|Year : 2015 | Volume
| Issue : 4 | Page : 215-219
Evaluation of styloid process using digital panoramic radiographs
Manishkumar Shete, Yogita Khalekar, Raghvendra Byakodi
Department of Oral Medicine Diagnosis and Radiology, Vasantdada Patil Dental College, Sangli, Maharashtra, India
|Date of Web Publication||23-Nov-2015|
Department of Oral Medicine Diagnosis and Radiology, Vasantdada Patil Dental College, Sangli, Maharashtra
Context: The styloid process (SP) is an anatomical structure, whose clinical importance is not well understood. Proper clinical and radiographic evaluation can detect an elongated styloid process (ESP) and calcification of the stylohyoid ligament. SP is said to be elongated if it is longer than 3 cm in length. Anatomical variations are very common. It has been reported that 2-28% of the general population show radiographic evidence of mineralization of a portion of the stylohyoid chain. SP could be elongated although symptoms are present only in some individuals. Panoramic radiography is most economical and readily available imaging modality to view the SP bilaterally. Aim: The aim of this present study was to assess the SP on digital panoramic radiographs. Subjects and Methods: The study was conducted on 500 digital panoramic radiographs available as a soft copy in our Radiology Department. These radiographs were taken using a digital panoramic system. The radiographic length of the SP was measured on both sides using the measurement toolbars on the accompanying analysis software. Statistical Analysis Used: The collected data was entered in a spreadsheet (Excel 2007, Microsoft, Richmond, USA) and was analyzed using statistical analysis software (SPSS version 17, Chicago, USA). Results: Average length of SP on the left side was 34.54 ± 7.54 mm and 33.02 ± 6.70 mm in male and female population, respectively. The average length of SP on right side was 35.30 ± 7.46 mm and 34.54 ± 7.31 mm in male and female population, respectively. The length of both styloids increased with age and males had longer styloids than females. Elongated styloids were present in 82.2% of the panoramic radiographs. Langlais type I elongated styloids were more common than others. Conclusions: Panoramic radiography is useful for detection of an ESP and/or ossification of the stylohyoid ligament in patients with or without symptoms and helps to avoid a misdiagnosis of tonsillar pain or pain of dental, pharyngeal, or muscular origin.
Keywords: Anatomical variations, elongated styloid process, panoramic radiograph, stylohyoid ligament, styloid process
|How to cite this article:|
Shete M, Khalekar Y, Byakodi R. Evaluation of styloid process using digital panoramic radiographs. SRM J Res Dent Sci 2015;6:215-9
|How to cite this URL:|
Shete M, Khalekar Y, Byakodi R. Evaluation of styloid process using digital panoramic radiographs. SRM J Res Dent Sci [serial online] 2015 [cited 2019 Jul 18];6:215-9. Available from: http://www.srmjrds.in/text.asp?2015/6/4/215/170237
| Introduction|| |
The name styloid process (SP) was derived from the Greek word 'stylos' meaning a pillar. Embryologically SP, the stylohyoid ligament and the lesser cornu of hyoid bone are developed from the second brachial arch called Reichert's cartilage. Because of the cartilaginous origin the ligament has the potential to mineralize. The SP is a cylindrical, long cartilaginous bone which arises from the temporal bone in front of the stylomastoid foramen. The attached structures include stylopharyngeus, stylohyoid and styloglossus muscles, and stylohyoid and stylomandibular ligaments. Many nerve and vessels, such as carotid arteries, are adjacent to the SP. ,, The normal SP length is approximately 20-30 mm. The SP length which is longer than 30 mm is considered to be SP elongation (SPE). 
The SPE may cause symptoms such as dull aching pain localized in either or both the sides of the throat. The pain may be referred to the ear or mastoid region of the affected side. It may cause pain on swallowing (dysphagia) or an abnormal sensation of foreign body in the pharynx. More uncommonly symptoms, such as tinnitus or otalgia, may occur. When these symptoms are present, it is called Eagle's syndrome (ES).  There are various mechanisms for the stroke such as dissection, plaque formation, or rupture. However, in case of elongated styloid process (ESP), stroke can occur due to compression of carotid arteries. 
Shorter distance between the styloid and internal carotid artery is important risk factors for carotid artery dissection. 
The ES is diagnosed by both radiographical and physical examination. More commonly panoramic radiography is used to determine SPE. Computed tomography is useful for complimentary information to that provided by panoramic radiography. 
| Materials and methods|| |
A total of 500 digital panoramic radiographs available in our Radiology Department were selected for the study. We have selected all 500 radiographs in which SPs of both sides were seen clearly while radiographs having positioning and magnification errors were excluded during this selection process. These radiographs were taken with a digital panoramic system (Kodak 8000C, India) under standard exposure factors, as recommended by the manufacturer.
The selected radiographs were of patients above 18 years of age. The apparent length of the SP was measured with the help of the measurement tools on the accompanying software (Kodak, version 6.7, India). The magnification factor used for the machine was 1.29. The length of the SP was measured as the distance from the point where the SP left the tympanic plate to the tip of the process, regardless of whether or not the SP was segmented. SPs measuring more than 30 mm were considered as elongated. If the stylohyoid or stylomandibular ligaments were ossified, they were measured along with the SP, as part of the ESP because radiographically it is difficult to distinguish ossified ligaments from SP as a separate entity.
The type of elongation of the SPs was also classified as per Langlais et al. [Figure 1]. 
|Figure 1: The classification of elongated styloid process-type I: Elongated; type II: Pseudoarticulated; type III: Segmented|
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| Results|| |
The collected data were entered in a spreadsheet (Excel 2007, Microsoft, Richmond, USA) and were analyzed using statistical analysis software (SPSS version 17, Chicago, USA).
