Eagle syndrome: Classic and carotid artery types

Abstract

OBJECTIVE: To present a number of cases with elongated styloid process (Eagle) syndrome and to discuss the clinical presentation of this disorder. METHODS: A clinical study of patients operated on at King Abdul-Aziz University Hospital, Riyadh, from 1992 to 1996. RESULTS: The study group consisted of seven patients (six females and one male ranging in age from 20 to 43 years). Symptomatically, two distinct groups of patients could be identified: the classic syndrome (including three patients), which occurs in the tonsillectomized patients, and the styloid-carotid artery syndrome (including four patients), which occurs independently of tonsillectomy. In the first type, patients usually complain of spastic and nagging pain in the pharynx radiating to the mastoid region. In the second group, patients usually complain of attacks of syncope in association with pharyngeal pain referred to the course of the carotid artery. Diagnosis is made by history taking, palpating the tonsillar fossa, and radiographic demonstration of the process. Three-dimensional computed tomography reconstruction images were found to be very reliable in measuring the actual length of the styloid process and the stylohyoid ligament. CONCLUSION: This unusual disorder should be considered in the differential diagnosis of facial pain in some patients and as the cause of syncope in other patients. The paper discusses the embryologic, anatomic, pathogenetic, clinical, and therapeutic aspects of elongated styloid process with calcified stylohyoid ligament and the differential diagnosis is detailed.

Headnote

Abstract

Objective: To present a number of cases with elongated styloid process (Eagle) syndrome and to discuss the clinical presentation of this disorder.

Methods: A clinical study of patients operated on at King Abdul-Aziz University Hospital, Riyadh, from 1992 to 1996.

Results: The study group consisted of seven patients (six females and one male ranging in age from 20 to 43 years). Symptomatically, two distinct groups of patients could be identified: the classic syndrome (including three patients), which occurs in the tonsillectornized patients, and the styloid-carotid artery syndrome (including four patients), which occurs independently of tonsillectomy. In the first type, patients usually complain of spastic and nagging pain in the pharynx radiating to the mastoid region. In the second group, patients usually complain of attacks of syncope in association with pharyngeal pain referred to the course of the carotid artery. Diagnosis is made by history taking, palpating the tonsillar fossa, and radiographic demonstration of the process. Three-dimensional computed tomography reconstruction images were found to be very reliable in measuring the actual length of the styloid process and the stylohyoid ligament.

Conclusion: This unusual disorder should be considered in the differential diagnosis of facial pain in some patients and as the cause of syncope in other patients. The paper discusses the embryologic, anatomic, pathogenetic, clinical, and therapeutic aspects of elongated styloid process with calcified stylohyoid ligament and the differential diagnosis is detailed.

Headnote

Key words: anatomy temporal bone, carotid artery syndrome, Eagle syndrome, glossopharyngeal neuralgia, hyoid bone embryology, styloid syndrome, three-dimensional computed tomography radiology

Sommaire

Objectif Presenter des cas de patients avec le syndrome de processus styloide allongee (Eagle) et d'en discuter la presentation clinique.

Methode: Etude retrospective de patients operes entre 1992 et 1996 a l'hopital universitaire King Abdul-Aziz, Riyadh, Arabie Saoudite.

Resultats: Sept patients ages entre 20 et 43 ans (6 femmes et un homme) forment le groupe a l'etude. Selon la symptomatologie, on peut distinguer deux groupe: Le syndrome classique (3 patients) qui n'arrive que dans le groupe amygdalectomise et la version stylo3de-artere carotide (4 patients) qui arrive independamment du statut des amygdales. Les patients du premier groupe se plaignent habituellement dune douleur lancinante et spasmodique du pharynx avec irradiation vers la mastoide. Dans le second groupe, les patients se plaignent d'attaques de syncope avec douleur pharyngee irradiant sur le trajet de la carotide. Le diagnostic se fait a I'histoire et a la palpation de la fosse amygdalienne. Le rayon-X confirme le diagnostic. La tomodensitometrie axiale en trois-dimensions est tres fiable pour mesurer la longueur de 1'apophyse et du ligament stylo-hyoidien.

