Vascular Eagle syndrome

Vascular Eagle syndrome is the form in which the styloid process affects one of the major blood vessels of the neck. The term was first used for the carotid artery: Watt Eagle described a "styloid process-carotid artery syndrome" in 1949, twelve years after his first description of the condition1. Compression of the internal jugular vein, the other vascular form, has its own jugular compression page.

Vascular complications are seldom described compared with the classic form. Among 231 published patients with vascular complications, an artery was involved in 67.5% and a vein in 32.5%2.

How the styloid process affects the carotid artery

The internal carotid artery, the main artery supplying the brain, runs up toward the skull close to the tip of the styloid process. An elongated or inward-pointing styloid can affect it in three ways:

• Compression. The styloid presses on the artery and narrows it, often only when the head is turned to one side.
• Dissection. Repeated contact with the bone can tear the inner lining of the artery. Blood then tracks into the artery wall, narrowing or blocking it, and a clot can form and travel to the brain.
• Pseudoaneurysm. A tear can leave a bulge in the artery wall.

Each of these can reduce blood flow to the brain or send clots into it, which is why the main risk of the carotid form is stroke2. Symptoms often depend on head position, because turning the head changes how close the styloid lies to the artery34.

Symptoms

The symptoms are those of reduced blood flow to the brain, damage to the artery, or both:

• brief episodes of weakness, numbness, loss of vision or trouble speaking (transient ischemic attacks)
• stroke
• headache and pain in the neck, face or around the eye
• Horner syndrome: a drooping eyelid, a small pupil and less sweating on one side of the face
• dizziness or fainting, sometimes on turning the head

In a 2024 review of 497 published patients, headache and Horner syndrome were more common in the vascular form than the classic form, and neck movement was more often a trigger (12 of 33 patients). Men made up 70.1% of patients with the vascular form3. Among published patients with arterial complications, 46.8% had a stroke2.

Stroke symptoms need emergency care. Call your local emergency number straight away, even if they pass5.

Carotid dissection and the styloid process

Carotid artery dissection is an important cause of stroke in younger adults, and the styloid process is one suspected cause6. Two recent reviews have examined the link.

A 2026 meta-analysis compared the anatomy of the styloid in 270 patients with carotid dissection and 377 people without. In the better-quality studies, the styloid process lay closer to the artery on the side of the dissection. Its length and angle showed no association7. Distance from the artery, rather than length, may therefore be the more useful measurement, although the studies were few and varied.

A 2025 review collected 84 published patients whose dissection was linked to the styloid process. About half (52%) were treated conservatively, with medication to prevent clots, and a third of those (33%) had a recurrence. None of the patients treated first with styloidectomy had a recurrence6. There are no treatment guidelines specifically for styloid-related dissection.

Pain and the carotid artery

Eagle attributed some of the head and face pain in his carotid cases to pressure on the artery1. Whether pain comes from the artery itself or from the sympathetic nerve fibers that surround it remains a matter of debate, and patients with the vascular form often have the throat and ear symptoms of the classic form as well.

Diagnosis

The key test is CT angiography, a CT scan taken while contrast dye flows through the arteries8. It shows where the styloid tip lies in relation to the carotid artery and whether the artery is narrowed, torn or bulging. Scans repeated with the head turned can show compression that appears only in certain positions4. After a stroke or transient ischemic attack, the usual stroke investigations are carried out as well.

Because an elongated styloid is common, found on about a quarter of sides of the neck9, and styloid-related strokes are rare, an elongated styloid found by chance isn't, on its own, a sign that a stroke is likely. What raises concern is a styloid lying very close to the carotid artery in someone with symptoms, or a dissection on the same side.

Treatment

Treatment has two aims: to protect the brain from further clots, and to remove the structure injuring the artery.

Medication to prevent clots, usually antiplatelet drugs or anticoagulants, is the standard treatment for carotid dissection. Styloidectomy removes the styloid process so that it can no longer injure the artery. Operating through the neck lets the surgeon see and protect the artery. In some patients a damaged artery is also treated from the inside with a stent10.

