Posttraumatic spinal cord lesions without skeletal or discal and ligamentous abnormalities: the role of MR imaging.

The thoracic spine is different from other mobile segments of the spine because of the presence of ribs and their articulations. The rib cage makes the thoracic spine much more stable and, during trauma, provides additional strength and energy-absorbing capacity. This leads to the conclusion that severe trauma is required to damage the thoracic spine, and the skeletal injury is usually evident on radiographs. A spontaneous reducible vertebral luxation (dislocation) is not easy to identify, even with magnetic resonance (MR) imaging. Subtle changes in thoracic spine osseous injuries are not seen on radiographs but may be demonstrated on computed tomography (CT) scans. MR imaging can also demonstrate the posterior ligamentous lesions. In this study, we present three cases of thoracic spinal cord changes without spinal fracture and one disk herniation (degenerative chronic disease). These patients had a permanent neurologic deficit (complete paraplegia); plain radiographs and CT scans showed nothing abnormal. MR imaging showed lesions in the thoracic spinal cord and, in one case, a posttraumatic disk herniation. In cases of post-traumatic cord lesions, MR imaging provides diagnostic information that appears to exceed other imaging modalities. The existence of a neurologic deficit indicates MR as the first examination in cases of traumatic spinal lesions.