506 - Crowned Dens Syndrome: A Case Report

Case Diagnosis: Crowned Dens Syndrome (CDS)

Case Description: A 85-year-old male underwent evacuation of a left subdural hematoma (SDH) due to altered mental status. Two days later, he experienced right arm weakness, leading to a repeat evacuation due to re-accumulation of the SDH. Following stabilization, the patient was admitted to acute inpatient rehabilitation. Shortly thereafter, he developed symptoms including fever, headache, severe neck pain, and cervical paraspinal stiffness. CT head showed no acute findings, but laboratory results revealed erythrocyte sedimentation rate of 75 mm/Hr and C-reactive protein level of 165 mg/dl. CT cervical spine confirmed the diagnosis of CDS. Subsequent MRI redemonstrated retroodontoid pseudopannus. The patient was initiated on prednisone and colchicine for the management of calcium pyrophosphate dihydrate (CPPD), which led to significant symptom improvement.

Discussions: CPPD is characterized by crystal deposition in the synovial and periarticular tissues, with its exact pathophysiology not completely understood. Crystals can induce inflammation by increasing interleukin secretion by synovial lining cells. CDS, an underdiagnosed syndrome, involves CPPD deposition on the odontoid process. It is often misdiagnosed as conditions such as meningitis, polymyalgia rheumatica (PMR), and giant cell arteritis (GCA) due to the similar presentation of symptoms including fever, neck pain or stiffness, and headaches. Treatment typically involves non-steroidal anti-inflammatory drugs (NSAIDs) and low-dose steroids, which typically lead to symptom improvement, as observed in our patient.

Our case posed a diagnostic challenge as spinal tap was contraindicated due to the underlying SDH. Timely imaging is crucial during acute attacks, as CT performed after calcifications have been reabsorbed can miss detection

Conclusions: Recognition of CDS in elderly patients presenting with acute neck pain and fever is essential, as it can mimic more common syndromes like meningitis. Proper diagnosis prevents unnecessary interventions. Effective communication with the patient's primary care provider is vital for ensuring appropriate long-term management and preventing unnecessary diagnostic evaluations.