Conclusions: Cette pathologie inhabituelle doit etre consideree dans le diagnostic differentiel des douleurs faciales et des syncopes. Ce papier discute l'embryologie, I'anatomie, la pathogenese, la clinique, le diagnostic differentiel et le traitement du syndrome d'Eagle.

Elongation of the styloid process has been well reported as a source of pain in the head and neck region. This condition is known as Eagle syndrome.l In the literature, little attention is given to the fact that the syndrome includes two distinct groups of patients: the classic syndrome-tonsillectomized patients and the patients with syncopes and carotidynia (pain referred into the distribution of the carotid artery).

This report describes seven patients seen in the Otolaryngology Department of King Abdul-Aziz University Hospital in Riyadh from 1992 to 1996. The report includes both types of the disease. The anatomic, epidemiologic, and pathogenic aspects of styloid elongation are discussed, and the literature dealing with the subject is reviewed.

Patients

Seven patients underwent surgery for symptomatic elongated styloid process in the otolaryngology department. There were six women and one man; the youngest patient was 20 years old and the oldest was 43 years old. Bilateral elongation of the process was demonstrated radiologically in all patients; however, only one patient was bilaterally symptomatic. Surgical intervention was conducted under general anaesthesia via a cervical incision in two patients and using the intraoral approach in the other five. There were no postoperative complications. The follow-up periods ranged between 18 months and 4 years with a mean of 2.6 years. All patients were completely relieved following surgery, and no recurrence was reported.

The clinical data on the patients are summarized in Table 1. Two cases, one case from each type of the syndrome, are described in more detail.

Case Reports

Case I

A 20-year-old female Saudi student complained of attacks of pain on the left side of the neck for 6 months, which appeared 6 weeks following tonsillectomy. The pain site extended from the hyoid bone to the mastoid process and sometimes radiated to the left ring and small fingers. The pain was dull aching and increased during speaking and coughing and was exaggerated when she became nervous and tense and not aggravated by moving the head from side to side. The patient denied any history of neck trauma. She had seen a number of physicians and dentists and was unable to get an explanation of her symptoms.

Table 1

Examination revealed mild pain by palpation of the left tonsillar fossa. Similar but less severe pain could be elicited in the right side. Neurologic examination was normal. Computed tomography (CT) to the neck demonstrated bilateral thick elongated styloid processes and ossification of the stylohyoid ligaments, which were not fused to the processes (Fig. 1). Images of threedimensional CT reconstruction showed the exact full lengths of the elongated styloid processes and the ossified stylohyoid ligaments (Fig. 2).

Surgical intervention for shortening of the left styloid process was conducted under general anaesthesia via intraoral approach. There was no postoperative complication, and the patient was completely relieved from the pain immediately following the operation. No recurrence was reported in the 4-year follow-up period.

Case 2

A 43-year-old Sudanese housewife complained of continuous pain in the right side of the neck and jaw extending upward toward the head and ear of several years duration. The pain was aggravated by deglutition. Also, she gave a history of intermittent swelling on the right side of her neck, intermittent frontal and temporal headaches accompanied by photophobia, and scintillations in the right eye. These symptoms were not associated with the "swallowing" pain. There was no family history of migraine. Dental and neurologic examinations revealed no abnormalities, except for slight anisocoria without ptosis or anhydroses. There was no carotid bruit or bulge, but her left carotid pulse was prominent. Deep palpation on the carotid reproduced her pain.

Diagnosis of styloid process syndrome was based on palpation of the tonsil, which produced the typical symptoms, and by the three-dimensional CT reconstruction images, which confirmed elongated styloid processes without calcification of the stylohyoid ligaments (Fig. 3). The right styloid process measured 2.67 cm and the left styloid process was 2.54 cm in length. The patient refused to have carotid angiogram.

Surgical shortening of the styloid process was performed via an intraoral approach under general anaesthesia proceeded by tonsillectomy in the usual way. The right elongated styloid was exposed by dividing the tonsillar bed muscle fibres over the tip of the process and extending the incision vertically upward. The muscles were retracted and the process was divided with bone-cutting forceps, starting at the superior end to avoid retraction of the free end by the muscular and ligamentous attachment.

