Abstract
Objective
To determine the incidence of retropharyngeal calcific tendinitis (longus colli tendinitis) in a general urban adult population.
Study Design
Observational study in a municipal medical center.
Setting
Single tertiary referral center.
Methods
All symptomatic patients with a differential diagnosis of retropharyngeal calcific tendinitis underwent fiber-optic assessment, laboratory studies, and imaging studies. The main outcome measure was the incidence of retropharyngeal calcific tendinitis.
Results
Thirteen patients with symptoms suggestive of retropharyngeal calcific tendinitis were evaluated in our institution between January 2008 and December 2011. Final diagnosis was made by means of a computed tomographic scan: 8 patients had retropharyngeal calcific tendinitis, 1 had retropharyngeal abscess, and the remaining 4 had other deep neck infections. The mean annual crude retropharyngeal calcific tendinitis incidence was 0.50 cases per 100,000 person-years, and the standardized incidence was 1.31 for the age-matched population.
Conclusions
Retropharyngeal calcific tendinitis is not a rare disease and is probably underdiagnosed because symptoms are nonspecific, treating physicians are often unfamiliar with this entity, and it is a self-limiting pathology.
Retropharyngeal calcific tendinitis (RCT; “acute calcific prevertebral tendinitis” or “longus colli tendinitis”) is considered a rare disease and one that is secondary to inflammation of the longus colli muscle.1,2 Originally described by Hartley in 1964, 3 the pathogenesis was clarified in 1994 by Ring et al, 4 who demonstrated the deposition of calcium hydroxyapatite crystals in the superior oblique tendon fibers of the longus colli muscle. Risk factors, such as repetitive trauma, recent injury, ischemia, inflammation, or tissue necrosis, appear to play a role in the pathophysiology of RCT. 5 Calcific tendinitis presenting in other locations appears to have similar mechanisms and risk factors. 6
Common symptoms of RCT include neck pain (94%), limited neck movement (45%), odynophagia (45%), neck stiffness (42%), and dysphagia (27%). 7 Other findings of RCT may include low-grade fever, elevated levels of inflammatory markers, and an elevated white blood cell count. The extended differential diagnosis of RCT includes pharyngitis, epiglottitis, retropharyngeal abscess (RPA), infectious spondylitis, traumatic injury, cervical disk herniation, meningitis, muscle spasm, and neoplasm. 8
Computed tomography (CT) of the neck should be the first and definitive step in diagnosing RCT. 9 Principal radiographic findings of RCT include prevertebral soft-tissue swelling extending from the C1 to C6 vertebrae and the presence of amorphous calcifications.9,10 Classically, calcifications affect the superior oblique portion of the longus colli muscle at the level of the C1-C2 vertebrae. 11 This should not be confused with a collection in the retropharyngeal space. The lack of enhancement surrounding the effusion is helpful in differentiating a reactive effusion from an abscess. RCT may have similar CT findings as those seen in other conditions, such as infectious spondylitis, vertebral fracture, anteriorly bowed transverse process, and a calcified and protruded cervical disc.5,10,12 Magnetic resonance imaging (MRI) is not usually necessary for this diagnosis, but it can sometimes demonstrate marrow edema in the adjacent vertebrae. 13
There is recent mounting evidence that the incidence of RCT may be much higher than previously thought and that it may often be missed because of its benign course. The objective of the current study is to determine the incidence of RCT in a general urban adult population.
Methods
Study Area
Tel-Aviv is the second largest city in Israel in terms of overall population, and it is located in the central part of Israel (32° 4′ 50″ N, 34° 46′ 50″ E). Between 2008 and 2011, the population of the Tel-Aviv metropolitan area included 384,400 inhabitants in 2008, 390,100 inhabitants in 2009, 402,600 inhabitants in 2010, and 404,750 inhabitants in 2011, yielding an average of 395,462.5 person-years for each year. Inhabitants aged 25 to 44 years accounted for 38.53% of the population, thus constituting 152,371.5 person-years for each year. The Tel-Aviv “Sourasky” Medical Center is the only municipal hospital, and it contains 1150 admission beds with an average of 475,004 admission days per year. The emergency department (ED) has an average of 130,338 visits per year (127,345 in 2008, 126,477 in 2009, 133,252 in 2010, and 134,279 in 2011).
