Elongated styloid process and Eagle's syndrome L Montalbetti, D Ferrandi, P Pergami, F Savoldi Fondazione Istituto Neurologico, C. Mondino, Pavia, Italy Cephalalgia Montalbetti L, Ferrandi D, Pergami P, Savoldi F. Elongated styloid process and Eagle's syndrome. Cephalalgia 1995;15:80-93. Oslo. ISSN 0333-1024 A controversial entity, Eagle's syndrome, is reviewed. After an anatomical description of the maxillo-vertebro-pharyngeal region we summarize the causative, diagnostic and therapeutic aspects of the syndrome. Two different conditions are often report ed as Eagle's syndrome: one characterized by dysphagia and unilateral pharyngeal pain radiating to the ear and worsened by swallowing; the other characterized by pain in the head and neck region due to compression of the neurovascular structure by an elongated styloid process. The latter also includes typical cranial neuralgias (such as glossopharyngeal neuralgia) and carotidynia. We believe that the term "Eagle's syndrome" is legitimate only in the first case and in those "atypical" painful hea d and neck conditions related to an elongated styloid process and relieved by styloidectomy. We believe Eagle's syndrome deserves consideration in the International Headache Classification. € Eagle's syndrome, elongated styloid process, stylalgia, st ylohyoid syndrome L Montalbetti, Fondazione Istituto Neurologico C. Mondino, via Palestro 3, 1-27100 Pavia, Italy. Tel. ± 39 382 3801, fax. ±39 380 286. Received 8 June 1994, accepted 30 November 1994 The stylohyoid syndrome is a generally unknown and rarely identified anatomical and clinical entity involving the oro-maxillo-facial region. In 1937 Eagle (1) detailed the symptomatic mineralization of the stylohyoid-stylomandibular ligament complex. The anomaly had been described as early as 1652 by Marchetti, however (2). Eagle continued to study this condition, reporting more than 200 cases (1, 3-7). Eagle's syndrome has also been called: stylohyoid syndrome, styloid syndrome, elongated proce ss syndrome (8), stylalgia (9), styloid-stylohyoid syndrome (10), styloid dysphagia (11), chronic styloid angina (12), temporal rheumatic styloiditis (13), stylocarotid syndrome and the Garel-Bernfeld syndrome (14). Subsequent to Eagle's first descri ption the disorder has been documented in brief reports (15-58) and in comprehensive reviews (59-68). The Headache Classification Committee of the International Headache Society quoted the stylohyoid syndrome as "not sufficiently validated" (69). The aim of this work is to present a critical review of this controversial syndrome. History The first studies on the styloid process date back to the 16th century. In 1543, Vesalius observed some stylohyoid chain abnormalities in animals (70), and in 1652 Marchetti (2) first described an elongated styloid process, considering it to be a "pa raphysiologic" variant. Morgagni mentioned the anomaly in his Epistola in 1752 (71). By the end of the 19th century, numerous stylohyoid chain anatomical anomalies (72, 73), sometimes symptomatic (74-76), had been described and surgical removal was p roposed for symptomatic cases (77). Later the advent of diagnostic radiology led to the ante-mortem detailed imaging of these abnormalities. At the beginning of the 20th century, Dwight correlated facial-neck pain and anatomical variations of the stylohyoid ligament and provided one of the first insights into pathogenetics (78). During the same period, isolated anatomical and clinical obs ervations were reported (79-91), as well as cases of symptomatic fractures (92-94). Other major reviews were published in the 1930s (95, 96) and several cases were reported (97-99). Garel had already characterized "chronic styloid angina" in 1921, ho wever (12), while in 1932 Bernfeld (14) cited the "styloid process syndrome". From 1937 to 1949, Eagle carefully investigated the syndrome, which would later bear his name (1, 3, 5), pointing out that approximately 4% of individuals with an elongated styloid process suffered from facial-pharyngeal pain. Although Eagle suggeste d tonsillectomy as the causative event, in the same period Fritz evaluated 43 patients reporting that only 11 had had tonsillar surgery (100). Epidemiology There is great variability in the literature concerning the frequency of stylohyoid chain anomalies (10, 59, 60, 66, 101, 103-108) (Table 1). This is probably due to different criteria for radiographic evaluation and patient selection (101). Women (1 02) and