Abstract
INTRODUCTION: Calcium pyrophosphate crystal deposition (CPPD) disease is an under-recognised crystal arthropathy in the elderly population. It can be misdiagnosed as gout, osteoarthritis, or polymyalgia rheumatica. Recent studies have identified three inflammatory phenotypes of CPPD disease: acute crystal arthritis, chronic polyarticular arthritis and crowned dens syndrome (CDS). CDS is an uncommon phenotype characterised by acute or subacute cervical pain resulting from CPPD or hydroxyapatite crystals deposition in the cervical spine. Computed tomography (CT) imaging is diagnostic, typically revealing a crown- or halo-like radiopaque density surrounding the atlanto-axial articulation. CASE DESCRIPTION: A 95-year-old gentleman presented with a 12 month history of progressive neck pain and stiffness. His symptoms had started abruptly and gradually worsened, resulting in significant restriction of neck movements. There was no history of headache, jaw claudication, visual disturbances, weight loss, fever, joint swelling or history of CPPD involving peripheral joints. He reported no relief from simple analgesics. His past medical history included generalised osteoarthritis (with bilateral hip and bilateral knee replacements), heart failure, stage 4 chronic kidney disease (CKD) and chronic obstructive pulmonary disease (COPD). His current medications were furosemide, cholecalciferol, mirtazapine, quinine sulphate, paracetamol, oxycodone, and topical ibuprofen gel. Family history was notable for generalised osteoarthritis in his siblings and children. On examination, he had severely restricted neck movements in all directions. There were no swollen or tender peripheral joints and no tophi detected. Bouchard’s and Heberden’s nodes were observed bilaterally. Neurological examination was nonrevealing, with preserved muscle strength in his upper limbs; power in the lower limbs could not be reliably assessed due to deconditioning. Cardiopulmonary examination revealed clear lungs and a fourth heart sound (S4), with no murmurs. Laboratory investigations showed elevated inflammatory markers (CRP 78 mg/L, WBC 14.1 x10(9)/L, and neutrophils 11.82 x10(9)/L), anaemia (Hb 96 g/L) and impaired renal function (eGFR 22 mL/min/1.73m²). Serum calcium, magnesium, and immunoglobulin levels were within normal limits. A CT scan of the cervical spine demonstrated multilevel cervical spondylosis with facet and uncovertebral joint arthrosis, a partially calcified pseudomass posterior to the dens compressing the thecal sac and abutting the spinal cord (Figures 1-2), resulting in spinal canal stenosis. Small erosions at the odontoid process were also noted, suggestive of CPPD disease (Figure 3). Based on all findings, a diagnosis of CDS secondary to CPPD was made (fulfilled ACR/EULAR 2023 criteria). Given his comorbidities, including heart failure, low-dose prednisolone (7.5–10 mg/day) was initiated. Despite a reduction in CRP level (decreased to 26 mg/L), there was no clinical improvement at the 8 week follow-up. Considering his advanced age, comorbidities and limited mobility, the focus of management is optimising pain control with oxycodone, and physiotherapy. DISCUSSION: Chronic neck pain is common in the elderly population, with the majority of cases attributed to degenerative spinal changes. In contrast, neck pain with an acute onset accompanied by elevated inflammatory markers in this population warrants thorough evaluation for differential diagnoses, including meningitis, discitis, spinal infection, and polymyalgia rheumatica. CDS, which is a lesser-known manifestation of CPPD disease, is likely to be overlooked as a cause of acute neck pain in the elderly population. According to a recent meta-analysis, CDS was misdiagnosed as meningitis in 20% of cases. CDS is a rare but specific manifestation of CPPD disease. Its prevalence is thought to be 5–7% among CPPD patients. It is possible that CDS is underdiagnosed as MRI is usually preferred to CT when it comes to spinal imaging. In our case, the patient’s symptom onset and clinical history were characteristic for CDS. While most patients are diagnosed during the acute phase, our patient appeared to have presented in the chronic phase of the syndrome. Notably, a significant number of patients may be asymptomatic, with the diagnosis made solely based on characteristic imaging findings, such as odontoid calcifications. According to recent meta-analyses, nonsteroidal anti-inflammatory drugs (NSAIDs) and short courses of corticosteroids are the most commonly used treatments, followed by colchicine. Most patients respond within a few weeks, and the overall prognosis is favourable. In our case, NSAIDs could not be initiated due to the presence of heart failure and severely reduced renal function. A low-dose prednisolone was given to minimise the impact on his cardiac function. However, it did not improve his symptoms. Possible explanations include the patient being evaluated during the chronic phase—potentially beyond the optimal treatment window—and the low corticosteroid dosage. Our current management plan focuses on optimising pain control. KEY LEARNING POINTS: Neck pain in the elderly can be a diagnostic challenge. While chronic symptoms are likely due to a degenerative causes, acute presentations typically prompt evaluation for infectious aetiologies such as meningitis, which leads to invasive procedures such as a lumbar puncture being undertaken. Literature review indicates that meningitis remains the most common differential diagnosis in such cases. However, in the right clinical context, particularly in someone with extensive chondrocalcinosis in their peripheral joints, a CT scan of the cervical spine should be considered. This approach may reduce the need for a lumbar puncture. As CPPD disease gains wider recognition within the rheumatology community, it is our hope that awareness of CDS will also increase.