedly increased total flow volume (an increase of 133%) in both vertebral arteries, antegrade ipsilateral ophthalmic arterial flow, and a reduced vessel diameter with increased flow resistance in the ipsilateral common carotid artery. Ten patients with distal internal carotid artery dissection showed a similar color-coded duplex pattern, but the reductions in the internal and common carotid artery diameters and increase in collateral flow from the vertebral artery were less prominent than those in hypoplasia. The ipsilateral ophthalmic arterial flow was retrograde in 40% of patients with distal internal carotid artery dissection. In addition, thin-section axial and sagittal computed tomograms of the skull base could show the small diameter of the carotid canal in internal carotid artery hypoplasia and help distinguish hypoplasia from distal internal carotid artery dissection.

CONCLUSIONS

Color-coded carotid duplex sonography provides important clues for establishing a diagnosis of internal carotid artery hypoplasia. A hypoplastic carotid canal can be shown by thin-section axial and sagittal skull base computed tomography to confirm the final diagnosis.

Internal carotid artery agenesis associated with a rare collateral pathway: supraclinoid-supraclinoid anastomosis. A case report

Internal carotid artery (ICA) agenesis is an infrequent vascular anomaly, less than 0.01% of the population. Here we report a case of internal carotid agenesis with a rare collateral pathway, via supraclinoid ICA anastomosis to the contralateral supraclinoid ICA.

Congenital horner syndrome with heterochromia iridis associated with ipsilateral internal carotid artery hypoplasia

Background

Horner syndrome (HS), also known as Claude-Bernard-Horner syndrome or oculosympathetic palsy, comprises ipsilateral ptosis, miosis, and facial anhidrosis.

Case Report

We report herein the case of a 67-year-old man who presented with congenital HS associated with ipsilateral hypoplasia of the internal carotid artery (ICA), as revealed by heterochromia iridis and confirmed by computed tomography (CT).

Conclusions

CT evaluation of the skull base is essential to establish this diagnosis and distinguish aplasia from agenesis/hypoplasia (by the absence or hypoplasia of the carotid canal) or from acquired ICA obstruction as demonstrated by angiographic CT.

An important clue in the sonographic diagnosis of internal carotid artery agenesis: ipsilateral common carotid artery hypoplasia

A 42-year-old female patient, who had been diagnosed with an occlusion of her left internal carotid artery (ICA) following Doppler ultrasonographic (US) and digitally-subtracted angiographic (DSA) examinations performed in an outer healthcare center in order to eliminate the underlying cause of her complaint of amorosis fugax, later applied to our hospital with the same complaint. At Doppler US performed in our hospital's radiology department, her right common carotid artery (CCA) was normal, but her left CCA was hypoplastic. The right internal artery (ICA) was validated as normal. At the left side, however, the ICA was apparent only as a stump and it did not demonstrate a continuity. The diagnosis of ICA agenesis was confirmed by the utilization of Doppler US, CT, and DSA imaging, and it was concluded also that ipsilateral CCA hypoplasia could be evaluated as an important clue to the diagnosis of ICA agenesis.

Agenesis of the internal carotid artery: associated malformations including a high rate of aortic and cardiac malformations

BACKGROUND

Agenesis of the internal carotid artery (ICA) is a rare congenital anomaly occurring in less than 0.01% of the population, often incidentally discovered in pediatric populations. We recognized a high incidence of additional congenital malformations in children with ICA agenesis.

OBJECTIVE

Our study reports nine cases of ICA agenesis and co-existent malformations and discusses implications of the association.

MATERIALS AND METHODS

We conducted a retrospective chart review of nine children evaluated at our institution with imaging findings of ICA agenesis.

