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Year : 2018  |  Volume : 9  |  Issue : 1  |  Page : 26-28

Bilateral elongated styloid process in human dry skull

1 Department of Anatomy, SRM Dental College, SRM University, Chennai, Tamil Nadu, India
2 Department of Anatomy, Indira Gandhi Medical College and Research Institute, Puducherry, India

Date of Web Publication16-Mar-2018

Correspondence Address:
Mr. P Ravi Shankar
Department of Anatomy, SRM Dental College, SRM University, Ramapuram Campus, Chennai, Tamil Nadu
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/srmjrds.srmjrds_68_17

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Introduction: Styloid process (SP) is a bony projection present anteromedial to stylomastoid foramen, projecting downward from the inferior surface of the temporal bone. The normal length ofSP ranges between 20 and 25 mm, elongated styloid process is also known as Eagle's syndrome, a rare condition that may irritates or disrupts adjacent anatomical structures. Objectives: To report a case of dry skull with elongated styloid process and to discuss possible risk of compression of neurovascular structures associated with it. Materials and Methods: Fifty three adult Human Dry Skull were measured for the following parameters using Digital Vernier Caliper in the Department of Anatomy, SRM Dental College, Chennai1. Length of SP2. Distance between the two Styloid processes at the base3. Distance between the two Styloid processes at the tip4. Thickness at the base of SP5. Distance between the SP and stylomastoid foramen. Results: Out of 53 adult dry skulls studied, one skull identified for bilateral elongated styloid process. The length of the right SP is 3.13 cm and of left is 3.17 cm. Thickness at the base of right SP was 5.6 cm, and the left was 4.7 cm. Distance between the two SPs at the base was measured as 6.93 cm whereas distance between the two SPs at the tip was found to be 5.64 cm. The distance between the SP and stylomastoid foramen on the right was 1 cm and on the left side was 1.2 cm. Conclusion: Although symptoms of Elongated styloid process (EPS) are well known in the literature, it is rarely on the forefront of the clinician's mind. Awareness of EPS and knowledge of the anatomy associated with it may help clinicians to differentiate from other Neurological conditions.

Keywords: Eagle's syndrome, styloid process, stylomastoid foramen

How to cite this article:
Shankar P R, Ananthi K S, Krishanan P L. Bilateral elongated styloid process in human dry skull. SRM J Res Dent Sci 2018;9:26-8

How to cite this URL:
Shankar P R, Ananthi K S, Krishanan P L. Bilateral elongated styloid process in human dry skull. SRM J Res Dent Sci [serial online] 2018 [cited 2023 Jun 7];9:26-8. Available from:

  Introduction Top

Styloid process (SP) is a slender needle-like projection, pointing downward from the tympanic part of temporal bone, located anterior to the stylomastoid foramen, derivative of the second brachial arch from the proximal surface of Reichert's cartilage. This process provides attachment to three muscles and two ligaments. They are styloglossus, stylopharyngeus, stylohyoid muscles, stylomandibular ligament, and stylohyoid ligament.[1]

The SP in some cases could enlarge and compress the structures that exit through the Jugular and hypoglossal canals. The stylohyoid ligament that extends between the SP and hyoid bone sometimes get ossified at the proximal end to form an abnormally elongated SP. It was Eagle in 1937, first defined “stylalgia” as an autonomous entity related to abnormal length of the SP or mineralization of the stylohyoid ligament complex and the pain related to this condition.[2]

  Materials and Methods Top

Out of 53 adult dry skulls studied in the Department of Anatomy, SRM Dental College, Chennai, one skull presented with elongated SP (ESP) [Figure 1]. The following parameters were measured using Digital Vernier Caliper.
Figure 1: Bilateral elongated styloid process

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  1. Length of SP
  2. Distance between the two SPs at the base
  3. Distance between the two styloid processes at the tip
  4. Thickness at the base of SP
  5. Distance between the SP and stylomastoid foramen.

  Results Top

The length of the right SP is 3.13 cm [Figure 2] and of left is 3.17 cm. Thickness at the base of right SP was 5.6 cm, and the left was 4.7 cm. Distance between the two SPs at the base was measured as 6.93 cm whereas distance between the two SPs at the tip was found to be 5.64 cm. The distance between the SP and stylomastoid foramen on the right was 1 cm and on the left side was 1.2 cm.
Figure 2: Measuring right styloid process with Digital Vernier Caliper

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  Discussion Top

The normal length of the SP is of approximately 25 mm, as described by Eagle; hence, any length exceeding that size would be considered elongated. However, some authors consider the SP elongated if the length is more than 30 mm. Studies performed by anatomists have proven that 2%–4% of the overall population have either an elongated or a calcified SP.[3],[4] The cause of elongation of the SP has not been fully elucidated. Several theories have been proposed.[5]

  • Congenital elongation due to persistence of a cartilaginous analog of stylohyoid
  • Calcification of stylohyoid ligament by unknown process
  • Growth of osseous tissue at the insertion of the stylohyoid ligament
  • Traumas and tonsillectomy.

