A Nodular Calcification of the Alar Ligament Simulating a Fracture in the Craniovertebral Junction
K.-B. Sima and
J.K. Parkb
a Department of Neurosurgery, College of Medicine, Cheju National University Hospital, Jeju City, South Korea
b Department of Radiology, College of Medicine, Cheju National University Hospital, Jeju City, South Korea
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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 x 7.6 x 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.
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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 signal intensity without any pathologic change.
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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.
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