Elongated Styloid Process: A Morphometric Study, with Radiological Evaluation in Dry Human Skulls, with its Clinical Implications
Original Article
Anatomy Section
DOI: 10.7860/IJARS/2017/25195:2243
Elongated Styloid Process: A
Morphometric Study, with Radiological
Evaluation in Dry Human Skulls, with
its Clinical Implications
Apurba Patra, Rajan Kumar Singla, Harsimarjit Kaur, Rimple Bansal, Mannat Singla
ABSTRACT
Introduction: Length of Styloid Process (SP) varies widely.
It can be very short and hidden by vaginal process or it can
be elongated to reach hyoid bone. The antiquity anatomists
have been observing the incidence of elongated SP and
their correlation with occurrence of Eagle’s syndrome.
Aim: The present study aimed to determine the incidence
of the elongated styloid process, their anterior and medial
angulations and thickness in order to highlight their possible
etiological importance in clinical and surgical conditions.
Materials and Methods: The study was done on both
sides of 50 dry skulls without any obvious deformity. The
length, angulations and maximum thickness of the styloid
processes at base and tip were measured with the help of
Vernier calipers and expressed as mean±SD. Each skull
was carefully examined for the presence of elongated
styloid process (length > 30 mm). The skulls with elongated
SP were separated and further investigated radiologically
(digital X-ray) to know their morphology, radiographic
pattern of calcification and to classify them accordingly.
Results: Out of the 100 sides of 50 skulls, elongated SP
was observed on nine sides, amongst them five skulls
(10%) were with unilateral and two (4%) with bilateral
elongation of SP. The means of length, anterior and
medial angulations and thickness at the level of base and
tips of styloid process of right side were 21.90±8.603
mm, 57.50±2.682°, 65.48±2.426°, 4.30±0.248 mm and
2.26±0.279 mm, on the left side were 20.80±5.757
mm, 59.30±2.288°, 63.80±3.687°, 4.70±0.318 mm,
2.49±0.301 mm respectively. The data was statistically
compared between the right and left sides and found
to be statistically insignificant (p>0.05). Based on the
radiological evaluation of elongated SPs, type I (elongated)
morphology with partial pattern of calcification was found
to be most common.
Conclusion: Elongated SP (length>30 mm) was seen more
frequently unilaterally (10%) as compared to bilateral (4%).
When bilateral, it was more on right side as compared to
the left side. Whether normal or elongated, the length of
SP was more on right side as compared to the left side
and thickness at base and tip was more on left side as
compared to the right side. Thus, right SP grows more in
length while left grows more in thickness. An elongated SP
is important not only clinically but also academically and
ontogenically.
Keywords: Anatomic variation, Digital panaromic radiograph, Eagle’s syndrome, Stylohyoid ligament
Introduction
The Styloid Process (SP) is a slender and cylindrical bony
projection, arising from the base of the petrous temporal bone
[1]. Its base lies just in front of the stylomastoid foramen and
its tip projects in antero-inferior direction lying in between
internal and external carotid arteries and in relation to the
lateral pharyngeal wall and tonsillar fossa [2]. The structures
attached to it include three muscles namely styloglossus,
stylopharyngeus, stylohyoid and two ligaments namely
stylohyoid and stylomandibular. Laterally, the SP is covered
by the parotid gland [3]. Embryologically, SP originates from
the cartilage of the second pharyngeal arch along with the
stylohyoid ligament and the lesser cornu of hyoid bone;
together, these three structures form an apparatus known as
stylohyoid apparatus or stylohyoid complex [4]. The length of
the SP normally ranges between 20 and 30 mm [5] and varies
from person to person and even between the two sides of
the same individual. The SP longer than 30 mm is said to
be elongated. It may be unilateral or bilateral [6] and usually
accompanied by calcified stylohyoid and stylomandibular
International Journal of Anatomy, Radiology and Surgery. 2017 Jan, Vol-6(1): AO07-AO13
7
Apurba Patra et al., Elongated Styloid Process
www.ijars.net
ligaments. The elongation of the SP can trigger a series of
clinical symptoms such as odynophagia, dysphagia, pain in
cervicofacial region, tinnitus and trismus. The elongated SP
along with this set of clinical symptoms is known as styalgia or
“Eagle’s syndrome’’ [7]. The incidence of Eagle’s syndrome is
very controversial [8]. Eagle found the incidence of elongated
SP to be 4% in the general population, of which only 4%
display symptoms [7]. The SP presents with widely varied
morphology. The knowledge of the morphology of elongated
SP is immensely important to the ENT surgeons, Dental
surgeons, Anthropologists, Clinicians and Radiologists.
The prime objective of the present study was to know the
incidence of elongated SP, their angulations, thickness,
morphology and radiographic patterns of calcification in dry
human skulls.
Group A: Length of SP <30 mm on both the sides.
Group B: Length of SP >30 mm on one or both the sides
(Elongated SP). Group B was further divided into two
subgroups.
Subgroup B1 with elongated SP on one side only. Subgroup
B2 with elongated SP on both the sides.
Angulations were measured with the help of a protactor. The
medial angle was defined as the angle on the medial side of
SP between its long axis and the line connecting the bases of
both SP [Table/Fig-2a] while the anterior angle was measured
between Frankfurt plane and long axis of the SP on its anterior
side [Table/Fig-2b]. Measurements of all the parameters
studied were tabulated and compared between the normal
and elongated SP.
MATERIALS AND METHODS
This descriptive study was conducted on 50 dry human skulls
of North Indian origin, irrespective of sex, obtained from the
bone keeping room of Anatomy Department of Government
Medical College Patiala, India, during January to April in 2016.
The skulls of children, skulls with broken SP and skulls with
any pathological conditions were excluded from the study.
The present study mainly focused to estimate the incidence
of elongated SP, their length, thickness and angulations to the
different planes. The length and maximum thickness of the SP
(both at the level of its base and tip) were measured with the
help of digital Vernier calipers with the least count of 0.01 mm
[Table/Fig-1]. The base of SP was considered as the junction
of the petrous and tympanic portions of the temporal bone on
its Inferior surface [9]. SP with length more than 30 mm was
considered as an elongated SP [10]. According to the length,
the skulls were divided into two groups.
[Table/Fig-2a-b]: (a) Measurement of medial angulations with
protractor. Angle on the medial side of SP between its long axis and
the line joiningthe bases of both SP.
(b) Anterior angulations measured between the Frankfurt Plane and
the long axis of the SP on its anterior side.
Skulls with elongated SP were further evaluated radiologically
with digital X-ray to know their r (...truncated)
