|Year : 2015 | Volume
| Issue : 1 | Page : 25-28
The styloid process: Morphological variations in South Indian population
Roopashri Rajesh Kashyap1, Rajesh Shanker Kashyap2, Vathsala Naik1, Raghavendra Kini1
1 Department of Oral Medicine and Radiology, A.J. Institute of Dental Sciences, Mangalore, Karnataka, India
2 Department of Periodontics, Yenepoya Dental College, Mangalore, Karnataka, India
|Date of Web Publication||10-Mar-2015|
Dr. Roopashri Rajesh Kashyap
Department of Oral Medicine and Radiology, A.J. Institute of Dental Sciences, Mangalore - 575 004, Karnataka
Source of Support: None, Conflict of Interest: None
Context: The styloid process is a cylindrical bony outgrowth located in front of the stylomastoid foramen and it extends from the temporal bone outward. Elongation of the styloid process may be responsible for the irritation of a number of structures coursing through the parapharyngeal space. The styloid process presents with varied morphology. Aims: This is a study carried out to analyze the prevalence of various morphological patterns of the styloid process in South Indian population. Subjects and Methods: A total of 1200 digital panoramic radiographs were analyzed for the morphological assessment of the styloid process. The types and the pattern of calcification were determined based on the classification proposed by Langlais et al. Statistical Analysis Used: Cross tabulation using SPSS version 16. Results: Among the types of the styloid process, elongated type was the most common type present on both the sides. Among the patterns of calcification, completely calcified was the most common type observed, followed by calcified outline pattern. Conclusions: It is important for the clinicians to be aware of the variations seen in the morphological pattern of the styloid process as panoramic radiograph is a routine screening radiograph. Our study contributes to the literature, adding important information about the diversity of the styloid process in the South Indian population.
Keywords: Calcification patterns, Eagle′s syndrome, Panoramic radiographs, Styloid process
|How to cite this article:|
Kashyap RR, Kashyap RS, Naik V, Kini R. The styloid process: Morphological variations in South Indian population. Indian J Otol 2015;21:25-8
| Introduction|| |
The styloid process is a cylindrical bony outgrowth located in front of the stylomastoid foramen and it extends from the temporal bone outward. Because of its strategic position, any abnormality in its structure may lead to nonspeciﬁc clinical symptoms, including pharyngeal pain localized to the tonsillar fossa, dysphagia, referred otalgia, foreign body sensation in the throat and temporary voice changes. These symptoms can be confused with various other diseases such as facial neuralgias, temporomandibular, oral and dental diseases. 
Styloid process elongation can be assumed if either the styloid process or the adjacent stylohyoid ligament ossiﬁcation shows an overall length of >30 mm. Elongated styloid process accounts approximately to 4-7% of the population and only 4% are symptomatic.  Studies in India have estimated that in 19.4-52.1% of the general population there was radiographic evidence of an elongated styloid process. 
Several imaging modalities are capable of detecting elongated styloid process such as plain radiographs, panoramic radiographs and computed tomography. Styloid process elongation could be an incidental ﬁnding in some asymptomatic individuals. Abnormal angulation rather than elongation of the styloid process may be responsible for the irritation of a number of structures coursing through the parapharyngeal space.  The styloid process is positioned between the internal carotid artery and external carotid artery and positioned posterolateral to the tonsillar fossa. Medial to the styloid process is the internal jugular vein along with cranial nerves VII, IX, X, XI and XII. Its tip is close to the external carotid artery laterally and medially, it is close to the internal carotid artery with sympathetic chain.  Precise knowledge about the anatomy of both normal and abnormal styloids is important for clinicians, surgeons, and radiologists. 
