What defines the extent of spinal cord injury severity?

The severity of a spinal cord injury is primarily defined by the level of cord function that remains below the injury site. This means assessing how much movement, sensation, and autonomic function are preserved in the body segments below the point of injury. For example, an injury at a higher level of the spinal cord (such as cervical) may result in more extensive loss of function compared to an injury at a lower level (such as lumbar). The classification of spinal cord injuries is based on the neurological level of injury, which helps in understanding the implications for mobility, independence, and overall prognosis for recovery.

The other options, while they may have some relevance, do not provide the definitive measure of injury severity that the level of cord function does. Immediate symptoms can vary and may not fully reflect underlying damage, while the duration of symptoms and a patient's age can influence recovery but do not define the injury's intrinsic severity.