Crowned dens syndrome: reports of six cases and review of the literature

Abstract

Case

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).

Outcome

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.

Conclusion

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.

Background

Crowned dens syndrome (CDS) is acute pseudogout of the neck, and causes neck pain characterized by the calcification of periodontoid articular tissues due to calcium pyrophosphate dihydrate (CPPD) deposition. It was first reported by Bouvet et al. in 1985.1 CDS is a radioclinical syndrome defined by the radiographic calcifications in a crown‐like configuration around the odontoid process, accompanied clinically with acute neck pain in cervico‐occipital area, often with neck stiffness, fevers and raised inflammatory markers. CDS is thought to be a rare condition; however, it is frequently misdiagnosed.2 Here, we have reported six cases of crowned dens syndrome, and provided a review of the literature. The aim of this report is to highlight CDS as an important differential diagnosis in patients presenting with acute neck pain.

Case Presentations

The presenting six cases were three male and three female, aged from 45 to 89 (average age 72). Computed tomography (CT) in all cases showed calcification around the dens of axis. Medical history of pseudogout attack were seen in two cases, and Bechet disease or hyperuricemia were seen in one. Neck pain in all cases were relieved within at least 10 days, treated by non‐steroidal anti‐inflammatory drugs (NSAIDs) in five cases, and one by acetaminophens. (Table 1)

Table 1.

Six cases of crowned dens syndrome

Case	Age	Sex	Past medical history	Chief complaints	Body temperature on arrival (°C)	WBC (μL)	CRP (mg/dL)	Pain duration (days)	Treatment (medication)
Case 1	81	Male	Myocardial infarction, cerebral infarction, benign prostatic hyperplasia, hypertension, hyperlipidemia.	Neck pain	36.6	12,300	11	9	NSAIDs
Case 2	72	Male	Chronic subdural hematoma, hyperuricemia, benign prostatic hyperplasia	Neck pain	37.3	6,900	15.5	5	NSAIDs
Case 3	89	Female	Hypertension, hyperlipidemia, osteoporosis	Neck pain, low back pain, left knee pain, fever	37.0	16,100	19	3	NSAIDs
Case 4	45	Male	Bechet disease,colon cancer, psuedogout attack in both knees	Neck pain, fever	38.2	10,000	9.9	10	NSAIDs
Case 5	76	Female	Hypertension	Neck pain, fever	37.3	7,900	13.9	7	NSAIDs
Case 6	69	Female	Psuedogout attack in Rt knee	Neck pain, fever	37.5	8,500	5.8	7	Acetaminophen

CRP, C‐reactive protein; NSAIDs, non‐steroidal anti‐inflammatory drugs; WBC, white blood cell count.

Case 1

An 81‐year‐old male was transferred by an ambulance after 2 min of syncope during cooling his neck with ice packs for neck pain. His medical history included old myocardial infarction, cerebral infarction, benign prostatic hyperplasia, hypertension and hyperlipidemia. His body temperature was 36.6°C°C, and serum investigations revealed raised white blood cells (WBC) of 12,300/μL and C‐reactive protein (CRP) of 11.0 mg/dL. There were no systemic disorders on examination except of stiff neck, and since CT of the neck showed calcification area posterior to the odontoid process (Fig. 1), he was diagnosed as having vasovagal syncope lead by neck pain from CDS. He was treated by NSAIDs, which provided symptomatic relief in 9 days.

Figure 1.

Axial (a) and sagittal (b) computed tomography (CT) views demonstrating calcification posterior to the odontoid process.

Case 2

A 72‐year‐old male suffered an acute neck pain 5 days after having drainage of chronic subdural hematoma. His medical history included hyperuricemia and benign prostatic hyperplasia. His body temperature was 37.3°C, and serum investigations revealed WBC of 6900/μL, CRP of 15.5 mg/dL and procalcitonin of 0.06 μg/L. Multiple blood cultures were taken, and broad spectrum antibiotics commenced to cover meningitis. There were no systemic disorders on examination except stiff neck. Since cervical CT showed significant calcification area posterior to the dens of axis (Fig. 2), he was diagnosed as having CDS. Antibiotics were discontinued and treated by NSAIDs, which provided symptomatic relief in 5 days.

Figure 2.

Axial computed tomography (CT) views (a) demonstrating calcification posterior to the odontoid process. (b) Enlarged view.

Case 3

An 89‐year‐old female presented with a 3‐day history of neck pain, low back pain, left knee pain and fever. Her medical history included hypertension, hyperlipidemia and osteoporosis. Her body temperature was 37.0°C. Her left knee was swelling, however neither crystalloid nor bacteria were identified from the synovial fluid of the left knee. Serum investigations revealed raised WBC of 16,100/μL and CRP of 19.0 mg/dL. CT of the neck showed a calcification area of the transverse ligament of the atlas (Suppl. Fig. S1), consistent with a diagnosis of CDS. By taking NSAIDs, her pain was significantly relieved the next day, and fully recovered in two additional days.

