
==== Front
J Neurosurg Case Lessons
J Neurosurg Case Lessons
J Neurosurg Case Lessons
Journal of Neurosurgery: Case Lessons
2694-1902
American Association of Neurological Surgeons

39250828
10.3171/CASE24344
CASE24344
SpineSpineCervicalCervicalVascular-DisordersVascular DisordersCase Lesson
Spontaneous asymptomatic common carotid artery dissection resembling a carotid web: illustrative case
Takahashi Toshihide MD, PhD 1
Yanaka Kiyoyuki MD, PhD 1
Aiyama Hitoshi MD, PhD 1
Saura Minami MD 1
Kajita Michihide MD 1
Takahashi Nobuyuki MD, PhD 2
Marushima Aiki MD, PhD 34
Matsumaru Yuji MD, PhD 34
Ishikawa Eiichi MD, PhD 4
1 Departments of Neurosurgery, Tsukuba Memorial Hospital, Tsukuba, Ibaraki, Japan
2 Departments of Radiology, Tsukuba Memorial Hospital, Tsukuba, Ibaraki, Japan
3 Department of Stroke and Cerebrovascular Diseases, University of Tsukuba Hospital, Tsukuba, Ibaraki, Japan
4 Department of Neurosurgery, Institute of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
Correspondence Eiichi Ishikawa: University of Tsukuba, Ibaraki, Japan. e-ishikawa@md.tsukuba.ac.jp.
INCLUDE WHEN CITING Published September 9, 2024; DOI: 10.3171/CASE24344.

Disclosures The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

09 9 2024
09 9 2024
8 11 CASE2434425 5 2024
10 7 2024
© 2024 the authors
2024
the authors
https://creativecommons.org/licenses/by-nc-nd/4.0/ CC BY-NC-ND 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

BACKGROUND

Carotid artery dissection is a common cause of ischemic stroke, predominantly affecting the internal carotid artery, with rare involvement of the common carotid artery (CCA). The limited literature makes diagnosis and management challenging, particularly in asymptomatic patients. In this report, the authors present a unique case of spontaneous, asymptomatic CCA dissection that resembled a carotid web, shedding light on its clinical spectrum and management.

OBSERVATIONS

A 70-year-old man was diagnosed with an intimal flap in the left CCA. Although the findings resembled those of a carotid web, cerebral angiography confirmed the presence of an intimal flap and arterial wall irregularities indicative of vascular dissection. Endarterectomy successfully prevented the stroke, and the postoperative recovery was uneventful. Pathological examination confirmed the diagnosis of CCA dissection.

LESSONS

Spontaneous CCA dissection, though rare, presents significant diagnostic and therapeutic challenges. Because of morphological similarities, differentiating the diagnosis from a carotid web can be difficult. Available treatment strategies include antiplatelet therapy and surgical intervention. In this case, endarterectomy was chosen to avoid antithrombic treatment in anticipation of further invasive treatments for other conditions. The successful outcome highlights the potential as a treatment option, emphasizing the need for an individualized approach to each patient.

https://thejns.org/doi/10.3171/CASE24344

carotid web
common carotid artery
dissection
intimal flap
ABBREVIATIONS

CCA = common carotid artery
CT = computed tomography
MRI = magnetic resonance imaging.
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pmcCarotid artery dissection is a known cause of ischemic stroke, especially in young adults.1–3 This condition typically arises from a tear in the arterial wall and predominantly affects the internal carotid artery, whereas occurrences in the common carotid artery (CCA) are rare.4 The etiology of dissection varies, including the extension of aortic dissection, traumatic injury, and spontaneous events, with the latter being particularly uncommon.5 Despite its infrequency, spontaneous CCA dissection presents significant diagnostic and management challenges, as evidenced by the limited literature, which includes only 30 reported cases.6 Clinical manifestations of spontaneous CCA dissection often include hemiplegia resulting from ischemic stroke or head and neck pain.7 However, asymptomatic cases are exceedingly rare, with only one documented instance thus far.8 Given the clinical complexity and lack of a standardized treatment protocol, managing CCA dissection requires a customized approach for each patient.

In contrast, a carotid web, representing a focal intimal thickening within the carotid artery, has emerged as a potential cause of ischemic stroke.9 Characterized by a thin fold of the vessel wall projecting into the arterial lumen, carotid webs disrupt blood flow dynamics, predisposing individuals to local thrombosis and subsequent thromboembolic events. Here, we report the unique case of an asymptomatic, spontaneous CCA dissection, which resembled a carotid web on imaging and was successfully treated with endarterectomy. This represents only the second documented case of spontaneous and asymptomatic CCA dissection, offering valuable insights into the clinical spectrum and management of this rare condition.

