Pseudogout of the Transverse Atlantal Ligament: An Unusual Cause of Cervical Myelopathy

BACKGROUND: Calcium pyrophosphate dihydrate deposition in the cervical spine is infrequently symptomatic. This is especially true at the craniocervical junction and upper cervical spine. CASE REPORT: A 70-year-old previously healthy woman presented with a progressive cervical myelopathy of four months duration. RESULTS: Examination revealed sensorimotor findings consistent with an upper cervical myelopathy. Radiological studies (plain radiographs, computed tomography, and magnetic resonance imaging) revealed C1-2 instability, and a well-defined extradural 3 cm x 1 cm retro-odontoid mass causing spinal cord compression. Transoral resection of the mass was performed followed by posterior C1-2 stabilization. Histological examination of the mass confirmed calcium pyrophosphate dihydrate deposition. Follow-up examination showed marked clinical and radiological improvement. CONCLUSION: Although uncommon, calcium pyrophosphate dihydrate deposition disease should be considered in the differential diagnosis of extradural mass lesions in the region of the odontoid.