Crowned dens syndrome

Introduction Calcium pyrophosphate disease (CPPD) can present both acutely with hot, swollen and painful joints, often with an underlying trigger, or with chronic forms of arthritis resulting in slower joint destruction. A rare and often misdiagnosed presentation is crowned dens syndrome (CDS). Classically, these patients present with neck pain, possible fever and raised inflammatory markers. Peripheral joints may also flare with CPPD simultaneously and there may be a precipitating event. We describe two cases of CDS recently encountered at Poole Hospital in Dorset. Case description Case 1: A 74-year-old male presented with acute onset foot pain, neck pain, fever, elevated CRP (192 mg/l) and normal urate (226micromol/l). He had hypomagnesaemia (0.22mmol/l) and hypocalcaemia (1.99mmol/l). He reported three months of diarrhoea and took omeprazole 20 mg twice daily. He had a negative infection screen with normal vitamin D and parathyroid hormone levels. CT C-spine showed soft tissue calcification around the odontoid peg and down to C2. However, initially the radiology reporting did not clearly identify CDS as a possible differential; an input from the rheumatologist was required for re-reporting of the scan with CDS in mind. He was successfully treated with a weaning course of oral prednisolone starting at 15 mg daily, weaning by 5 mg weekly and switching his omeprazole to famotidine. Case 2: An 85-year-old lady presented to the community team with 10 months of intractable cervical pain, headaches and difficulty sleeping. An MRI of the C-spine showed erosive and hypertrophic changes at the C1/2 articulation; a CT showed calcification of the ligaments posterior to the odontoid PEG. Following a spinal MDT discussion, a more chronic form of CDS was thought to be the most likely diagnosis. She was treated with non-steroidal anti-inflammatory drugs (lack of response), colchicine (intolerance) and targeted injection. Discussion We describe two patients with CDS - one presenting acutely and the other with a more chronic history. This highlights the challenge in diagnosing CPPD as the clinical picture can be highly variable. A high index of suspicion is required, especially in elderly patients presenting with neck pain; in such situations, a CT scan of the cervical spine allows rapid exclusion of fractures, identification degenerative disease and diagnosis of CDS. Another interesting observation was that one of our patients had hypocalcaemia and hypomagnesaemia, both of which could potentially be involved in the pathogenesis of CPPD/CDS. Although hyperparathyroidism and resulting hypercalcaemia can cause CPPD in its more chronic form, hypocalcaemia may result in the mobilisation of calcium pyrophosphate crystals, triggering an inflammatory response and acute CPPD. Magnesium is a cofactor for alkaline phosphatase which is involved in breakdown of pyrophosphate; a deficiency in magnesium can result in pyrophosphate build up, which can trigger pseudogout attacks. Furthermore, magnesium is involved in parathyroid hormone and thereby calcium regulation; a significant deficiency in magnesium can cause a hypocalcaemia which can precipitate acute pseudogout as well. Common causes for low magnesium include the use of proton pump inhibitors and chronic diarrhoea, which can be addressed to reduce the risk of future attacks of CPPD. This case highlights the importance of investigating for an underlying cause for CDS. We suggest that all patients with CDS and acute CPPD have a bone profile and magnesium performed, both of which are easily available; identifying and addressing these electrolyte abnormalities and their causes can help treat the CDS and prevent future attacks. From our cases, a weaning course of prednisolone over weeks appears to be successful in treating CDS. Shorter courses may risk a relapse and treatment-resistant cases may benefit from the addition of colchicine. Key learning points Our cases highlight four key learning points: • Elderly patients presenting with acute neck pain without any history of trauma and raised inflammatory markers, a high index of suspicion for CDS and an early investigation with CT of the cervical spine allows rapid diagnosis of this condition and exclusion of other differentials. • CDS can often have an underlying trigger precipitating the CPPD. Two important causes we highlight here are low calcium and low magnesium, both of which can play a role in the pathogenesis of acute CDS presentations. • Despite having had reported CT scans on the cervical spine, CRS was not initially reported by the reporting radiologist suggesting under-recognition of this condition. • We suggest the use of a weaning regime of prednisolone initially as a successful treatment option with lower chance of relapse. Colchicine and targeted injections can be alternatives.

