Basiocciput hypoplasia results in shortening of the clivus and is always associated with basilar invagination. 13 there is an increased prevalence of neural dysgenesis such as the chiari malformation or syringohydromyelia reported to occur in 25 35 of patients with basilar invagination.
At the group level patients with charge syndrome had a smaller clivus and larger welcher angle than controls.
Basiocciput hypoplasia. This was done by measuring from the basion the point of the clivus at the midpoint on the anterior margin of the foramen magnum to the ventral ba xs and dorsal ba es margins of the visible synchondrosis. Basiocciput hypoplasia was found in 70 and basilar invagination in 29. 20 basioccipital hypoplasia has been defined as hypoplasia of 1 of the 5 clival segments sclerotomes of the clivus simplified from fujita et al 14.
14 here we evaluated the incidence and severity of basioccipital hypoplasia in charge syndrome. 14 the welcher angle is formed by the intersection between the nasion tuberculum line and the tuberculum basion line. Hypoplasia of the basiocciput can be found in manifestations of the occipital vertebra in atlas assimilation in atlanto occipital fusion and in such conditions as platybasia and basilar impression.
None of the patients had a chiari i malformation. Many of the congenital abnormalities around the foramen magnum are accompanied and manifested by dysplasia of the occipital bone.