RESULTS

Seven children (78%) had congenital aortic or cardiac anomalies including coarctation (4), hypoplastic left heart (1), tetralogy of Fallot (1), and muscular ventricular septal defect (VSD) (1). Four children were diagnosed with an inherited disorder: Alagille syndrome (1), PHACE syndrome (1), VACTERL association (1), and methylenetetrahydrofolate reductase (MTHFR) gene variant (1). Additional congenital anomalies are also described.

CONCLUSION

In the setting of ICA agenesis, we report a robust association with congenital aortic and cardiac anomalies, as well as a broad spectrum of additional anatomical abnormalities that can occur in the setting of known genetic syndromes or as isolated findings. Knowledge of the natural history of ICA agenesis and associated anomalies will guide optimal care for these children.

Agenesis of the internal carotid artery associated with ipsilateral Horner syndrome in a child

Agenesis of the internal carotid artery is a rare, usually asymptomatic congenital anomaly. Patients may remain asymptomatic because a network of collaterals develops in response to agenesis of the internal carotid artery, which is usually diagnosed as an incidental finding after magnetic resonance imaging. The collateral circulation is prone to developing aneurysms and subarachnoid hemorrhages. We report on a 16-year-old boy with a 1-year history of chronic daily headache. He manifested left-sided miosis and ptosis, with no evidence of anhidrosis, flushing, or pain. He was diagnosed with agenesis of the internal carotid artery with established collateral circulation. The association of Horner syndrome with agenesis of the internal carotid artery is not well reported. Agenesis of the internal carotid artery should be further evaluated to delineate the underlying mechanism, using computed tomography to examine the integrity of the bony carotid canal. Hypoplasia or agenesis of the carotid canal will confirm the congenital cause of the condition. If the canal is intact, dissection of the internal carotid artery should be considered.

Left internal carotid artery agenesis associated with basilar and left vertebral artery aneurysm

Agenesis of the internal carotid artery (ICA) is a rare congenital anomaly. Most of the patients are asymptomatic and it is usually discovered incidentally by computed tomography (CT) or magnetic resonance imaging (MRI). There is close association of the cranial aneurysms and subarachnoid hemorrhage with ICA agenesis. We present a case of a 61-year-old male with left ICA agenesis associated with basilar artery and left vertebral artery aneurysms. The patient complained of headaches and numbness on the right-side of the face. Physical examination showed high blood pressure (210/90 mmHg). Neurological examination revealed nystagmus and decreased sensation on the right-side of the face. Agenesis of left ICA, left carotid canal with basilar and left vertebral artery aneurysms were demonstrated incidentally using CT, MRI, and digital subtraction angiography, as a part of an evaluation for suspected cerebrovascular accident.

Unilateral agenesis of the internal carotid artery presented as transient ischaemic attack: a case report

Dysgenesis of the internal carotid artery (ICA) is a rare vascular disorder with a variety of different grades (agenesis, aplasia, and hypoplasia). The left internal carotid artery is reported to be affected by dysgenesis three times more often than the right one. Most of the patients with dysgenesis of the internal carotid artery are asymptomatic. We report a case of a patient with right internal carotid artery agenesis presented to our hospital as transient ischaemic attack. CT scans at skull base level with bone settings showed absence of the right carotid canal, consistent with congenital agenesis of the internal carotid artery. MR imaging of the brain revealed signal void of the intracranial portion of right internal carotid artery. Maximum intensity projection reconstruction confirmed the agenesis of the right ICA, with the right middle cerebral artery fed through a dilated posterior communicating artery and the right anterior cerebral artery supplied by the anterior communicating artery (fetal type of collateral flow). In patients with agenesis of the internal carotid artery non-invasive imaging techniques are currently the mainstay of diagnosis.

Unilateral agenesis of the internal carotid artery

Unilateral agenesis of the internal carotid artery (ICA) is an extremely rare anomaly. Diagnosis is often incidental in a radiological examination. Recognition of this anomaly has important clinical implications because other life-threatening conditions can be associated and it must be taken into account when planning carotid surgery. We report a case of 64-year-old man with agenesis of the ICA.

