Imaging diagnosis
Case 159
【Progress】
She was given non-steroid anti-inflammatory drugs for pain relief.
【Discussion】
The odontoid process is a crucial supporting point to connect skull and cervical spine. Thanks to the odontoid process, the head can rotate right and left, and anterior and posterior fixing the cervical spine. Besides, other various membranes, ligaments and muscles assist to support the skull. Of these, alar ligament, apical ligament, transverse ligament, longitudinal band are imperative to support odontoid process and assist to accommodate the motion of the odontoid process. Transverse ligament and longitudinal band is called cruciform ligament. Transverse ligament runs across the odontoid process (dens) posteriorly and attaches the bilateral lateral body of C1. Longitudinal band also runs across the dens body posteriorly and extends from occipital bone to the dense base. Then, transverse ligament and longitudinal band is of a crucial-form configuration. They function the dens to stay in adjacent to anterior arch of C1. Apical ligament extends from occipital bone to dens tip and situates anterior to the longitudinal band. Alar ligaments are paired ligaments extending from occipital bone to the dens top. They function the dens not separate from the occipital bone.
The stress to the dens and these ligaments causes the minor injuries, producing fibrous cartilage from ligament and/or fibrous tissue and resulting in the deposit of calcification (1, 2). In remittent and chronic stress, the product of repairing mechanism causes the compression of dura matter and cervical spine, causing nuchal pain. Namely, crowned dens syndrome which indicates calcification of transverse ligament (3, 4), peri- or retro-odontoid pseudotumor which indicates reparation of longitudinal band (5) and alar ligament calcification (6, 7) are listed to cause the nuchal pain.
Besides those, ossification of longitudinal ligament (OPLL) and calcified tendinitis of longus colli muscle are listed to differentiate. The longus colli muscle is a paired muscle and situates anterior to the vertebral body and extends from atlas to the 3rd thoracic vertebrae (8-10) . Calcified tendinitis of longus colli muscle should be differentiated from retropharyngeal abscess in imaging diagnosis.
In our case, CT showed peri-dens calcification corresponded to the alar ligament and transverse ligament and MRI showed looking like peri-odontoid pseudotumor. The calcification of alar ligament and transverse ligament was limited in the right side, which was unclear to be explained the reason.
【Summary】
We present a fifty two-year-old female suffering from right neck pain for a long time. The neck CT showed calcified lesion corresponded to the right alar ligament and transverse ligament and the neck MRI showed the right peri-dens pseudotumor. It is borne in mind that there are four ligaments supporting odontoid process: transverse ligament, longitudinal band (both called crucial-form ligaments), apical ligament and alar ligament. There are three possible lesions causing nuchal pain; crowned dens syndrome related to calcification of transverse ligament; peri-odontoid pseudotumor by fibrous cartilage proliferation and/or fibrosis related to dens damage or alar ligament: retro-odontoid pseudotumor by fibrous cartilage proliferation and/or fibrosis related to dens damage or longitudinal band. Besides those, calcified tendinitis of longus colli muscle and OPLL are listed to cause nuchal pain. CT and MRI are important tools to differentiate them. In our case, calcifications of alar ligament and transverse ligament were demonstrated on CT and MRI.
【References】
1.Jain N, et al. CT and MR imaging of odontoid abnormalities: A pictorial review. Indian J Radiol Imaging. 2016 Jan-Mar; 26(1): 108–119.
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7.Soubai RB, et al. Calcification of the alar ligament of the cervical spine in a patient with rheumatoid arthritis. Pan Afr Med J 2012;13:41
8.Ade S, Tunguturi AM, Mitchell A. Acute Calcific Longus Colli Tendinitis: An Underdiagnosed Cause of Neck Pain and Dysphagia. Neurological Bulletin 2013;5:1-6,
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2019.8.28