title: Posterior atlantooccipital subluxation in Down syndrome.
abstract: Three Down syndrome patients with posterior atlantooccipital (AO) subluxation are described. All are asymptomatic. The subluxation becomes manifest during active extension of the neck and reduces in flexion. Methods of assessing posterior AO subluxation are discussed. The abnormality is attributed to ligamentous laxity in patients with Down syndrome.
mesh_terms: D000293:Adolescent; D000328:Adult; D001269:Atlanto-Occipital Joint / Q000000981:diagnostic imaging*; D002648:Child; D004314:Down Syndrome / Q000150:complications* / Q000000981:diagnostic imaging; D006801:Humans; D004204:Joint Dislocations / Q000150:complications / Q000000981:diagnostic imaging*; D008297:Male; D011859:Radiography