Vascular Eagle Syndrome in Elderly Patients Diagnosed by Dynamic Magnetic Resonance Angiography: A Case Report and Literature Review

Abstract

Dynamic assessment by computed tomography angiography or digital subtraction angiography is important for the diagnosis of vascular eagle syndrome, although these require the use of contrast media. Magnetic resonance angiography with neck flexion and extension, named dynamic magnetic resonance angiography, can dynamically evaluate the relationship between the internal carotid artery and the styloid process with no use of contrast media. A 74-year-old male with chronic kidney disease was rushed to our hospital due to recurrent infarction in the left cerebral hemisphere. Magnetic resonance angiography in the neutral neck position showed no abnormality in the left internal carotid artery, but computed tomography revealed bilateral elongated styloid process. Dynamic magnetic resonance angiography was performed to show that the left internal carotid artery was compressed by the styloid process during neck flexion but not during neck extension. Carotid ultrasound revealed a thrombus in the high cervical portion of the left internal carotid artery. Styloidectomy was performed, and cerebral infarction has not recurred since then. Dynamic magnetic resonance angiography may be a useful diagnostic modality without using contrast media for vascular eagle syndrome.

Introduction

Eagle syndrome is characterized by an elongated styloid process or a calcified stylohyoid ligament, which compresses the surrounding tissues and causes a variety of symptoms.¹⁾ The incidence of the elongated styloid process is 4% of the population, of which only 4% become symptomatic.²⁾ Eagle syndrome is divided into two types: the classic type, in which compression or strangulation of the lower cranial nerves causes pharyngeal pain, dysphagia, facial pain, and neck pain; and the vascular type, known as vascular eagle syndrome, in which compression of the internal carotid artery (ICA) causes stenosis, occlusion, or dissection, resulting in transient ischemic attack (TIA) or cerebral infarction (CI).^3-5)

Vascular eagle syndrome is a rare cause of CI in the middle-aged patients and extremely rare in elderly patients.^6,7) Because it often occurs during neck movement, computed tomography angiography (CTA) and digital subtraction angiography (DSA) have been reported to be diagnostically useful for assessing vessel-bone positioning.^7-9) However, elderly patients often have renal dysfunction and are reluctant to use contrast media; therefore, novel diagnostic modalities need to be explored. Magnetic resonance angiography (MRA) with neck flexion and extension, named dynamic MRA, can evaluate the relationship between the ICA and the styloid process without contrast media.

Here, the authors present the case of an elderly patient with vascular eagle syndrome that was diagnosed using dynamic MRA.

Case Report

A 74-year-old male with a medical history of mental retardation, diabetes mellitus, and chronic kidney disease (CKD) was rushed to our hospital due to sudden onset of right hemiparesis. Diffusion weighted magnetic resonance imaging (DWI) showed scattered acute CIs in the frontal and occipital lobes (Fig. 1A and B). MRA in the neutral position showed no abnormalities in the main artery (Fig. 1C), with the absence of the P1 portion of the left posterior cerebral artery and the presence of the A1 portion of the left anterior cerebral artery (Fig. 1D). Paroxysmal atrial fibrillation was detected on Holter electrocardiogram, and oral administration of apixaban 10 mg/day was started. Right hemiparesis improved with rehabilitation and the patient was discharged to his former facility, with a modified Rankin scale (mRS) score of 3.

Fig. 1.

Diffusion weighted magnetic resonance imaging (DWI; A, B, E, and F), magnetic resonance angiography (MRA; C, D, and G) in the neutral position, and computed tomography (CT; H) at the first and second admissions.

At the first admission, DWI shows scattered acute cerebral infarctions (CIs) in the left frontal and occipital lobes (A and B). MRA in the neutral position shows no abnormalities in the main cerebral arteries (C and D), with the absence of the P1 segment of the left posterior cerebral artery and the presence of the A1 segment of the left anterior cerebral artery (D). At the second admission, DWI shows scattered acute CIs in the left frontal and temporal lobes (E and F). MRA shows occlusion of the M3 portion of the left middle cerebral artery (G). CT shows bilateral elongated styloid processes (H; right, 4.9 cm, and left, 4.1 cm). L, left

One year and 4 months later, the patient was brought to our hospital again due to sudden onset of right hemiparesis and motor aphasia during neck flexion. Since his previous stroke, he had several episodes of syncope when flexing his neck. Urgent DWI showed scattered acute CIs in the frontal and temporal lobes (Fig. 1E and F). MRA showed occlusion of the M3 portion of the left middle cerebral artery (Fig. 1G) and no abnormality of the left ICA. However, computed tomography (CT) revealed bilateral elongated styloid processes (Fig. 1H; right, 4.9 cm; left, 4.1 cm). Because of his advanced age, comorbidity of CKD, and lack of the left ICA abnormality on MRA, the patient was afraid to use contrast media. Thus, dynamic MRA with neck flexion and extension was performed and showed that the left ICA (arrow) was compressed by the styloid process (arrowhead) during neck flexion (Fig. 2A-C) but not during neck extension (Fig. 2D-F). Carotid ultrasound confirmed the presence of a thrombus (double arrow) in the high cervical portion of the left ICA (Fig. 3A).

