[Bony malformations of the cranio-vertebral junction and its clinical relevance (author's transl)].

A statistical analysis is performed in 86 cases suffering from osseous malformation of the cranio-vertebral junction. The material consists of 71 cases with basilar impression, 8 cases with hypoplasia or absence of the odontoid process, and 7 cases with a congenital atlanto-epistropheal dislocation. The patients are clinically asymptomatic in 23 cases, and are marked by a para-respectively tetraparesis in 28 cases, by bulbar-pontine-cerebellar disorders in 24 cases, and by syringomyelia in 11 cases. A control group is included consisting of 30 cases without neurological symptoms and with a normal radiological finding of the cranio-vertebral region. The following measured values are taken in consideration to perform a statistical calculation using the simple variance analysis: The height of the odontoid process above of McGregor's line, the distance between the back of the odontoid process and the inner limit of the arch of C1, and, concerning the groups with hypoplasia of the odontoid process process and with atlanto-axial dislocation, the narrowing of the spinal canal at the level of C1 dependent on movements of the head. The measured values are referred to the different clinical syndromes and are described and divided according to its statistical significance related to the clinical groups.