Journal of Indian Academy of Oral Medicine and Radiology

: 2008  |  Volume : 20  |  Issue : 1  |  Page : 1--5

Eagle syndrome: A review of current diagnostic criteria and evaluation strategies

Vishlesh Arora, Arvind Shetti, Vaishali Keluskar 
 Department of Oral Medicine and Radiology, Institute of Dental Sciences, Belgaum, Karnataka, India

Correspondence Address:
Vishlesh Arora
Department of Oral Medicine and Radiology, Institute of Dental Sciences, Belgaum, Karnataka


The mineralized and elongated styloid process and Eagle«SQ»s syndrome are similar processes of elongation in which mineralization of the stylohyoid ligament leads to styloid process of the temporal bone. The mineralized and elongated styloid process and Eagle«SQ»s syndrome differ significantly in terms of the symptoms displayed and the treatment modalities that are sought. The mineralized and elongated styloid process refers to unilateral or bilateral elongation of the styloid process that does not result in any significant pain, discomfort, or limitation of neck movement. It often remains asymptomatic until it is discovered on extraoral radiographs. Eagle«SQ»s syndrome refers to pain and discomfort in the cervicofacial region resulting specifically from the elongated styloid process. Surgical shortening may be the only treatment that will alleviate the patient«SQ»s symptoms.This article reviews the entire process of elongation pertaining to the styloid process and discusses the associated syndromes, including current knowledge of the theories of elongation, diagnostic criteria and treatment strategies.

How to cite this article:
Arora V, Shetti A, Keluskar V. Eagle syndrome: A review of current diagnostic criteria and evaluation strategies.J Indian Acad Oral Med Radiol 2008;20:1-5

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Arora V, Shetti A, Keluskar V. Eagle syndrome: A review of current diagnostic criteria and evaluation strategies. J Indian Acad Oral Med Radiol [serial online] 2008 [cited 2021 Oct 16 ];20:1-5
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The styloid process of the temporal bone lies anterior to the stylomastoid foramen. It is attached by cartilaginous tissue. The process normally measures 25 mm in length, although it varies in length from person to person and even from side to side of the same person. [1],[2],[3]

Although researchers agree that elongation is common, symptoms asso­ciated with elongation are uncommon unless the calcification has progressed through the stylohyal complex to in­duce symptoms. Diagnosis is a clinical challenge for general dentists when the symptoms appear, as symptoms may emerge in a variety of manifestations. Common symptoms include foreign body sensation in the throat, dysphagia, and intermittent facial pain related to the mineralized and elongated styloid process (MESP). Various studies have reported incidence of the MESP ranging from 1.4-30%.

Elongation usually results from ossi­fication within the stylohyoid ligament. The ossification usually occurs in the upper end of the ligament and is in keeping with the styloid process, al­though it has been reported as starting at the lower end of the stylohyoid liga­ment, at the lesser cornu of the hyoid bone, and, less commonly, in the mid-portion. [4] Subjects with elon­gated styloid processes at least 40 mm long had the highest incidence of dis­comfort on swallowing. The majority of patient with styloids less than 30 mm were symptom-free.

 Anatomic and Embryological Considerations

The styloid process normally projects down, forward and slightly medially. The tip of the process is situated between the internal and external carotid arteries. It lies posterior to the tonsillar fossa and lat­eral to the pharyngeal wall; muscular and ligamentous structures are attached at var­ious locations on the process. Three mus­cles are attached to the process, the sty­lopharyngeus (arising from the base and innervated by the glossopharyngeal nerve), the stylohyoid (attached to the middle portion and innervated by the fa­cial nerve), and the styloglossus (originat­ing from the extremity of the process and innervated by hypoglossal nerve).

The two ligaments in relation to the process are the stylomandibular and the stylohyoid. The styloman­dibular ligament is inserted at the apex of the process and attaches at the angle of the mandible. The stylohyoid ligament inserts to the apex of the process and at­taches at its far end to the lesser cornu of the hyoid bone. The stylohyoid chain consists of the styloid process, the lesser cornu of the hyoid bone, and its connect­ing ligament (usually the stylohyoid liga­ment). The chain is derived from the sec­ond branchial or hyoid arch known as Reichert's cartilage. In many mammals, this cartilage gives rise to a series of four bony parts: the tympanohyal, stylohyal, epihyal and ceratohyal. [5] In humans, it is believed that the tympanohyal fuses with the stylohyal and the petrous part of the temporal bone to form the styloid process. Normally, the epihyal cartilage degenerates but its fibrous sheath re­mains; this sheath is the stylohyoid liga­ment. [6] The ceratohyal or hypohyal carti­lage persists and becomes the lesser cornu of the hyoid bone. [7] Variation in the ossi­fication and fusion of these various parts can result in marked variation in the chain's appearance.

