What is spinal cord injury?
Many misconceptions abound concerning spinal cord injury. For example, many people believe that the spinal cord below the injury site dies after injury. Others think that the injured spinal cord is like a cut telephone wire and can be fixed by reconnecting the cut ends. Some people think that the vertebral column is the spinal cord. Some doctors even have misleading and inaccurate ideas about spinal cord injury. For example, many doctors casually use the word transection to refer to severely injured spinal cords, when in fact, that term should only be applied to the extremely rare situation when the spinal cord has been cut and the cut ends are separated.
Spinal cord injury usually results from trauma to the vertebral column. Displaced bone or disc then compresses the spinal cord which is the bundle of nerves housed in the vertebral column. Spinal cord injury can occur without obvious vertebral fractures. Conversely, you can have spinal fractures without spinal cord injury. It can also result from loss of blood flow to the spinal cord. Many people may have had mild spinal cord injury without thinking that it is spinal cord injury. For example, over a million people per year get “whiplash” in car accidents; they often have neck pain, weakness, and sensory loss that may last days or even months. Athletes who play football or other contact sports can suffer a transient loss of function, that is, paralysis and sensory loss for minutes or even hours. Sometimes, people can get spinal cord injury without any obvious cause, a condition called transverse myelitis.
Spinal cord injuries are usually defined by vertebral level and neurological level, as well as severity. Vertebral levels are indicated by which bony vertebrae have been fractured or show damage. Multiple bony vertebra may be injured. For example, an injury that causes the C5 vertebra to slip relative to C4 may be called a C4/C5 injury because it compresses the C4 and C5 spinal cord. Spinal cord levels do not necessary correspond to vertebral levels. For example, the C5 spinal cord lies in the C4 vertebral segment. The cord ends at the L1 vertebral level even though the spinal roots continue and exit between the appropriate vertebral segments.
For many years, there was no standardized way of referring to spinal cord injury levels. Surgeons generally referred to the injury level by the vertebrae that are damaged. Neurologists and physiatrists, however, tend to refer to the level of spinal cord injury based on the neurological loss. Neurologists identify the level of injury as the first segmental level that shows sensory or motor loss. In contrast, physiatrists identify injury level from lowest spinal cord level that has normal motor and sensory function.