Fig. 2.

Dynamic magnetic resonance angiography (MRA) with neck flexion and extension.

Dynamic MRA shows that the left internal carotid artery (arrow) is compressed by the styloid process (arrowhead) during neck flexion (A, sagittal T1-weighted magnetic resonance imaging; B, MRA; and C, axial MRA imaging) but not during neck extension (D, sagittal T1-weighted magnetic resonance imaging; E, MRA; and F, axial MRA imaging). L, left

Fig. 3.

Carotid ultrasound and intraoperative findings of styloidectomy.

Carotid ultrasound shows a thrombus (double arrow) in the high cervical portion of the left internal carotid artery (ICA; A). Intraoperative findings show that the posterior belly of the digastric muscle (asterisk) is retracted cephalad, and that the elongated styloid process (arrowhead) is resected about 3 cm from the tip (B; pre-styloidectomy, C; post-styloidectomy, and D; resected styloid process). Arrow, ICA; double arrowhead, external carotid artery.

Considering the absence of left P1 segment and the presence of left A1 segment, the scattered CIs were thought to be due to thromboembolization from the left ICA, and the patient was diagnosed with vascular eagle syndrome. Systemic heparinization was started, and styloidectomy via an anterior sternocleidomastoid incision was performed 11 days after admission. During the surgery, the posterior belly of the digastric muscle was retracted cephalad, and an elongated styloid process was resected about 3 cm from the tip (Fig. 3B-D). Postoperatively, CI did not recur and the patient was discharged to the facility with an mRS score of 4.

Discussion

In the present case, MRA in the neutral position showed no abnormality of the left ICA in an elderly patient with recurrent CIs. However, vascular eagle syndrome was suspected due to the elongated styloid process found on CT and diagnosed by using dynamic MRA with neck flexion and extension.

Vascular eagle syndrome has been found to be more prevalent in middle-aged patients.⁸⁾ A recent review by Pagano et al.¹⁰⁾ reported that the mean age of patients with vascular eagle syndrome was 48.2 years. There are limited reports of vascular eagle syndrome in elderly patients. To the best of our knowledge, nine cases of vascular eagle syndrome aged 70 years or older have been reported, including the present case (Table 1).^11-18) Eight patients (88.9%) were male and four (44.4%) had atherosclerosis risk factors. No case had a history of cerebral ischemia; four patients (44.4%) presented with TIA and the other five patients (55.6%) presented with CI. Neck movement at onset was observed in four cases (44.4%). Five cases (55.6%) occurred due to ICA compression by the elongated styloid process, two cases (22.2%) occurred due to ICA dissection, one case reported by Budinčević et al.¹⁷⁾ occurred due to ICA compression by dissecting aneurysm of external carotid artery (ECA), and one case had no description of the mechanism. Seven of nine cases (77.8%) were diagnosed using CTA; Chuang et al.¹¹⁾ used CTA in the neutral and symptomatic positions. Although this method is very useful, it requires a high dose of contrast medium.¹¹⁾ On the other hand, in case 7, MRA showed ICA compression by an ECA dissecting aneurysm rather than the relationship between the styloid process and the ICA.¹⁷⁾ Four cases (44.4%) were treated by styloidectomy, and three (33.3%) were treated with medication, followed by carotid artery stenting in one case. Although the treatment strategy for vascular eagle syndrome remains controversial, styloidectomy seems to be an acceptable treatment for elderly patients.

Table 1.

Summary of Patients with Vascular Eagle Syndrome Older Than 70 Years of Age

Case	Author, year	Age, sex	Comorbidity	Symptoms	Neck movement at onset	Mechanism	Side	Diagnostic modality	Treatment	Reference
1	Chuang et al., 2007	77 yrs., M	None	TIA (aphasia, rt. hemiparesis, and numbness)	Rotation to left and flexion	Compression	Lt.	CTA in the neutral and symptomatic positions	Styloidectomy	(11)
2	Todo et al., 2012	80 yrs., M	Acromegaly	TIA (dizziness and near syncope)	Yes	Compression	Lt.	CTA	Styloidectomy	(12)
3	Ogura et al., 2015	80 yrs., M	Cholecystectomy, HTN, and prostatomegaly	TIA (positional vertigo)	Yes	Dissecting AN	Lt.	CTA	Styloidectomy	(13)
4	Kavi et al., 2016	70 yrs., M	CKD	CI (aphasia and rt. hemiplegia)	N/A	Compression	Lt.	CTA	N/A	(14)
5	Mann et al., 2017	73 yrs., F	None	TIA (dizziness and lightheadedness)	Rotation to left	N/A	N/A	N/A	N/A	(15)
6	Aldakkan et al., 2017	85 yrs., M	ICH, CKD, and DLP	CI (aphasia, rt. hemiparesis, and rt. conjugate deviation)	None	Dissecting AN	Rt.	CTA	ASA	(16)
7	Budincˇevic´ et al., 2018	85 yrs., M	None	CI (dysarthria and confusion)	None	Compression by ECA dissecting AN	Rt.	CTA and MRA	ASA	(17)
8	Okada et al., 2022	72 yrs., M	N/A	CI (dysarthria and consciousness disorder)	None	Compression	Lt.	CTA	1) ASA, CLO, and argatroban 2) CAS	(18)
9	Present case	74 yrs., M	CKD, DM, and mental retardation	CI (aphasia and rt. hemiparesis)	None	Compression	Lt.	Dynamic MRA	Styloidectomy

