Diagnostic challenges in internal carotid artery fenestration: a 78-year-old woman presenting with transient ischemic attack—a case report

Abstract

Background

Internal carotid artery fenestration is a rare vascular anomaly that may present with transient ischemic attack symptoms due to localized flow disturbances. It is important to report such cases, as they present unique diagnostic challenges and clinical implications, particularly when associated with systemic vascular risk factors such as diabetes and hypertension. Differentiating internal carotid artery fenestration from other conditions, such as internal carotid artery dissection, is crucial for appropriate management and patient outcomes.

Case presentation

A 78-year-old Iranian female patient with a medical history of uncontrolled diabetes mellitus and hypertension presented to the emergency department with sudden-onset double vision, dizziness, and weakness in her left limbs. Symptoms lasted for 15 minutes and fully resolved. Neurological examination revealed mild weakness in the left upper and lower limbs but no sensory deficits. A bruit was detected over the left carotid artery, raising suspicion for carotid artery disease. Blood tests showed elevated blood glucose, and imaging studies, including carotid Doppler ultrasound, revealed irregularities and increased intima–media thickness, suggesting early vascular changes. Brain computed tomography scan was normal, and computed tomographic angiography of the head and neck revealed an incidental finding of internal carotid artery fenestration at the cervical segment. The fenestration appeared as a mild fusiform dilation of internal carotid artery with no signs of dissection or thrombosis. The patient was started on dual antiplatelet therapy (aspirin and clopidogrel) and optimized for blood pressure and lipid control. She was discharged with no residual neurological deficits, and follow-up was arranged for continued management of her cardiovascular risk factors.

Conclusion

This case highlights the diagnostic challenges and clinical relevance of internal carotid artery fenestration, particularly in patients with systemic vascular risk factors. Although internal carotid artery fenestration is often asymptomatic, it can be associated with cerebrovascular complications, such as ischemic events. In this case, the transient symptoms likely resulted from localized hemodynamic disturbances due to the fenestrated artery. While there is no established consensus on the management of asymptomatic internal carotid artery fenestration, dual antiplatelet therapy and risk factor optimization remain key strategies. Further research is needed to better understand the implications of internal carotid artery fenestration and to refine diagnostic and management protocols for these rare vascular anomalies.

Introduction

Internal carotid artery (ICA) fenestration is a rare anatomical variant that has gained attention owing to its potential clinical implications, including cerebrovascular complications such as ischemia, dissection, and aneurysm formation. First reported in 1928, ICA fenestration is characterized by a splitting of the arterial lumen, which can lead to hemodynamic disturbances and increase the risk of cerebrovascular events. Although ICA fenestration is typically considered a benign anomaly, its association with transient ischemic attacks (TIAs), strokes, and other vascular complications has sparked growing interest in its clinical significance.

ICA fenestration is often difficult to distinguish from other vascular anomalies, particularly ICA dissection, which can present with similar symptoms but has a different underlying pathology. The differentiation between ICA fenestration and pseudofenestration, a phenomenon caused by vessel dissection, remains a significant challenge in clinical practice. Imaging modalities such as computed tomographic angiography (CTA) and magnetic resonance imaging (MRI) play an essential role in diagnosing ICA fenestration and differentiating it from other vascular disorders [1, 2].

While many cases of ICA fenestration are asymptomatic, recent literature has shown that its presence can contribute to neurological symptoms, particularly in the setting of underlying risk factors such as hypertension, diabetes mellitus, and dyslipidemia [3, 4]. Moreover, the management of ICA fenestration, especially in asymptomatic cases, remains controversial. Clinical guidelines are well-established for the management of ischemic events related to vascular dissections and TIAs, but treatment protocols for ICA fenestration without associated complications are still under debate [5].

This case report presents a 78-year-old female individual who experienced a TIA with symptoms consistent with ICA fenestration. We aim to explore the clinical presentation, diagnostic challenges, and management strategies related to ICA fenestration, drawing insights from previous documented cases [6, 7]. By reviewing the current literature, we hope to highlight the complexity of diagnosing and managing this rare condition, which requires careful consideration of patient history, risk factors, and advanced imaging techniques to guide appropriate treatment decisions.