The published results favor removing the styloid. Among 231 patients with vascular complications, 79 were treated first with styloidectomy: 78.5% were cured, 19.0% improved and 2.5% had a recurrence. Of 106 treated first with medication alone, 24.5% were cured, 28.3% improved and 47.2% had a recurrence2. In a separate review of 16 patients with neurological deficits, 87.5% were cured, with complications in 6.2%10.

These figures come from published case reports. Patients chosen for surgery may have differed from those treated with medication, and no trial has compared the two. The treatment page describes styloidectomy and its risks.

References

1. Eagle WW. Symptomatic elongated styloid process; report of two cases of styloid process-carotid artery syndrome with operation. Arch Otolaryngol. 1949;49(5):490-503. doi:10.1001/archotol.1949.03760110046003 PubMed ↩
2. Thielen A, Brizzi V, Majoufre C, Nicot R, Schlund M. Eagle syndrome and vascular complications: a systematic review. Int J Oral Maxillofac Surg. 2025;54(1):31-42. doi:10.1016/j.ijom.2024.09.011 PubMed ↩
3. Hassani M, Grønlund EW, Albrechtsen SS, Kondziella D. Neurological phenotypes and treatment outcomes in Eagle syndrome: systematic review and meta-analysis. PeerJ. 2024;12:e17423. doi:10.7717/peerj.17423 PubMed ↩
4. Bănică DA, Zamfirescu VI, Rusu MC, Brezean I. Compression syndromes of the stylohyoid complex: neural, arterial, and venous phenotypes in a dynamic neurovascular corridor. Tomography. 2026;12(9):127. doi:10.3390/tomography12090127 PubMed ↩
5. Cleveland Clinic. Eagle syndrome. Reviewed June 25, 2024. Accessed October 3, 2026. Source ↩
6. Klail T, Sachs L, Panos LD, et al. Styloid process-related internal carotid artery dissection: extensive literature review of diagnosis, treatment and outcomes (exemplified with a single-center case series). Neuroradiology. 2025;67(6):1355-1364. doi:10.1007/s00234-025-03616-y PubMed ↩
7. Klail T, Kalioras E, von Gernler M, et al. Anatomical characteristics of the styloid process associated with internal carotid artery dissection: a systematic review and meta-analysis of controlled trials. Front Radiol. 2026;6:1788985. doi:10.3389/fradi.2026.1788985 PubMed ↩
8. RadiologyInfo.org (American College of Radiology and Radiological Society of North America). CT angiography (CTA). Reviewed June 15, 2026. Accessed October 3, 2026. Source ↩
9. Triantafyllou G, Paschopoulos I, Duparc F, Tsakotos G, Papadopoulos-Manolarakis P, Piagkou M. The anatomy of the stylohyoid chain: a systematic review with meta-analysis. Diagnostics (Basel). 2025;15(7):925. doi:10.3390/diagnostics15070925 PubMed ↩
10. Lisan Q, Rubin F, Werner A, Guiquerro S, Bonfils P, Laccourreye O. Management of stylohyoid syndrome: a systematic review following PRISMA guidelines. Eur Ann Otorhinolaryngol Head Neck Dis. 2019;136(4):281-287. doi:10.1016/j.anorl.2019.05.002 PubMed ↩

Related pages

• Jugular vein compressionJugular vein compression between the styloid and C1: how it happens, its link with intracranial hypertension, diagnosis, and surgery versus stenting.
• Symptoms of Eagle syndromeEagle syndrome symptoms: throat and ear pain in the classic form, stroke warning signs with carotid involvement, and head pressure with jugular compression.
• Diagnosis and imagingHow Eagle syndrome is diagnosed: examination, CT with 3D reconstruction, CT angiography and venography, jugular pressure tests and reading a report.
• Treatment of Eagle syndromeHow Eagle syndrome is treated: medication and injections, styloidectomy through the mouth or neck, robotic and minimally invasive surgery, and results.