Congenital agenesis of internal carotid artery with ipsilateral Horner presenting as focal neurological symptoms

Internal carotid artery (ICA) agenesis is a rare developmental anomaly and is most frequently asymptomatic, but it may also present as cerebrovascular accidents. The association with Horner’s syndrome is exceptional. We present three cases of agenesis of ICA associated with Horner’s syndrome and hypochromia iridum presenting as focal neurological symptoms. A system of collaterals develops as a consequence of agenesis of the ICA, making the majority of cases asymptomatic. Three types of collateral circulations have been described. These collaterals increase the risk of aneurysm formation and the occurrence of life-threatening subarachnoid hemorrhages. The association of congenital Horner’s syndrome and hypochromia iridum without anhidrosis is highly suggestive of sympathetic pathway injury early in life. Such signs should prompt further diagnostic evaluation to demonstrate the presence of the agenesis of the carotid canal. Early diagnosis is essential to rule out potentially life-threatening associated vascular anomalies.

Unilateral agenesis of the internal carotid artery in CHARGE syndrome

CHARGE syndrome is a multisystemic disorder comprising colobomas, heart defects, choanal atresia, retarded growth and development, genital hypoplasia, ear anomalies and deafness. The CHD7 gene on chromosome 8q12.1 was recently shown to be a major gene involved in the etiology of this syndrome. We describe a girl with CHARGE syndrome who had a novel mutation of CHD7 associated with agenesis of the left internal carotid artery. She had presented with recurrent episodes of photophobia and vomiting since the age of 6 years. Since her symptoms were well controlled by cyproheptadine, migraine-like attacks were considered. CHD7 molecular confirmation in this patient provides further evidence to support the occurrence of a vascular anomaly suggested from animal models of CHARGE syndrome with molecular delineation. We report this case to emphasize the importance of neurologic signs of photophobia and to highlight the broad clinical variability in this pleiotropic disorder.

Internal carotid artery agenesis and basilar artery aneurysm with third nerve palsy

Agenesis of the internal carotid artery is an extremely rare vascular anomaly, occurring in less than 0.01% of the population. In most patients, this vascular anomaly is asymptomatic because the contralateral internal carotid artery, external carotid artery, or vertebrobasilar artery systems provide a sufficient arterial collateral blood supply. Carotid agenesis is evident in adults more often than in pediatric patients. We report on a 2-month-old baby with unilateral agenesis of the right internal carotid artery, basilar artery aneurysm, and right third cranial nerve palsy. These abnormalities were diagnosed incidentally using computed tomography, magnetic resonance imaging, and magnetic resonance angiogram as part of an evaluation for suspected encephalitis. According to our review of the literature, this report is the first to describe unilateral agenesis of the carotid artery presenting with ipsilateral oculomotor nerve palsy.

A Case of Congenitally Absent Left Internal Carotid Artery: Vascular Malformations in 22q11.2 Deletion Syndrome

Our report is on a Hispanic boy for whom, shortly after birth, clinical suspicion of 22q11.2 deletion syndrome (22q11.2DS) was raised as a result of his characteristic features, including facial dysmorphisms and hypotonia. The 22q11.2DS was confirmed by fluorescence in situ hybridization (FISH), noting a 22q11.2 deletion. Further evaluation revealed complete congenital absence of the left internal carotid artery and focal pachygyria of the left hemisphere. Multiple cardiac and vascular anomalies have been previously described in 22q11 deletion syndrome, but congenital absence of the internal carotid has not been previously reported in the literature. We present a clinical case report in detail of this unique 22q11.2 deletion syndrome associated finding.

Agenesis of bilateral internal carotid artery associated with basilar artery fenestration mimicking intra-arterial thrombus: a case report

Bilateral internal carotid artery agenesis is a very rare congenital anomaly, which may be accompanied by various types of associated vascular abnormalities, included intracranial aneurysms or dolichoectatic change of posterior circulation. In this article, we present unique, and to the best of our knowledge, the first case of bilateral internal carotid agenesis associated with basilar artery fenestration, which resembles intra-arterial floating thrombus.

