Two surgical cases of os odontoideum in spondyloepiphyseal dysplasia (SED) tarda were reported. The first case was a 34-year-old male suffering from intractable neck pain with bilateral numbness in his hands due to myelopathy. The radiogram demonstrated atlantoaxial subluxation and invagination of the posterior arch of C1 into the foramen magnum.
CT-myelogram showed the spinal cord to be compressed between the posterior arch of C1 and the base of the odontoid process. The second case was a 28-year-old male who developed tetraplesia after falling down. His radiogram demonstrated posterolateral atlantoaxial subluxation.
In both cases, the posterior arch of C1 was located close to the foramen magnum and was unable to be reduced downward. Both cases required occipitocervical fusion using a fan-like rod. We experienced two cases of SED congenita with similar radiological findings to SED tarda. Narrowing of the atlanto-occipital interval and loss of motion were also seen in SED congenita experienced previously. Their finding may be characteristic of case with os odontoideum in SED.
The first case achieved a good recovery after surgery, however, the second case remained tetraplegic.
