Article Text
Abstract
Crowned dens syndrome is a rare presentation of calcium pyrophosphate deposition disease. It is characterised by severe occipital pain and neck stiffness. Acute presentations are typically accompanied by fever and an inflammatory response and hence can be misdiagnosed as polymyalgia rheumatica or meningitis. Chronic relapsing presentations may be misdiagnosed as cervicogenic neck pain or occipital neuralgia. We present a patient who presented with a chronic relapsing form of crowned dens syndrome and discuss the epidemiology, typical presentation and management of this eminently treatable condition.
- clinical neurology
- headache
- pain
Statistics from Altmetric.com
Clinical vignette
A 78-year-old man who worked as a tailor presented with a two and a half year history of chronic headache and neck stiffness. The headache was of maximal intensity over the craniocervical junction. He also reported bi-occipital burning scalp pain. The symptoms had persisted throughout the previous 2 years, but their intensity had fluctuated over the course of weeks. The pain could frequently be disabling and during exacerbations interfered with his ability to sleep.
His medical background included hypertension, hypercholesterolaemia, type 2 diabetes mellitus, gastro-oesophageal reflux disease and benign prostatic hypertrophy. His medications included esomeprazole, clopidogrel, dutasteride, tamsulosin, atorvastatin, candesartan, amlodipine and metformin.
On examination, there was moderate to severe reduction in neck movement, particularly on rotation and lateral flexion. Comprehensive neurological examination was otherwise normal. There was no significant limb joint arthropathy.
Investigations included normal full blood count, routine biochemistry including calcium and magnesium, erythrocyte sedimentation rate (12 mm/hour), serum C-reactive protein (0.7 mg/L) and plasma parathyroid hormone concentration.
CT cervical spine showed multilevel cervical spondylosis that was initially thought to explain his pain. We gave him simple analgesics, pregabalin and a targeted combination of local anaesthetic and corticosteroid injections, first to the left C2/3 and right C3/4 facet joints and then subcutaneously to both greater occipital nerves. Unfortunately, no treatment significantly controlled his pain.
We performed an integrated single photon emission tomography (SPECT)/CT scan to better evaluate target sites for further facet joint injection. This showed avidly increased uptake at the anterior border of the dens (see figure 1). There was also calcification of the transverse ligament of the atlas consistent with the ‘crowned dens syndrome’. The remaining cervical spine showed mild C5/6 and C6/7 discovertebral arthritis. There was no superimposed active facet joint arthritis.
He tried a tapering course of prednisolone starting at 20 mg/day and colchicine 0.5 mg twice daily. At his last follow-up, he was taking slow release paracetamol 1330 mg twice daily with a moderate, sustained improvement in symptoms.
Crowned dens syndrome
The first report of crowned dens syndrome was in 1980.1 It is a rare but treatable cause of upper neck pain and stiffness. The syndrome arises following the formation of calcium pyrophosphate crystals within the periodontoid ligaments. The crystals induce inflammation as well as the production of matrix metalloproteinases and prostaglandins, leading to pain, swelling and in severe cases erosion of the underlying joint. The radiological appearance of crystal deposition on CT scanning is a halo sign around the os dens, hence the term ‘crowned dens’ (see figure 1).
Calcium pyrophosphate deposition disease is an arthropathy caused by the deposition of calcium pyrophosphate crystals. It typically manifests as polyarticular arthritis, affecting the knee, wrist, shoulder and metacarpophalangeal joints. Acute flares of the condition or ‘pseudogout’ most commonly affect the knee or wrist, can last several weeks, with associated local pain and swelling as well as a systemic inflammatory response. Crowned dens syndrome is essentially an attack of pseudogout in the atlantoaxial joint. It typically presents acutely or subacutely with moderate to severe neck pain, worst at the base of occiput and neck stiffness. The inflammatory nature of the condition means that acute presentations are often accompanied by fevers and raised inflammatory markers (in 70%–80%), leading to the not infrequent misdiagnoses of polymyalgia rheumatica or even acute meningitis.1 On rare occasions, the inflammatory process can progressively erode the atlantoaxial ligaments and even the dens itself leading to atlantoaxial instability, cord compression and progressive tetraparesis.