Agenesis of internal carotid artery in a child with ipsilateral Horner's syndrome

Horner's syndrome is characterized by a classic triad of ipsilateral pupillary miosis, partial eyelid ptosis, and facial anhydrosis. This case study reports a 7-year-old boy with right miosis, mild blepharoptosis, and iris hypopigmentation detected in a routine pediatric follow-up without ipsilateral facial anhydrosis, flushing, or pain. There was no history of birth trauma and test with cocaine provoked no response of the right pupil, suggesting right Horner's syndrome. Mediastinal tumor was ruled out and brain magnetic resonance imaging incidentally showed absence of flow in the right internal carotid artery. Subsequent magnetic resonance angiography demonstrated agenesis of the right internal carotid artery without other vascular-associated malformations. The final diagnosis was right, congenital Horner's syndrome due to ipsilateral internal carotid agenesis. We describe in detail the radiological findings and pathophysiological mechanisms of this unusual association.

Agenesis of the internal carotid artery with transcavernous anastomosis presenting with an anterior communicating artery aneurysm--a case report and review of the literature

Arterial communication between cavernous segments of the carotid arteries associated with unilateral agenesis of the internal carotid artery (ICA) is extremely rare. We herein present a case of unilateral ICA agenesis with transcavernous anastomosis that presents with an anterior communicating artery (ACoA) aneurysm, and discuss its embryogeny and clinical implications. A 55-year-old woman with no significant medical history was admitted to our hospital for further examination of agenesis of the left ICA, which was detected in a routine medical examination. She was free of clinical symptoms and had no neurological deficits. Radiological evaluation revealed agenesis of the left ICA with transcavernous anastomosis. Moreover, an incidental multilobulated aneurysm was detected at the ACoA. She underwent microsurgical clipping for this aneurysm, and the post-operative course was uneventful. Investigation of collateral pathways helps our understanding of the segmental nature of carotid artery development. Recognition of this anomaly also has important implications in the surveillance and detection of associated cerebral aneurysms.

Non-visualization of the internal carotid artery with a normal ipsilateral common carotid artery Doppler waveform: a finding suggesting congenital absence of the ICA on colour Doppler ultrasound

We report a case of congenital absence of the left internal carotid artery (ICA) that presented with left-sided facial numbness. On MRI of the brain, occlusion of the left cavernous ICA was suggested. On colour Doppler ultrasound (CDS), the left ICA was not visualized and the ipsilateral common carotid artery (CCA) showed normal flow in systole and diastole. Combined with the correct identification of the left external carotid artery (ECA), these findings were suggestive of congenital absence of the ICA rather than occlusion. The final diagnosis of congenital absence of the ICA was confirmed with CT of the skull base.

Aortic arch abnormality in a patient with Klippel-Feil syndrome

We present a case of a 43-year-old female with headaches, progressive paresthesias of the upper extremities, and vertigo. Ultrasonography could not visualize the left internal carotid artery (ICA). Magnetic resonance imaging (MRI) showed complete fusion of the C5, C6, and C7 levels, representing Klippel-Feil deformity. Angiography showed a unique abnormality of the aortic arch with complete absence of the left ICA. An embryologic defect associated with this type of abnormality is proposed, with defects of development of the third aortic arch and the aortic sac secondarily.

Unilateral agenesis and hypoplasia of the internal carotid artery: a report of three cases

We report one patient with agenesis and two with hypoplasia of the internal carotid artery (ICA) from an angiographic series of 1275 consecutive patients. In all three patients, MRI and MR angiography were used to establish the anatomical situation; however, they may not clearly distinguish between hypoplasia and agenesis or acquired stenosis or occlusion of the ICA. In such cases, CT of the skull base may be obtained to clarify matters. In all patients, retrograde flow via a large posterior communicating artery was demonstrated. Single-photon emission computed tomography confirmed both the adequacy of cerebral perfusion and the preservation of vasomotor reactivity.