Case presentation

A 78-year-old Iranian female patient was brought to the emergency department following a sudden onset of double vision, dizziness, and weakness in her left upper and lower limbs. The symptoms lasted for 15 minutes before completely resolving. The patient had no associated headache, nausea, or loss of consciousness. There was no history of prior strokes, transient ischemic attacks, or trauma.

Her past medical history was significant for uncontrolled diabetes mellitus (DM) and hypertension (HTN). She was on the following medications: metformin 1000 mg twice daily (BID), valsartan 80 mg BID, and atorvastatin 40 mg once daily.

Upon examination in the emergency department, the following findings were noted:

Double vision during symptom onset, but resolved at the time of examination. Normal visual acuity, visual fields, and fundoscopy. Movement of extraocular muscles was intact with no nystagmus or gaze palsies. Speech was clear, and language comprehension was normal. Mild weakness in the left upper and lower limbs (4/5 strength); the right side was normal. Reflexes were normal and symmetric in all four limbs. No sensory deficits observed. A bruit was detected over the left carotid artery, raising suspicion of underlying carotid artery disease.

The following tests were performed to investigate the potential causes of the TIA symptoms:

Blood glucose was elevated, suggesting suboptimal glycemic control in the setting of known diabetes mellitus.

Serum electrolytes were within normal limits, ruling out significant electrolyte imbalances that could contribute to neurological symptoms.

Complete blood count (CBC) was normal, with no signs of inflammation, anemia, or other hematological abnormalities.

Coagulation studies (prothrombin time [PT], partial thromboplastin time [PTT], and international normalized ratio [INR]) were within normal limits, excluding significant coagulopathies that might increase the risk of thrombosis or hemorrhagic events.

Fasting lipid panel revealed elevated low-density lipoprotein (LDL) and total cholesterol levels, consistent with dyslipidemia and increased cardiovascular risk.

Hemoglobin A1c was 9.2%, confirming poorly controlled diabetes.

Carotid Doppler ultrasound was performed to further assess the cervical arteries and rule out significant stenosis. It showed increased intima–media thickness (IMT) and intimal irregularities without significant plaques or critical stenosis.

Echocardiography was performed to assess for potential cardioembolic sources. The study was normal, showing no evidence of intracardiac thrombi, valvular abnormalities, or reduced ejection fraction.

Brain computed tomography (CT) scan showed no evidence of ischemia or hemorrhage, ruling out an acute stroke (not shown). To rule out a vascular disease, a CTA of the head and neck was performed. It revealed an incidental linear hypodense filling defect in the left cervical ICA at the upper cervical segment, just proximal to the skull base, dividing the lumen into two distinct channels with mild fusiform dilation (5 mm in diameter, 4 mm in length), consistent with ICA fenestration (Fig. 1, 2).

Fig. 1.

Cervical computed tomographic angiography. A below the level of fenestration: normal internal carotid artery; external carotid arteries are noted bilaterally. B At the level of fenestration: short segment mild fusiform dilation of left internal carotid artery is seen. There is a linear intraluminal septum at this level, splitting the lumen of internal carotid artery into two distinct channels (red arrow). C Above the level of fenestration: internal carotid artery shows normal diameter and morphology. Blue arrows indicate the normal luminal diameter proximal and distal to the fenestrated segment. Red arrows on axial and coronal sections demonstrate a short-segment fusiform dilation of the carotid artery and its division into two distinct lumens, representing fenestration

Fig. 2.

Cervical computed tomographic angiography (coronal image): there is short-segment fusiform dilation of the distal left cervical internal carotid artery with two distinct lumens suggestive of fenestration. Red arrows on axial and coronal sections demonstrate a short-segment fusiform dilation of the carotid artery and its division into two distinct lumens, representing fenestration

The patient was admitted for observation and received the following: dual antiplatelet therapy (aspirin and clopidogrel); optimized antihypertensive therapy to achieve target blood pressure; and lipid-lowering therapy adjustment to improve LDL control. Lifestyle modifications were also recommended, including dietary changes, exercise, and strict glycemic control to manage her diabetes.

