DELAYED TRAUMATIC TETRAPLEGIA

In some patients with traumatic tetraplegia no radiological evidence of fracture or dislocation of the cervical spine is found. If myelography or necropsy fails to reveal protrusion of an intervertebral disc the mechanism of the cord injury may remain a mystery. At one time it was believed that hyperfiexion caused dislocation of the posterior 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 unabl