Elongation Pattern of Styloid Process in Saudi Population: A Factor to Remember in the Prevention of Eagle Syndrome

Keywords

Elongated Styloid Process; Eagle Syndrome; Panoramic Radiograph.

Introduction

X-ray consider the window that view all activities of the human body, either normal anatomy the body or abnormal, physiological or pathological activities.

One of the divisions of x-ray is Orthopantomogram (OPG) or Panorama radiography which is a radiologic technique that provides an overview of the jaws and surrounding structures [1]. The panoramic radiograph enables the dentist to see a wide area of the maxilla and mandible. [2, 3] It considered one of the best imaging modalities to view the styloid process bilaterally [4]. The styloid process is a cylindrical bone that emerges from the temporal bone in front of the stylomastoid foramen. It usually around 25 mm in length, but it can vary from person to person, and even within the same person, from side to side [5].

Elongated SP has been examined in several populations by distinctive methods and techniques, either advanced or traditional. Wide variation prevalence of SP elongation was noted, extending from 4 to 30% [6].

Elongated SP comes usually with no symptoms. Eagle et al., [7] reported only 4 to 10.3% symptomatic cases characterizing Eagle syndrome or as it's also known styloid syndrome.

Eagle syndrome symptoms may include throat pain or foreign body sensation, dysphagia, or facial pain. It may also cause neck or throat pain that radiate to the ipsilateral ear [8]. The cause is unknown, but several hypotheses have been proposed, including congenital elongation due to the persistence of an embryonic cartilaginous outgrowth, calcification of the stylohyoid ligament, and development of bone tissue at the ligament's insertion [9, 10].

The styloid process can be assessed using an anatomical structure. An elongated styloid process and calcification of the stylohyoid ligament can be detected with proper clinical and radiographic examination [11].

This aim of this study is to determine the prevalence of styloid process patterns in Saudi population.

Materials and Methods

This cross-sectional study included 2010 digital PRs selected randomly for adult patients who visited five major hospitals in the Qassim region (Qassim University Dental Hospital, King Fahd Specialist Hospital, Buraydah Central Hospital, King Saud Hospital, and Alrass General Hospital) for dental treatment between January 2017 and December 2017. From a diagnostic standpoint, the included digital radiographs had to be adequate, with optimum contrast and density and no distortion or obscuring structure. Poor-quality radiographs with insufficient exposure times or incorrect angulations were removed from this study. All digital radiographs for adult patients that met the study's criteria were examined extensively, and the patients' demographic details, such as gender and age, was registered. Patient information was kept private. This research was carried out in strict compliance with the World Medical Association's Declaration of Helsinki, and it was approved by the Ethics Committee at the College of Dentistry, Qassim University (EA/501/2017).

The radiographs were collected from the hospitals' digital archives and imported into the College of Dentistry at Qassim University, Radiology department's computer system, where they were then displayed. Advanced digital radiograph imaging software (DIGORA ® for Windows 2.7; SOREDEX) was used to examine them.

A single professional oral and maxillofacial radiologist reviewed and interpreted all of the radiographs. In a darkened room, all of the radiographs were investigated on the same 21-inch LCD monitor resolution (1920 1200 at 60 Hz); the same environmental conditions prevailed during the examination of all of the radiographs (Figure 1, 2, 3, 4). Each original digital image was magnified using the software's magnification feature, then manipulated by the examiner to improve the image's contrast and brightness to provide the clearest image in the examined areas.

Sample divided into 1209 and 801 male and female respectively. They were aged between 20-75 years. Data were collected regarding age, gender and styloid process morphology based on Langlais’ classification [12] who classify the pattern of SP to 3 types. (Table 1). SPSS software version 20.0 was used to analyze the collected data with a confidence interval of 95%.

Results

Evaluating the styloid processes for 2010 panoramic radiographs divided into 1209 and 801 male and female respectively. Sample age ranged between 20 and 75 years old with a mean of 34.3 ± 13.9 years. The prevalence of type I elongation pattern (uninterrupted integrity of styloid process) was 382 cases (19.1%), of them, 207 and 176 male and female respectively. The mean age of positive type I is 38±13.9 years.

Type II (Pseudoarticulation pattern) showed in only 34 cases (1.7%), of them 18 and 16 male and female respectively with mean age 35±13.9 years. Type III was present by 92 cases (4.6%) divided into 60 and 32 male and female respectively with mean age 37±13.9 years. Normal SP (Non elongated SP; the tip of the process does not cross the mid portion of mandible body) was showed in 1502 (74.8%), of them 924 male and 578 female. Although there were no significant association between gender and SP elongation.

