A lateral plain radiograph of the cervical spine best visualizes the rostral migration of the dens into the foramen magnum. Regardless of the presence or absence of symptoms, virtually all patients who have radiographic evidence of cranial settling should undergo surgical stabilization. As in atlantoaxial subluxation, closed reduction using cervical traction should be attempted first. Unlike isolated atlantoaxial subluxation, posterior stabilization in cranial settling should extend rostrally to the occiput. Postoperatively, the patient is immoblilized in a Minerva jacket and observed with serial radiographs.
Immobilization is maintained until evidence of fusion is seen radiographically.
The consequent instability contributes to intervertebral disk destruction, which causes further loss of spinal integrity. Clinical manifestations caused by arthritic changes and neural element compression include neck pain, radiculopathy, and myelopathy. As in upper cervical spine instability, cervical traction is used initially in an attempt to establish normal spinal alignment. Reducible lesions are then stabilized posteriorly, using posterolateral fusion with lateral mass plate fixation. Postoperatively the patient is immobilized in a Philadelphia collar and followed with serial radiographs.