Eagle syndrome: symptomatic elongation of the styloid process

A 63-year-old male with a history of previous ICU admission requiring intubation presented with shortness of breath ongoing for one month with acute severe stridor. ENT was consulted and hypomotility of the larynx with subglottic stenosis was discovered on nasopharyngolaryngoscopy. The patient had worsening shortness of breath and hypoxemia following this procedure, and required awake tracheostomy placement. Subsequently, the patient complained of neck pain, which he reported was chronic but had worsened slightly in the acute phase.

Initial imaging with frontal and lateral neck soft tissues radiography was performed which demonstrated elongation of the bilateral styloid bones and extensive ossification of the bilateral stylohyoid ligaments, with bulky pseudoarthroses of the ossified stylohyoid ligament (figures 1a, 1b). Follow-up computed tomography (CT) of the neck soft tissues with intravenous contrast redemonstrated massive ossification of the bilateral stylohyoid ligaments with a pseudoarthrosis below the skull base and at the junction of the ossified ligament and hyoid bone (figures 2-4). The patient’s stylohyoid process measured 8.7 cm on the right, and 6.3 cm on the left. No other findings to explain the patient’s neck pain were revealed.

Background

The cause of Eagle syndrome is unknown and is likely multifactorial, however, genetics and a history of trauma are thought to play a role. It is more common in women than men [3:1] [1]. There has been an association of onset with surgery in the neck, typically tonsillectomy, due to anatomical distortion during the procedure. In this case, tracheostomy may have uncovered the patient’s symptoms. One study suggested around 4% of the population have an elongated styloid alone [2]. However, the vast majority of these cases were asymptomatic. In most cases, Eagle syndrome refers only to symptomatic elongation of the styloid process.

Clinical Perspective

The main symptoms of Eagle syndrome typically include recurrent neck and head pain which is worsened by movements of the head and neck. Other symptoms include foreign body sensation, pain in the ear, odynophagia, and dysphagia [1]. Symptoms are typically due to degenerative changes in the stylohyoid bone, exacerbated by compression of nearby structures including vessels and cranial nerves. Classic-type Eagle syndrome involves compression of the cranial nerves, specifically trigeminal [V], facial [VII], glossopharyngeal [IX], vagus [X], and typically presents with foreign body sensations and dysphagia-like symptoms [1,3]. Carotid-type Eagle syndrome involves compression of the carotid sheath, with pain in the eyes and visual disturbance being common [1,3].

Imaging Perspective

CT imaging remains the gold-standard for diagnosis of Eagle syndrome, and will provide the best visualization of styloid length and its effect on adjacent structures. The normal length of a styloid process is less than 2.5 cm. Depending on the source, a styloid length of 3 or 4 cm has been considered the threshold for abnormal [3]. In addition to showing an elongated styloid bone, there will typically be abnormal ossification of the styloid process and stylohyoid ligament; these abnormalities are usually seen bilaterally. Plain radiographs, ideally taken in both anteroposterior and lateral views, is typically the first imaging modality to reveal pathology and can be used to determine if there is lateral deviation of the styloid [4]. Additionally, CT angiography can be used adjunctly with routine CT imaging if there is suspicion for carotid-type Eagle syndrome.

Outcome

In asymptomatic patients, a conservative approach can be utilized; this is typically in cases where Eagle syndrome is found incidentally as it does not affect overall mortality or morbidity when asymptomatic. Medical therapy with analgesics and lifestyle modifications, including a softened diet, oral analgesics, local injections, and antidepressants are viable options for patients who have mild symptoms [3]. In more severe symptomatic cases, the preferred treatment is surgical involving styloidectomy through transcervical or transoral route [5]. Prognosis following surgical management is favorable, with most patients attaining complete resolution of symptoms. The patient in the present case report was incidentally found to have Eagle syndrome, and decided to be treated symptomatically.

Take Home Message

Eagle syndrome is the symptomatic manifestation of elongation of the styloid process and is confirmed when a styloid length of 3 or 4 cm is seen on plain radiography or cross-sectional imaging. Typically, Eagle syndrome can be managed symptomatically, although styloidectomy may be pursued in severe cases.

Written informed patient consent for publication has been obtained.