The patient's symptoms were relieved immediately with no recurrence during a 24-month follow-up period.

Discussion

Figure 1

Figure 2

The styloid syndrome is named after Eagle,1,2 who was the first to focus attention on the styloid process as a cause of pain distinguishable from primary glossopharyngeal neuralgia. The syndrome is more frequent in women than in men.3 Patients are usually older than 30 years and rarely younger.2,3 It is of interest that the age of this series' patients ranged between 20 and 43 years. Bilateral elongation is quite common both clinically (by palpatory) and radiologically,4 although bilateral symptoms are very rare.5

The styloid process gives attachment to three muscles and two ligaments. Figure 4 (after Haas modification6) shows its relationship to the surrounding nerves.

Embryologically, the styloid process is part of the hyoid chain that is derived from Reichart's cartilage7 of the second bronchial arch and has four separate embry

1. The tympanohyal, which appears before birth and fuses to the petrous temporal bone to form the tympanic portion of the styloid process and the stapes.

2. The stylohyal, which appears after birth and forms the main body of the styloid process.

3. The ceratohyal, which becomes the stylohyoid ligament during the intrauterine stage. Calcifications of the stylohyoid ligament are found in up to 4% of the population.

4. The hypohyal, which forms the lesser corms and the upper part of the body of the hyoid bone.' Several theories have been suggested to explain the pathogenesis of the long styloid:

1. The persistence of the cartilaginous element connecting it to the temporal bone, which then becomes ossified into bone .2

2. Partial or total ossification of the stylohyoid ligament, in which the tip of the elongated process would correspond to the proximal part of the secondary ossified ligament merged with the process.8

3. Abnormal ossification in the styloid apparatus at the junctions of the embryologic components causing elongations or expansions in the bone. This may explain the tortuousity and the new bone formation of many styloid processes at the tendon's attachment.' This theory is based on the histologic evidence of metaplastic changes of the subperiosteal cells in the vicinity of the ligaments' insertion.

According to different reports, the normal length of the styloid process is 2.5 to 3 cm long, but considerable variation occurs from S to 7.5 cm.9 The prevalence of elongated styloid process varies in the literature. Eagle reported that about 4% of the population have elongation of the process.2 Kaufman et al. demonstrated 7.3%II radiologic elongation? The position and contour of the styloid process may be more important than length.' The process may be smooth and well corticated or it may be bulky with an irregular contour.

Neural and vascular structures and their relationship to the stylohyoid process are important in understanding the etiology of the symptoms described in Eagle syndrome. The tip of the normal styloid usually lies between the external and internal carotid arteries. The internal carotid artery, the internal jugular vein, and the accessory, hypoglossal, vagus, and glossopharyngeal nerves are medial and close to the stylohyoid apparatus. The external carotid artery is closely related lateral to the process.

There is controversy in the literature as to whether the syndrome truly exists. The problem of craniocervical pain and its many etiologies and the observation in many patients of asymptomatic elongated process have led some authors to question the cause-and-effect relationship of radiographic finding and the symptoms complex.10 Eagle has divided the styloid process syndrome patients into two groups according to the mode of presentation.1 The first group is the "classic styloid process syndrome" with symptoms of spastic and nagging pain in the pharynx radiating into the mastoid region. A feeling of a foreign body in the throat, dysphagia, or distortion of taste sensation may also be experienced. All of his original patients had had tonsillectomy with dense scar tissue in the tonsillar fossa. A hard mass was palpated in the fossa, which on radiography proved to be an ossified stylohyoid ligament. Palpation of the mass reproduced the symptoms. Eagle believed that the scar tissue has incorporated branches of the glossopharyngeal nerve, occasionally the fifth, and rarely the seventh or tenth cranial nerve. The second group of patients delineated by Eagle was the "styloid process-carotid artery syndrome," which may occur whether or not the tonsils have been removed. In this group, patients complain of pain in the neck at a point opposite the tonsillar fossa and extending upward over the side of the head along the distribution of the carotid artery. Also, intermittent frontal or temporal headaches, otalgia, or blackout spells can occur. Eagle postulated that this was due to outward elevation of the internal carotid artery by an underlying elongated styloid process.2 The tip of a styloid process of normal length lies between the internal and external carotid arteries just above the bifurcation, lying more externally than the external carotid artery.

