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Table of Contents   
ORIGINAL RESEARCH  
Year : 2011  |  Volume : 22  |  Issue : 5  |  Page : 673-677
Elongated styloid process: Is it a pathologic condition?


1 Department of Oral & Maxillofacial Radiology, Dental Research Center, Faculty of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran
2 Department of Oral Medicine, Dental Research Center, Faculty of Dentistry, Mashhad University of Medical Sciences, Mashhad, Iran

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Date of Submission17-Dec-2009
Date of Decision16-Jul-2010
Date of Acceptance10-Nov-2010
Date of Web Publication7-Mar-2012
 

   Abstract 

Objectives: The aims of this study were to evaluate the length, morphology, and calcification patterns of the elongated stylohyoid process (ESP) on panoramic radiographs and to investigate the symptoms related to it. We then addressed the question: Is ESP a pathologic condition or a physiologic phenomenon?
Materials and Methods: In this study, 207 stylohyoid complexes were evaluated based on length, radiographic appearance, and calcification pattern on panoramic radiographs. Similar to previous studies, we considered 30 mm as a threshold for elongation of the process. Complexes were classified into two groups based on length: ESP (greater than or equal to 30 mm) and normal (less than 30 mm). Clinical symptoms were evaluated by using a questionnaire and clinical examination. Data were analyzed by the Kolmogorov-Smilonov test, Mann-Whitney U test, and Spearman correlation.
Results: The average length of the stylohyoid complex was 31.7 mm. The median was 30.0 mm and corresponded to the threshold for the ESP. The Spearman correlation between the length of the complex and age was 0.323 (P=0.0001). "Continuous" and "calcified outline" were the most frequent morphology and calcification pattern, respectively, for both groups. Clinical symptoms related to ESP were not detected.
Conclusion: Classification of the stylohyoid complexes based on apparent length on panoramic radiographs in elongated and normal types appears to be incorrect. Considering that the radiographic appearance of the ESP and normal groups was similar and pathologic symptoms were not detected and that there was a relationship between age and length of the complex, elongation of this complex can be considered as a physiologic phenomenon.

Keywords: Calcification, panoramic radiography, stylohyoid complex

How to cite this article:
Anbiaee N, Javadzadeh A. Elongated styloid process: Is it a pathologic condition?. Indian J Dent Res 2011;22:673-7

How to cite this URL:
Anbiaee N, Javadzadeh A. Elongated styloid process: Is it a pathologic condition?. Indian J Dent Res [serial online] 2011 [cited 2014 Oct 1];22:673-7. Available from: http://www.ijdr.in/text.asp?2011/22/5/673/93455
The styloid process (SP) arises from the temporal bone immediately in front of the stylomastoid foramen. Its shape is cylindrical, tapering gradually toward the apex. The apex of the SP is clinically important because it is located between internal and external carotid arteries, just lateral to the tonsillar fossa within the lateral pharyngeal wall. The tip of this process is continuous with a ligament that extends to the lesser cornu of the hyoid bone.

In the panoramic radiographs, the stylohyoid complex is observed to have different morphology and sizes. [1] This type of radiography is used frequently by dentists, and sometimes some of the clinical symptoms, such as facial pain, chronic headache, throat discomfort, otalgia, dysphagia, difficulty in swallowing, and the sensation of a foreign object lodged in the throat, are related to the size of this complex. [1],[2],[3],[4],[5]

Relation of a few syndromes, such as Eagle and stylohyoid syndrome, with this process has been reported, but there are controversial reports in the relationship between the prevalence of clinical symptoms and the length of this process. [1],[2],[6],[7],[8]

For size and morphology of the stylohyoid complex, different classifications are used. [1],[6],[9] On the basis of size, this process is divided into two types, normal and elongated. The threshold for elongation is highly variable and, depending on the publication, has a range from 25 to 40 mm and more. [1],[2],[9],[10],[11],[12] But many publications consider 30 mm as the threshold. [2],[6],[8],[13],[14],[15],[16],[17],[18] Lengths under this threshold are normal, and lengths above this are considered elongated, or are occasionally called "abnormal." [13]

In this article, we studied the size, morphology, calcification pattern, and clinical symptoms related to the stylohyoid process.


