Dynamic changes of the spinal canal in patients with cervical spondylosis at flexion and extension using magnetic resonance imaging

RATIONALE AND OBJECTIVES. The authors determine the dynamic changes of the spinal canal during flexion and extension in patients with cervical spondylosis. METHODS. Forty-six patients were studied inside a whole-body magnetic resonance (MR) scanner with between 50 degrees of flexion and 30 degrees of extension, using a positioning device. At neutral position (0 degrees) and maximum flexion and extension sagittal T2-weighted turbo spin echo sequences were acquired. RESULTS. A significant (P less than or equal to 0.05) increase of spinal stenosis was found at extension (48%, 22 of 46 patients) when compared with flexion (24%, 11 of 46). Cervical cord compression was diagnosed at flexion in 5 patients (11%) and at extension in 9 patients (20%). Concerning the number of patients with cervical cord compression at flexion and extension, significant differences (P less than or equal to 0.05) were found in patients with degenerative changes at four segments compared with patients with one segment involvement. CONCLUSIONS. Magnetic resonance imaging identified a significant percentage of increased spinal stenosis at flexion and, especially, at extension, which was not observed at neutral position (0 degrees), Flexion and extension MR imaging demonstrates additional information using a noninvasive technique concerning the dynamic factors in the pathogenesis of cervical spondylotic myelopathy.