Int J Pharm Bio Sci 2016 Oct ; 7( 4): (B) 503 -506
Original Research Article
Anatomy
International Journal of Pharma and Bio Sciences
ISSN
0975-6299
ASSEMENT OF STYLOID PROCESS LENGTH IN ORTHOPANTOMOGRAM
- A RADIOGRAPHIC STUDY
DIVYADHARSHINI1 AND JAYANTH KUMAR V2*
1
Undergraduate Student, Saveetha Dental College, Saveetha University, Chennai
Senior Lecturer, Department of Oral Medicine & Radiology, Saveetha Dental College,
Saveetha University, Chennai
2*
ABSTRACT
Styloid process is a process or projection from the skull base with a normal length of 2.5-3.0 cm. In
certain individuals for a variety of reasons there may be an elongation of styloid process. Abnormally long
styloid process becomes symptomatic in patients and manifest as Eagle’s Syndrome. The aim of our
study was to retrospectively measure the length of the styloid process on archived
Orthopantomograms(OPG). This study was carried out in the Department of Oral Medicine & Radiology,
Saveetha Dental College, Chennai. In this study a total of 132 OPG’s were included into the study. After a
preliminary assessment 32 OPG’s were excluded for dimensional distortions and 100 were taken for the
final assessment. This sample had a composition of 53 males and 47 females. The mean length of males
right and left styloid process was 3.34 cm±0.69 and 2.95 cm±0.62 respectively. The mean length of
female right and left styloid process was 3.35 cm±0.77 and 3.05cm ±0.76 respectively.This study
revealed that the length of the styloid process on the right side was higher than the average and the left
side was normal within limits.
KEYWORDS: Styloid process, Orthopantomograms, Eagle’s syndrome, Soft tissue calcification
JAYANTH KUMAR V
Senior Lecturer, Department of Oral Medicine & Radiology, Saveetha Dental College, Saveetha University, Chennai
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Int J Pharm Bio Sci 2016 Oct ; 7( 4): (B) 503 -506
INTRODUCTION
A process is defined as a prominence or projection or
outgrowth from a structure. The styloid process , which
is derived from the Reichert’s cartilage of the second
branchial arch, is a cylindrical bony projection, of
approximately 2 to 3 cm in length, located in the
temporal bone, immediately in front of the
1,2
stylomastoidforamen. The styloid process is a long,
slender and pointed bony process projecting
downwards, forwards and slightly medially from the
temporal bone. It descends between the external and
internal carotid arteries to reach the side of the pharynx.
It is interposed between the parotid gland laterally and
internal jugular vein medially. External carotid artery
crosses tip of styloid process superficially. Facial nerve
crosses the base of styloid process laterally after it
emerge from stylomastoid foramen.The mean
radiographic length of the styloid process is usually 2-3
3
cm. When the styloid process length is longer than 3
cm, then it is referred to as elongated styloid
process.Upon scrutinizing the literature, it is found that
2-28% of the population have an elongated styloid
process. The elongated styloid process, when it causes
pain on rotating head, dysphagia and referred otalgia is
known as Eagle's syndrome.
Eagle an Otorhinolaryngologist, first described on a case report of
elongated styloid pro cess, hence the nameEagle’s
4
syndrome in 1937. Eagle considered tonsillectomy
responsible for the formation of scar tissue around the
styloid apex, with consequent compression or stretching
of the vascular and nervous structure contained in the
retrostyloid compartment.However Eagle's syndrome is
also discovered in patient's who have never undergone
tonsillectomy. In such cases, it may be caused due to
ossification of stylohyoid ligament complex, abnormal
angulation of styloid process, ossification of muscular
tendons, fracture and medialization of the ossified
stylohyoid ligament with incomplete repair due to
continuous hyoid bone movements and formation of
excessive granulation tissue.Eagle's syndrome is
associated
with disorders
causing
heterotopic
calcification such as abnormal calcium-phosphorus
metabolism and chronic renal failure. The syndrome is
divided into two main sub types based on cranial nerve
impingement and carotid arterial impingement. In cranial
nerve impingement patient develops symptoms related
to compression and irritation of cranial nerves V, VII, IX
and X such as facial pain while turning the head,
dysphagia, foreign body sensation, pain on extending
tongue, change in voice, sensation of hypersalivation
and tinnitus or otalgia. Compression of carotid artery
produces vascular and ischaemic symptoms, eye pain,
visual symptoms, parietal pain and syncope. With this
background we had proceeded to perform a
retrospective study on archived orthopantomograms to
ascertain the length of the styloid process. Though there
have been few studies done in the past this study was
repeated for the fact that were no studies based on
Tamil Nadu population and the earlier studies had not
mentioned the exposure parameters clearly.