   Materials and Methods Top


For the purpose of this cross-sectional study, panoramic radiographs of 108 unselected patients (73 female/35 male) aged 9 to 70 years (33.1 ± 1.9) were used, and 207 stylohyoid complexes were radiographically evaluated. Nine stylohyoid complexes were not clearly identified and, therefore, were withdrawn from the measurements.

All panoramic radiographs were made and evaluated in the same fashion. The lengths of stylohyoid complexes were measured directly on the radiographs with a ruler in millimeters from the caudal margin on the tympanic pleat to the tip of the stylohyoid complex. Clinical symptoms possibly related to the elongation of the stylohyoid complex were listed for patients on a questionnaire, and patients were asked to provide a positive or negative response to each symptom. If any sign or symptom was present, an expert in oral medicine evaluated the patient to determine the cause.

On the basis of previous studies, the stylohyoid complex length was considered elongated or as an elongated stylohyoid process (ESP) when it was equal to or longer than 30 mm and normal when it was shorter. [2],[6],[8],[13],[14],[15],[16],[17],[18]

The morphology of the stylohyoid complexes was classified according to three types [Figure 1]:

Type I - continuous. The radiographic appearance is characterized by an uninterrupted integrity of the stylohyoid complex regardless of its length.

Type II - segmented. This type consists of either short or long noncontinuous portions of the stylohyoid complex.

Type III - pseudoarticulated. In this type, the portions of the stylohyoid complex are apparently joined to each other.
Figure 1: The morphology of the stylohyoid complex. (a) Continuous (uninterrupted integrity of the stylohyoid complex); (b) pseudoarticulated (the portions of the stylohyoid complex are apparently jointed to each other; (c) segmented (noncontinuous portions of the stylohyoid complex)

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According to the classification of Langlais, there are four types of calcification patterns [6] [Figure 2]:

  • Calcified outline. This describes a thin radiopaque border with a central radiolucency that constitutes the majority of the process. This pattern is reminiscent of the radiographic appearance of a long bone.
  • Partially calcified. This describes a process that has a thicker radiopaque outline and almost complete opacification but small, sometimes discontinuous, radiolucent cores.
  • Nodular. This complex has a knobby or scalloped outline. It may be partially or completely calcified with varying degrees of central radiolucency.
  • Completely calcified. This process is totally radiopaque, with no evidence of a radiolucent interior.
Figure 2: Calcification patterns. (a) Calcified outline (a thin radiopaque border with a central radiolucency); (b) partially calcified (a thicker radiopaque outline and almost complete opacification); (c) nodular (a knobby or scalloped outline, with varying degrees of central radiolucency); (d) completely calcified (totally radiopaque)

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The length, morphology, and calcification pattern of the stylohyoid complex were determined for each patient. One-sample Kolmogorov-Smirnov, Mann-Whitney U, and bivariate correlation tests were used for data evaluation.


   Results Top


The one-sample Kolmogorov-Smirnov test showed that our data had no normal distribution (P=0.02).

Of 207 stylohyoid complexes, the range in length was 15-80 mm and the mean and median were 31.7 ± 1.5 and 30.0 mm, respectively.

One hundred and six (51.2%) stylohyoid complexes showed ESP. The length of the chain in this group was equal to or greater than 30 mm, while others had a normal length.

The Mann-Whitney U test showed no statistically significant differences in stylohyoid length between male and female subjects (P=0.1). The Spearman correlation coefficient between SP length and age was 0.323 (P<0.001). This finding indicated that the SP length was associated with increasing age [Figure 3].
Figure 3: The Spearman correlation coefficient between styloid process length and age (R=0.323)

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The most common morphology in both the ESP and normal groups was continuous, but segmentations and pseudoarticulation in the ESP group were more common than in the normal group [Figure 4].
Figure 4: The prevalence of the stylohyoid complex morphology in ESP and normal groups

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A calcified outline of the stylohyoid complex was the most common pattern in both the ESP (51.9%) and normal (49.1%) groups [Figure 5].
Figure 5: The prevalence of the stylohyoid complex patterns in ESP and normal groups

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Fifteen percent of evaluated subjects gave positive responses to the questionnaire. These patients had stylohyoid complexes with a 36.9 mm mean length. The most common symptom was frequent dizziness followed by frequent headaches (11.1%) [Table 1].
Table 1: The prevalence of symptoms

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Evaluation of patients with positive symptoms revealed that none of the symptoms were related to the stylohyoid complex. Anxiety, TMJ disorders, dental problems, migrain headaches, and systemic diseases were the most common etiologies.


