A DIGITAL PANORAMIC RADIOGRAPH STUDY OF LENGTH OF STYLOID PROCESS IN NEPALESE POPULATION

Address for Correspondence: Dr. Arun Dhakal Assistant Professor, Department Of Anatomy, Chaitwan Medical College, Nepal. E-Mail: arund@mail.ru Introduction and Objectives: The mean radiographic length of the styloid process has been reported to be between 20 to 30 mm. Although the reason for its variable development is not clear, elongation of the styloid process is recognized as one of the numerous causes of pain in the craniocervical region. Length of the styloid process in the Nepalese population has not been carried extensively to date. With this in mind our study aims to measure the length of styloid process on panoramic radiographs and determine the variation in age, sex and sides of the elongated styloid process. Material and methods: A total of 200 digital panoramic radiographs which were available as soft copies in the department of Oral and Maxillofacial Radiology, Chitwan Medical College, were selected for the study. The unpaired t test, and two-way ANOVA were used for statistical analysis. Results: Elongated styloid processes were present in 36% of the panoramic radiographs. The mean lengths of the elongated right and left styloid processes were 33.57 ± 6.02 mm and 36.21 ± 6.47 mm, respectively and the difference between them was statistically significant. Mean length of the right and left side styloid processes in males was 33.37±6.5 mm and 36.41±7.3 mm, whereas in females it was 34.24±6.24 mm and 37.01±6.12 mm respectively. Conclusion: Elongated styloid process is frequently seen in the elderly population with no correlation to gender.

The length of the styloid process measures usually around 2 to 3 cm.When more than 3 cm it is called an elongated styloid process causing dull pain in the ears, throat or mastoid region, difficulty in swallowing, foreign body sensation, symptoms of temperomandibular dysfunction like limited or asymmetric jaw movements or even carotid artery compression syndrome with rare cases of strokes [3][4][5][6][7][8].Long styloid process was first described in 1652 by The styloid process (SP) is slender and pointed, and projects anteroinferiorly from the inferior aspect of the temporal bone.Its length varies, ranging from a few millimetres to an average of 2.5 cm.arises [1].

MATERIALS AND METHODS
This study involved a total of 200 digital panoramic radiographs which were available as soft copies in the department of Oral and Maxillofacial Radiology, Chitwan Medical College, of patients referred for radiography in the department.The selected radiographs were of patients above 10 years of age.Radiographs not showing or partially showing the styloid processes and having positioning and magnification errors were excluded from the study during the selection process.These radiographs were taken with a digital panoramic system (Gendex Orthoralix 9200) that used a fiber optic charged couple device (CCD) sensor as the image receptor.Exposure parameters used for the digital panoramic machine were 66 kVp, 12 mA current with an exposure time of 12 seconds as recommended by the manufacturer.The approximate length of the styloid process was measured with the help of the measurement tools accompanying the software (VixWin™ Platinum, Version 2).The magnification factor used for the machine was 1.27.The lengths of the styloid process were measured on its anterior aspect from the point of emergence of the process to their tips, regardless of whether or not the styloid process was segmented (    The radiographs of 200 patients were aged between 10 and 80 years.In  4]. Out of the 200 radiographs, 52 showed bilateral elongation of the styloid process and 20 showed unilateral elongated styloid processes (12 on the right side and 8 on the left side) [Table 5].Thus, 72 panoramic radiographs (36%) showed at least one elongated styloid process.In the 200 radiographs studied, a total of 400 styloid processes were evaluated.Out of these, 124 styloid (31%) were elongated [64 on the right side (51.61%) and 60 on the left side (48.38%)] [Table 2].Elongated styloid processes were more prevalent in the age group of 51 -60 years and in those > 70 years of age [Table 3].The morphological characteristics of the SP have been studied by several researchers [5,3,17,20,21] using different methodologies.The results of these studies show that the prevalence of elongated styloid process varies between 0,4-84,4% of the population.The result of our study is in agreement with literature.Various outcomes could be due to dissimilarity in the age group and sample size.Comparing the outcomes of the prevalence of elongated styloid process is impossible because of racial, ethnical, anatomical variations, differences in the procedure of measurement devices and observer variation.Study suggests that panoramic radiograph are a suitable tool for epidemiological studies [21] though precise evaluation using two-dimensional radiographic as panoramic radiographs could be challenging due considerations like projection, magnification and distortion of the styloid process [21].Elongated styloid process is often asymptomatic, and its pathogenesis is still unknown.Various hypotheses include ossification of the stylohyoid ligament, reactive metaplasia/ hyperplasia, anatomic variation, ageing, developmental anomaly and trauma leading to loss of elasticity in the stylohyoid ligament [21].Our result suggests that elongated styloid process is common in elderly people which may be due to the calcification of the stylohyoid ligament with aging [22].Also left sided elongated styloid processes were significantly much longer than the right sided elongated styloid processes.Concerning gender no statistically significant variation was observed in the unilateral, bilateral or overall elongation of the styloid process which is in agreement with other studies [4,23].

CONCLUSION
This study provides a data on elongated styloid process of Nepalese population visiting a tertiary center in the mid western part of Nepal.Elongated styloid process is commonly seen in the elderly people with no association to gender.

DISCUSSION
Arun Dhakal, Sushma Pandey.A DIGITAL PANORAMIC RADIOGRAPH STUDY OF LENGTH OF STYLOID PROCESS IN NEPALESE POPULATION.
Arun Dhakal, Sushma Pandey.A DIGITAL PANORAMIC RADIOGRAPH STUDY OF LENGTH OF STYLOID PROCESS IN NEPALESE POPULATION.with elongated styloid process.The mean lengths of the elongated right and left styloid processes were 33.57± 6.02 mm and 36.21 ± 6.47 mm, respectively.Age group between 21-30 years has a significantly smaller elongated styloid process than the other age groups.Length of the styloid process in relation to gender was insignificant [Table Table 1 length of the styloid process shows a positive correlation with age.Out of 200 there were 72 radiographs RESULTS

Table 1 :
Mean Length of the styloid process in different age groups.
Average length of the styloid (mm)

Table 2 :
Mean length of the left and right elongated styloid processes.
P value: 0.020 SD-standard deviation, SEM-Standard error of mean

Table 3 :
Difference between the mean elongations of styloid process according to age group.
a: difference statistically significant with age group 21-30 years b: difference statistically significant with age group 31-40 years c: difference statistically significant with age group 41-50 years

Table 4 :
Mean length of the elongated left and right styloid processes in the two sexes.

Table 5 :
The percentage distribution of unilateral and bilateral elongation of styloid process.