Similarly to acute pseudogout elsewhere, exacerbations are more frequent after local trauma, during acute illnesses and postoperatively. There can also be chronic relapsing presentations with fluctuating exacerbations of neck pain and stiffness. As with other manifestations of calcium pyrophosphate deposition disease, the crowned dens syndrome typically affects those aged over 60 years and its associated risk factors include hypomagnesaemia and hyperparathyroidism.
Incidence
The true incidence of crowned dens syndrome is unknown. Calcium pyrophosphate deposition disease probably affects 4%–7% of European people, although these estimates are based on the presence of joint chondrocalcinosis on plain radiographs, for which there are other causes. Only 25% of patients with calcium pyrophosphate deposition disease manifest as acute pseudogout. The frequency of periodontoid calcification in people with calcium pyrophosphate deposition disease is between 40% and 60%, depending on the study. In one series, periodontoid calcification was an incidental finding in 88/554 (15.9%) patients undergoing a CT scan of head.2 Of these patients, 18 (20%) were currently or had previously suffered from pseudogout including 11 (12.5%) who developed crowned dens syndrome.2
Diagnosis
The diagnosis is made on the basis of a combination of a typical clinical picture and dedicated CT imaging of the atlantoaxial joint. CT shows calcification in the periodontoid ligaments between the dens and the atlas. The extent of calcification can be quantified and an increasing grade correlates with an increased likelihood of developing inflammatory neck pain. CT can also show soft tissue thickening, subchondral cyst formation and exclude alternative causes of neck pain. MR scanning can show inflammatory change but shows calcification less well than CT scanning. Nuclear medicine techniques, such as integrated SPECT/CT imaging can help, particularly in subacute/chronic cases where alternative sources of degenerative neck pain are possible.
Treatment
Treatment mimics that of the management of pseudogout. A short course of a non-steroidal anti-inflammatory drug (NSAID) is first line. The condition typically settles within days to weeks of starting NSAIDs. Patients who cannot tolerate NSAIDs or for whom they do not work can use low dose corticosteroids (10–20 mg). Colchicine can also be tried although experience is limited. Risk factors for calcium pyrophosphate deposition disease such as low magnesium and hyperparathyroidism should also be addressed.
Key points
Crowned dens syndrome is an important differential diagnosis in a patient presenting with occipital neck pain and stiffness; it needs recognising early to help prevent misdiagnosis of a meningitic syndrome or polymyalgia rheumatica.
The typical patient is aged over 60 years and may have other manifestations of calcium pyrophosphate deposition disease, including polyarticular arthritis with or without acute attacks of pseudogout affecting the knee or wrist joints.
The diagnosis rests on a combination of a typical clinical picture and dedicated CT of the atlantoaxial joint showing calcification with or without swelling of the periodontoid ligaments.
Initial treatment is with a course of non-steroidal anti-inflammatory drugs for 2–3 weeks, or if these are not tolerated or effective a short course of corticosteroids.
Footnotes
Contributors All authors have contributed equally.
Competing interests None declared.
Patient consent Obtained.
Provenance and peer review Not commissioned; externally peer reviewed. This paper was reviewed by Brendan Davies, Staffordshire, UK, and Nick Silver, Liverpool, UK.
Other content recommended for you
- The 2023 ACR/EULAR classification criteria for calcium pyrophosphate deposition disease
- Pseudogout or pseudolymphoma? Calcium pyrophosphate deposition disease of the cervical spine: a rare presentation and literature review
- Unusual cause of neck pain
- Delayed diagnosis of an upper cervical epidural abscess masked due to crowned dens syndrome
- Case report: crowned dens syndrome in a patient with seronegative rheumatoid arthritis
- Jolt accentuation of neck pain: a novel physical finding for crowned dens syndrome
- Calcium pyrophosphate dihydrate crystal deposition disease and MRSA septic arthritis of the atlantoaxial joint in a patient with Tourette syndrome
- Severe systemic inflammatory response syndrome immediately after spinal surgery in a patient with axial gout
- The clinical implication of cervical interspinous bursitis in the diagnosis of polymyalgia rheumatica
- Posterior C1-C2 calcium pyrophosphate dihydrate crystal deposition disease