Eagle's syndrome. (Imaging Clinic).

The symptoms of Eagle's syndrome are a foreign-body sensation in the throat, dysphagia, and intermittent facial pain related to an elongated styloid process and a calcified stylohyoid ligament. (1) The case illustrated here is that of a 45-year-old woman who had experienced an acute trauma to the neck. Computed tomography (CT) detected soft-tissue swelling at the level of the oropharynx and hypopharynx, a heavily calcified styloid process, and a calcified stylohyoid ligament (figure 1). Prior to the trauma, the patient had a history of symptoms consistent with Eagle's syndrome.

Eagle described a group of patients who had symptoms of intermittent and nagging pain in the pharynx that radiated to the mastoid region, a foreign-body sensation in the throat, dysphagia, and taste disturbance. (6) His original patients had a history of tonsillectomy that resulted in scar tissue in the tonsillar fossa. Eagle believed that the scar tissue incorporated branches of the glossopharyngeal nerve. Radiographs demonstrated an ossified stylohyoid ligament. (2,6) Eagle also described a second group of patients who complained of pain along the distribution of the carotid artery. (6) Surgical exploration revealed compression of the external carotid artery by the styloid process; surgical removal of the process alleviated the symptoms. (3) Compression of the external carotid artery in patients with similar clinical findings has also been seen on angiographic imaging. (4) The diagnosis of Eagle's syndrome is made by radiographic imaging and by physical examination when an elongated and calcified stylohyoid ligament can be palpated in the tonsillar area. In the case illustrated here, the heavily calcified and thickened stylohyoid ligament was clearly identified on digital scout radiography (figure 2) prior to CT, as well as on axial images (figure 1).

Although approximately 4% of the general population is thought to have an elongated styloid process and a calcified stylohyoid ligament, only a small percentage of this group (4 to 10%) is symptomatic. (3) Nearly all of these calcified stylohyoid ligaments are considered to be anatomic variants that are of no clinical concern. (4) The stylohyoid apparatus has four distinct segments: tympanohyal, stylohyal, ceratohyal, and hypohyal. The ligamentous part of that apparatus originates in the ceratohyal cartilage and extends from the stylohyoid to the lesser cornu of the hyoid bone. (5) More important than the elongation of the styloid process and the calcification of the stylohyoid ligament is the thickening or ossification of those structures. This ossification should be differentiated from an incidental calcification of the stylohyoid ligament in asymptomatic individuals. The cause of stylohyoid calcification is not well understood, but it might be related to congenital factors such as persistence of a cartilag inous analog or an embryonic precursor to the styloid process.

The pathophysiology of the symptoms is also not clearly understood. Possible causes include previous trauma or an inflammatory process that produces a proliferation of granulation tissue and results in calcification or ossification. Calcification can lead to compression of the adjacent structures that are innervated by the glossopharyngeal and trigeminal nerves and the chorda tympani. There might also be impingement of the plexus of the carotid sheath that produces irritation of the sympathetic nerves. (2,6)

The treatment of Eagle's syndrome is beyond the scope of this report. Briefly, it can be treated surgically to relieve the compression or managed conservatively to relieve the symptoms.

References

(1.) Baugh RF, Stocks RM. Eagle's syndrome: A reappraisal. Ear Nose Throat J 1993;72:341-4.

(2.) Balbuena L, Jr., Hayes D, Ramirez SG, Johnson R. Eagle's syndrome (elongated styloid process). South Med J 1997;90:331-4.

(3.) Murtagh RD, Caracciolo JT, Fernandez G. CT findings associated with Eagle syndrome. AJNR Am J Neuroradiol 2001;22:1401-2.

(4.) Keats TE. An Atlas of Normal Roentgen Variants That May Simulate Disease. 5th ed. St. Louis: Mosby, 1992:718-20.

(5.) Lorman JG, Biggs JR. The Eagle syndrome. AJR Am J Roentgenol 1983;140:881-2.

(6.) Eagle WW. Elongated styloid process: Symptoms and treatment. Arch Otolaryngol 1958;64:172-6.