Severe headache complicated by vertical atlantoaxial subluxation in diffuse systemic sclerosis with crowned dens pattern calcification.

We report a 34-year-old female case of diffuse systemic sclerosis (SSc) with generalized ectopic calcification, who developed severe headache with vertical atlantoaxial subluxation (AAS) complicated by calcification around the odontoid process (crowned dens pattern calcification). Although a rare complication, AAS should be considered as a differential diagnosis of severe headache in SSc patients with extensive calcification.