Figure 3

Figure 4

There are several mechanisms that explain the exact cause of pain in the syndrome:

1. The pain may be the result of mechanical irritation of the pharyngeal mucosa from a fixed elongated styloid process in a highly mobile area.4 Also, pain may be produced by post-tonsillectomy fibrosis, causing stretching of the sensory nerve endings of the fifth, seventh, ninth, and tenth cranial nerves, all branches of which supply the involved area.2

2. Fracture of an ossified stylohyoid ligament by a sudden head movement and nonunion caused by constant movement of the hyoid bone. Subsequent proliferation of granulation tissue could cause pressure on the surrounding structures, resulting in pain.l

3. Pressure on the carotid artery by the styloid process that may affect the circulation and produces irritation of the sympathetic nerves of the arterial sheath and pain.2,4

4. Degenerative changes in the tendon of the stylohyoid muscle insertion called "insertion tendinosis."12 Similar phenomena are seen in other narrow-based muscle insertions, directly at their anchorage to the bone like "tennis elbow." Another cause of stylalgia in the absence of an elongated styloid process may be a hyoid bursitis.13

The following factors have been suggested to explain the development of pain in patients previously free of SyMptoMS3: rheumatic styloiditis caused by pharyngeal infections, trauma to the styloid process, scarring of tonsillectomy, and shortening of the cervical spines by degenerative changes affecting the styloid process direction.

The differential diagnosis of stylalgia should include all organic and inorganic causes of head and neck pain, especially other neuralgic pain. The glossopharyngeal neuralgia usually presents with severe recurrent lancinating pain of momentary duration and is frequently stimulated by hot or cold stimuli and sometimes by the slightest movements of the tongue. The pain from an elongated styloid process is usually nagging and rarely severe. The diagnosis of stylalgia is based on the physician's alertness to the syndrome, detailed history, palpation of the tonsillar fossa, and radiologic demonstration of the elongated styloid process.

The patient usually complains of the characteristic dull, nagging pain that becomes worse during deglutition. The pain is usually unilateral, extending from the hyoid bone upward toward the mastoid process or downward to the upper borders of the sternum.4 Clinical diagnosis is established by palpation of the styloid process through the tonsils or the lateral pharyngeal wall. A styloid process of normal length is usually not palpable.ls A firm, tender resistance represents an elongated styloid process. The specific painful symptoms may be elicited by palpation of the styloid process. The diagnosis can be confirmed if symptomatic relief follows local infiltration of the styloid process with an anaesthetic agent. The styloid process is felt as a bony cord or bony point. The longer the styloid process, the higher the positive results of palpation.16 The height of the patient, length and thickness of the neck, position (anterior and medial angulation) of the styloid process, and experience in palpation also affect the positive results of palpation. False negative results could be due to inadequate local anaesthesia, poor palpation technique, tonsil hypertrophy, profound tonsil adhesion, short index finger of the doctor, or if the styloid process is not impinging on the pharyngeal wall.

The suspected diagnosis of elongated symptomatic styloid process is confirmed by radiologic studies of the skull, plain x-ray tomography, and CT. Conventional CT of the cervical spine shows only elongated styloid process in the axial view. Three-dimensional CT reconstruction of the neck allows precise measurement of length of the elongated styloid process and the ossified stylohyoid ligament.

Conservative treatment like reassurance and diazepam, heat application,17 traditional Chinese medicine,14 and local infiltrations with anaesthetics or steroids17' have been described to alleviate symptoms of stylalgia with varying degrees of success. However, the most satisfactory and effective treatment is surgical shortening of the process via oral or external approach.

