["Dynamic" MR imaging of the cervical cord in patients with cervical spondylosis and ossification of the posterior longitudinal ligament--significance of dynamic cord compression].

This investigation was designed to assess the influence of dynamic cord compression on severity and course of myelopathy. Sixty-seven patients studied comprised 54 cases of cervical spondylosis and 13 cases of ossification of the posterior longitudinal ligament. These patients underwent "dynamic" MR imaging of the cervical spine. MR images in the sagittal view were obtained in three different neck positions: flexion, neutral, and extension. MR imaging was performed with a 0.15 T resistive unit. For technical reasons, the body coil was used. The pulse sequence was 500/30 (Tr msec/echo time msec) for T1 images. The spinal cord compression was accelerated in 32 cases when extended, in 2 cases when flexed, and in 4 cases when both extended and flexed. In 21 cases, we compared myelograms with MR images in a same neck position. Findings of myelograms well corresponded with those of MR images on 83 percent of intervertebral levels. The patients with dynamic cord compression were proved to have severer long tract signs, and their disability was regressive or progressive case by case for an average of 21-month follow-up. The "dynamic" MR imaging can provide dynamic nature of spinal cord compression, and prognostic clues.