In 1964, Lengele and Dhem proposed the developmental theory about the elongated styloid process, based on the morphogenesis of Reichert's cartilage. [8] To establish the mechanisms involved in the morphogenesis of the so-called elon­gated styloid process, a comparative mi­croradiographic and histological study was performed on 19 long and short processes. Some morphological differ­ences between short and long processes were noticed. Numerous partially calci­fied cartilaginous islets were observed within the trabecular bone of very long styloid processes or covering their tip. Although calcified fibrous tissue or calci­fied fibrocartilage sometimes contributed to the thickening of an enlarged styloid process, the authors reported that the growth of the process did not seem to re­sult from calcification or ossification of the stylohyoid ligament. Mechanical stresses stretch the second branchial arch during fetal development and the mor­phogenesis of the styloid process may in­duce a variable involvement from the dif­ferent parts of Reichert's cartilage. Lengele and Dhem concluded that the elongated styloid process should he con­genital; however, they agreed that further growth still was possible through the car­tilaginous cap of the tip of the styloid process. [8]

 Clinical Features and Examination

According to studies performed on the elongated styloid process between 1964 and 1986, symptomatic patients usually were over the age of 40. [9],[10] There was no sex predilection in the majority of the studies. When pain and discomfort upon swallowing, foreign body sensation in the throat, or a limitation of mandibular movements appear to be associated with the radiographically detectable MESP, the condition known as Eagle's syndrome (also known as elongated styloid process syndrome) is diagnosed.

An extensive review concerning the association between cervicopharyngeal pain and stylohyoid ossification placed patients in three broad categories based on their symptoms (the stylohyoid, pseu­dostylohyoid, or Eagle's syndromes). [11] The same study reported that Eagle's syn­drome typically involves patients with a recent history of neck trauma or surgical procedures (for example, a tonsillecto­my) who show radiographic evidence of an elongated styloid process. Clinical palpation of such elongation or calcifica­tion usually can be performed chairside. Patients may complain of sensation of a foreign body in the throat, pain on swal­lowing, or neurologic pain in the head and neck region; they also may have sig­nificant pain in the temporomandibular joint (TMJ) region, radiating to the sub-auricular and submandibular regions. The term stylohyoid syndrome applies to patients of any age, although most usual­ly are older than 40 at the time of diag­nosis; while these patients may not have significant symptoms, the ossification can be demonstrated on routine extrao­ral radiographs. [12] Such ossification also may be palpable clinically.

Pseudostylohyoid syndrome is reserved for patients older than 40 who have no history of trauma and no radiographic or clinical evidence of stylohyoid chain ossi­fication. These patients have symptoms identical to those of stylohyoid syndrome patients but do not have radiographic or clinical findings of ossification within the ligament. It is proposed that these people have tendonitis at the junction of the sty­lohyoid ligament and the lesser horn of the hyoid bone resulting from the degen­erative and inflammatory changes in the tendinous portions of the stylohyoid in­sertion. [4]

Langlais et al . reported on a subgroup of patients with constant parietal headaches; these patients were theorized as having a "stylo-carotid syndrome." [4] The differential diagnosis depends on the symptoms. The most common inclusions are glossopha­ryngeal neuralgia, sphenopalatine neural­gia (also known as Sluder's syndrome), his­tamine cephalgia (cluster headaches), migraine headaches, carotidynia, myofas­cial pain dysfunction, impacted third mo­lars, and other conditions associated with dysphagia, otalgia and tinnitus. [4]

The effects of hyperflexion/hyperex­tension (that is, whiplash) injuries are ex­acerbated by the presence of this unex­pected calcified structure. Researchers have correlated the ligamentous ossifica­tion of the stylohyal complex and osteo­phytes of the cervical spine, concluding that a significant correlation exists be­tween cervical diffuse idiopathic skeletal hyperostosis (DISH) and various styloid process-stylohyoid ligament complex ab­normalities. [13]

The examination of the sty­loid region can be performed by seating the patient in a chair with firm back sup­port. The palpation of the styloid region of the neck can be conducted bimanually and digitally by standing behind the pa­tient. An intraoral examination method includes visualizing the tonsillar area with a tongue blade or a mouth mirror and dig­ital palpation of the area. Patients whose referred pain is in the tonsillar area will be able to respond to the palpatory stimulus.

