Delayed Traumatic Tetraplegia.

intervertebral joints, with contusion of the cord by the neural arch at the moment of injury, and that spontaneous reduction accounted for the subsequent normal radiographic appearances. This theory was criticised by Cramer and McGowan (1944), and Barnes (1948) showed that a posterior dislocation in flexion that was capable of spontaneous reduction did not produce sufficient narrowing of the spinal canal to impinge on the cord. Furthermore, Roaf (1960) was unable to produce a flexion dislocation of the posterior joints without also causing a crush fracture of a vertebral body. In a few reported cases necropsy has revealed rupture ofthe anterior longitudinal ligament with a tear through an intervertebral disc. Barnes(1948) attributed this injury to ahyperextension dislocation, and suggested that the neural arch had contused the cord. Taylor and Blackwood (1948) reported a similar case and offered the same explanation. But Roaf (1960) was unable to rupture the anterior longitudinal ligament by hyperextension without also fracturing the neural arch. A tear through the anterior longitudinal ligament and disc, without fracture, could be produced only by rotational or shearing forces, just as dislocation without fracture could only be produced by rotational force. This suggests that a transient displacement, with a tear of the anterior longitudinal ligament and disc, could occur only with a rotational or shearing force, and that it is by scissoring that a direct contusion of the cord may be produced. There remain those cases in which no fracture, no dislocation and no tear of the anterior longitudinal ligament or disc have been found. Crooks and Birkett (1944) and Barnes (1948) drew attention to the frequency of this type of traumatic tetraplegia in older patients with arthritis of the cervical spine. Barnes tentatively suggested that cord contusion might result from simple hyperextension of a spinal cord already narrowed by osteophytes and by the