MATERIALS AND METHODS
The
study
was
conducted
on
archived
orthopantomogram radiographs available in the
Department of Oral Medicine and Radiology, Saveetha
Dental College, Chennai. These radiographs were from
patients who were subjected to radiographic
examination for other dental problems. A total of 132
radiographs of patients aged between 13 to 58 were
taken. From this group about 32 were excluded due to
poor diagnostic quality. The radiographs were exposed
with Orthophos Sirona XG 3D hybrid machine,Germany.
The exposures were taken at 60-64 kvp with 8-12 mA
depending on the built of the patient. Out of the
radiographs 53 were obtained from males and 47 from
females.The images were exported to Jpeg format in 1:1
proportions. Then the images were analysed with Adobe
Photoshop ver7.0,USA. The length of the styloid
process was measured from the base of the tympanic
plate to the tip of the process. The measurements were
recorded in mm due to the default nature of the software
and later the measurements were converted to cm for
easier comparison with the prior literature. Fig 1 shows
the sample measurement taken for one radiograph.
Statistical Analysis
The data obtained was tabulated using Microsoft
Excel,Redmond,USA. The results were analysed with
Statistical Package for Social Sciences,(SPSS)ver 17.0.
The expected statistical analysis was to compare the
mean lengths of the right and left sides, and between
genders. When the comparison was done between the
right and left side in the same the gender paired t test
was used and between genders comparison for the right
and left side was done with unpaired t test. The level of
significance was fixed at p of 0.05.
Figure 1
Opg showing the method of measuring
the styloid process length
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Int J Pharm Bio Sci 2016 Oct ; 7( 4): (B) 503 -506
RESULTS
The study evaluated 132 orthopantomographs. Out of these 32 were discarded for poor diagnostic quality. A final set
of 100 OPG's were taken for evaluation. Among the 100OPG's 53 (53%) were males and 47 (47%) were females. The
styloid process length was measured on the left and right sides. The results obtained in the study are tabulated
below.(table 1).
TABLE 1
The mean length of styloid process in males and females
Males
N=53
Females
N=47
Right
Left
3.34±0.69
2.95±0.62
3.35±0.77
3.05±0.76
The mean length of the styloid process on the right side for males was 3.34±0.69mm. The mean length of styloid process on the left side
was 2.95±0.62. The null hypothesis assumed was no difference in length between the males and females. For the given scenario the
statistical analysis performed was paired sample t test. The results were statistically significant (p<0.05) with the difference between the
right and left being different. (Table2)
TABLE 2
Comparison of the mean length of the styloid process in
the right and left side for males
Right
Left
Mean
3.34
2.95
S.D
0.60
0.62
P value
<0.05
The mean length of styloid process in the right side was 3.35±0.77mm and left was 3.05 ±0.76mm in the left side . The paired sample t test
analysis was performed which had yielded statistically significant (p<0.05) between the right and left sides. (Table 3)
TABLE 3
Comparison of the mean length of the styloid processin
the right and left sides for females.
