Panoramic radiograph showing bilateral mineralization of the stylohyoid ligament.(from Color Atlas of Oral and Maxillofacial Diseases)
Three-dimensional radiographic reconstruction of the same patient showing complete ossification of the stylohyoid ligament, which attaches to the hyoid bone.(from Color Atlas of Oral and Maxillofacial Diseases)
Eagle syndrome is an uncommon pain condition in which elongation of the styloid process or mineralization of the stylohyoid ligament results in a variety of clinical symptoms. The styloid process, a slender projection of bone arising from the inferior portion of the temporal bone, is connected to the hyoid bone in the neck by the stylohyoid ligament. The internal and external branches of the carotid artery are located on either side. Some degree of elongation of the styloid process or mineralization of the stylohyoid ligament is not unusual, although the reported prevalence varies widely, from 4% to greater than 40%. Regardless, only about 4% of individuals with radiographic evidence of such mineralization develop Eagle syndrome.
Eagle syndrome is characterized by unilateral pain in the anterior lateral neck, which may be precipitated by swallowing, turning the head, or yawning. This pain may radiate to the ear or temporomandibular joint. Other symptoms can include dysphagia and the sensation of a foreign body in the throat. In addition, compression of the adjacent carotid arteries can result in syncope, transient ischemic attacks, and even carotid artery dissection. Some authors distinguish between “classic” Eagle syndrome and stylohyoid syndrome. In classic Eagle syndrome, the symptoms develop after tonsillectomy, presumably due to development of scar tissue around the mineralized stylohyoid complex. Stylohyoid syndrome (stylocarotid syndrome) is not associated with a prior tonsillectomy but is thought to be due to direct impingement of the calcified stylohyoid complex upon the carotid arteries and adjacent sympathetic nerve fibers.
Treatment depends on the severity of the symptoms. Mild examples of Eagle syndrome may be managed conservatively using nonsteroidal antiinflammatory drugs and local injection of corticosteroids and anesthetics. More severe cases require partial surgical removal of the elongated styloid process, which can be accomplished by either a transoral tonsillar approach or an extraoral cervical approach. The prognosis after surgery is good.