Case 4

A 45‐year‐old male was presented with fever and acute neck pain. His medical history included Bechet disease and pseudogout attack of bilateral knee. His body temperature was 38.2°C, and serum investigations revealed raised WBC of 10,000/μL and CRP of 9.9 mg/dL. There were no systemic disorders on examination. CT of the neck showed pale calcification posterior of the dense (Suppl. Fig. S2), and was diagnosed as having CDS. He was treated with NSAIDs, which provided symptomatic relief in 10 days.

Case 5

A 76‐year‐old female presented with neck pain for a duration of one week. She had medical history of hypertension. Her body temperature was 37.3°C. Serum investigations revealed normal WBC of 7,900/μL and raised CRP of 13.9 mg/dL. CT of cervical neck showed calcification posterior of odontoid process (Suppl. Fig. S3), consistent with a diagnosis of CDS. By taking NSAIDs for a week, her pain disappeared without recurrence.

Case 6

A 69‐year‐old female presented with fever and neck pain. Her medical history included pseudogout attack in her right knee. Her body temperature was 37.5°C. Serum investigations revealed normal WBC of 8,500/μL and raised CRP of 5.8 mg/dL. CT of the neck showed calcification of the transverse ligament of the atlas (Suppl, Fig. S4), consistent with a diagnosis of CDS. By taking acetaminophens, her pain relieved after 7 days.

Discussion

Crowned dens syndrome is acute pseudogout of the neck, which is diagnosed by acute neck pain, presence of inflammatory indicators, and evidence of calcium deposits around the odontoid process on radiographs.1 CT imaging is the standard imaging method for CDS. In most patients, periodontoid calcification will not be able to be detected on plain radiography.3 Histological or microscopic confirmation from peripheral joint aspiration may be helpful, but is not required.

The onset of CDS is typically acute, but may sometimes be chronic. Patients typically present with severe neck pain, often with significant restriction of cervical rotation.3 CRP is often grossly increased. Neurological complications are rare; however, large cervical CPPD deposits may result in spinal stenosis or cervical myelopathy.4

Although involvement of the cervical spine is rare in pseudogout, cervical intervertebral discs, posterior longitudinal ligaments, ligamentum flavum, facet joints and the transverse ligament can be affected.5

Crowned dens syndrome predominantly affects women more than the age of 70. The majority (65%) of patients have demonstrable articular chondrocalcinosis within primary sites of CPPD deposition,2 such as knee, wrist and ankle joints. However, cervical spine involvement in patients with peripheral CPPD deposits is probably unrecognized.

Many pseudogout patients in peripheral joints may have radiological evidence of coexisting CPPD deposition within the cervical spine; however, the majority will be asymptomatic.6, 7 Pseudogout per se and radiological evidence of periodontoid calcification are both independent predictors for the development of neck pain and progression to CDS.6

Although all of our cases demonstrated calcification posterior to the odontoid process on CT imaging, it can appear elsewhere around the odontoid process. In the radiological classification of CDS proposed by Goto et al., CPPD deposition may be found posterior only (50%), posterolateral (27.5%), circular (12.5%), anterior (5%) or lateral (5%) to the odontoid process.3 Cervical MRI is generally useless in making the diagnosis; however, it may be worth considering excluding myelopathy, discitis or malignancy.

Crowned dens syndrome is rarely seen in emergency departments, however, from a retrospective survey conducted by Goto et al.,3 the prevalence of CDS in patients with acute neck pain was 2%, suggesting that the incidence may be higher than previously thought. It may be misdiagnosed as polymyalgia rheumatica (PMR), meningitis, giant cell arteritis, discitis, cervical spondylosis, rheumatoid arthritis and ankylosing spondylitis.2

Since the majority of CDS patients fully recovers within a week of high dose NSAIDs, corticosteroid, colchicine or combination therapy,3, 8 and these are also the general treatments for most causes of neck pain, the majority of patients with CDS are probably treated at emergency rooms or at orthopedics departments without considering CDS as a differential diagnosis. Therefore, we believe that a huge number of cases are never diagnosed, and this may be reason for the low incidence of CDS.

Conclusion

We have reported six cases of CDS. It is rarely diagnosed in the emergency room; however, more than half of patients of pseudogout patients in peripheral joints may have CPPD deposits in the cervical neck. We should consider CDS as an important differential diagnosis in patients who present with acute neck pain.

Conflict of Interest

None.

Supporting information

Figure S1. Axial (a) and sagittal (b) CT views demonstrating calcification posterior to the odontoid process.

Figure S2. Axial CT view demonstrating calcification posterior to the odontoid process.

Figure S3. Axial CT view demonstrating calcification posterior to the odontoid process.

Figure S4. Axial (a) and sagittal (b) CT views demonstrating calcification posterior to the odontoid process.