Tarsal Tunnel Syndrome
The numbness and tingling, burning or cramping you are feeling in your toes or your foot or heel is due to nerve compression, and called tarsal tunnel syndrome. A large nerve, the Posterior Tibial nerve, crosses behind your ankle, on the inside of your foot. Where the nerve crosses behind the ankle there is a tunnel with bone on the deep side and a fibrous roof above. Within this tunnel the large nerve divides into three branches, one to your heel, the Calcaneal nerve, and two to your toes and small muscles of the foot, the Medial and Lateral plantar nerves. Each of the two plantar nerves, the medial and lateral plantar nerves, have separate smaller tunnels just under the foot where compression may also occur. Even the smallest branch, the Calcaneal to your heel, goes through a very tight fibrous tunnel and can become compressed.
Pressure on these nerves can come from either swelling within the tunnel, such as occurs after a broken or badly sprained ankle, or from swelling within the nerve, such as occurs in association with medical problems like diabetes. It can also occur when the foot is mechanical unstable. Sometimes there may be arthritis of the ankle joint, a cyst or ganglion associated with the foot tendons or the ankle joint that causes the pressure upon the nerve. There are times when it is just not clear what has caused the problem.
When the nerves in these tunnels receive increased pressure, their blood flow decreases and damage is done. When this happens, the nerve responds with altered sensations such as tingling and numbness and burning pain. Sometimes this is so severe that it feels as if the whole foot is asleep. Often the symptoms are worse after standing or walking, when the fluid begins to collect in the foot. Night time is usually the worse time. The small muscles may give you a cramping feeling as they begin to lose their nerve supply. If just the Calcaneal branch is affected, the symptoms may seem the same as a bone spur on the heel or of plantar faciitis, an inflammation along the bottom of the foot. Special testing can be done to diagnose this problem.
Treatment is focused on decreasing the pressure on the nerves. This is first attempted by the use of Orthotic inserts which mechanically correct the foot. If this does not work then surgery is usually indicated.
