Case Report : A 42-year-old Caucasian
male was referred complaining of discomfort and
swelling in the right submandibular region which
intermittently increased in size and subsided
over several days, but was not related to
mealtimes. A sharp pain was also present on
yawning and sudden movement of the head over
a period of one year. There was no relevant
medical history. On examination, a large bony
hard swelling was palpable over the whole of the
right submandibular region.
A panoramic radiograph showed that the right
stylohyoid ligament had calcified in one piece
from the base of the skuil to within 2 mm of the
lesser cornu of the hyoid borie. Its width was
irregular ranging from 7 to 21 mm and the hyoid
end widened out with a concave surface, giving
an appearance analagous to the epiphysis of a
limb bone. The left stylohyoid ligament was also
calcified, but to a lesser degree. A retained
root was present in the left lower first molar
region associated with a radicular cyst 0.75 cm
in diameter.
Discomfort was felt in the posterior region
of the floor of the mouth on sucking a Vitamin C
tablet and therefore a sialogram of the right
submandibular gland was performed. There was no
duct dilation, but the gland and the proximal
end of the main duct were displaced laterally by
the calcified stylohyoid ligament. Complete
clearance of contrast in less than 3 min after
removal of the catheter demonstrated excellent
glandular function.
A CT scan was undertaken to exclude other
pathology. The enlarged styloid process was
shown to be intimately related to the medial
surface of the right submandibular salivary
gland and the lateral displacement of the gland
confirmed. A 3-D reconstruction of this reaion
showed the gross enlargement of the right
styloid process. In spite of this enlargement,
the patient did not feel that the intermittent
nature of the discomfort was sufficient to
warrant surgical interference and he has
therefore been kept under review. The left lower
first molar root together with the associated
radicular cyst was removed under local
anaesthesia.
Discussion : The styloid process and
stylohoid ligament are remnants of the second
pharyngeal arch cartilage. The unossified
cartilage disappears and its perichondrium
persists as the ligament. Hence the styloid
process can elongate to a variable length,
potentially impinging on adjacent structures,
causing a variety of symptoms. The dissimilarity
in the diameter and length of the right and left
stylohyoid ligaments in the case illustrated is
difficult to explain. Statistics show that
between 2% and 4% of the general population
present radiographic evidence of mineralisation
of the stylohyoid compleX2 but the majority of
these arc reported to bc symptomless. The
unusual presenting féatures of the right
stylohyoid ligament in this case appear to bc
dictated more by the direction of the
enlargement than its size.
Since Eaglel first reported this condition,
a variety of associated clinical features have
been listed of which pain, migranous headache, a
foreign body sensation in the throat and
difficulty in swallowing have been commonly
described. Local symptoms of pain may be present
in the region of the ear, temporomandibular
joint or in the neck, especially on turning the
head. Originally, Eagle described two distinct
syndromes, the classic styloid and the carotid
artery syndromes. The classic styloid process
syndrome was thought to manifest predominantly
following tonsillectomy and rarely prior to it.
The explanation given was that after a
tonsillectomy, discomfort may occur due to
stretching or compression of nerve endings of V,
VIII, IX or X cranial nerves because of fibrous
tissue formation in the tonsillar fossa near the
elongated styloid process. The carotid artery
syndrome which is due to pressure of the
elongated styloid process on the sympathetic
nervous tissue in the walls of the carotid
arteries, is not dependant on
tonsillectomy.
An appreciation of the anatomy in this
region shows that the medial surface of the
submandibular gland in its posterior part is
directly related to the stylohyoid ligament.
Therefore an enlarged stylohyoid apparatus could
cause pressure symptoms resulting in
intermittent obstruction of the salivary gland
system. Although the mechanism of yawning is
not fully understood, it is generally known that
the stylohyoid apparatus bears an intimate
relationship to the structures of the tongue,
the lateral wall of the oropharynx and larynx
that are involved in the process of yawning.
The diagnosis was confirmed by the presence of
an acute swelling on sucking a Vitamin C tablet,
the presence of a grossly enlarged and calcified
stylohyoid ligament on routine radiography,
absence of intraglandular pathology on the
sialogram and the displacement of the salivary
gland by the stylohyoid apparatus as shown on
both sialography and CT. When discussing the
differential diagnosis of submandibular salivary
gland obstruction and pain on yawning, an
enlarged stylohyoid ligament should be
considered as a contributing cause.