Considering the age variable, study find patients between 30-50 years significantly more affected with type I pattern. The least pattern prevalence was type II pattern, it was seen mostly in age group 26-40 with 2.4%. Type III most commonly seen in 26-40 age group with total percentage 7.4%. Normal SP was reported mostly in the youngest age group 18-24 years with 626 cases. ( Table 2).

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Figure 1:

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Figure 1. Radiograph show Type 0 elongated SP.

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Figure 2:

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Figure 2. Radiograph show Type 1 elongated SP.

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Figure 3:

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Figure 3. Radiograph show Type 2 elongated SP.

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Figure 4:

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Figure 4. Adiograph show Type 3 elongated SP.

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Table 1:

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Table 1. Type of elongated SP according to combined Langlais and modified MacDonald - Jankowski classifications.

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Table 2:

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Table 2. Descriptive analysis of study variables.

Discussion

Styloid process term is derived from the Greek word " Stylos " which mean a pillar. It's a cylindrical bone originated from the temporal bone frontal to the stylomastoid foramen [5].

The anatomy of styloid complex includes styloid process of the temporal bone, stylohyoid ligament and lesser horn of the hyoid bone. SP can be described as slender, pointed, bony projection from the inferior aspect petrous temporal bone. Usually, its length starting from a few millimeters to an average of 2.5 cm. Its proximal part is unsheathed by the tympanic plate, while muscles and ligaments are attached to its distal part [13, 14].

Styloid process had been classified by Langlais according to the type of elongation. Langali classified the styloid process elongation to three types of complexes. Type I, elongated; Type II, pseudoarticulated; and type III, segmented [12].

The diagnosis of elongation of SP were done depending on panoramic radiographs by many studies including Asutay et al. [15] on East Eagean, Gracco et al. [16] on Italian, Vieira et al. [17] on Brazilian and Sakhdari et al. [18] on Iranian. Other studies had evaluated the SP elongation based on dry skulls, including Vadgaonkar et al. [19] on indian, Sakaew et al. [20] on Thai, Custodio et al. [21] on brazilian, Natsis et al. [22] on greek.

Cone beam computed tomography can be used as an advanced diagnostic tool to assess the SP pattern, Buyuk et al. [23], Donmez et al. [24], and Öztunç et al, [25] used it on Turkish population, Kailasam et al [26], and Ramadoss et al. [27], on Indian population, Khairallah A [28], used it on Lebanese population, Andrei et al. [29] used it on Romanian population.

The normal length of SP ranges between 20 to 30 mm, below 20 mm considered as short SP. [30] While many studies suggest that SP considered elongated when it is longer than 30 mm. [20, 30- 32]. Although, there is limited number of studies consider the SP elongated when it exceeds 45 mm [33].

Our study found the prevalence of elongated SP in 36.8% of total samples, all 36.8% have SPs lengthening more than 30 mm and crossing the mid portion of mandibular body. While 56.6% of the samples have normal length SPs ranging between 20-30 mm and the tip of the process did not crossed the mid portion of mandible body.

In the present study, men were slightly more affected with different pattern of SPs, although no significant difference were proven considering male to female sample number.

Our investigation showed 293 out of 879 cases with unilateral elongated SPs while bilateral was reported in 586 cases. This is consisted with other studies including Sakhdari et al. [18], and Vieira et al. [17].

Further researches using CT or CBCT for a three-dimensional evaluation of the styloid process is required, to investigate in specific the prevalence of different pattern SP in Qassim population, Saudi Arabia.

Conclusion

Styloid process has many patterns and variations that could be detected on digital panoramic radiographs taken daily in most of dental clinics. Dentists should be trained to detect patients with such variation so that signs associated with Eagle syndrome are not misinterpreted.

Ethical Approval

This research was carried out in strict compliance with the World Medical Association's Declaration of Helsinki, and it was approved by the Ethics Committee at the College of Dentistry, Qassim University (EA/501/2017).

Data Availability

The collected data used to support the findings of this study were supplied by [Ministry of Health, Saudi Arabia,] under license and so cannot be made freely available. Requests for access to these data should be made to [Ministry of Health, Department of Dentistry, 00966937].