Introduction Crowned dens syndrome (CDS) is a rare manifestation of crystal arthritis, characterised by calcium crystal deposition around the odontoid process of the second cervical vertebra. This is classically associated with head trauma, and is more frequently described in patients over the age of 60 and the female sex. The authors thus present an atypical case of CDS affecting a male patient in his mid-50s without a prior history of head injury. The case is unique in that surgical management was also required to manage the CDS, and this is exceedingly rare in the literature. Case description A gentleman in his mid-50s was brought to the emergency department with severe neck pain and fever, starting suddenly in the preceding hours. The pain radiated to his occiput, with worsening on movement of the cervical spine. The patient had no past medical or surgical history of note. He worked as a salesman and was a non-smoker. Examination revealed limitation of cervical spinous movements due to pain, and evidence of myelopathy. He was found to have bilateral loss of power and sensation in his upper and lower limbs, throughout virtually all muscle groups. He was also hyperreflexic. The initial suspicion was bacterial meningitis, and he was duly admitted for a lumbar puncture. The results of the investigations are summarised in the table below. The rheumatology team was consulted because of the pannus on radiology. Rheumatoid factor and anti-citrullinated C-peptide levels were undetectable. Given the radiological findings and the symptomatology, a diagnosis of CDS was made. Due to the presence of myelopathy, medical management was not recommended in isolation. Prednisone 1 mg/kg/day and colchicine 0.5 mg three times a day were started, and the patient simultaneously underwent a posterior cervical decompression and fusion, with C1 laminectomy. Intense rehabilitation and continued medical management ensured a good prognosis for the patient. His inflammatory markers normalised rapidly. He was treated with three months of colchicine and prednisolone, and repeat imaging confirmed resolution of his CDS findings. He is currently off treatment and doing well. Discussion The first challenge of CDS is suspecting it as a differential diagnosis. In this case, the patient did not satisfy the common demographics associated with the disease. Firstly, the patient is younger than the typical cohort of CDS. Secondly, the patient is of the male sex, and CDS has been described as being commoner in females. Finally, most cases in the literature have occurred in the context of cervical spine or head trauma, whereas the patient in this case did not experience any of these triggers. Despite the imaging findings, the radiologists and the neurosurgeons were unaware of the possibility of CDS, thus highlighting a lack of awareness about this crystal arthropathy. CDS involves calcium pyrophosphate or hydroxyapatite deposition around the dens. Therefore, by extrapolation, medical management resembles that of calcium pyrophosphate deposition disease (CPPD), with NSAIDs and/or colchicine being used as first-line treatment options. Whilst colchicine was commenced in this case, the patient unfortunately experienced the most severe complication of CDS - cervical myelopathy. Therefore, current evidence (whilst very limited) supports the use of glucocorticoids to decrease the degree of pannus at the dens. Surgical intervention was a necessity in this case because of the presence of myelopathy. The prognosis of CDS is good if surgery is timely, and in this case the patient was able to regain his lost sensorimotor functions. There have been reports of relapses of the disease, but so far the patient has remained in remission. Earlier recognition would have avoided the lumbar puncture procedure, as well as the unnecessary prescription of broad-spectrum antibiotics. Key learning points 1. CDS is an under-recognised cause of acute neck pain in adults and left untreated can cause neurological disability. 2. The main differential diagnosis is meningitis, but early use of imaging can identify CDS as the culprit. CDS can be reliably diagnosed using CT imaging, with classic calcifications in the ligaments surrounding the dens being seen. 3. The CRP levels are grossly elevated in cases of CDS, with most patients experiencing fever as well. CT imaging should be obtained prior to a lumbar puncture. 4. The presence of myelopathy and neurological deficits indicates the need for operative intervention. 5. CDS responds to colchicine and corticosteroids, with a treatment duration of 2-4 weeks. 6. CT scans cannot reliably monitor disease activity, as the calcific changes persist for months after treatment. 7. Colchicine prophylaxis should be considered in patients experiencing multiple relapses over the span of two years.

