代寫assignment CASE REPORT A Nodular Calcification of the Alar Ligament Simulating a Fracture in the Craniovertebral Junction
K.-B. Sim
J.K. Park
SUMMARY: We report a case of an incidental nodular calcification of the alar ligament simulating a
fracture in the craniovertebral junction of a previously healthy 24-year-old man. Three-dimensional CT
and MR imaging revealed a 7.2
7.6
4.0 mm nodular calcification in the right alar ligament with
normal adjacent bony structures. Serial cervical dynamic radiographs and open-mouth views showed
that the cervical spine was stable without any change in the calcification.
Calcification in the alar ligament is rare, though some cases
with calcification of the transverse or alar ligament have been
reported.1,2 It usually develops as a result of traumatic injury or
inflammatory disease, especially in the elderly.1,2 In some cases, it
is associated with neck pain, relieved by anti-inflammatory drugs
and neck immobilization.1 Calcification or ossification of the alar
ligamentmaybe anuncommonnormal variant andmaymimic a
fracture of the craniovertebral junction (CVJ).
We present a case of incidentally found nodular alar ligament
calcification in a patient with craniocerebral injuries, which was
initially considered as a fracture of the odontoid process.
Case Report
A 24-year-old man was involved in a rollover traffic crash. Initially, he
was admitted to an outside facility and presented unconscious with a
contusion on his left forehead. He underwent radiography and CT of the
head, which showed multiplane craniofacial bone fractures to the frontal
and sphenoid sinus and left orbital roof, with a bifrontal hemorrhagic
contusion. A nodular bony fragment was noted between the right occipital
condyle and the odontoid tip in the basal cuts of the brain CT, suggesting
a free segment of fractured bone (Fig 1A). The patient was referred
to our hospital shortly thereafter. He had no remarkable history.
Results of routine laboratory investigations were within normal limits.
Initially findings of cervical spine radiographs were also within normal
limits.
Two days after admission, his consciousness improved, and he complained
of severe headache, anosmia, and severe neck pain with limited
neck motion. Neurologic examination showed that muscle strength, sensation,
and deep tendon reflexes of the upper and lower extremities were
normal. Multidetector CT with 3D reconstruction revealed a well-defined
7.2
7.6
4.0 mm oval nodular calcification in the retro-transverse
ligament and supraodontoid tip area along the course of the right
alar ligament. The surface of the calcification was smooth without any
jagged lines (Fig 1B, -C). A bone marrow component was not present in
the calcification. The adjacent occipital condyle, odontoid process, and#p#分頁標題#e#
neural arch of the atlas were apparently normal. Findings of cervicalMR
imaging also were normal, except for a nodular mass with low signal
intensity in the right alar ligament area. In the coronal planes of T1-
weighted spin-echo images (TR/TE, 700/14), the left alar ligament was
identified with intermediate signal intensity. In contrast, the right alar
ligament could not be properly identified because of a nodular calcification
with low signal intensity coalescing with the ligament (Fig 2). The
calcification was larger than the anatomic boundaries of alar ligament.
The medial short segment of the ligament connected the calcification
with the odontoid tip.
Fluoroscopic imaging through an open-mouth view showed a calcified
nodule in the right side of periodontoid tip area in the CVJ (Fig 3).
Serial open-mouth views also denoted the calcification to be consistent,
without change of size during 2 months. Serial flexion and extension
radiographs of the cervical spine revealed no evidence of instability of the
CVJ and upper cervical spine. Technetium-Tc99m methylene dihydroxyphosphonate
bone scintigraphy 14 days after trauma showed intense
uptake in the fractured area of the frontal and sphenoid sinus butno
uptake in the CVJ. The neck pain gradually improved with anti-inflammatory
analgesics and physiotherapy, without limitation of neck motion,
especially rotatory movement, during 2 months.Thepatient did not have
other ossifications in the other spinal ligaments or upper and lower extremities
or any generalized disorders.
Discussion
The alar ligaments are strong rounded structures, which arise on
both sides of the upper part of the odontoid process and, passing
obliquely upward and laterally, are inserted into the medial surface
of the condyles of the occipital bone. They play an important
role in stabilizing the head during rotatory movements at the
CVJ. These ligaments can be assessed well by the use of highresolution
MR imaging, including proton-attenuation weighted
sequences. On the basis of these study results, the orientation of
the alar ligaments is highly variable, and asymmetry of these ligaments
is common in asymptomatic individuals.3 Lesions of the
alar ligament with or without associated rotational instability
have been discussed as a possible cause of whiplash-associated
disorders; however, the structural alteration of the alar ligament
related to acute whiplash injury is extremely rare.4,5
Calcification in the alar ligament is very rare, regardless of
cause. It usually develops with increasing prevalence after the
age of 40 years, especially in the elderly, following minor
trauma or as a consequence of inflammatory disease.1,2,6
Kobayashi et al1 reported 2 cases of alar ligament calcification
related to neck pain. A 37-year-old man and a 59-year-old#p#分頁標題#e#
woman had pharyngodynia and prior nuchal pain without
previous trauma history, which improved gradually with an
anti-inflammatory drug therapy and neck immobilization. CT
revealed a nodular calcification in 1 patient and a poorly delineated
calcified lesion surrounding the odontoid process in
the other patient. Serial CT demonstrated that the calcifications
shrank and disappeared with time. The authors assumed
Received September 2, 2005; accepted after revision October 5.