 Radiographic Features and Classification

Elongation and mineralization of the sty­lohyoid ligament complex can be ob­served readily on panoramic radiographs [Figure 1]. However, because the panoramic radiographs are obtained pri­marily for the visualization of teeth and associated bony structures within the jaws, observing the mineralized stylohy­oid complex within the pantomograms is inconsistent and often distorted. This is due to the fact that the styloid process frequently lies outside of the panoramic focal trough depending on the patient positioning. The images become distort­ed due to the unreliable magnification within the posterior focal trough of the panoramic machines. Lateral skull view, reverse Towne view [Figure 2] and posterior-anterior views of the skull also demonstrate the unilateral or bilateral presence and elongation of the styloid process. The mineralized stylohyoid ligament is easy to recognize when it ex­tends below the mandibular border or when its attachment to the mandibular cornu of the hyoid bone can be seen on the radiographs.

Radiographic features alone are not enough to distinguish the symptomatic from the asymptomatic elongated styloid processes. When the posteroanterior ra­diographs show extreme medial devia­tion, the carotid artery subtype may be considered. [4] Langlais et al. proposed a ra­diographic classification of the elongated and mineralized stylohyoid ligament complex. Their classification included three types of abnormal radiographic ap­pearances and four patterns of calcifica­tion/mineralization [Figure 3] (see [Table 1] and [Table 2]).

 Diagnosis and Management

An elongated styloid process may be one cause of aggravated maxillofacial or cran­iocervical pain. Diagnosis requires a thorough clinical examination of the head and neck and should be confirmed radiographically. Panoramic radiographs or bilateral lateral oblique radiographs should be taken for patients who are ex­amined in a dental office setting for oropharyngeal discomfort, chronic cervi­cofacial pains, or chronic headaches. Ra­diographically, the mineralized styloid process falls under any of the aforemen­tioned types of elongation or the patterns of mineralization. The outcomes of treatment have no bearing on the type of elongation or pattern of mineralization. The classification is designed to help den­tists understand the variation among the different elongation patterns and may even offer clues as to the etiology of the elongation.

Eagle's syndrome can be a secondary cause of glossopharyngeal neuralgia. Glos­sopharyngeal neuralgia may be a life-threatening condition as a result of as­sociated cardiovascular complications. Even when life-threatening complica­tions are absent, glossopharyngeal neu­ralgia can be a severely debilitating dis­ease, leading to depression, suicidal tendencies, fear of swallowing, weight loss and malnutrition. Due to the elon­gated styloid process, Eagle's syndrome is considered an important etiological factor for precipitation of secondary glossopharyngeal neuralgia. [11] A stylec­tomy is effective for Eagle's syndrome and should be considered before em­barking on any neurosurgical procedure.

The effects of hyperfiexion/hyperex­tension/whiplash injuries can be exacer­bated by the presence of the calcified sty­loid. Additional symptoms may include neck or throat pain radiating to the ipsi­lateral ear. Diagnosis usually can be made by physical examination. Digital palpation of the styloid process in the tonsillar fossa exacerbates the pain. This diagnosis should be considered if symptoms can be . relieved by injecting an anes­thetic solution in to the tonsillar fossa.

Surgical shortening is the universally accepted treatment for confirmed elon­gation of the styloid process. Multi­disciplinary management yields optimal results; some studies have recommended an intraoral approach (that is, trans-ton­sillar fossa excision). Other authors have preferred an extraoral cervical approach, believing that surgical visuali­zation was optimal and the risk of deep cervical infection was minimal. Trans-tonsillar fossa excisions is a simple technique that does not result in greater morbidity than a routine tonsillectomy, although the trans-tonsillar approach has been criticized for inadequate surgical shortening of the styloid process due to poor visualization of the surgical field. Dentists must weigh the advantages and disadvantages of each technique and se­lect the procedure that is appropriate for the patient.

Cases in which a MESP alone is present do not require any immediate treatment, although patients should be warned about the elongation of the sty­loid process.


Although the elongated styloid process is not an entirely new entity, studies of symptomatology and diagnostic strate­gies involving different population groups have produced new information about the various types of elongation, patterns of calcification, and symptomatology. When evaluating the chronic oro­facial or cervicofacial pain, elongation of the styloid process should always be con­sidered. Proper selective radiographic techniques and examination of the ton­sillar and cervical areas may reveal elongation or mineralization in the stylohy­oid complex, which may be the cause of the elongated styloid process. The styloid elongation should be included in the list of differential diagnoses for evaluating headaches, tonsillar discomfort, pain re­ferred to the jaw region, difficulty in swallowing and the inability to move the jaw from side to side during lateral excur­sions. Symptomatic cases of stylohyoid elongations should be referred to as Ea­gle's syndrome. When complex patterns of stylohyoid chain mineralization ap­pear on plain radiographs and tomo­grams with no signs of disabling symp­toms, mineralized and elongated styloid process may be the more appropriate di­agnosis.


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