Eagle syndrome is defined as the set of signs and symptoms resulting from an elongated styloid process or the calcification of the stylohyoid ligament [1,2]. This rare condition occurs secondary to irritation or compression of adjacent structures caused by an abnormal styloid process [3]. Clinical manifestations of classic Eagle syndrome are diverse and may include neck pain, dysphagia, odynophagia, and the sensation of a foreign body in the cervical region [4]. Although neck pain is a prevalent and significant complaint in the outpatient setting, Eagle syndrome is an exceedingly rare cause that is not commonly included in the differential diagnosis of cervical pain [5]. We present a case of Eagle syndrome and discuss this entity as a rare differential diagnosis of neck pain. This case report is presented in accordance with the Updating Consensus Surgical Case Report (SCARE) 2020 guidelines [6].

A 39-year-old woman, with no significant past medical or surgical history, presented with a 9-month history of neck pain localized to the left supraclavicular region. She did not report paresthesia or other neurological symptoms. Her symptoms began as intermittent neck pain, usually occurring after exercise and relieved by painkillers. Over time, episodes of neck pain became more frequent, and she began experiencing episodes of odynophagia, prompting her to seek medical attention. On examination, she had neck pain localized to the left side, but no muscle tenderness was detected. Intraoral examination was unremarkable. Laboratory results were within normal limits. Neck ultrasound and cervical spine magnetic resonance imaging were performed, both of which showed no significant findings. Due to persistent pain and diagnostic uncertainty, a neck computed tomography scan was obtained, which demonstrated elongation of both styloid processes and calcification of the stylohyoid ligament, predominantly on the left side, confirming the diagnosis of Eagle syndrome as the cause of her neck pain (Fig. 1).

Subsequently, an elective left cervicotomy was performed for left styloidectomy with vascular control. The surgery was conducted under general anesthesia with nasotracheal intubation and the head in slight hyperextension, turned toward the contralateral side. The skin incision was made below the inferior border of the mandible to avoid the marginal mandibular branch of the facial nerve, between the anterior border of the sternocleidomastoid muscle and the hyoid bone. The platysma and superficial cervical fascia were incised. Intraoperatively, elongation of the styloid process and calcification of the stylohyoid ligament were observed. Resection of the styloid process and the calcified ligament was performed without complications (Fig. 2).

The specimen was sent for anatomopathological examination, which confirmed mineralization of the stylohyoid ligament (Fig. 3).

The patient had an uneventful postoperative course and was discharged on the first postoperative day. Outpatient follow-up at the first and fourth weeks after surgery was unremarkable. The pain did not recur, and no other symptoms were reported up to 1 year postoperatively. She continues to receive follow-up at the Head and Neck Unit but has not required any long-term treatment for the right side thus far.

Eagle syndrome is a rare clinical condition caused by an elongated styloid process or calcification of the stylohyoid ligament, leading to compression or irritation of surrounding structures [1-3]. Symptoms are variable and may include neck pain, dysphagia, odynophagia, and a sensation of a foreign body [4]. Because the clinical presentation of Eagle syndrome is nonspecific and variable, it can easily be mistaken for a wide range of other cervical conditions, resulting in delayed diagnosis, especially when pain is the only clinical manifestation, as in our patient’s case. The condition was first described by Eagle in 1937 [7]. While it is estimated that up to 4% of the general population may have an elongated styloid process, only a small percentage are symptomatic [3]. Stylohyoid abnormalities frequently occur bilaterally, but symptoms are classically unilateral, though rarely they may be bilateral [3,8]. Patients are typically over 30 years of age, with a female-to-male ratio of approximately 3:1 [1,7]. Although neck pain is a common and significant issue in outpatient practice, Eagle syndrome is an exceedingly rare cause that is not usually considered in the differential diagnosis of cervical pain [5].

When Eagle syndrome is suspected, definitive diagnosis is established by computed tomography scan of the skull and neck, which is considered the gold standard [9]. In our patient, recurrent neck pain prompted the computed tomography scan that confirmed the diagnosis. Suspecting this condition can be highly challenging due to its rarity and the nonspecific nature of its clinical presentation. Surgical intervention is frequently the treatment of choice in patients with Eagle syndrome [9]. In our case, the patient’s pain resolved following unilateral styloidectomy, demonstrating that the left calcified stylohyoid ligament was the source of her symptoms. Postoperative follow-up by a Head and Neck specialist is strongly recommended. Our patient remained stable, without further symptoms, pain, or other complications at 1 year after surgery.

In this report, we present Eagle syndrome as an exceedingly unusual possibility in the differential diagnosis of neck pain that should, despite its rarity, be considered in cases involving recurrent neck pain.