Diagnostic Criteria
Diagnosis of RCT was based on (1) clinical history and symptoms, (2) physical examination (including an endoscopic evaluation), (3) laboratory tests, and (4) CT scan. Clinical history and symptoms included neck pain, limited range of neck movement, odynophagia, throat pain, and dysphagia. As part of the routine protocol of the ED, the patients first underwent an examination by an emergency physician and then were further evaluated as needed, including laboratory tests. All patients suspected as having a pharyngeal etiology for their symptoms were further examined by an otolaryngologist, who performed a full head and neck examination (including a fiber-optic endoscopy) to determine whether there was asymmetry of the pharynx. Patients with suspected RCT were immediately sent for a CT scan within the ED.
This study was approved by the Tel-Aviv “Sourasky” Medical Center Helsinki review board.
Imaging Studies
All patients with suspected RCT underwent a CT scan for definitive diagnosis. Imaging criteria included (1) prevertebral soft-tissue swelling, (2) amorphous calcification anterior to C1-C6, (3) absence of rim-enhancing collection in the retropharyngeal space, and (4) absence of suppurative retropharyngeal lymphadenopathy ( Figure 1 ). 10 All RCT cases were finally reevaluated by the senior head and neck radiologist of the medical center (A.B.) to confirm the radiological diagnosis.
Contrast-enhanced axial computed tomography of a 32-year-old woman with retropharyngeal amorphous calcification and expansion of the retropharyngeal space diagnosed with retropharyngeal calcific tendinitis.
Statistical Analyses
Annual crude and age-specific incidences were calculated (2008 to 2011). The 95% confidence intervals (CIs) were calculated based on the Poisson distribution. Both the χ2 and the McNemar tests were used to test the significance of RCT incidence in the population. Statistical significance was determined as P < .05. Epidemiologic and statistical analyses were carried out using SPSS 15.0 software (SPSS Inc, Chicago, IL).
Results
Eight new cases of RCT were diagnosed during the study period. There were 5 women (62.5%) and 3 men (37.5%, P = NS) whose mean age at diagnosis was 36.6 ± 5.2 years (range, 26-44 years). The greatest percentage of cases was patients in the fourth decade of life, followed by the fifth and third decades ( Figure 2 ). The main clinical signs and symptoms of patients with RCT included neck pain (100.0%), lost range of neck movements (75.0%), odynophagia (75.0%), throat pain (37.5%), and dysphagia (12.5%; Figure 3 ). Patients’ complaints initiated 2 to 4 days prior to ED referral by a general practitioner (GP; mean, 2.625). Only 1 patient had a clear recollection of a recent minor head trauma. Six patients had bulging of the posterior wall on physical examination using fiber-optic laryngoscopy (75%). The laboratory results showed that the leukocyte range for the RCT patients was 7.2 to 15.0 g/L (mean, 10.72; median, 10.2; SD, 2.90) and that the C-reactive protein range was 2.3 to 120.0 mg/L (mean, 54.81; median, 57.5; SD, 42.88). Six patients were initially treated with antibiotics generally started by their GP or in the ED on arrival (75%). The time interval from basic evaluation in the ED to final diagnosis was 12 hours to 3 days. All patients reported resolution of symptoms after 4 to 14 days (median, 9 days). None of the patients has had recurrence of symptoms to date.
Incidence in percentage of retropharyngeal calcific tendinitis cases per age group.
Comparison of the frequency of the most common symptoms noted at presentation among 8 patients diagnosed with retropharyngeal calcific tendinitis. ROM indicates range of motion.
One new case of adult RPA was diagnosed. The patient was a 48-year-old man with a medical history of ulcerative colitis. His laboratory tests showed a white blood cell count of 38.8 g/L and a C-reactive protein count of 198 mg/L. The CT scan clearly demonstrated a rim-enhancing collection in the retropharyngeal space. This patient underwent emergent surgery with intraoperative findings of pus collection that was drained from the retropharyngeal region during the procedure.