Objectives To assess the prevalence of calcification surrounding the odontoid process (odontoid calcification) with crowned dens syndrome (CDS) and without CDS (non-CDS) and investigate factors that may related to the onset of CDS. Methods Retrospective review of consecutive patients visited Sir Run Run Shaw Hospital between 1 January 2018 and 5 November 2019 who were identified to have odontoid calcification on cervical computed tomography (CT) images. Those who presented with an acute or subacute episode of cervico-occipital pain were defined as CDS, others were non-CDS. Results We diagnosed 69 cases of odontoid calcification among 2902 cervical CTs of 2556 patients (69/2556, 2.70%), 19 (19/2556, 0.74%) cases of which were CDS, 50 (50/2556, 1.96%) cases were non-CDS. Mean age was 71 (54–86) years old in odontoid calcification patients. The male-to-female ratio of patients with odontoid calcification was 27:42 (0.64). The prevalence of odontoid calcification was 69/1497 (6.14%) in individuals over 50 years old, The prevalence was 0.59% (4/679), 5.05% (26/515), 11.49% (27/235) and 20% (12/60) in patients aged 50–59, 60–69, 70–79 and 80–89 years old, respectively. Age and female gender were predictive factors of odontoid calcification. Lower hemoglobin (Hgb), red blood cell count (RBC), higher C-reactive protein (CRP), pain scale score were found in CDS patients comparing with non-CDS group. No difference of age, gender, hypertension, diabetes mellitus, smoking, alcohol history, creatinine, white blood cell count, mean corpuscular volume, uric acid, calcium was found between the two groups. Conclusions Odontoid calcification is a common radiological entity in patients older than 50 years. Lower Hgb, RBC, higher CRP, pain scale score were found in CDS patients comparing with non-CDS.

Crowned dens syndrome (CDS) is defined as acute cervical or occipital pain due to a local inflammatory reaction related to calcifications in the ligaments surrounding the odontoid process. Virtually, all previous descriptions of CDS have related to calcium pyrophosphate dehydrate (CPPD) arthropathy. We prospectively identified a total of twenty-four consecutive inpatients with Crowned dens syndrome from January 2016 to December 2017 in our institution. All patients (age range 54 to 87 years, 67% females) presented with acute onset pain in the upper neck and/or occiput accompanied with extreme neck stiffness. Most patients (79%) had elevated inflammatory markers. Four patients underwent temporal artery biopsy, which was negative for arteritis in all cases, and one was subjected to lumbar puncture, which was non-contributory. Seventeen patients (71%) had known rheumatic disease on presentation: 10 patients had the diagnosis of calcium pyrophosphate dehydrate arthropathy, 3 patients had ankylosing spondylitis, 2 patients had rheumatoid arthritis, 1 patient had Behcet's disease, and 1 suffered from Familial Mediterranean Fever. In 4 more patients, crowned dens syndrome was the presenting symptom of calcium pyrophosphate dehydrate disease. All patients were treated with glucocorticoids as 0.5 mg/kg prednisone plus colchicine 0.5 mg bid resulting in dramatic improvement in both clinical (head/neck pain alleviated and cervical spinal mobility regained) and laboratory measures. Crowned dens syndrome should be considered, and craniocervical junction imaged in the context of acute cervical or occipital pain with stiffness and elevated inflammation markers not only in patients previously diagnosed with calcium pyrophosphate dehydrate arthropathy but also in diverse clinical settings.Key Points• This report highlights that crowned dens syndrome should be considered in various clinical setting besides calcium pyrophosphate dehydrate (CPPD) arthropathy.• Vigilance to this syndrome allows rapid treatment and may spare the patient unnecessary invasive procedures (i.e., temporal artery biopsy or lumbar puncture).

