Foramen magnum syndrome caused by a dolichoodontoid process.

A 21-year-old Japanese man with basilar impression with an anomalous configuration of the odontoid process and many other vertebral anomalies is reported. We thought that posterior decompression alone would be hazardous; therefore, in one session, the odontoid tip and anterior arch of the atlas were removed transorally, and posterior fixation between the occipital squama and the lamina of C-3 using acrylic plastic was performed. This treatment resulted in marked clinical improvement and required only a short hospital stay.