Kinetic change of spinal cord compression on flexion-extension magnetic resonance imaging in cervical spine

We aimed to determine the changes in cervical canal diameters and spinal cord compression at each level from C2-3 to C7-T1 in flexion and extension positions and to study the use of flexion-extension magnetic resonance imaging (MRI). We also aimed to assess the changes in the length of the spinal cord in flexion and extension positions of the cervical spine.Flexion-extension MRI scans were performed consecutively on sixty-six patients with neck pain with/without neurogenic symptoms of the cervical spine. All patients were treated conservatively. We investigated the length of the cervical spinal cord (LSC), length of the cervical spinal anterior column (LAC), length of the cervical spinal posterior column (LPC), spinal canal diameter, and severity of cord compression in flexion, neutral, and extension positions.At each intervertebral level (from C2-3 to C7-T1), the average spinal canal diameter showed significant decrease from flexion to extension positions (P < 0.05). The average LSC, LAC, and LPC were decreased on extension of the neck compared with flexion (P < 0.05). Higher stages were found in extension position than in flexion position with statistically significant differences (P < 0.05).The use of flexion-extension MRI may demonstrate true pathology that contributes in the pathogenesis of cervical degenerative disease (CDD). Higher stages in spinal cord compression were found in extension position than in flexion position. However, higher stages in spinal cord compression in extension position did not necessarily cause severe myelopathy. This finding is an important evidence for conservative therapy on patient neck position education.