Introduction Crowned dens syndrome (CDS) is a rare manifestation of calcium pyrophosphate deposition disease (CPPD) affecting the cervical spine, particularly the atlantoaxial joint. It typically presents in older adults with acute or subacute neck pain and restricted range of motion. Diagnosis is often delayed due to low clinical suspicion and the technical challenges of joint aspiration in this region. Computed tomography (CT) is the diagnostic modality of choice, revealing characteristic chondrocalcinosis around the odontoid process. We report the case of a 74-year-old Caucasian man who presented with severe neck pain and limited mobility ultimately diagnosed with CDS. Case description A 74-year-old Caucasian man with a medical history of non-inflammatory myositis, recurrent pseudogout, osteoarthritis, and hypertension presented with severe acute neck pain and limited range of motion. He reported experiencing five to six similar episodes over the previous five months. At the time of clinical assessment, he was not experiencing an acute flare; physical examination was unremarkable aside from chronic neck discomfort. Routine blood tests, including C-reactive protein, white cell count, liver function, serum magnesium, and uric acid, were within normal limits. Autoimmune screening was negative for rheumatoid factor and antineutrophil cytoplasmic antibodies. Previous joint aspirations from the right knee (2018) and right wrist (2020) had confirmed calcium pyrophosphate crystals, consistent with a history of pseudogout. A cervical spine CT scan demonstrated calcification of the ligaments around the odontoid process, consistent with CDS, along with moderate-to-severe canal stenosis at C5–C6 and C6–C7. The patient was started on colchicine 500 mcg twice daily and over-the-counter magnesium supplementation. At four-month follow-up, he reported no further pseudogout flares and a marked improvement in quality of life. He was advised to continue colchicine with plans to taper the dose gradually. Given his underlying myopathy, he was counselled on potential colchicine-related complications, including colchicine-induced myopathy. Discussion This case underscores the diagnostic challenge posed by CDS, a rare but important consideration in elderly patients presenting with acute neck pain. CT imaging was pivotal in confirming the diagnosis, consistent with existing literature. Interestingly, our patient had normal inflammatory markers, contrasting with most published cases that report elevated C-reactive protein and white cell count. This supports the need for a high index of suspicion and the use of imaging, even when laboratory parameters are normal. The patient responded well to colchicine, in line with case reports and the EULAR recommendations for CPPD management. However, the use of colchicine in patients with pre-existing myopathy necessitates caution, due to the risk of colchicine-induced myopathy. Regular clinical and biochemical monitoring is advised in such cases. This case contributes to the growing body of literature on CDS and highlights both the diagnostic utility of CT and the therapeutic role of colchicine. Key learning points Crowned dens syndrome should be considered in the differential diagnosis of acute neck pain in elderly patients, even when inflammatory markers are normal. Early recognition and treatment with colchicine can significantly improve outcomes and prevent recurrent flares. CT remains the diagnostic gold standard for CDS. Clinicians should be mindful of potential colchicine toxicity in patients with underlying muscle disorders and monitor accordingly. This case adds to the limited literature on CDS and reinforces the need for increased clinical awareness of this uncommon but treatable condition.

Crowned Dens Syndrome

Crowned Dens Syndrome (CDS) is a rare but important consideration in the differential diagnosis of cervical spine pain in older adults. CDS is characterized by calcium pyrophosphate dihydrate (CPPD) crystal deposition around the odontoid process, often leading to symptoms that overlap with more common conditions such as rheumatoid arthritis (RA), meningitis, or cervical spondylosis. We report the case of a 74-year-old male with chronic neck pain and restricted cervical range of motion. Advanced imaging revealed characteristic calcifications surrounding the odontoid process, pannus formation, and erosive changes at the C1-C2 articulation, consistent with CDS. Clinical evaluation supported a diagnosis of CPPD-related CDS. The patient was successfully managed conservatively with nonsteroidal anti-inflammatory drugs and physical therapy, with notable symptomatic improvement over time. This case reinforces the utility of CT imaging in diagnosing CDS and differentiating it from other inflammatory or degenerative cervical conditions. Awareness of CDS and a high index of suspicion are essential for early diagnosis, appropriate treatment, and avoidance of unnecessary interventions. Conservative management remains effective in most cases; however, further studies are necessary to evaluate alternative therapies for refractory presentations.

