OS ODONTOIDEUM - CLINICAL RADIOLOGICAL AND THERAPEUTIC ASPECTS

On the basis of a review of the literature and personal observation of 13 cases the diagnosis and treatment of os odontoideum are described and discussed critically. The patients are classified into 4 groups as suggested by Rowland et al. (1958), viz. (1) local symptoms (neck pain, torticollis, etc.); (2) transitory episodes of paresis after minor or major injuries; (3) progressive or permanent myelopathy; and (4) cerebral symptoms (dizziness, bulbar symptoms, etc.). The radiological diagnosis entails evaluation of the degree of atlanto-axial instability and deformity of the spinal canal. A phenomenon often encountered in these patients, but not yet described in the literature, is narrowness of the ring of the atlas contributing to potential compression of the spinal cord at this level. The findings suggest that there is a correlation between radiological deformity of the spinal canal and the clinical picture. The greatest narrowing in the sagittal diameter at the level of the atlas is found in the patients with a progressive myelopathy. The indications for surgical intervention depend not only on the clinical picture and the radiological findings, but also on the general condition of the patient, his occupation and temperament, and on the skill of the surgeon and anaesthetist. Decompressive laminectomy is a highly dangerous procedure which does not abolish the instability; therefore it should not be used. Surgical fusion by wiring and grafting of the C1/C3 region is also risky, although large series of cases have been reported, without operative complications. The severe complications in the present series (2 deaths, 1 transient deterioration) all occurred in patients with chronic progressive myelopathy. On the other hand, in this group of patients the indications for operation are most urgent because of the progressive nature of the lesion. The indications for surgical fusion appear less urgent in patients with post-traumatic myelopathy, because of the transient character of the symptoms. The incidental observation of a permanent or even progressive myelopathy after several transient episodes, however, strengthens the indications for early surgical intervention, although in this group of patients it is mainly preventive in character. No indication for surgery exists in patients with local symptoms only, because of the surgical risk, although the long-term results of surgical fusion in such cases are good. In patients with cerebral symptoms, again because of the risks, we are reluctant to consider surgical fusion. If no surgical treatment is advised, a trial of immobilization of the neck with a collar can be undertaken. While the immediate results may be good, a recurrence of symptoms is to be expected when the collar is discarded. © 1969.