Illustrative Case

A 70-year-old man with no history of hypertension, hyperlipidemia, diabetes, or significant trauma underwent a routine medical checkup and was incidentally found to have a renal mass and a thyroid nodule. During the neck ultrasound to investigate the thyroid nodule, an intimal flap was identified in the left CCA (Fig. 1), prompting a referral to our department for suspicion of a carotid web. FIG. 1. Neck ultrasound showing an intimal flap protruding into the lumen of the left CCA (arrow).

Upon initial assessment, the patient was alert and asymptomatic. Head and neck magnetic resonance imaging (MRI) and computed tomography (CT) angiography revealed an intimal flap on the posterolateral wall of the left CCA, distant from the carotid bulb, accompanied by wall irregularities (Fig. 2A–C). Subsequent cerebral angiography confirmed the presence of an intimal flap and a double lumen in the posterolateral wall of the left CCA (Fig. 2D and E). Due to contrast medium stagnation in the flap area, antiplatelet therapy was initiated to prevent ischemic stroke. Although the morphology of the intimal flap resembled a carotid web, the irregularities of the vessel wall and the lesion location away from the carotid bulb raised suspicions for an asymptomatic CCA dissection. FIG. 2. Three-dimensional (3D) CT angiography of the cervical blood vessels (A) and cervical magnetic resonance (MR) angiography (B) demonstrate vessel wall irregularities in the left CCA (circle, arrow). Axial time-of-flight MR angiography shows a double lumen (C, arrowhead). Left CCA, anteroposterior view (D), and 3D rotational angiography, axial view (E), show an intimal flap and a double lumen on the posterior outer wall of the CCA, distal to the carotid bulb (double arrows, double arrowheads).

Although urgent treatment was not required for the renal mass and thyroid nodule, further invasive interventions were anticipated depending on disease progression. In patients with such conditions, oral antiplatelet agents could pose a hindrance. Considering the presence of an intimal flap and irregularities of the vessel wall, an endarterectomy, which included intimal flap resection, was performed to avoid the risk of future ischemic stroke.

The common, internal, and external carotid arteries were exposed with the patient under general anesthesia. Externally, the area with the intimal flap appeared slightly swollen, yet the adventitia was well preserved (Fig. 3A). Upon incision of the CCA, a portion of the intima was found to have dissociated from the vessel wall, forming a flap (Fig. 3B). Flap resection and endarterectomy of the surrounding intima were then performed (Fig. 3C), with several intimal stay sutures placed to prevent dissection progression. FIG. 3. Intraoperative images. A: The CCA, internal carotid artery, and external carotid artery are exposed. The area with the intimal flap (arrow) appears slightly swollen, though the adventitia is well preserved. B: The CCA is incised, revealing the intimal flap (double arrows). C: The intimal flap is resected.

Postoperative MRI revealed no signs of cerebral infarction and showed resolution of the intimal flap and a double lumen in the left CCA. Pathological examination confirmed the detachment of part of the intima from the vessel wall, thereby confirming the diagnosis of CCA dissection (Fig. 4). The patient experienced an uneventful recovery and was discharged on the 8th postoperative day. After imaging confirmed the disappearance of the intimal flap, antiplatelet therapy was discontinued due to pending surgery on other organs. Currently, the patient is under outpatient follow-up and is awaiting treatment for the renal and thyroid masses. FIG. 4. A pathological image of the excised specimen demonstrates a portion of the intima (arrowhead) detached from the internal elastic plate (arrow), indicating vascular dissection. Elastica van Gieson stain.

Patient Informed Consent

The necessary patient informed consent was obtained in this study.

Discussion

Spontaneous CCA dissection is rare, with only about 30 cases reported to date. Although its exact cause remains elusive, traditional vascular risk factors do not consistently correlate with its occurrence, suggesting potential genetic or structural predispositions.10 This limited understanding of its pathogenesis underscores the diagnostic and therapeutic challenges associated with CCA dissection. Unlike the well-established antithrombotic-centered treatment protocols for internal carotid artery dissection, optimal management strategies for CCA dissection have yet to be defined.5 This case contributes valuable insights into the diagnostic approach and treatment considerations for managing asymptomatic CCA dissection, thus enriching the scarce literature on this topic.

