Eagle Syndrome

Eagle Syndrome 

An uncommon cause of facial pain, Eagle syndrome (also known as stylohyoid syndrome) is caused by pressure on the internal carotid artery and surrounding structures, including branches of the glossopharyngeal nerve, by an abnormally elongated styloid process, a calcified stylohyoid ligament, or both.

The pain of Eagle syndrome is sharp and stabbing and occurs with movement of the mandible or turning of the neck.

The pain starts below the angle of the mandible and radiates into the tonsillar fossa, temporomandibular joint, and base of the tongue. A trigger point may be present in the tonsillar fossa. Injection of the attachment of the stylohyoid ligament to the styloid process with local anesthetic and steroid serves as a diagnostic maneuver and a therapeutic maneuver.

What are the Symptoms of Eagle Syndrome

Eagle syndrome is most often a diagnosis of exclusion. Patients suffering from Eagle syndrome present with a history of sudden, sharp neuritic pain that begins below the angle of the mandible and radiates into the tonsillar fossa, temporomandibular joint, and base of the tongue.

The pain is triggered by swallowing, movement of the mandible, or turning of the neck. The intensity of pain is moderate to severe and unpleasant. The neurological examination is normal. The pain of Eagle syndrome may be triggered by palpation of the tonsillar fossa.

How is Eagle Syndrome diagnosed?

In patients with Eagle syndrome, radiographs and computed tomography (CT) scans of the region of the styloid process show an elongated styloid process that is often associated with a calcified stylohyoid ligament.

The diagnosis of Eagle syndrome may be strengthened by a diagnostic injection of the attachment of the stylohyoid ligament to the styloid process with local anesthetic. Pain relief after this injection suggests a local cause for the pain rather than a more distant cause, such as glossopharyngeal neuralgia or retropharyngeal tumor.

Differential Diagnosis

Eagle syndrome can be distinguished from glossopharyngeal neuralgia because the pain of glossopharyngeal neuralgia is characterized by paroxysms of shock-like pain in a manner analogous to trigeminal neuralgia, rather than the sharp, shooting pain on movement that is associated with Eagle syndrome.

Because glossopharyngeal neuralgia may be associated with serious cardiac bradyarrhythmias and syncope, the clinician must distinguish the two syndromes.

The clinician should always evaluate a patient with pain in this anatomical region for occult malignancy.

Tumors of the larynx, hypopharynx, and anterior triangle of the neck may manifest with clinical symptoms identical to those of Eagle syndrome.

Because of the low incidence of Eagle syndrome relative to pain secondary to malignancy in this anatomical region, Eagle syndrome must be considered a diagnosis of exclusion.

Treatment

Many patients with Eagle syndrome respond to a series of therapeutic injections of the attachment of the stylohyoid ligament to the styloid process with local anesthetic and steroid.

To perform this procedure, an imaginary line is visualized running from the mastoid process to the angle of the mandible. The styloid process should lie just below the midpoint of this line. The skin is prepared with antiseptic solution.

A 22-gauge, 1½-inch needle attached to a 14-mL syringe is advanced at this midpoint location in a plane perpendicular to the skin. The styloid process should be encountered within 3 cm. After contact is made, the needle is withdrawn slightly out of the periosteum or substance of the calcified ligament. After careful aspiration reveals no blood or cerebrospinal fluid, 5 mL of 0.5% preservative-free lidocaine combined with 80 mg of methylprednisolone is injected in incremental doses.

Subsequent daily nerve blocks are performed in a similar manner, substituting 40 mg of methylprednisolone for the initial 80-mg dose. Ultrasound-guided needle placement may improve the accuracy of needle placement and decrease the incidence of needle-related complications.

Surgical excision of the styloid process and calcified stylohyoid ligament may be required in some cases.

The sharp, shooting pain associated with Eagle syndrome also may be treated with gabapentin.

Gabapentin is started at a single nighttime dose of 300 mg and titrated by 300-mg increments every 2 days in divided doses until pain relief is achieved or a total daily dose of 3600 mg is reached. Alternatively, carbamazepine or phenytoin may be tried.

Complications

The major complications associated with this injection technique are related to trauma to the internal jugular and carotid artery. Hematoma formation and intravascular injection of local anesthetic with subsequent toxicity are common complications of this technique.

Inadvertent blockade of the motor portion of the glossopharyngeal nerve can result in dysphagia secondary to weakness of the stylopharyngeus muscle. If the vagus nerve is inadvertently blocked, dysphonia secondary to paralysis of the ipsilateral vocal cord may occur.

A reflex tachycardia secondary to vagal nerve block also is observed in some patients. Inadvertent block of the hypoglossal and spinal accessory nerves during glossopharyngeal nerve block results in weakness of the tongue and trapezius muscle.

Clinical Pearls

Eagle syndrome is an uncommon cause of facial pain. Because of the low incidence of Eagle syndrome relative to pain secondary to malignancy in this anatomical region, Eagle syndrome must be considered a diagnosis of exclusion. The clinician should always evaluate a patient with pain in this anatomical region for occult malignancy.

Tumors of the larynx, hypopharynx, and anterior triangle of the neck may manifest with clinical symptoms identical to those of Eagle syndrome.