Congenital atlanto-axial dislocation.

Report about 105 personally operated cases of congenital atlanto-axial dislocation. This fairly common malformation in India occurs three times more in males than in females, 50% show symptoms before the age of 20 years, the other half during the third decade of life. Transient attacks of cervical cord compression occur with progressive motor and posterior column defect, and sometimes unconsciousness and cerebellar involvement are characteristic. The diagnosis is proved by X-rays including tomograms and dynamic studies. Three types of malformation can be differentiated: Group I with assimilation of the atlas, group II with anomalies of the odontoid process and group III with a normal atlas and axis. The different types and subtypes are described in detail as well as the pathological and pathogenic factors. The treatment and personal experiences show that the early treatment with posterior decompression, sometimes combined with posterior fusion was unsuccessful and resulted in a high mortality and morbidity. The antero-lateral approach, described by the author proved to be the method choice. The prognosis is dependent on the extent of the damage to the cord before treatment. Early diagnosis and treatment lead to excellent results.