The intraoral approach is a simple surgical technique, is less time consuming, and avoids neck scarring. The process can be easily identified and excised in most cases. However, it may provide inadequate visualization of the bony process and its neurovascular relationship that increased the risks of trauma to the external carotid artery and to the facial nerve. The risk of bacterial contamination following the opening of the pharynx into the neck is minimized by the use of prophylactic antibiotics. The external approach that is carried via a neck incision provides an adequate exposure of the surgical field. However, it leaves an undesirable neck scar.

Conclusion

The Eagle syndrome deserves consideration in the work-up of patients with neck pain of obscure origin. The syndrome includes two groups of patients: the classic post-tonsillectomy syndrome patients and the styloid-carotid artery syndrome patients.

Seven cases of Eagle syndrome were reported and presented in detail, one case of each group with threedimensional CT reconstruction images demonstrating the exact length of the styloid process and the stylohyoid ligament. In the oral approach, the superior part should be cut first and then the inferior end of the styloid process and its calcified ligament to avoid its retraction by its muscular and ligamental attachment.

The embryology, anatomy, pathogenesis, diagnosis, and possible lines of treatment were discussed.

Acknowledgement

I would like to express my appreciation to the King Abdul-Aziz City for Science and Technology (KACST) as they provided me with the reference I need to complete my work and to Dr. Fawziah Al Kandari, Medical Labor, for her valuable advice throughout. Acknowledgement must be given to Dr. Yousry El Sayed for his fruitful review and to Mrs. Connie Unisa-Marfil for her secretarial work.

References

References

1. Eagle WW. Elongated styloid process. Report of two cases.

Arch Otolaryngol 1937; 25:584-587.

2. Eagle WW. Symptomatic elongated styloid process. Report of two cases of styloid process-carotid artery syndrome with operation. Arch Otolaryngol 1949; 49:490-503.

3. Harma R. Srylalgia. Acta Otolaryngol Suppl (Stockh) 1967; 244:149-155.

4. Kaufman SM, Elzay PR, Irish EG. Styloid process variation, radiological and clinical study. Arch Otolaryngol 1970; 91:460-463.

5. Strause M, Zohar Y, Laurian N. Elongated styloid process syndrome: intraoral versus external approach for styloid surgery. Laryngoscope 1985; 95:976-979.

6. Haas P, Beyer WF, Hirschfelder H. Das styloid-syndrome. Z Orthop 1991; 129:521-524.

7. Hamilton Wj, Boyd JD, Mossman HW. Human embryology. 4th Ed. Cambridge: W. Heffer & Sons, 1972:538-539. 8. Steinman EP. A new light on the pathogenesis of the styloid syndrome. Arch Otolaryngol 1970; 91:171-174.

9. Gossman JR, Tarsitano jj. The. stylohyoid syndrome. j Oral Surg 1977; 35:555-560.

10. Frommer J. Anatomic variations in the stylohyoid chain and their possible clinical significance. Oral Surg 1974; 38:659667.

11. Balasubramanian S. The ossification of the stylohyoid ligament and its relation to facial pain. Br Dent J 1964; 116: 108-111

References

12. Steurman EP. Styloid syndrome in absence of an elongated process. Acta Otolaryngol (Stockh) 1968; 66:347-356.

13. Nelson LA. Hyoid bursitis. Tex St J Med 1940; 36:435-438. 14. Zhang Y-Lin, Liao D, Wei Y, Bai G. Styloid process syndrome "length and palpation of the styloid process." Chin Med J 1987; 100(1):56-57.

15. Kelly RJ, Jackson FE, Delave DP, Dunn J. The Eagle syn

References

drome. Hemicrania secondary to elongated syCd Stylflld pigs.

IFS Navy Medical 1973; 65(4):11-16.

16. Paparella MM,A3; Shumrick DA, Meyerhoff Wi.; Seid AB. Otolaryngology head & neck. 1st Ed.; Vol. 3. PhiladElphia: WB Saunders, 1977:

17. 1i7. Styloid process syidtome or stylohyoid syndrome? Acta Otorhinolarygol BeIg Tome 1978; 32:27. 278.