Dissection is less likely to occur in the CCA than in the internal carotid and vertebral arteries. This reduced susceptibility could be attributed to the classification of the CCA as an elastic artery, which is rich in elastic fibers in its tunica media layer. In contrast, the internal carotid and vertebral arteries are categorized as muscular arteries and contain fewer elastic fibers.11, 12 The abundance of elastic fibers in the CCA can contribute to its resilience against dissection. Additionally, an alternative theory suggests that the anatomy of the CCA and adjacent structures can provide resistance and protection.7

Observations

It is essential to differentiate between a carotid web and dissection before initiating treatment, with particular attention to the location and shape of the lesion aiding this differentiation. Carotid webs are characteristically slender and focal, located on the posterior wall of the carotid bulb. In contrast, dissections often extend beyond the carotid bulb and can be accompanied by intramural hematoma, carotid occlusion, flow velocity changes, and pseudoaneurysm.5 However, web-like structures have also been reported in the common carotid and vertebral arteries.13 Notably, changes near the flap, such as wall irregularities, are highly indicative of dissection and can be critical in differentiating these conditions.

In our patient, the imaging findings of a nonocclusive intimal flap in the CCA were initially suggestive of a carotid web. Carotid webs, characterized by shelf-like intraluminal projections, can present similarly to the intimal flaps seen in dissection. This case underscores the importance of comprehensive imaging and clinical evaluation in distinguishing between these entities to avoid misdiagnosis and guide appropriate management.

Although no standard treatment exists for CCA dissection, referencing strategies for carotid web treatment can inform approaches to prevent ischemic stroke. Antithrombotic therapy is pivotal; however, related studies indicate a 30% stroke recurrence rate following such therapy for carotid webs.14, 15 Similarly, though we think that antithrombotic treatment will be a first-line treatment for asymptomatic dissections, it alone can be insufficient to prevent stroke in patients with CCA dissection. As a result, endarterectomy and carotid stenting have been widely used to treat carotid artery webs. However, when considering surgical treatment for dissection, attention should be paid to the anatomical differences between a vascular dissection and a carotid web. Unlike carotid webs, where pathological changes occur only in the intima, dissection lesions can extend to the adventitia. Therefore, surgical preparations must include strategies to repair the adventitia in patients with such conditions.

In our patient, the continuation of antithrombotic therapy was undesirable due to planned invasive treatments for other organs following the treatment for the CCA dissection. Consequently, endarterectomy was selected over carotid artery stenting to avoid the need for long-term antiplatelet therapy. It is expected that antithrombotic therapy will be continued after carotid endarterectomy for vascular stenosis due to arteriosclerosis. However, in our patient, antithrombotic therapy was discontinued because surgical treatment of other organs was planned. There is debate as to whether antithrombotic therapy should be continued when removing nonatherosclerotic lesions that could be a source of embolism, and this should be considered after the accumulation of future cases. Intraoperative findings revealed preserved adventitia, which made endarterectomy a feasible option. However, had the adventitial structure been compromised, removal and replacement with a patch or vascular graft might have been necessary. To be ready for such situations, materials such as a polytetrafluoroethylene vascular patch were prepared in advance, underscoring the importance of anticipating various surgical scenarios in patients with dissection.

Lessons

Spontaneous asymptomatic dissection of the CCA is a rare and clinically challenging condition that requires careful consideration in the differential diagnosis of carotid artery lesions. While endarterectomy represents a promising treatment option, further research is necessary to elucidate its long-term effectiveness and safety in this specific context. Collaborative efforts to standardize diagnostic criteria and develop treatment algorithms are essential to improve clinical outcomes for patients with asymptomatic CCA dissection.

Acknowledgments

We thank Alexander Zaboronok of the University of Tsukuba Institute of Medicine, Department of Neurosurgery, for professional and language revision.

Disclosures

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author Contributions

Conception and design: Yanaka, Matsumaru. Acquisition of data: N Takahashi, Matsumaru. Analysis and interpretation of data: Yanaka, Kajita, N Takahashi, Marushima. Drafting the article: T Takahashi. Critically revising the article: Yanaka, Kajita, Marushima. Reviewed submitted version of manuscript: Ishikawa, T Takahashi, Aiyama, Kajita, Marushima, Matsumaru. Approved the final version of the manuscript on behalf of all authors: Ishikawa. Administrative/technical/material support: Aiyama, Saura, Marushima. Study supervision: Ishikawa, Marushima, Matsumaru.

Correspondence

Eiichi Ishikawa: University of Tsukuba, Ibaraki, Japan. e-ishikawa@md.tsukuba.ac.jp.
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