Eagle Syndrom: A rare and underdiagnosed condition

Eagle Syndrome is a rare condition characterised by neuropathic and vascular symptoms resulting from an elongated or abnormally angled styloid process that interferes with adjacent structures. First noted in 1652 by Pietro Marchetti, it was more precisely described by Watt Eagle in the mid-20th century. [1] The styloid process, a thin bony projection from the skull base, serves as an attachment point for muscles and ligaments. While a normal styloid process measures 21–30 mm, an extension beyond 30 mm is a potential risk for Eagle Syndrome.[2]

The exact cause of styloid elongation is unclear, but proposed theories include post-traumatic hyperplasia, reactive metaplasia leading to ligament ossification, congenital elongation due to persistent cartilaginous precursors, and aging-related degenerative changes. [3,4] Although styloid elongation is relatively common, only about 4% of affected individuals experience symptoms. [5] The syndrome is categorised into three subtypes: neuropathic, carotid, and jugular. The neuropathic type results from cranial nerve compression and is more common in women, presenting symptoms such as throat pain, dysphagia, otalgia, tinnitus, and a foreign body sensation. [6] The carotid type, more prevalent in men, arises from compression of the cervical carotid artery and is associated with symptoms including headaches, dizziness, visual disturbances, speech and motor deficits, and, in severe cases, transient ischemic attacks (TIA) or strokes. [2,7] The jugular type, a recently proposed variant, involves compression of the internal jugular vein and has been linked to migraines, Ménière’s disease, subarachnoid hemorrhages, and pulmonary embolisms. [8]

The mechanisms underlying carotid Eagle Syndrome and its association with ischemic strokes remain poorly understood. Two primary hypotheses suggest that either (1) repeated microtrauma from the elongated styloid process leads to carotid artery dissection, aneurysm formation, and thrombosis, or (2) the styloid process compresses the internal carotid artery, restricting blood flow. [9] Unlike the neuropathic form, which is triggered by swallowing and jaw movements, the carotid variant is exacerbated by head movements. [7] Carotid dissection is a frequent and serious complication. [10] CT angiography is the gold standard for diagnosing styloid-vascular conflicts, but its limitations include the inability to assess positional changes that may reveal dynamic compression. [6]

Treatment options are either conservative or surgical. Conservative management includes pain relief with NSAIDs, corticosteroids, muscle relaxants, and local anesthetic injections, but symptom relief is usually temporary. Surgery, specifically styloidectomy, is the definitive treatment. This procedure can be performed via an intraoral approach, which is minimally invasive but carries risks of infection and nerve damage, or an external approach, which provides better exposure but results in visible scarring. Emerging endoscopic and robotic-assisted techniques offer promising alternatives. [11]

Currently, no official guidelines exist for managing carotid Eagle Syndrome. Treatment generally follows standard protocols for ischemic stroke, TIA, or carotid dissection. The choice between anticoagulants and antiplatelet therapy remains debated. [12] In cases wth persistent ischemic symptoms, severe blood flow restriction, or aneurysm progression, carotid stenting may be considered. Styloidectomy is often recommended alongside stenting to prevent complications such as stent compression or fracture. [13] Despite its potential severity, carotid Eagle Syndrome remains underdiagnosed, and further research is needed to refine diagnostic techniques and establish standardised treatment protocols.

References:

1. Saccomanno, S., Quinzi, V., D’andrea, N., Albani, A., Paskay, L. C., & Marzo, G. (2021). Traumatic events and eagle syndrome: Is there any correlation? a systematic review. Healthcare (Switzerland), 9(7), 1–13. https://doi.org/10.3390/healthcare9070825
2. Fusco, D. J., Asteraki, S., & Spetzl, R. F. (2012). Eagle’s syndrome: Embryology, anatomy, and clinical management. Acta Neurochirurgica, 154(7), 1119–1126. https://doi.org/10.1007/s00701-012-1385-2
3. Steinmann, E. P. (1968). Styloid syndrome in absence of an elongated process. Acta Oto-Laryngologica, 66(1–6), 347–356. https://doi.org/10.3109/00016486809126301
4. Costantinides, F., Della Flora, F., Tonni, I., Bodin, C., Bazzocchi, G., Artero, M. L., Castronovo, G., Vettori, E., Nicolin, V., & Di Lenarda, R. (2021). Elongation of the styloid processes in kidney-transplanted patients: The role of ectopic calcification as possible cause of Eagle syndrome. Cranio – Journal of Craniomandibular Practice, 39(4), 321–325. https://doi.org/10.1080/08869634.2019.1640919
5. Pokharel, M., Karki, S., Shrestha, I., Shrestha, B. L., Khanal, K., & Amatya, R. C. M. (2013). Clinicoradiologic evaluation of Eagle’s syndrome and its management. Kathmandu University Medical Journal, 11(44), 305–309. https://doi.org/10.3126/kumj.v11i4.12527
6. Nastro Siniscalchi, E., Raffa, G., Vinci, S., Granata, F., Pitrone, A., Tessitore, A., Micari, A., Vizzari, G., Benedetto, F., Catalfamo, L., Squillacioti, A., Germanò, A., & De Ponte, F. S. (2022). Eagle syndrome: Lights and shadows of an underestimated condition of multidisciplinar interest. Advances in Oral and Maxillofacial Surgery, 5(December 2021), 100243. https://doi.org/10.1016/j.adoms.2021.100243
7. Hassani, M., Grønlund, E. W., Albrechtsen, S. S., & Kondziella, D. (2024). outcomes in Eagle syndrome: systematic review and meta-analysis. PeerJ, 12(6), 1–34. https://doi.org/10.7717/peerj.17423
8. Zamboni, P., Scerrati, A., Menegatti, E., Galeotti, R., Lapparelli, M., Traina, L., Tessari, M., Ciorba, A., De Bonis, P., & Pelucchi, S. (2019). The eagle jugular syndrome. BMC Neurology, 19(1), 1–7. https://doi.org/10.1186/s12883-019-1572-3
9. Aldakkan, A., Dunn, M., Warsi, N. M., Mansouri, A., & Marotta, T. R. (2017). Vascular Eagle’s syndrome: Two cases illustrating distinct mechanisms of cerebral ischemia. Journal of Radiology Case Reports, 11(8), 1–7. https://doi.org/10.3941/jrcr.v11i8.3040
10. Tardivo, V., Castaldi, A., Baldino, G., Siri, G., Bruzzo, M., Del Sette, M., & Romano, N. (2022). Internal carotid artery dissection related to abnormalities of styloid process: is it only a matter of length? Neurological Sciences, 43(1), 459–465. https://doi.org/10.1007/s10072-021-05350-8
11. Bargiel, J., Gontarz, M., Marecik, T., Szczurowski, P., Gąsiorowski, K., Zapała, J., & Wyszyńska-Pawelec, G. (2023). Minimally Invasive Cervical Styloidectomy in Stylohyoid Syndrome (Eagle Syndrome). Journal of Clinical Medicine, 12(21). https://doi.org/10.3390/jcm12216763
12. Pagano, S., Ricciuti, V., Mancini, F., Barbieri, F. R., Chegai, F., Marini, A., Marruzzo, D., Paracino, R., & Ricciuti, R. A. (2023). Eagle syndrome: An updated review. Surgical Neurology International, 14, 389. https://doi.org/10.25259/SNI_666_2023
13. Hooker, J. D., Joyner, D. A., Farley, E. P., & Khan, M. (2016). Carotid stent fracture from stylocarotid syndrome. Journal of Radiology Case Reports, 10(6), 1–8. https://doi.org/10.3941/jrcr.v10i6.1618