Eagle’s syndrome- Stylohyoid syndrome

Why it is called Eagle’s Syndrome

It was Eagle in 1937 an ENT surgeon at Duke University, Watt W. Eagle, described the first cases defined as “stylalgia” secondary to calcification of the stylohyoid ligament or elongated styloid process or to mineralization of the stylohyoid ligament. Usually asymptomatic, it occurs in adult patients ranged from 30 to 50 years. Females are affected more often than males

Anatomy of Styloid Process

The stylohyoid complex is made of styloid process, stylohyoid ligament, and the small cornus of the hyoid bone. All these structures are derivate from Reichert’s cartilage of the second branchial arch. The styloid process is an elongated conical projection of the temporal bone that lies anteriorly to the mastoid process, between the internal and external carotid arteries, and laterally the tonsillar fossa. In this space, the internal carotid artery, the internal jugular vein, the facial, glossopharyngeal, vagus, and hypoglossal nerves are located. From the styloid process, the stylohyoid, the styloglossal, and the stylopharyngeal muscles, and the stylohyoid and the stylomandibular ligaments originate. The normal length of the styloid process is individually variable, but in the majority of patients it is about 20 mm.

Clinical features of Eagle’s Syndrome

The symptoms of Eagle’s syndrome are a foreign-body sensation in the throat, dysphagia, and intermittent facial pain related to an elongated styloid process and a calcified stylohyoid ligament. Eagle described a group of patients who had symptoms of intermittent and nagging pain in the pharynx that radiated to the mastoid region, a foreign-body sensation in the throat, dysphagia, and taste disturbance. His original patients had a history of tonsillectomy that resulted in scar tissue in the tonsillar fossa. Eagle believed that the scar tissue incorporated branches of the glossopharyngeal nerve.

Eagle also described a second group of patients who complained of pain along the distribution of the carotid artery.

Pathophysiology

Although approximately 4% of the general population is thought to have an elongated styloid process and a calcified stylohyoid ligament, only a small percentage of this group (4 to 10%) is symptomatic.

The ligamentous part of that styloid apparatus originates at the tip of the stylohyoid to the lesser cornu of the hyoid bone. More important than the elongation of the styloid process and the calcification of the stylohyoid ligament is the thickening or ossification of those structures. This ossification should be differentiated from an incidental calcification of the stylohyoid ligament in asymptomatic individuals. The cause of stylohyoid calcification is not well understood, but it might be related to congenital factors such as persistence of a cartilaginous analog or an embryonic precursor to the styloid process.

Other possible causes include previous trauma or an inflammatory process that produces a proliferation of granulation tissue and results in calcification or ossification. Calcification can lead to compression of the adjacent structures that are innervated by the glossopharyngeal and trigeminal nerves and the chorda tympani. There might also be impingement of the plexus of the carotid sheath that produces irritation of the sympathetic nerves.

Diagnosis

Diagnosis is made both radiographically and by physical examination. Palpation of the styloid process in the tonsillar fossa is indicative of elongated styloid in that processes of normal length are not normally palpable. Palpation of the tip of the styloid should exacerbate existing symptoms. If highly suspicious for Eagle syndrome, confirmation can be made by radiographic studies. Most frequently, a panoramic (OPG) radiograph is used to determine whether the styloid process is elongated. In reviewing these radiographs, it should be noted that the normal length of the styloid in an adult is approximately 2.5 cm whereas an elongated styloid is generally >3 cm in length.

Although Eagle syndrome is thought to be caused by an elongated styloid process or calcified stylohyoid ligament, the presence of an elongated styloid process is not pathognomonic for Eagle syndrome because many patients with incidental findings of an elongated styloid process are asymptomatic.

Lateral view radiographs of the skull can be substituted for panoramic radiographs (as in this case), and an anteroposterior view radiograph should be obtained to determine whether there is any lateral deviation of the styloid.

3D CT is useful in that it provides more accurate information and will help the surgeon planning preoperative.

Treatment

Medical

• Analgesics

• Anticonvulsants

• Antidepressant

• Local infiltration with steroids or long-acting local anesthetic agents

Surgical

Styloidectomy is the treatment of choice. Styloidectomy can be performed by an intra- or an extraoral approach .The intraoral approach may result in a restricted operative field, in the possibility of an incomplete control over many important vascular and nervous structures and in the risk of deep cervical infections. On the other hand, external surgical approach results in cutaneous scars, longer hospitalization, and risks of facial nerve injuries. The treatment’s choice usually depends on the experience of the surgeon.

Transoral styloidectomy

First remove the tonsil on the affected side. The muscles of the pharyngeal wall are dissected, separated, and retracted. Then, an incision was made on the periosteum at the tip of the styloid process. The periosteum was stripped from the tip and the styloid process was exposed and caudal part was excised and the pharyngeal wall was sutured.

Extraoral approach

The external approach starts with a cervical incision at the upper two thirds of the anterior margin of the sternocleidomastoid muscle to the hyoid bone. After identification and incision of the platysma muscle and the superficial cervical fascia, the parotid fascia is reflected anteriorly and the carotid sheath and the sternocleidomastoid posteriorly in order to reach the posterior belly of the digastric muscle and the vascular-nervous bundle of the neck. The styloid process can now be palpated. Aponeurotic and muscular insertions are separated from the styloid process. Styloidectomy is then performed.