Further investigations were scheduled for a comprehensive evaluation of the cerebrovascular and cardiovascular systems, including 24-hour Holter monitoring to assess for arrhythmias and evaluate cardiac risk factors.

The patient was discharged with no residual neurological deficits and was advised to follow up regularly for further management of her diabetes, hypertension, and dyslipidemia.

Discussion

The carotid arteries develop from the branchial/pharyngeal arches. The dorsal and the ventral aortas are connected via a series of developing blood vessels known as the aortic arches. There are six such arches, which give rise to various arteries in an adult human. The proximal one-third of the third aortic arch forms the common carotid artery, while the distal one-third, together with the dorsal aorta, gives rise to the ICA [1].

Anatomical variants and vascular malformations of the anterior circulation are diverse, including fenestration, duplication, agenesis, aplasia, hypoplasia, and infundibulum [2, 5, 6]. ICA fenestration is a rare but well-documented phenomenon. It was first reported in an autopsy in 1928, while the earliest cases of arterial fenestration in the vertebral artery were encountered in 1886. Literature reviews suggest that its prevalence is far lower than other congenital vascular variants of the carotid artery, such as agenesis, hypoplasia, or duplications. Most cases are identified incidentally during imaging or autopsy, and the true prevalence remains uncertain owing to limited large-scale studies. Its rarity underscores the importance of reporting such cases to better understand clinical implications and guide management [8].

The embryologic formation of ICA fenestration likely occurs during the fetal period at 12–14 mm, where abnormal flow patterns during critical periods of vascular development, the presence of anatomical obstacles (for example, nerves, bony structures, or enlarged vasa vasorum), and dissection are proposed as mechanisms. In many reported cases, the vessel showed signs of dissection, which has been considered a complication or the cause of fenestration, leading to the term “pseudofenestration” [3–5, 7].

Differentiating between ICA fenestration and ICA dissection can be challenging. Key points for differentiation include clinical presentations, location, associated conditions (for example, intramural hematoma, previous trauma), and imaging features. In ICA fenestration, the involved segment is typically short, with smooth walls and no signs of dissection. By contrast, ICA dissection tends to show contour irregularities, luminal asymmetry, vessel wall ectasis, and pseudoaneurysmal dilation. In ICA dissection, the distal lesions are located below the skull base (typical for traumatic cervical ICA dissection) [2].

Although cervical ICA pseudofenestration has been associated with irregularities in the vessel lumen and aneurysmal dilatations, these characteristics are not present in all cases [4]. Our case demonstrated two distinct channels with mild fusiform dilation of the left ICA just below the level of the foramen magnum. The well-developed, equal-sized lumens showed smooth wall structures, with no signs of dissection, as confirmed by CTA, which is consistent with left cervical ICA fenestration. Clinical presentations of ICA fenestration can range from ipsilateral stroke and TIA to cervical pain, with associations to dissection, occlusion, aneurysm, and subarachnoid hemorrhage (SAH) [2, 3].

While ICA fenestration may increase the risk of dissection and stroke, the management of asymptomatic fenestration remains controversial. Clinical guidelines are well-established for the management of vascular dissections and TIAs, but there is no consensus on treatment for intact fenestrated ICAs. In cases with complications such as aneurysms or acute occlusion, treatment options such as endovascular procedures or open surgery may be considered [9].

Follow-up examinations of ICA fenestration are recommended. MRI is considered the best option for follow-up, while ultrasound may be useful, although it is challenging to assess vascular anomalies near the skull base [4].

In the present study, a patient presented with sudden onset of double vision, dizziness, and weakness in her left upper and lower limbs. These symptoms lasted about 15 minutes before completely resolving. Investigations, including ultrasound, revealed irregularities and increased IMT, without significant plaques. Brain and cervical CTA confirmed ICA fenestration. Given the patient’s medical history (HTN and DM) and recent TIA, the decision was made to continue aspirin (ASA) and clopidogrel as antiplatelet therapy.

The identification of ICA fenestration in our patient, who presented with TIA symptoms, provides an opportunity to explore its clinical implications. ICA fenestration is a rare vascular anomaly with uncertain clinical significance. However, its presence has been associated with hemodynamic disturbances and cerebrovascular complications, including ischemia, dissection, and aneurysm formation. In this case, the fenestration likely contributed to the patient’s transient symptoms through localized flow perturbations, compounded by significant systemic vascular risk factors.

