[Os odontoideum. A neurologic syndrome after orthopedic reduction of a C1-C2 subluxation].

A case of os odontoideum associated with a C1-C2 subluxation is described. During the reduction procedure by external manipulation, bulging of the membrana tectoria resulted into medullary compression followed by a neurological syndrome. An occipito-C2 arthrodesis was performed later on when the neurological status recovered back to normal. The case reported underlines the possibility of neurological damage following closed reduction of a C1-C2 subluxation, while the surgical procedure should not be incriminated. The pathogenic mechanism may not be properly understood if closed reduction is followed by surgical treatment during the same session.