Eagle syndrome is a medical condition in which the styloid process is abnormally long, extending over 1.18 in (30mm), and the stylohyoid ligament has undergone calcification. Though the exact causes remain debated, this condition has been linked with aging and trauma and is more common in females than males. The condition may present symptoms of chronic dull pain, or sharp pains when swallowing, stretching the tongue, or turning the head. Roughly 4% of the general population have an elongated styloid process, but only 4-10% of these patients exhibit symptoms, making Eagle syndrome fairly rare.
The term styloid process has three different applications in anatomy: radius, ulna, and temporal. Eagle syndrome is concerned with the temporal styloid process, a thin bone which protrudes downward and outwards from the base of the temporal bone in the skull, close to the ear. The temporal styloid process articulates with several muscles and nerves that help control the tongue and larynx. It also connects with the stylohyoid ligament, a fibrous band that attaches the styloid process to the stylohyoideous muscle, which controls the floor of the mouth.
The exact causes of this syndrome are not known, though several explanations have been offered. The syndrome was first described by Dr. Watt W. Eagle, an otolaryngologist at Duke University in 1937. He believed chronic irritation in the stylohyoid region or scar tissue from a surgical trauma could cause ossification, or hardening, of the ligament and osteitis, a condition in which bones grow irregularly. Doctors have also suggested that the ossification occurring in Eagle syndrome is linked to endocrine disorders in menopausal women. Others believe that Eagle syndrome may stem from trauma caused in the development stages of the styloid process.
There are two forms of Eagle syndrome, as proposed by Eagle. The first, “classic” form occurs after a local trauma or surgical stress, such as from a tonsillectomy. The classic form presents symptoms of chronic, dull pain on the side of the head affected and, in some cases, a bulge between the roof of the mouth and the back of the throat on the same side. Pressure on this bulge will likely cause increased pain.
The second form, known as “stylocarotid syndrome,” occurs when the styloid process is deformed so that it extends sideways and compresses the internal or external carotid artery. A patient with the second form of Eagle syndrome may experience pain along the artery on one side of the neck when turning the head, and pain above or below the eye, depending on which artery is affected. This form is not related to a history of tonsillectomy.
If a patient exhibits these symptoms, a doctor may diagnose the patient by palpating (touching) the tip of the styloid process and ordering an x-ray called a computed tomography (CT) scan. Doctors often prescribe anti-inflammatory and pain medications, but if the case is severe, the patient may require styloidectomy surgery to remove the problematic portion of the styloid process. Surgery may be conducted from the outside of the neck (extraoral) or from the inside (intraoral), but intraoral is preferred.