Acute calcific tendonitis of the longus colli muscle

Findings

Figure 1: Scout image from CT scan of the head demonstrates prevertebral soft tissue swelling and loss of physiologic cervical lordosis. This finding prompted further evaluation with contrast-enhanced CT scan of the neck.
Figure 2, Figure 3, and Figure 4: Axial (Figure 2 and Figure 3) and reformatted sagittal (Figure 4) contrast-enhanced CT images of the neck demonstrate enlarged right longus colli muscle, focal amorphous calcification within it (Figure 2 and Figure 4), as well as smooth, nonenhancing prevertebral and retropharyngeal effusion (Figure 3 and Figure 4).
Figure 5 and Figure 6: Axial (Figure 5) and reformatted sagittal (Figure 6) contrast-enhanced CT images of the neck with bone settings show focal, off-midline amorphous calcification anterior to C1/C2 level, within the superior tendon of the right longus colli muscle. There is also mild reversal of the physiologic cervical lordosis.

Differential Diagnosis:
- Retropharyngeal space abscess
- Retropharyngeal edema of different etiology (internal jugular vein thrombosis, previous surgery or radiation therapy)
- Accessory ossicle inferior to the anterior arch of C1
- Infectious spondylodiscitis


Diagnosis: Acute calcific tendonitis of the longus colli muscle


Acute calcific tendonitis of the longus colli muscle, also known as acute calcific retropharyngeal (or prevertebral) tendonitis, is a clinical syndrome (originally described by Hartley in 1964) that usually affects adults in the 3rd through 6th decades of life. The presumed mechanism of disease is calcium hydroxyapatite crystal deposition within the superior oblique fibers of the longus colli muscle. Acute symptoms develop when these contained deposits rupture, triggering an acute inflammatory process that usually lasts 2 to 3 weeks. The typical clinical presentation is acute to subacute onset of neck pain, dysphagia, or odynophagia; patients may also have low-grade fever and paraspinal muscle spasm, as well as recent history of upper respiratory infection or minor trauma to the head or neck. Mild leukocytosis, elevation of C-reactive protein and erythrocyte sedimentation rate are occasionally present.

The pathognomonic radiographic findings consist of calcific prevertebral (or retropharyngeal) density on the lateral radiograph of the neck, typically at C1/C2 level (inferior to anterior arch of C1), with associated soft tissue thickening. CT is more sensitive than plain radiography for detection of characteristic amorphous calcification, which is usually off-midline and clearly separate from the vertebral body; its appearance varies from punctate to dense, prominent concretions. Retropharyngeal space edema and specific smooth retropharyngeal effusions usually extend from C1 to the C5 level. MR imaging is not typically necessary for the diagnosis, but may be useful in confirming and further defining the abnormality. T2-weighted images demonstrate hyperintense retropharyngeal space fluid with an acute inferior margin. Diffuse swelling of the longus colli muscle and associated C1/C2 bone marrow edema have also been reported. After administration of intravenous contrast, there may be diffuse prevertebral soft tissue and/or longus colli muscle enhancement. Hypointense calcifications can be detected inferior to the anterior arch of C1 within the superior longus colli tendon, however these are easy to miss on MR.

The most important differential diagnosis is a retropharyngeal space abscess, which would require aggressive antibiotic therapy and possible surgical drainage. Distinction from abscess is easy if four key observations are made: 1) the fluid smoothly expands the retropharyngeal space in all directions; 2) there is absence of an enhancing wall around this fluid, as would be seen in a true retropharyngeal abscess; 3) there is absence of associated suppurative (or presuppurative) retropharyngeal space lymph nodes with low-density centers; 4) there are pathognomonic tendinous calcifications within the longus colli.

Most cases are self-limiting and resolve within several weeks of the onset of symptoms. The calcifications may disappear when the soft tissue swelling recedes. Treatment is usually conservative and consists of analgesics and a short trial of NSAIDs. If symptoms are severe, the patients may require a short course of corticosteroids. Early diagnosis is important to avoid invasive diagnostic and therapeutic procedures. Follow-up imaging is not necessary due to the self-limiting nature of this condition.