Mechanism of injury and instability of cervical cord injuries without remarkable Xp evidence of injury

In 27 patients with no radiographic evidence of injury, spinal cord injury was depicted as low signal intensity on MRI. In 4 patients who had spontaneous reduction of the anterior dislocation, remarkable instability was observed. Among the other 23 patients, two patients had each two injured sites, and the remaining patients had only one injuried site. Injured sites were not correlated with the development of spondylosis or the antero-posterior diameter of the spinal canal, but well correlated with ossification of the posterior longitudinal ligament. Many of the patients had surgical evidence of horizontal rupture of the anterior longitudinal ligament and intervertebral disk. In these cases, although the spinal cord was instable at the level of extension, it was stable at the level of midline flection. Excessively extended injury with no associated anterior longitudinal ligament was considered attributable to the strictured spinal canal. (Namekawa, K)