Nerve Conditions of the leg and foot
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.
Diagram of the Tarsal Tunnel Simplistic view
"Neuroma"- This is a localized nerve entrapment that is usually located between the 2nd and 3rd Metatarsal necks or the 3rd and 4th Metatarsal heads. It is usuallly aggravated by shoe gear especially ones that are too small for your feet. Sometimes it feels better with massaging the foot. It feels like a burning type of pain that is usually at the base of the toes and may radiate and cause numbness or tingling. It is a compression type of syndrome where the nerve to the toes is compressed by the surrouding tissue which is bone, ligament (Deep Transverse Intermetatarsal Ligament-DTIL), and tendons. The nerve becomes damaged and irritated by being compressed against these structures and causes pain.
Treatment is usually started by shoe modification as well as Orthotics. Cold laser is also something that can be tried as well. If this fails then injection therapy using either Cortisone or Sterile Alcohol can be attempted. If surgery is needed then a decompression can be performed through a small incision to release the DTIL and take away the compression. Success rate is about 85% and you can return to normal activity in about 6 weeks. Then as a last resort the nerve can be removed and possibly burried into muscle to prevent recurrence or a stump neuroma. This requires 3 weeks of non-weightbearing. It is necessary to look for other problems such as Tarsal Tunnel which can sometimes mask or act like a neuroma or entrapment in the toes.
Restless Leg Syndrome- This condition which usually presents as a problem where you have to move your legs and shake them to try and get relief. This often occurs while you are sleeping. This diagnosis is often treated with medication that can reduce the symptoms but does not cure the problem. In many of these cases the cause of this problem is a localized entrapment of the Common Peroneal nerve located just below the knee on the outside. Often times the patient will have back pain as well. A simple local anesthetic injection can help make the diagnosis of entrapment and then a simple 15 minute out patient procedure to decompress the nerve and the relief is almost immediate and is about 85% successful.
Deep Peroneal Nerve Entrapment or "Anterior Tarsal Tunnel Syndrome"- This is a compression that is over the area on the top of the foot between the base of the first and second metatarsals. It can be caused by tight shoe gear over the area or trauma to the area. The first line of treatment is to make sure that nothing tight is pressing on the nerve such as shoes. If this is not the problem and the pain is bad enough then a simple 12 minute out patient procedure can be performed to decompress this area by cutting the short extensor tendon the the Big toe which is often responsible for compression in this area. This is about 90% successful and has a minimal recovery just a few weeks.
