The first ever case report on Calcific Longus Colli Tendinitis seems to be reported by Hartley in 1964 [1,2,3,4. Since then few case reports have been made so the knowledge of this pathology is still scarce among physicians.

Longus Colli Muscle is located in the prevertebral area and consists on three segments, upper oblique fibres, vertical fibres and lower oblique fibres, spanning from the anterior arch of C1 and running bilaterally on the anterolateral border of the cervical vertebral bodies and anterior tubercles of their transverse processes down to the anterior portion of T1 - T3 [5,6,7], it is manly a cervical flexor, ipsilateral side flexor and it has a certain degree of cervical rotation.

Acute Longus Colli Calcific Tendinitis (LCCT) presents most commonly with the triad consisting of Neck Pain, Neck stiffness and Odynophagia, and a slight elevation of ESR and C-reactive protein [6, 8,9,10,11,12,13,14] although others have reported fever [15], trismus [7] and torticollis [6, 16] as accompanying symptoms, although none of the patients presented in this small series had fever.

LCCT has often a self-limiting course that is resolved in one to three weeks in patients from 30 to 60 years [6, 10, 17], and it is believed that it’s caused by the deposition of hydroxyapatite crystals on the upper oblique fibers of the Longus Colli Muscle (LCM), often at C1-C2 level. Rupture and resorption of these crystals cause an aseptic foreign-body type inflammatory response and results in the formation of reactive fluid in the retropharyngeal space surrounding the muscle, which is believed to be the cause of neck pain and the accompanying symptoms. Recently Yamamoto et al. [17] described three stages of the disease: pre-calcification, calcific, and post-calcific. During the resorptive stage of the calcific stage, calcific deposits are invaded by macrophages, polymorphonuclear cells and fibroblasts. This is the most painful stage and it is believed that the calcific deposits are being replaced by granulation tissue. Others have studied the possible causes that lead to calcific depositions in tendons like the supraspinatus tendon and Achilles tendon, and have proposed five stages of the disease pre-calcific, formative, resting, resorptive and post-calcific. The pre-calcific phase is characterized by fibrocartilaginous metaplasia of tendon cells that leads to the formation of calcium foci separated by fibrocartilage cells (formative phase). Posteriorly comes the resting phase where the multifocal calcium deposition presents, surrounded by the metaplastic fibrocartilage cells, that subsequently gets surrounded by macrophages/multinucleated cells that phagocyte calcific debris -this is believed to be the most painful phase-, finally resulting in the post-calcific phase where the calcific deposit gets reabsorbed and is replaced by granulation tissue [18, 19]. Rui et al. [20] suggested a possible erroneous differentiation of tendon-derived stem cells into chondrocytes or osteoblasts may be the possible mechanism leading to calcific tendinopathy, although the exact mechanism why this happens is yet to be clarified.

Usual imaging studies consist of X ray, CT and Contrast MRI. Plain lateral radiography is usually unable to show calcific deposits on the anterior C1 arch [Fig. 1]. CT is currently the gold standard for identification of the calcific deposit usually at C1-C2 level on the anteroinferior margin of the anterior arch of C1 [Fig. 2]. It is also useful to evaluate the retropharyngeal space in patients with LCCT where it is often found to be slightly increased (should be less than 4 mm in a normal CT) but without clear signs that would be expected to find in a retropharyngeal abscess like hydro-aerial collection, rim enhancement or suppurative lymphadenopathy. On the other hand, contrast MRI is not very useful to identify the calcific deposits on the C1 arch [Fig. 3], but its usefulness lies in the fact that it can easily show rim enhancement in the case of an abscess and also, it is useful to identify cases of spondylodiscitis [11, 21].

Lateral cervical spine radiography of a patient with Longus Colli Calcific Tendinitis where a calcific deposit (white arrow) is clearly identified on the anteroinferior border of the anterior arch of C1

Left: Axial CT of a patient with a clear calcification on the anteroinferior border of the anterior arch of C1 (white arrow). Right: On Sagittal CT there is also a thin hypodense tissue (white arrow heads) that runs from C1 to C5 corresponding to retropharyngeal edema

Sagittal T2 MRI of a patient with Longus Colli Calcific Tendinitis, it is not possible to clearly identify a calcific deposit on the anteroinferior border of the anterior arch of C1. It is notable the presence of a hyperintense image along the anterior aspect of the cervical spine running from C1 to T3 in the retropharyngeal space, corresponding with soft tissue edema (white arrow heads)

As mentioned before, differential diagnosis such as retropharyngeal abscess, meningitis [22] and spondylodiscitis, is challenging, so the physician must know clearly how to identify the clinical and radiological signs of a LCCT, of special importance is the retropharyngeal abscess since it is the most important mimicker of this pathology, and mistakenly diagnosing them may lead to needless interventions such as biopsy/aspiration, patient discomfort and unnecessary antibiotic prescription [6, 21, 23, 24].

Treatment usually consists of non-steroidal anti-inflammatory drugs (NSAIDs) as the first line of treatment, in severe cases or in patients with intolerance to NSAIDs corticosteroids and opioids may be prescribed [3, 6, 23, 25,26,27]. Some authors recommend rest and neck immobilization but there is lacking evidence that these interventions are useful.