Cervical CT-Dependent Diagnosis of Crowned Dens Syndrome in Calcium Pyrophosphate Dihydrate Crystal Deposition Disease

BackgroundCalcium pyrophosphate dihydrate crystal deposition disease is a condition in which calcium pyrophosphate dihydrate crystal is deposited in joint cartilage and ligaments. Calcium pyrophosphate dihydrate crystal deposition disease that involves calcification around the odontoid process of the second cervical vertebra is called crowned dens syndrome. Crowned dens syndrome is accompanied by fever in addition to acute and intense neck, posterior head, and temporal pain; thus, distinguishing crowned dens syndrome may be difficult in the presence of odontogenic infection. To the best of our knowledge, this is the first report describing a patient with crowned dens syndrome with coexisting odontogenic infection.Case presentationA 75-year-old Japanese woman was examined in the Emergency Department of this hospital due to a chief complaint of worsened buccal swelling on the left side. An odontogenic infection was considered, and she underwent her first examination. She presented with a body temperature of 37.4 °C, marked swelling and tenderness of her left lower eyelid through to her left cheek, and pain on the left temporal area. Blood tests revealed a leukocyte count of 6700/μL and a C-reactive protein level of 7.15 mg/dL. There was swelling and pain around the gingiva and acute purulent apical periodontitis of left maxillary second premolar. Cellulitis of the left cheek was diagnosed. After performing drainage of the pus, antibiotic treatment was initiated. Although her clinical symptoms improved, blood tests on day 9 of hospitalization revealed a leukocyte count of 6500/μL and a C-reactive protein level of 25.62 mg/dL, which were indicative of worsening symptoms. Computed tomography was performed to evaluate remote infection and images revealed a calcification around the odontoid process of her second cervical vertebra. When she was referred to the Orthopedic Surgery Department, pseudogout of the cervical spine was diagnosed. Subsequently, oral acetaminophen was initiated, and both her leukocyte count and C-reactive protein improved markedly.ConclusionsIn the presence of persistent fever and abnormally high leukocyte and C-reactive protein indicative of an inflammatory reaction, coexistence of pseudogout should be considered. In particular, when symptoms of temporal pain are present, the possibility of pseudogout of the cervical spine must be considered in the differential diagnosis.

Crowned Dens Syndrome (CDS) is an acute inflammatory neck pain linked to Calcium Pyrophosphate crystal deposition surrounding the odontoid process. This systematic review and meta-analysis aim to illuminate the Features and Diagnostic Challenges of CDS. PubMed, Web of Sciences, and Scopus databases were searched in July 2024 to include all studies on CDS without publication year or language restrictions. Demographic, clinical, laboratory, and radiological data, in addition to treatment regimens and outcomes, were extracted and analyzed. PROSPERO registration number is CRD42024575491. We analyzed 153 reports, including 196 CDS patients, with a mean age of 73.13 ± 12.95 years and an almost equal female-to-male ratio. Neck pain was the most common symptom (96.8%). CRP and ESR were elevated in 91.4% and 80.7% of cases, respectively. CT scans had the highest detection rate for abnormalities (97.3%), compared to MRI (68.4%) and plain radiographs (79.4%). NSAIDs were the most frequently used treatment (62.5%), with improvement observed in 96.6% of cases. Meningitis was the most common misdiagnosis (21.4%), leading to a higher likelihood of plain radiographs and lumbar punctures. In contrast, patients with neck tenderness and restricted range of motion had a lower risk of misdiagnosis. Patients who were initially misdiagnosed were more likely to undergo LP (13.1% Vs. 34.8%; P-value < 0.001). CDS is an elderly disease that usually presents as acute neck pain with elevated inflammatory markers and is frequently misdiagnosed as meningitis. Recognizing key clinical features may improve diagnosis and management.

