Sympathetic nerves run on the front surface of the spinal column and not inside the spinal canal, like the nerves that provide sensation and strength to the legs. These nerves are part of the autonomic nervous system, which controls functions such as blood flow and temperature regulation to the arms and legs, sweating, heart rate, digestion, and blood pressure, among others. A sympathetic nerve block involves using fluoroscopic guidance (x-ray) to inject numbing medicine around the sympathetic nerves in the low back or neck to temporarily... read full review »