The aim of this study was to investigate the morphological characteristics of the mineralized styloid process with the help of digital panoramic radiographs.
| Subjects and Methods|| |
A total of 1200 digital panoramic radiographs, which were available as soft copies in the hard drive of the computer in the Oral Radiology Department of A.J. Institute of Dental Sciences were selected for the study. Only those radiographs, showing the styloid processes of both the sides were included while radiographs having positioning and magnification errors were excluded during the selection process. These radiographs were taken with a digital panoramic system (Kodak 8000C Digital Panoramic and Cephalometric System made in France by Trophy for Carestream Health, Inc., Toronto, Canada) under standard exposure factors, as recommended by the manufacturer. The selected radiographs were of patients above 10 years of age. The types and the pattern of calcification were determined for both right and left styloid process based on the classification proposed by Langlais et al.  [Table 1] and [Figure 1], [Figure 2], [Figure 3], [Figure 4]. The collected data were entered in a spreadsheet (Microsoft Excel 2007) and was analyzed using statistical analysis soft ware SPSS. (SPSS Inc. 1989-2007, Version 16, Team EQX, Chicago).
|Table 1: Classification of types and calcification patterns of the styloid process |
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| Results|| |
Among the 1200 radiographs available, only 507 radiographs were considered for the study. 258 radiographs were of females and 249 were of males. Among the types of the styloid process, type 1 (elongated) was the most common type present on both the sides [Table 2].
Among the pattern of calcification, completely calcified was the most common type observed, followed by calcified outline pattern [Table 3]. No significant difference was found in the type and pattern of calcification on right and left sides.
| Discussion|| |
The styloid process is a cylindrical, long cartilaginous bone located on the temporal bone in front of the stylomastoid foramen. The normal styloid process length is approximately 20-30 mm. The styloid process tapers toward its tip that lies in the pharyngeal wall lateral to the tonsillar fossa. The styloid process elongation is known as Eagle syndrome when it causes clinical symptoms such as neck and cervicofacial pain. It is assumed that these signs and symptoms originate from the compression of the styloid process on some neural and vascular structures in their vicinity. 
Embryologically, the styloid process, the stylohyoid ligament and the lesser cornu of the hyoid bone are developed from the second branchial arch cartilage called Reichert's cartilage. Because it is of the cartilaginous origin, the ligament has the potential to mineralize. There can be several variations of the styloid chain, including the length of the process, thickness of the segments, angle and direction of the deviation, and the degree of ossification.  Therefore, it is necessary to define the type of elongation and calcification of each styloid in order to describe its radiographic appearance. 
Awareness about the clinical and radiologic presentation of the styloid process elongation is important for all health practitioners involved in the diagnosis and treatment of head and neck pain. Eagle syndrome, sometimes called styloid or stylohyoid syndrome, is defined as the symptomatic elongation of the styloid process or mineralization of the stylohyoid ligament complex. Panoramic radiograph is a common modality for evaluating styloid process elongation. 
Various theories have been proposed to explain the ossification of stylohyoid ligaments, namely, theory of reactive hyperplasia, reactive metaplasia, anatomic variance, and aging and developmental anomaly, due to loss of elasticity in the ligament simulating tendinosis.  Morphometric and morphologic variations of the styloid process may be the important factors to be taken into account in the preparatory planning and during surgery. 
Literature search revealed various studies done to evaluate the morphological characteristics of the styloid process. Most of the studies from different parts of the world have shown type 1 being the most common type of the styloid process, followed by type 2 and type 3 similar to our study [Table 4]. ,,,, Most of the studies have shown the type A as the most common pattern of calcification ,, [Table 5]. In our study, type D was the most common pattern of calcification seen followed by type A. It is similar to the study conducted on a South Indian population by Sudhakara Reddy et al.
|Table 4: Comparison of various studies on types of calcification of the styloid process |
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|Table 5: Comparison of various studies on patterns of calcification of the styloid process |
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| Conclusion|| |
It is important for the clinicians to be aware of the natural variations seen in the morphological pattern of the styloid process as panoramic radiograph is a routine screening radiograph. Our study contributes to the literature, adding important information about the diversity of the styloid process in the South Indian population. However, the clinical importance of different morphological patterns has not been clearly understood so far. A radiographic classification of the styloid process may help to clarify the diagnosis and aid in surgical planning. Further evaluation needs to be done whether there is any increased chance for occurrence of Eagle's syndrome with any particular pattern of calcification.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]