Of 500 patients, 448 patients showed ESP, 374 patients showed bilateral elongation, and 74 patients showed unilateral elongation, making a total of 822 ESP of 1000 correspond to 82.2% prevalence of ESP.
After evaluating all the radiographs for types of SP, we have found that on right side, 65.8% of the population had type I ESP, 17% had type II ESP, and 2.8% had type III and on left side, 64.4% of the population had type I ESP, 13.4% had type II ESP, and 1.2% had type III ESP [Figure 2],[Figure 3] and [Figure 4].
|Figure 2: The orthopantomogram shows a Langlais type I styloid process (arrow)|
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|Figure 3: The orthopantomogram shows a Langlais type II styloid process (arrow)|
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|Figure 4: The orthopantomogram shows a Langlais type III styloid process (arrow)|
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Correlation of length of SP with the age showed that length was increasing with the age advancement [Graph 1 [Additional file 1]].
The average length of SP on the left side was 34.54 ± 7.54 mm and 33.02 ± 6.70 mm in male and female population, respectively. The average length of SP on the right side was 35.30 ± 7.46 mm and 34.54 ± 7.31 mm in male and female population, respectively [Table 1].
Male population showed longer SP compared to female population.
| Discussion|| |
The ES is characterized by recurrent pain in the oropharynx and face due to an ESP or calcified stylohyoid ligament. The SP is a slender outgrowth at the base of the temporal bone, immediately posterior to the mastoid apex. It lies caudally, medially, and anteriorly toward the maxillo-vertebro-pharyngeal recess (which contains carotid arteries, internal jugular vein, facial nerve, glossopharyngeal nerve, vagal nerve, and hypoglossal nerve).
Eagle considered tonsillectomy responsible for the formation of scar tissue around the styloid apex, with consequent compression or stretching of the vascular and nervous structures contained in the retrostyloid compartment (in particular, the glossopharyngeal nerve and perivascular carotid sympathetic fibers).  However, ES is also discovered in patients who have never been subjected to tonsillectomy. So many other factors have been considered, such as the following:
- The ossification of the stylohyoid ligament complex, causing contraction of the stylopharyngeal muscle and stretching of the XII cranial nerve.
- The fracture and medialization of the ossified stylohyoid ligament, with incomplete repair due to continuous hyoid bone movements and formation of excessive granulation tissue.
- The ossification of muscular tendons leading to irritation of the structures nearby.
- The abnormal length associated with abnormal angulation of the SP.
An ESP occurs in about 4% of the general population while only small percentages (between 4% and 10.3%) of these patients are symptomatic. So, the true incidence is about 0.16%, with a female:male predominance of 3:1. Bilateral involvement is quite common but does not always involve bilateral symptoms. No significant difference is detectable between the right and left sides. 
"ESP" is a term used since the publication by Eagle in reports concerning findings in both dentomaxillofacial and ear-nose-throat patients. This term denotes an SP exceeding its normal length. Eagle's definition was: "The normal SP measures between 2.5 and 3 cm." His method of measurement was not described, but his examples showed lateral radiographs of the skull.  Today, reports concerning the SP and measurements of its length are mostly based on panoramic radiographs. However, the geometry does not correspond to that in Eagle's method, yet the values given in these studies relating to anatomy, clinical epidemiology, or anthropology for normal and ESPs are similar to those proposed by Eagle. For example, in a study presented by Gulnara Scaf titled, "Diagnostic reproducibility of the ESP," the ESP was considered to be present when the measurements were 30 mm or more. In this study, the prevalence of ESP was 12.6%.  Bozkir et al.  also considered the measurement of 30 mm or more as ESP in 100 panoramic radiographs of edentulous patients. In our study, the prevalence of ESP was 15.47% and all the patients were asymptomatic. Many other studies had also used similar criterion for ESP. ,,, The study conducted by Radfar et al. considered Calcified SPs longer than 30 mm were to be elongated and were used for this study; 220 panoramic radiographs (22%) revealed such elongated processes. This retrospective study indicated that there is no clinical significance when ESPs are found coincidentally.  Ilgüy et al. evaluated the PRs of 860 subjects in terms of SPE. Of these patients, 32 patients (3.7%) had SPEs.  Erol conducted a similar study performed on 900 panoramic radiographs of 900 patients. The SPs were found to be longer than 30 mm in 12 cases; in 8 of these cases, elongation was bilateral; and in 4 cases, it was unilateral, making a total of 20 elongated processes of a possible 1800 - An incidence of 1.1%. 
In our study, we have found 82.2% of the ESPs, this may be due to the difference in regional factors including dietary factors and ethnicity. In our study, we have found the incidence of ESP is more in male population, this finding correlates with the similar study done by More et al.  However, this finding differed from those of some other researchers, who found an increased incidence in females.  According to our knowledge, this is the first study done in Maharashtra population in India.
Patient head positioning is important in panoramic radiography because poor positioning techniques may result in structures lying outside the focal trough, causing images to be blurred and distorted with lack of definition. The distortion can create images that are either too wide or too narrow, depending on whether the structures are on the film or source side of the focal trough.  This highly suggests the re-evaluation of standards which explain the elongation of SP on panoramic radiography.
| Conclusion|| |
Panoramic radiography is useful for detection of an ESP and/or ossification of stylohyoid ligaments in patients with or without symptoms and can thus help avoid misinterpretation of the symptoms as tonsillar pain or pain of dental, pharyngeal, or muscular origin. Due to the medial angulation of the SP and superimposition of other skeletal structures, some errors may occur when measuring the length of the styloid. Further imaging studies are required to correlate the symptoms with an ESP as well as with the type and pattern of elongation of the SP.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]