Traumatic injury to the spinal cord can be divided into complete and incomplete subtypes, based on complete or partial absence of neurologic function below the level of injury. Incomplete spinal cord injury has been shown to occur following cervical hyperextension or flexion injury in the setting of preexisting cervical spinal stenosis. The broad spectrum of symptoms from incomplete spinal cord injury includes weakness and sensory deficits potentially affecting upper and lower extremities, as well as bowel, bladder, and sexual dysfunction in severe cases. The most common type of incomplete spinal cord injury is central cord syndrome, which is characterized by a more severely impaired motor function in the upper than the lower extremities [1, 8, 10, 13, 16]. Progressive neurological deficit has also been reported to occur due to C1–C2 pannus formation in the setting of rheumatic disease [4, 12, 17, 19, 20]. Crowned dens syndrome (CDS) is a rare but known cause of decreased cervical range of motion and severe axial neck pain, in the setting of calcium deposition around the odontoid, for which medical treatment with nonsteroidal anti-inflammatory drugs and/or steroids has been reported [2, 7]. Patients with CDS may present with symptoms of cervical myelopathy caused by a mass containing calcium pyrophosphate dihydrate (CPPD) at the atlantoaxial articulation and/or in the transverse ligament and/or in the ligamentum flavum [3, 9, 11, 14, 15]. According to the findings of Goto et al. evaluating 2,023 patients with neck pain as the chief complaint, 40 patients were identified with CDS, indicating a prevalence of 2.0% [7]. Chang et al. reported an overall prevalence of radiographically evident atlantoaxial CPPD deposition of 12.5%, which was increasing with age [5]. However, severe and gradually progressive neurological deterioration due to an isolated large mass consisting of calcium pyrophosphate at the C1–C2 level causing functional quadriplegia is rare, and, therefore, the optimal treatment remains to be determined. Surgical decompression and stabilization may alleviate the compression on the cervical spinal cord [11], yet the potential for neurological recovery remains to be further elucidated. We report the case of an 87-year-old male diagnosed with quadriplegia resulting from CDS who made an excellent recovery following surgical decompression.

Crowned Dens Syndrome: Report of Three Cases and a Review of the Literature

Dear Editor, A 90-year-old man visited our emergency department owing to neck pain and occipital headache. The pain occurred suddenly a few days previous, and had become gradually worse. He had a history of cerebral infarction, dementia, and cholelithiasis, but was not on any medication. The patient’s vital signs were stable excluding a body temperature of 37.5°C. Physical examination showed the reduction of passive cervical spine movements with posterior neck pain and occipital headache. Rotation, extension, and flexion in the neck were all limited. However, there was no tenderness in the nape of the neck. In terms of neurological findings, overall cranial nerve, motor, and sensory nervous systems were intact. In laboratory data, the value of the C-responsive protein was 4.34 mg/dL (normal range, 0.0–0.1 mg/dL); all other findings were unremarkable. Computed tomography (CT) of the neck showed crown-shaped calcium deposits surrounding the odontoid process (Fig. 1A, arrows), and dotted calcifications of the transverse ligament of the atlas (Fig. 1B, arrows).There were no other lesions causative of pain in brain or spine. By integrating the results, we diagnosed crowned dens syndrome (CDS). The chief complaint of patients of CDS is neck pain, due to calcification deposition around the odontoid process. The cause of CDS is thought to be the microcrystalline deposition, most often calcium pyrophosphate dihydrate crystals and/or hydroxyapatite crystals, in the transverse ligament of the atlas around the odontoid process. However, the pathophysiologic process has not been completely proven. Clinicians could confuse the differential diagnosis and misdiagnose CDS as meningitis, polymyalgia rheumatica, or dissecting aneurysm of the vertebral and basilar artery. In particular, meningitis must be considered first in the differential diagnosis because the triad of fever, headache, and neck stiffness due to meningitis are very similar to the symptoms of CDS. Using CT scans, CDS is identified in up to 5% of the patients over the age of 70 years who present to hospital with the chief symptom of neck pain. Therefore, it is not a rare entity but becoming unclear using plain radiography for the diagnosis because of improper images. Computed tomography is the gold standard for detecting calcification in transverse, apical, and alar ligaments. However, when the CT scan is carried out a long time after the onset of symptoms, calcification around the odontoid process may not be detected as it may have been absorbed. Non-steroidal anti-inflammatory drugs (NSAIDs) have been commonly used as first-line therapy for CDS. In cases without improvement using NSAIDs alone, treatment with moderate dosage of corticosteroids is recommended. In our case, NSAID therapy alleviated the patient’s symptoms completely. Taiki Yamada, Takeji Saitoh, Hironao Hozumi, Yoshiaki Takahashi, Masashi Nozawa, Toshiaki Mochizuki, and Atsuto Yoshino Department of Emergency and Disaster Medicine, Hamamatsu University School of Medicine, Hamamatsu, Japan