The other 4 patients were also sent for a CT scan according to departmental protocol, and their CT scan findings were diagnostic for other deep neck infections not originating in the retropharyngeal space.
The statistical analysis revealed that the mean annual crude incidence of RCT was 0.50 cases per 100,000 person-years (95% CI, 0.49-0.51) and that the standardized incidence was 1.31 for the age-matched population (95% CI, 1.28-1.34). Statistical analysis found RCT to be significantly more prevalent than RPA compared (P < .02).
Discussion
RCT is considered a rare disease, and a recent review of the literature revealed fewer than 80 published cases. 14 Questioning the notion that it is indeed a rare condition, a recent publication by Danish chiropractors suggested that RCT is probably underdiagnosed. 15 Eight new cases of RCT were diagnosed and treated in our institute between 2008 and 2011. In an effort to clarify the true incidence of RCT in the general population, we followed a strict diagnostic algorithm that included the following steps: (1) clinical history, (2) physical examination including a fiber-optic endoscopy, (3) laboratory tests, and (4) contrast-enhanced CT scan. As for specific clinical history pointing to RCT, we have not found recent trauma to be an important cue for diagnosis and actually found an unimpressive history such as low-grade fever and mild throat pain and odynophagia much more suggestive. On the other hand, physical examination can often show impressive findings since most patients diagnosed with RCT demonstrate bulging of the posterior pharyngeal wall. Lab tests have an unrevealing nature with regard to RCT, although they can lower suspicion for other more devastating entities such as retropharyngeal abscess; the leukocyte count may range from normal values to mild leukocytosis, and C-reactive protein is usually only mildly elevated in RCT patients, whereas in RPA patients, leukocytes and C-reactive protein are substantially elevated. 16 CT scan is imperative and should always be the next step since final diagnosis can be made only based on specific imaging criteria. Recently, it has been proposed that MRI can serve as a supplementary imaging study in unclear cases, 16 but we have found this rather redundant in our cohort since all cases were diagnosed with CT only.
After the final diagnosis of RCT is made and the antibiotic regimen is discontinued, patients are prescribed a twice-daily nonsteroidal anti-inflammatory drug and are discharged home. When quick relief is desired, a brief course of steroids can be given. The use of narcotics for pain relief is not recommended. Follow-up is scheduled 1 week after discharge, and patients are instructed to avoid physical activities and aggravating head movements until the next appointment. A second follow-up is scheduled in cases in which symptoms have not completely resolved. Routine CT scan is not recommended, and patients are then referred back to their GP.
Evaluation of results published here calls into doubt the true incidence of RCT. An annual incidence of 0.5 cases per 100,000 person-years suggests not only that is it not a rare disease but also that there are probably thousands of new cases every year that go undiagnosed worldwide. Furthermore, an age-matched incidence of 1.31 per 100,000 person-years indicates that RCT is not as rare a disease as initially thought and that it targets mainly individuals who are in their third to fifth decade of life, similar to a recent literature review showing an age distribution ranging from 21 to 65 years (mean, 42; n = 71). 9
The answer to the question as to how patients with RCT remain undiagnosed probably lies in the benign behavior of this disease. It is reasonable to consider that a large percentage of the patients probably do not seek medical attention in the first place, that many of those who do are misdiagnosed (eg, orthopedic etiologies and others), and that this self-limiting disease will subside after a few weeks. Obviously, sequential publications regarding RCT and a prospective multicenter trial including other geographic regions are needed to reveal the true incidence of RCT.
Conclusions
RCT is not a rare disease and is probably underdiagnosed because symptoms are nonspecific, treating physicians are often unfamiliar with this entity, and it is a self-limiting pathology. A structured algorithm well known to ED personal and ear, nose, and throat physicians can facilitate fast and efficacious diagnosis of RCT patients.
Author Contributions
Disclosures
Footnotes
Acknowledgements
Esther Eshkol is thanked for editorial assistance.
No sponsorships or competing interests have been disclosed for this article.