Right
Left
Mean
3.35
3.05
S.D
0.77
0.76
P value
< 0.05
Since the above tests showed that there is significant difference in the lengths between the right and left sides, we proceeded for the
next analysis to compare the mean length of each side between genders.The mean length of males right styloid process 3.34±0.69mm in
53 males and the mean length of females right styloid process was 3.35±0.77mm in 47 females. For the given scenario the unpaired
sample t test was used. The test yielded non-statistically significant (p>0.05) accepting the null hypothesis that there is no difference
between right side of males and right side of females. (Table 4)
TABLE 4
Comparison of the mean length of the styloid process in the
right side length between males and females
Males
Females
Mean
3.34
3.35
S.D
0.69
0.77
P value
P>0.05
The mean length of males left styloid process was 2.95±0.62mm and the mean length in females are 3.05±0.76mm. The results showed no
statistically significant difference (p>0.06) between males and females based on unpaired sample t test . (Table 5)
TABLE 5
Comparison of the mean length of the styloid process
in the left side between males and females
Males
Females
Mean
2.95
3.05
DISCUSSION
"Styloid process" is derived from the Greek word 'Stylos'
meaning a pillar. The styloid process is a long, slender
cylindrical bone arising from the temporal bone in front
S.D
0.62
0.76
P value
P>0.05
of the stylomastoid foramen. Styloid process along with
its five attachments is termed as styloid apparatus. The
styloid apparatus consists of three muscles: stylohyoid,
styloglossus and stylophayngeous; and two ligaments:
stylohyoid
ligament
and
stylomandibular
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Int J Pharm Bio Sci 2016 Oct ; 7( 4): (B) 503 -506
ligament.Embryologically, the styloid process and its
st
nd
ligaments are derived from the 1 and 2 branchial
arches which also gives rise to Reichert's cartilage.
During the development of foetus, Reichert's cartilage
links the styloid bone to the hyoid bone. The entire
stylohyoid apparatus is developed from four segments.
Base of the styloid process from tympanohyal portion,
shaft of styloid process from stylohyal portion, stylohyoid
ligament from ceratohyal portion and lesser cornu of
hyoid bone from hypohyal portion. Elongated styloid
process was first reported by Eagle concerning findings
4
in dentomaxillofacial and ear-nose-throat patient.
Radiological normal length of styloid process measures
between 2.5 to 3cms. Above 3cm is considered as
elongated styloid process. The exact cause for styloid
process elongation is poorly understood and several
theories had been proposed for the elongation of styloid
process. It could be due to growth of osseous tissue at
the insertion of stylohyoid ligament or it could be due to
calcification of stylohyoid ligament due to unknown
process or due to persistence of cartilaginous analog of
6,7
stylohyal. Stylohyoid retains some of its embryonic
cartilage which results in varying degrees of ossification
and elongation of stylohyoid chain. The mean length of
males right and left styloid process was 3.34cm±0.69
and 2.95cm±0.62 respectively. The mean length of
female right and left styloid process was 3.35cm±0.77
and 3.05cm±0.76 respectively. These findings were
consistent with the study conducted by Gokce et al in
Turkey population where the mean length of styloid
process was found to be 3.81cm±6.2 in males and
8
3.66cm±6 in females. In several studies conducted by
various author reveals that the styloid processes were
elongated more in males when compared to females
and more on the left side when compared to the right
9-11
10
side.
According to Shah SP study , the percentage
of styloid process elongation was 61.25% in males and
38.75% in females and left side (32.5%) was more
commonly elongated than the right side(16.25%). In
11
Balcioglu HA et al study , the length of the styloid
process of males is statistically greater than the females
in all age groups and on both sides. Upon review of
Literature an anthropological observation, the length of
the styloid has been reported at 7.01 cm in a skull
12
specimen from Venezuela. In another anthropological
study of 110 skulls, only 5 skulls had elongation of
styloid processof which 3 had bilateral elongation and
13
only 2 had unilateral elongation. In our study the length
was greater on the right side than the left side. This
difference could be attributed to the ethnic difference as
the earlier studies were not based on the Tamil Nadu
population. The limitation of our study was that the
sample size was small with 100 OPGs and inter
observer bias was not evaluated.
CONCLUSION
Our study yielded the average length of the styloid
process which was consistent with the studies earlier
reported in the literature. Further large scale studies are
required to prove the validity of the results obtained and
to check for interobserver agreeability.
CONFLICT OF INTEREST
Conflict of interest declared none.
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