A review of the literature reveals few documented cases similar to ours, offering valuable insights into the presentation, diagnosis, and management of ICA fenestration and pseudofenestration:

1. Hasegawa et al. (1985) highlighted ICA fenestration as a benign anatomical variant, laying the groundwork for its clinical understanding. This early study remains fundamental for distinguishing ICA fenestration from other vascular anomalies [1].

2. Nakamura et al. (1993) documented a case of ICA fenestration associated with an ischemic attack. This case is particularly relevant, as it demonstrates the potential clinical consequences of ICA fenestration, aligning with our observations of ischemic events in our patient. Such associations reinforce the need for timely identification and management of ICA fenestration to prevent ischemic complications [3].

3. Gailloud et al. (2004) described pseudofenestration of the cervical ICA, emphasizing the pathological process that mimics an anatomical variant but is related to traumatic causes. In contrast to our case, which involved true fenestration, their findings suggest a different etiology, complicating the diagnostic process. This distinction between true fenestration and pseudofenestration is critical, as it informs clinical decision-making and management strategies [2].

4. Gesheva et al. (2019) similarly described pseudofenestration of the cervical ICA, adding to the understanding of this condition. Their findings further highlight the challenges in diagnosing pseudofenestration, particularly in differentiating it from true ICA fenestration [6].

5. Mărginean et al. (2020) reported a case of ICA fenestration misdiagnosed as dissection, highlighting diagnostic challenges and the potential for misinterpretation of imaging studies. Similar to our findings, this case underscores the importance of distinguishing between fenestration and conditions such as dissections, ensuring appropriate management [5].

6. Zheng et al. (2020) reported a rare case of fenestration of an occluded ICA treated with stenting. This case provides a unique perspective on the management of ICA fenestration, especially in the context of occlusion and the use of endovascular techniques. It adds to the growing body of evidence supporting diverse management strategies for fenestration, particularly in complex cases [9].

The studies by Gailloud et al. [2] and Gesheva et al. [6] investigate the mechanisms underlying pseudofenestration and traumatic dissection. Our findings align with Gailloud et al.’s hypothesis that pseudofenestration is a pathological process, but differ from Gesheva et al.’s conclusion that traumatic factors play a significant role. This discrepancy may be attributed to differences in patient history and presentation, suggesting a need for further investigation into the etiological factors contributing to ICA fenestration and pseudofenestration.

Conclusion

Our case, in conjunction with the reviewed literature, highlights the complexity of diagnosing and managing ICA fenestration and pseudofenestration. The variability in presentation and outcomes underscores the need for a thorough understanding of these conditions to guide clinical practice and improve patient outcomes. Further research is necessary to clarify the underlying etiologies, refine diagnostic strategies, and optimize management approaches for these uncommon but clinically significant conditions.

Abbreviations

ICA

Internal carotid artery

TIA

Transient ischemic attack

DM

Diabetes mellitus

HTN

Hypertension

BID

Twice daily

CBC

Complete blood count

PT

Prothrombin time

PTT

Partial thromboplastin time

INR

International normalized ratio

LDL

Low-density lipoprotein

CTA

Computed tomographic angiography

MRI

Magnetic resonance imaging

ASA

Aspirin

SAH

Subarachnoid hemorrhage

Author contributions

MA and AH were involved in the the initial idea and concept for the study and the overall design of the research project. SR and ShN gathered the necessary data and information for the study. MG and SR drafted the manuscript. MA, AH, and MG contributed to editing and were involved in critically reviewing the manuscript for clarity, accuracy, and scientific rigor.

Funding

No funds, grants, or other support were received during the preparation of this manuscript.

Data availability

All data and materials are available from the corresponding author upon request.

Declarations

Ethics approval and consent to participate

This case report did not require approval from an ethics committee since it involved one patient. Additionally, informed consent to participate was obtained from the patient.

Consent for publication

Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.

Competing interests

The authors have no relevant financial or nonfinancial interests to disclose.