[Congenital disorders in the stability of the cranio-vertebral region].

A functional radiographic examination of the craniovertebral zone was conducted in 600 normal adults and in 15 children. Normal peculiarities of the interrelationship of the atlantoaxial articulation found in 542 persons were classified. In 58 of them (9.7%) excessive mobility of the atlantoaxial articulations was found, 50 of them having a subluxation of the Cruveilhier joint with a dynamic narrowing of the vertebral canal. The remaining 8 persons had an excessive mobility of C1 along the axis of the dens of C2 overlapping half of the anterior arch of C1 above the apex of C2-dens. Such chronic disorders in the interrelationship of the craniovertebral zone elements caused no neurological disorders. However, in unfavourable cases, like forced movements of the head, a severe acute pathogenetic neurological situation may occur.