However, because the fascia is bound on three sides by bone, the swelling is limited. If the muscle continues to swell beyond the fascia's ability to stretch, pressure is felt on the nerves, and blood vessels in the compartment. As swelling continues, the blood vessels are compressed so much that blood flow to and from the muscle is shut off, and the nerves are pinched to the extent that the feet and lower legs go numb. The most common response to this syndrome is pain toward the outside of the shin. The pain is felt over a greater area than a stress fracture, and it occurs at exactly the same time during exercise.
Fascial hernias are an indication that the shin pain felt is due to compartment syndrome.
These little balloon-like pouches bulge from under the skin on the lower shin. Small fascial hernias are common to allow blood vessels and nerves to expand. Larger holes can develop due to the pressure of compartment syndrome can actually allow muscle to be pushed through. This can cause pain and tenderness, numbness and tingling in the foot. While no one knows the exact cause of compartment syndrome, often it shows up long distance runners and sports that require a lot of running.