[Diagnosis of instability of the upper cervical spine by functional computed tomography].

The evaluation by means of functional x-rays, of rotatory instability of the upper cervical spine as a result traumatic or inflammatory destruction of the ligamentous apparatus, is unsatisfactory. Functional CT of the upper cervical spine allows measurement of the segmental rotatory movements. 9 healthy adults and 30 patients were examined after neck injury via functional CT's. A rotation between occiput and atlas greater than 9 degrees, between atlas and axis over 50 degrees, the left-right difference at the level C0/C1 greater than 6 degrees and at the level C1/C2 over 10.5 degrees point to a suspicion of hypermobility or instability.