Congenital absence or hypoplasia of the carotid artery: radioclinical issues

PURPOSE

Congenital anomaly of the carotid artery is a rare abnormality. It is usually discovered incidentally by color Doppler carotid sonography, angiography, computed tomography (CT), or magnetic resonance imaging (MRI) of the head and neck taken for some other reason. Most patients are not symptomatic because of sufficient cerebral circulation supplied to the defective area by the communicating arteries of the circle of Willis, intercavernous anastomosis, communicating arteries from external carotid artery, and by persistent embryologic arteries to the carotid artery territory. However, sometimes, this anatomic variation may eventually lead to some clinical signs and symptoms in particular circumstances in the head and neck of which surgeons are unaware. A retrospective study was designed to emphasize the characteristic radiologic and clinical picture in patients with the congenital absence (agenesis and aplasia) or hypoplasia of the carotid artery, to delineate the associated abnormalities and existing collateral vessels, and to find out its incidence.

MATERIAL AND METHODS

Five thousand one hundred cerebral MRI and/or catheter angiograms performed between February 1988 and March 2002 were reviewed for carotid artery abnormality.

RESULTS

Seven patients with congenital absence or hypoplasia (4 of these patients were presented with hypoplasia of internal carotid artery [ICA], 3 with absence of ICA) of ICA were identified (0.13%). The radiologic and clinical study of 5 patients with unilateral (3 of these patients were presented with hypoplasia and 2 with absence of ICA) and 2 patients with bilateral (1 was presented with absence of ICA, whereas the other was hypoplasia) congenital abnormality with absence or hypoplasia of ICA demonstrate that those patients are usually asymptomatic and they are diagnosed incidentally.

CONCLUSION

It has been concluded that the combined use of magnetic resonance angiography and CT scanning of the skull base may disclose small but patent ICA. Collateral vessels seem to be usual in such cases, but they may be prominent in cases of acquired vascular occlusion, or increased hemodynamic pressure in dysplastic changes in collateral arteries are known causes of aneurysms. The main vascular supply for the brain in patients with congenitally small (hypoplasia) or absent (agenesis or aplasia) ICA is the vertebrobasilar system in bilateral cases. However, contralateral carotid vessel is the dominant arterial supply for unilateral cases, which has to be borne in mind in surgical interventions to the involved side.

Subclavian artery aneurysm in association with congenital absence of ipsilateral internal carotid artery

Aneurysms of the subclavian artery are rare. Similarly, congenital absence of the internal carotid artery is an extremely rare vascular anomaly. In this report, we discuss the case of a 54 year-old woman with an unusual aneurysm of the right subclavian artery in association with congenital absence of the right internal carotid artery. The aneurysm was successfully surgically repaired. On the basis of the appearance of the aneurysm and the absence of known atherosclerotic risk factors in this patient, it is hypothesized that the aneurysm is, in fact, congenital and related to anomalous development of the embryonic aortic arch branches.

Congenital absence of internal carotid artery associated with hypogonadotropic hypogonadism--a case report

Congenital absence of internal carotid artery is a relatively rare disorder. It may be an isolated entity or combined with other organ or system anomalies. Investigations of a 19-year-old male patient with hypogonadotropic hypogonadism and hypothyroidism suffering from intracerebral and subarachnoid hemorrhages showed absence of the left internal carotid artery. The association of endocrinologic disorders and congenital absence of internal carotid artery is discussed with the pertinent literature. In conclusion, association of the absence of internal carotid artery and hypogonadism is extremely rare. Patients with absence of internal carotid artery may also have intracerebral and subarachnoid hemorrhages and should be followed up closely.