Rare congenital anomalies of the internal carotid artery: anatomic and radiologic aspects of three cases and review of the literature

Branch retinal artery occlusion with congenital common carotid artery and internal carotid artery occlusion: A case report

PURPOSE

To report a case of branch retinal artery occlusion (BRAO) of the left eye combined with left congenital common carotid artery occlusion (CCAO) and internal carotid artery occlusion (ICAO).

METHODS

Case report.

RESULTS

A 36-year-old man presented with sudden vision loss of only the left eye without any signs or symptoms of brain diseases. Fluorescein fundus angiography (FFA) showed left BRAO, and computed tomography angiography (CTA) of the head and neck showed entire left CCAO and ICAO. The patient's left vertebral artery was anastomosed with the left occipital artery via the muscular branch, supplying blood retrogradely to the left external carotid artery. The right internal carotid artery compensated for blood supply to the left anterior cerebral artery and middle cerebral artery via anterior communication, and the left posterior communication artery compensated for blood supply to the left middle cerebral artery.

CONCLUSIONS

To our knowledge, this study was the first to report a case of BRAO combined with congenital CCAO and ICAO with vision loss as the first symptom and proposed the importance of head and neck examination in retinal artery occlusion at the first visit to a doctor.

The ambiguous "internal carotid artery"-Ultrasound diagnosis of congenital absence of the internal carotid artery: A case report and review of the literature

RATIONALE

Congenital anatomical variation of internal carotid artery (ICA) rarely occurs, and congenital absence of the ICA is even rarer. Few reports are available on the diagnosis of congenital absence of the ICA by carotid doppler ultrasound (CDUS), and most cases have been identified by computed tomographic angiography (CTA) or digital subtraction angiography (DSA).

PATIENT CONCERNS

A 61-year-old male was admitted to our hospital due to dizziness for more than half a month. He was hypertensive and had been drinking and smoking for many years.

DIAGNOSES

The patient was diagnosed by carotid doppler ultrasound with congenital absence of the right ICA, confirmed by CTA and DSA. A nodular aneurysm in the anterior communicating artery was observed by CTA and DSA.

INTERVENTIONS

After relevant preoperative examinations were performed, the patient underwent right craniotomy and clipping of the aneurysm under general anesthesia 8 days after admission.

OUTCOMES

The patient recovered well after surgery and no relapses has been observed.

LESSONS

Congenital absence of the ICA is rare and usually diagnosed by CTA or DSA in clinical practice. If radiologists do not have adequate knowledge about the associated ultrasonic characteristics, a missed diagnosis may occur. As a noninvasive and rapid screening tool for cervical vascular diseases, carotid doppler ultrasound offers a new approach for the diagnosis of congenital absence of the ICA.

ICA agenesis with transcavernous anastomosis: a systematic review

PURPOSE

To present two cases of Internal Carotid Artery (ICA) agenesis and conduct a systematic review to assess for associations with other anomalies and intracranial aneurysms.

METHODOLOGY

We performed a retrospective review of published cases of patients with ICA agenesis with intercavernous anastomosis in MEDLINE database on August 2022 using search terms "internal carotid artery", "agenesis" and "transcavernous anastomosis". We also included two cases of ICA agenesis with type D collateral that we encountered.

RESULTS

Total of 45 studies that included 47 patients and two of our cases resulted in 49 patients. Only 70% of studies reported the location of a collateral vessel of which more than two-thirds were on the floor of sella. More than half of the vessels connected cavernous segments of ICA. A1 segment ipsilateral to the side of ICA agenesis was absent in most of the cases but was not true for all cases. Aneurysm was seen in more than one-quarter of the patients. It can also mimic microadenoma as in prior reported cases as well as in one of our cases.

CONCLUSION

ICA agenesis with type D collateral is a rare anomaly but clinically relevant due to the increased risk of an aneurysm or mimic microadenoma or false alarm for occlusion of ICA but knowledge of this rare variant can help in better management of these patients.

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.