Eagle syndrome, or ossification of the stylohyoid ligament, is a rare clinical-radiological entity, first described by the otolaryngologist W. Eagle in 1937. It is a little-known cause of severe neck and facial pain.
What is Eagle syndrome?
Eagle syndrome refers to the symptoms related to an elongation of the temporal bone’s styloid process or the stylohyoid ligament’s extension and calcification. The symptoms of this syndrome can vary since they are related to the compression of the neurovascular structures adjacent to these structures. It is a little-known cause of severe neck and facial pain.
Etiology and prevalence
Eagle syndrome appears in up to 18% of the general population, although only 4% of cases are clinically symptomatic. It is more frequent between 40 and 60 years of age and predominates in the female sex. In most symptomatic patients, the condition is bilateral.
Many authors affirm that the symptoms of this syndrome occur after one or several traumas or surgeries near the styloid process (tonsillectomy or dental surgery, among others).
Symptoms
Eagle described two varieties based on the compressed structures:
Classic syndrome
Due to intermittent compressive neuropathy of the branches of the cranial nerves V, VII, IX, and X and associated with the presence of discomfort in the throat, neck pain, otalgia, the sensation of a foreign body in the throat, dysphagia, and taste distortion associated with odynophagia.
Vascular or carotid syndrome
The compression of this artery is characterized by different types of pain depending on the location of the path of the carotid street affected by the reduction. Thus, the involvement of the internal carotid artery causes pain in the parietal, facial, and cervical regions, increasing with contralateral cervical rotation. External carotid involvement usually causes constant neck pain radiating to the eye, which increases with ipsilateral neck rotation. Compression of the carotid artery can be associated with tinnitus or ringing, deafness, difficulty speaking, and fleeting amaurosis (temporary loss of vision in one eye due to lack of blood circulation to the retina).
For another reason, incidental findings on the cervical spine or thorax X-rays have been described in clinically asymptomatic patients undergoing the study.
How is Eagle Syndrome diagnosed?
Given the similarity of its symptoms with other conditions or cervicofacial pain, it is an underdiagnosed pathology, which leads to diagnostic errors. It should be suspected that facial and cervical pain increases with flexion-extension movements and contralateral turns of the neck.
Diagnosis is based on both clinical criteria and radiological studies. According to the ICHD-III international classification of headaches, the diagnostic criteria are:
- Any headache, neck, pharyngeal, and facial pain meets the diagnostic criteria.
- Radiological evidence of elongation of the styloid process or extension and calcification of the stylohyoid ligament by performing a simple cervical spine X-ray and a CT scan with/without neck and skull base contrast.
- Causation demonstrated by at least two of the following:
- Pain is elicited or exacerbated by palpation of the stylohyoid ligament.
- Pain is triggered or exacerbated by head turning.
- Pain is significantly improved by local anesthetic infiltration into the stylohyoid ligament or by thyroidectomy.
- Pain is ipsilateral to the inflamed stylohyoid ligament.
- Another ICHD-3 diagnosis does not better explain symptoms.
How is Eagle Syndrome treated?
- The first-choice treatment is conservative, aimed at resolving the symptoms presented by each patient, and may include the use of analgesic, anti-inflammatory, and neuromodulatory drugs (gabapentin, carbamazepine, amitriptyline, valproic acid) as well as local infiltration with local anesthetics. or corticosteroids in the region of the tonsillar fossa.
- Physiotherapy can be considered a coadjuvant tool to conservative medical treatment to improve pain and patients’ quality of life.
- Surgical treatment is indicated when the conservative approach fails or in severe symptomatic forms, given the complexity and importance of the vascular and nervous structures in the area. It is based on surgical resection of the styloid process (thyroidectomy) or the stylohyoid ligament, either through the oropharyngeal approach or through the lateral neck approach; the success rate after surgery is very high if the surgical indication is correct and the patient is well selected.