AN: aneurysm; ASA: acetylsalicylic acid; CAS: carotid artery stenting; CI: cerebral infarction; CKD: chronic kidney disease; CLO: clopidogrel; CTA: computed tomography angiography; DLP: dyslipidemia; DM: diabetes mellitus; ECA: external carotid artery; F: female; HTN: hypertension; ICH: intracerebral hemorrhage; Lt.: left; M: male; MRA: magnetic resonance angiography; N/A: not available; Rt.: right; TIA: transient ischemic attack

Several etiologies for elongated styloid process or calcification of stylohyoid ligament have been proposed.^19-22) Murtagh et al.²⁰⁾ proposed three possible causes: first, residual embryonic cartilage tissue from Reichert's cartilage; second, calcification of the stylomandibular ligament; and third, expansion of bone tissue at the origin of the stylomandibular ligament. Other possible etiologies include reactive hyperplasia and metaplasia induced by trauma²¹⁾ or aging-related inflammation.²²⁾ In elderly patients, carotid artery factors may be added to these etiologies; because aging and hypertension may increase the tortuosity of ICA,²³⁾ the ICA, which is not compressed by the styloid process in younger people, may become compressed with age. As life expectancy increases, it is expected that there will be more opportunities to treat vascular eagle syndrome in older adults.

Cervical movement and specific posture often trigger ICA compression by the elongated styloid process.²⁴⁾ Trigger movements vary from case by case, including neck flexion, extension, and rotation;^6-9) however, dynamic assessments are crucial in diagnosing vascular eagle syndrome, regardless of the presence or absence of risks of ICA compression or dissection. In previous reports, CTA, DSA, and ultrasound were used for the dynamic evaluation.^{7,9-11,25,26)} DSA and CTA allow detailed evaluation of the anatomy between the ICA and the styloid process but require contrast media.^7,9-11) Although high-frequency linear ultrasound probe is often difficult to visualize the distal ICA, transoral ultrasonography and convex ultrasound probe can depict the high cervical ICA and the styloid process, evaluating dynamic changes and blood flow fluctuations in real time.^25-28) Transcranial doppler (TCD) provides only indirect findings, such as decreased cerebral blood flow.²⁹⁾ In addition, TCD cannot be performed if the bone window is insufficient. Dynamic MRA not only allows the evaluation of the relationship between the ICA and the styloid process without the use of contrast media and radiation but also allows the evaluation of CI because DWI is performed simultaneously. However, dynamic MRA has the following limitations: first, its bone imaging diagnostic ability is inferior to that of CT; second, it is difficult to capture images under excessive flexion, extension, and rotation; and third, the acquisition time is longer than that of DSA, although it is becoming shorter using compressed sensitivity encoding and parallel imaging in combination with deep learning.³⁰⁾ Despite these limitations, dynamic MRA may be useful for the screening of vascular eagle syndrome after confirming styloid process elongation with CT. Recently, it was reported that rotational cervical MRA is useful for diagnosing bow hunter's syndrome, a condition in which the vertebral artery becomes narrowed or occluded at the craniovertebral junction during neck rotation, causing ischemic symptoms in the vertebrobasilar artery circulation.³¹⁾ It is hoped that further cases will be accumulated in the future.

Conclusion

The authors reported the first elderly case of vascular eagle syndrome diagnosed by dynamic MRA. Although vascular eagle syndrome in elderly patients is extremely rare, the incidence of diagnosis is expected to increase as life expectancy increases. Elderly patients may have a different etiology of vascular eagle syndrome than younger patients, such as arterial tortuosity due to aging or hypertension. In elderly patients and those with renal dysfunction who are hesitant to use contrast media, dynamic MRA may be a useful diagnostic modality for vascular eagle syndrome.

Conflicts of Interest Disclosure

All authors have no conflict of interest.

Declaration of Patient Consent

The authors certify that all appropriate consents were obtained.

Funding Statement

This work was funded by Sanikai Foundation (grant number unavailable) to Hideki Nakajima.