From the Departments of Neurosurgery (K.-B.S.) and Radiology (J.K.P.), College of Medicine,
Cheju National University Hospital, Jeju City, South Korea.
Please address correspondence to Ki-Bum Sim, MD, Department of Neurosurgery, College
of Medicine, Cheju National University Hospital, 690 –716, #154, 3-Do 2-Dong, Jeju City,
that pharyngodynia and nuchal pain could be related to an
inflammatory reaction induced by deposition of calcium because
secondary arthritis was not observed and the symptoms
resolved as lesions decreased in size. We thought that their
cases could be categorized as a crowned dens syndrome
(CDS). CDS is a clinical radiologic entity consisting of periodic
acute cervico-occipital pain with fever, neck stiffness, and
biologic inflammatory syndrome and a radiologic calcium
crystal deposition surrounding the top and sides of the odontoid
process in a crown- or halolike distribution.6,7
In the present case, a nodular high attenuation in the periodontoid
area was found on the emergent axial brain CT performed
after severe head injury. There was lack of information
about the patient because he was found unconscious without any
witnesses after the trauma. Initially, we considered the possibility
of a fracture involving the odontoid process (type I fracture),
occipital condyle (type III fracture), or neural arch of the atlas in
the CVJ. In the clinical setting, 3D CT was very useful in defining
the location and characteristics of the high attenuation and in
demonstrating the normal adjacent bone. Although the patient
had neck pain with diminished neck motion, we ruled out CDS
because our patient was too young and healthy, without previous
experience of any neck pain. His neck pain and limited neck motion
were interpreted as symptoms of mild neck trauma, and the
symptoms resolved gradually by 2 months with anti-inflammatory
drugs and physiotherapy. Cervical MR imaging including a
proton-attenuation weighted sequence
was useful for finding any bone marrow
signal intensity within the lesion and for
defining the anatomic location and alar
ligament. Serial open-mouth views and dynamic radiographs of
the cervical spine demonstrated a persistent calcification without
reduction of its size and a stable cervical spine.
On the basis of this series of examinations, we concluded#p#分頁標題#e#
that the nodular calcification occurred in the right alar ligament
and was unrelated to trauma or inflammation and,
therefore, was an incidental finding. This under-recognized
entity must be considered in a differential diagnosis of a craniovertebral
injury, such as fractures of odontoid process
(type I) and occipital condyle (type III) and CDS.
References
1. Kobayashi Y, Mochida J, Saito I, et al. Calcification of the alar ligament of the
cervical spine: imaging findings and clinical course. Skeletal Radiol 2001;30:
295–97
2. Krakenes J, Kaale BR, Rorvik J, et al. MRI assessment of normal ligamentous
structures in the craniovertebral junction. Neuroradiology 2001;43:1089–97
3. Pfirrmann CW, Binkert CA, Zanetti M, et al.MRmorphology of alar ligaments
and occipitoatlantoaxial joints: study in 50 asymptomatic subjects. Radiology
2001;218:133–37
4. Ronnen HR, de Korte PJ, Brink PR, et al. Acute whiplash injury: is there a role for
MRimaging?—a prospective study of 100 patients. Radiology 1996;201:93–96
5. Krakenes J, Kaale BR, Moen G, et al. MRI assessment of the alar ligaments in
the late stage of whiplash injury: a study of structural abnormalities and observer
agreement. Neuroradiology 2002;44:617–24
6. WuDW,Reginato AJ, Torriani M, et al. The crowned dens syndrome as a cause
of neck pain: report of two new cases and review of the literature. Arthritis
Rheum 2005;15:53:133–37
7. Bouvet JP, le Parc JM, Michalski B, et al. Acute neck pain due to calcifications
surrounding the odontoid process: the crowned dens syndrome. Arthritis
Rheum 1985;28:1417–20
Fig 1. A previously healthy 24-year-old man was involved in a traffic crash and presented with severe craniocerebral injuries.
A, Initial axial CT scan shows a nodular calcification between the odontoid tip and the right occipital condyle, suggesting a fractured bone in the craniovertebral junction.
B, 3D volume-rendering image demonstrates a nodular calcification, 7.2
7.6
4.0 mm, between the occipital condyle and odontoid tip along the course of alar ligament. The bony
structures of the craniovertebral junction were normal.
C, Coronal multiplanar reconstruction image shows an attenuated calcific intensity in the region of the right alar ligament, with no remarkable bone marrow component. There is no evidence
of fracture in the odontoid process and occipital condyle.
Fig 2. MR image with coronal T1-weighted sequences
shows a nodular calcific attenuation (arrowhead) in the
lateral part of the right side alar ligament. It expands in
thickness and width beyond the anatomic boundaries of
alar ligament. The left alar ligament (white arrow) is a
well-defined structure running caudocranially from the
apex of odontoid to the occipital condyle, with intermediate#p#分頁標題#e#
代寫assignment signal intensity without any pathologic change.
Fig 3. Fluoroscopic image obtained through an open-mouth
view. A nodular calcified fragment (white arrow) is present
in the right periodontoid tip area with smooth margins.