title: Asymptomatic occipito-atlantal instability in Down syndrome (trisomy 21). Report of two cases in children.
mesh_terms: D001269:Atlanto-Occipital Joint / Q000000981:diagnostic imaging; D002648:Child; D004314:Down Syndrome / Q000150:complications*; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000150:complications* / Q000000981:diagnostic imaging; D011859:Radiography