   Discussion Top


In previous studies, the mean length of stylohyoid complex was shown to be variable, ranging from 10 to 36 mm. [9],[13],[19],[20] In our study, the mean length of the stylohyoid complex was 31.7 mm. Difference in this amount in different studies may be due to the average of the age samples because we found a relationship between age and the stylohyoid complex length. Other studies have also shown this relationship. [1],[9],[11],[13],[15],[21],[22],[23]

On this basis, ossification of the stylohyoid complex must be considered as a physiologic age phenomenon. However, Brenfied et al. believed that ossification of the stylohyoid process is completed 5-8 year old individuals/children and that no elongation occurs after this. [24]

The thresholds for the ESP quoted in the literature are different, but many of the studies consider 30 mm to be the threshold. [2],[6],[8],[13],[14],[15],[16],[17],[18] We too consider this as the threshold but believe this length does not respect the natural variation of the SP.

The median in our sample corresponded to the threshold for the ESP. Our results indicate that this threshold is too low since this has exceeded in 50% of normal patients.

Many factors, such as magnification of the different panoramic machines, the angle between the stylohyoid complex and the cranium base, and race of the patients, can affect the apparent length of the stylohyoid complex in the panoramic radiographs. Therefore, the apparent length of the stylohyoid complex cannot be considered as a scientific and valid criterion for classifying patients in the normal and elongated (abnormal) groups. Different values of ESP prevalence in the right and left sides and between males and females were reported even by researchers who agreed on the threshold for elongation. This confirms our hypothesis. [7],[14],[15],[16],[18],[21],[25],[26]

In this study, the most common morphology was the "continues" type in normal and ESP groups. A relationship between this morphology and the side of the complex or gender of the patients was not found, but segmented and pseudoarticulated types in the ESP group were more common than in the normal group. This may be due to the separation of the ossification centers in the stylohyoid complex, then the separated ossified segments joining to each other and building another morphology. The three muscles that stick to the SP (styloid m, styloglossus m, stylopharyngeus m) may affect the morphology of the ossified ligament.

The most common pattern of ossification was calcified outline in both groups. In previous studies of the ESP, complete and partial calcification were the most common patterns, but findings in other studies were similar to our results. [7],[27]

In our study, no patient symptom related to the length of the SP and the symptoms were due to other causes.

The incidence of stylohyoid complex symptoms appears to be rare, and this is supported by findings in the literature. [2],[6],[7],[8] As the apex of the stylohyoid is located between the internal and external carotid arteries and next to the nerves, it is possible that the distance from these organs has a role in the incidence of clinical symptoms. [28]

Our findings showed the following:

  • Many factors have affected the stylohyoid process apparent length on panoramic radiographs;
  • 50% of patients fall into the ESP group;
  • Radiographic appearance in the ESP and normal groups is similar;
  • There is a relationship between age and length of the complex;
  • We found no clinical symptom related to the ESP.
We concluded that classification of the stylohyoid complexes based on apparent length on panoramic radiographs into two types (elongated and normal) seems to be incorrect because there is no evidence of abnormality.

The situation and relationship of the stylohyoid complex to other organs are more important than its length for the incidence of clinical symptoms; therefore if any symptom was mentioned by the patient, advanced radiographic techniques, such as three-dimensional CT, are necessary for evaluation. Finally, we conclude that the elongation of the stylohyoid complex is a physiologic phenomenon but not a pathologic condition.


   Acknowledgments Top


This study was supported by the research center of Mashhad University of Medical Sciences. We wish to thank Dr. Ali Bagher pour for his valuable help.

 
   References Top

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Correspondence Address:
Najmeh Anbiaee
Department of Oral & Maxillofacial Radiology, Dental Research Center, Faculty of Dentistry, Mashhad University of Medical Sciences, Mashhad
Iran
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DOI: 10.4103/0970-9290.93455

PMID: 22406712

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