[Unusual coincidence of dens aplasia and atlas malformation with early childhood spastic tetraparesis. Case report on the differential diagnosis of inflammatory atlantoaxial dislocation].

We report on the case of a 33 year old woman with acute tetraparesis and radiological evidence of atlantoaxial dislocation who had to undergo several attempts at osteosynthetic stabilisation of the cervical spine. She was afflicted with a spastic walk since the early years of childhood which had been explained by encephalitis after umbilical sepsis. The etiology of this severe and grave cervical instability however was found in a very rare congenital developmental disturbance of the occipitocervical passage with dystope os odontoid, extreme hypoplasia of the dens axis and additionally an osseous link between left processus transversus atlantis and occiput. Diagnostic problems arose from a simultaneous psoriasis, because a psoriatic cervical spondylitis seemed possible.