There is a difference between true SP elongation and secondary ossification of the stylohyoid ligament. True elongation results in a smooth, regular, well-corticated bone of varying lengths projecting continuously from the skull base. Secondary stylohyoid ligament. Ossification usually results in an irregular surface with thickened areas that extend toward the lesser horn of the hyoid bone, usually with marked medial angulations. The ossified complex may be segmented with a thin cortex or a bulky irregular contour.[6]

Patil et al. (2014) stated that the interstyloid process distance at the base is 6.9 cm and at the tip was 6.4 cm, in our study, the interstyloid process distance at tip is narrow about 5.6 cm. Interstyloid process distance is clinically very important because it accommodates cranial nerves, larynx, esophagus, arteries and veins.[7] Over a 20-year period, Eagle reported over 200 cases and explained that the normal SP is approximately 2.5–3.0 cm in length. He observed that slight medial deviation of the SP could result in severe symptoms of atypical facial pain. As this space, accommodates vital structures of neck such as cranial nerves, larynx, esophagus, arteries, and veins,[8] the thickness of the SP at the base in our study on right side is about 5.6 cm and 4.7 cm on left side, thickness at the base is considerably higher in comparison with the studies conducted by the Margam et al., Rajanigandha Vadgaonkar and Sathish kumar et al. increased thickness at the base has greater risk in compressing the facial nerve. The distance between the SP and the stylomastoid foramen is 1 mm and 1.2 mm in the right and left sides, respectively, which does not coincide with the standard book of anatomy, very narrow space between the stylomastoid foramen and ST, will irritate the facial nerve. Eagle's syndrome is associated with unilateral or bilateral elongation of SP or stylohyoid ligament calcification. Patients with ES may present with a sore throat, ear pain, or even with foreign body symptoms in the pharynx secondary to pharyngeal and cervical nerve interactions.[9] Eagle describes two kinds of syndrome, classic styloid syndrome may occur after tonsillectomy with symptoms of dysphagia, odynophagis, and increased salivary secretion, foreign body sensation and sometimes vocal cord changes. The secondary stylocarotid syndrome caused by compression of stylohyoid complex exerting pressure on carotid arteries regardless of tonsillectomy and symptoms are caused by stimulation of sympathetic nerve plexus around the blood vessels.[10] Parietal headache, orbital pain can occur in severe case vision disturbances, and syncopal attacks can also occur.

Since the symptoms are variable and nonspecific, patients seek treatment in several different clinics such as otolaryngology, family practice, neurology, neurosurgery, psychiatry, and the last but not the least dentistry.[9]

ESP can be diagnosed and confirmed with lateral view of skull X-ray and skull base computed tomography scan. The symptoms can be relieved by either surgically or nonsurgically. A pharmacological approach by transpharyngeal infiltration of steroids or anesthetics in the tonsillar fossa has been used, and in surgical excision, the elongation will be made short by cutting it with the transtonsillar and external approaches, avoiding injury to the surrounding neurovascular structures.

  Conclusion Top

Patients complaining weakness in facial, tongue and pharyngeal muscles, syncope attack, should scrutinized for Eagle's syndrome. A clear anatomy about SP and clinical consequences due to its abnormal elongation is essential for neurologists, anatomists, psychiatrists, otorhinolaryngologists, and dentists.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Standring S. Gray's Anatomy: The Anatomical Basis of Medicine and Surgery. 40th ed. Edinburg: Elseiver Churchill Livingstone; 2008.  Back to cited text no. 1
Eagle WW. Elongated styloid process: Report of two cases. Arch Otolaryngol 1937:25:584-6.  Back to cited text no. 2
Keur JJ, Campbell JP, McCarthy JF, Ralph WJ. The clinical significance of the elongated styloid process. Oral Surg Oral Med Oral Pathol 1986;61:399-404.  Back to cited text no. 3
Buchaim RL, Buchaim DV, Shinohara AL, Rodrigues AC, Andreo JC, etal. Anatomical clinical and radiographis charecteristics of styloid syndrome (Eagle syndrome) a case report. Int J Morphol 2012; 30:701-4.  Back to cited text no. 4
Murtagh RD, Caracciolo JT, Fernandez G. CT findings associated with eagle syndrome. AJNR Am J Neuroradiol 2001;22:1401-2.  Back to cited text no. 5
Cawich S, Gardner M, Shetty R, Harding H. A post mortem study of elongated styloid processes in a Jamaican population. Internet J Biol Anthropol 2009;3:1.  Back to cited text no. 6
Kumar SS, Kumar ST, Morphometric study of styloid process the Temporal bone and its clinical importance. Int J Anat Res 2016;4:1.   Back to cited text no. 7
Breault MR. Eagle's syndrome: Review of the literature and implications in craniomandibular disorders. J Craniomandibular Pract 1986;4:323-37.  Back to cited text no. 8
Khandelwal S, Hada YS, Harsh A. Eagle's syndrome – A case report and review of the literature. Saudi Dent J 2011;23:211-5.  Back to cited text no. 9
Eagle WW. Symptomatic elongated styloid process; Report of two cases of styloid process-carotid artery syndrome with operation. Arch Otolaryngol 1949;49:490-503.  Back to cited text no. 10


  [Figure 1], [Figure 2]


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