The study objective was to examine the disease, demographic, and imaging features associated with different inflammatory phenotypes of calcium pyrophosphate deposition (CPPD) disease, ie, recurrent acute calcium pyrophosphate (CPP) crystal arthritis, chronic CPP crystal inflammatory arthritis, and crowned dens syndrome (CDS). Data from an international cohort (assembled from 25 sites in 7 countries for the development and validation of the 2023 CPPD classification criteria from the American College of Rheumatology/EULAR) that met the criteria were included. Three cross-sectional studies were conducted to determine the phenotypic characteristics of recurrent acute CPP crystal arthritis, chronic CPP crystal inflammatory arthritis, and CDS. Multivariable logistic regression analysis was used to calculate adjusted odds ratio (aOR) and 95% confidence interval (CI) to examine the association between potential risk factors and the inflammatory phenotype. Among the 618 people included (56% female; mean age [standard deviation] 74.0 [11.9] years), 602 (97.4%) had experienced acute CPP crystal arthritis, 332 (53.7%) had recurrent acute arthritis, 158 (25.6%) had persistent inflammatory arthritis, and 45 (7.3%) had had CDS. Recurrent acute CPP crystal arthritis associated with longer disease duration (aOR 2.88 [95% CI 2.00-4.14]). Chronic CPP crystal inflammatory arthritis was associated with acute wrist arthritis (aOR 2.92 [95% CI 1.81-4.73]), metacarpophalangeal joint osteoarthritis (aOR 1.87 [95% CI 1.17-2.97]), and scapho-trapezo-trapezoid (STT) joint osteoarthritis (aOR 1.83 [95% CI 1.15-2.91]), and it was negatively associated with either metabolic or familial risk for CPPD (aOR 0.60 [95% CI 0.37-0.96]). CDS was associated with male sex (aOR 2.35 [95% CI 1.21-4.59]), STT joint osteoarthritis (aOR 2.71 [95% CI 1.22-6.05]), and more joints affected with chondrocalcinosis (aOR 1.46 [95% CI 1.15-1.85]). CPPD disease encompasses acute and chronic inflammatory phenotypes, each with specific clinical and imaging features that need to be considered in the diagnostic workup.

We have reported six cases of Crowned dens syndrome (CDS) diagnosed by computed tomography (CT). Presenting cases were three male and three female, aged from 45 to 89 (averaged in 72). All cases showed calcification around the dens of axis in CTs. Neck pain in all cases relieved within at least 10 days, treated by non-steroidal anti-inflammatory drugs (NSAIDs) in five cases, and one by acetaminophens. Bouvet et al. first reported CDS in 1985, as acute pseudogout of the neck, which causes neck pain. CDS is a radioclinical syndrome defined by the radiographic calcifications in a crown-like configuration around the odontoid process, accompanied clinically by acute neck pain, often with neck stiffness, fevers and raised inflammatory markers. CDS is thought to be a rare condition; however, it is frequently misdiagnosed. CDS is an important differential diagnosis in patients presenting with acute neck pain.