Variation in the size of the styloid process
and the amount of ossification of the stylohyoid
ligament has been known by anatomists for
centuries. During the last 100 years there have
been sporadic reports of clinical symptoms both
before and after trauma (3, 4). The amount of
trauma associated with fracture of the styloid
process varies considerably in published
reports. In patients with minimal trauma or when
fracture is related to normal actions such as
yawning (4), a high index of suspicion is
helpful in making the diagnosis because the
elongated styloid process may be difficult to
image radiographically. Two cases are presented
that display the variability of clinical
setting, symptomatology, and methods of
diagnosis.
CASE REPORTS
Case 1. A 30-year-old female radiology
technician reported she got up quickly from bed
during the night, and felt weak shortly before
falling. After the fall she complained of
headache, neck pain, and difficulty swallowing.
Skull and cervical spine X-rays were interpreted
as negative but the pain was sufficient for her
to remain hospitalized for 1 day. CT scan of the
head, done because of persistent headache, was
negative. Review of the cervical spine and skull
X-rays showed a fracture of an elongated Ieft
styloid process. This was visible only on one
film (Fig. 1) of the anterior-posterior,
lateral, and oblique series. The patient was
discharged with a neck collar and analgesics and
slowly improved with conservative therapy. No
surgical excision of the bony fragment was
considered necessary.
Case 2. A 28-year-old male was admitted to
the emergency room shortly after a road traffic
accident. Upon initial evaluation and
resuscitation, the patient was unresponsive to
pain, with fixed pupils of 8 mm and
Cheyne-Stokes breathing. A 3 X 5 cm slightly
ecchymotic area of swelling was seen in the left
neck. No carotid artery abnormality was noted
and no facial injuries were present. The
mandible was intact. A CT scan of the head
showed considerable brain edema and only a small
subdural collection of blood. Scans were
continued without angulation at 10-mm increments
through the neck where a fracture of an ossified
left stylohyoid ligament was seen with
considerable soft-tissue swelling. This was
confimed with standard radiographs. Despite
intracranial pressure monitoring and intravenous
barbiturate therapy, the patient tient died of
brain injuries 2 days after the accident.
DISCUSSION
The styloid process and the stylohyoid
ligament are derived from the second branchial
arch. These structures are first formed in
cartilage. The cartilage of the styloid process
ossifies while the epihyal cartilage, which
connects the styloid process and the hyoid bone,
is usually reabsorbed. The stylohyoid ligament
is formed from the remnants of the epihyal
cartilage (2). In some individuals, a separate
epihyal bone forms when the epihyal cartilage
ossifies rather than reabsorbs. Porrath (6)
theorized that an ossified stylohyoid ligament
occurs as a result of true ossification, rather
than calcification due to stress or
degeneration, because there is radiographic
evidence of ossified stylohyoid ligaments in
children.
The styloid process may vary from 5 to 50 mm
in length and the stylohyoid ligament may ossify
from its origin at the styloid process to its
attachment at the hyoid bone (1). Variations in
these structures were first reported in 1652 by
Marchettis (3).
The styloid process serves as the origin of
some of the muscles and ligaments concerned with
deglutition and phonation and connects the hyoid
bone through the stylohyoid ligament to the base
of the skull. This may account for reports of
fracture related to yawning or gagging.
Fracture of an elongated styloid process or
ossified stylohyoid ligament may result in
symptoms of neck swelling, pain in the throat,
limitation of movement, hoarseness, dysphagia,
or sensation of a foreign body (3, 4).
Occasionally, patients may present with similar
symptoms without fracture. McGinnis (4)
described one man with a tender mass in the
right neck. An ossified stylohyoid ligament was
seen on X-ray. Several days later, while
yawning, the patient felt the ligament
fracture and the mass became acutely painful.
X-rays documented the fracture and following
resection of the inferior portion of the
fractured ligament the patient had no further
symptoms. Chandler (1) described four patients
with previous head and neck carcinoma who were
clinically thought to have recurrence of their
tumor but radiographie evaluation showed the
physical findings and symptoms were related to
variations in the styloid process and
ossification of the stylohyoid ligament. Hilding
(3) reported a fracture of an elongated styloid
process that occurred when a young man choked on
a piece of meat, but more commonly the fracture
is due to blunt trauma from automobile
accidents. Reports of this injury have not
mentioned respiratory difficulty, unlike reports
of fracture of the hyoid bone in which asphyxia
is a major concern (6). Although Case 2 had
considerable swelling in the hypopharynx, it was
not possible to separate respiratory difficulty
caused by the massive head injury from that
caused by the fracture of the ossified
stylohyoid ligament. Hyoid bone fracture is also
associated with fracture of the mandible, which
has not been reported with styloid process
fractures (5).
The clinical diagnosis of styloid process or
stylohyoid ligament fracture can be
substantiated with anteriorposterior, lateral,
and oblique X-rays. Informing the radiologist of
the suspected diagnosis caii be helpful because
the mandible, cervical spine, and occipital bone
all
may obscure the styloid process.
Polytomography is probably not helpful because
of the oblique course of the stylohyoid
apparatus, but spot filming with fluoroscopy can
separate overlying structures. Panorex
tomography, if available, may provide good
images. Computed tomography can be useful in
comatose patients who are difficult to position
for oblique films and who will probably be
examined by CT for head injury as in Case 2.
Scans should be done without gantry angulation
at increments of 5 to 10 mm from the base of the
skull through the hyoid bone. Extending the CT
examination to include this area will not
prolong the scan significantly and may add
valuable information about the cervical spine
and soft tissues of the neck.
Treatment of styloid process and stylohyoid
ligament fractures has varied from conservative
therapy with a neck collar and analgesia to
surgical resection (4).
Prior knowledge of the clinical symptoms of
stylohyoid ligament and styloid process
fractures may make the diagnosis easier by
expediting radiography, avoiding false diagnosis
of foreign body (3), and avoiding direct
laryngoscopy or biopsy.
REFERENCES
Chandler, S. R. Anatomic variations of the
stylohyoid complex and their clinical
significance Laryngscope 87: 1692-1701,
1977.
Goodman,
R. S. Fracture of an ossified stylohyoid
ligament Arch. Otolaryngol
107:129-130,1981.
Hilding, D. A. Fractures of an elongated
styloid process masquerading as a foreign body.
Ann. Otol Rhinol Laryngol 70: 689692,1961.
McGinnis, J.
M. Fractures of an ossified stylohyoid bone.
Arch. Otolaryngol 107:460,1981.
Papavaliliou, C. G., Speas, C. J. Fracture
of the hyoid bone. Radiology, 72: 872--874,
1959.
Porrath, S.Roentgenologic considerations of
the hyoid apparatus. AJR 105: 63-73,1969.
