Tarsal Tunnel Syndrome -
The Carpal Tunnel of the Foot and Ankle
Tarsal tunnel syndrome occurs on the inside part of the ankle (the side by the big toe) and is similar to carpal tunnel syndrome in cause and symptoms. The symptoms are most often sharp pain, burning pain, shooting pain and numbness which are worse when standing or walking. The ankle and inside foot and heel can also throb when not walking, especially after a lot of activity. The pain can be very severe, making it difficult to walk or even put weight on the foot. The pain usually occurs on the inside of the ankle and foot which can shoot down to the toes or up the leg or both.
Just as in carpal tunnel syndrome, tarsal tunnel syndrome is caused by pressure on the nerve due to tightness in the space where the nerve is. There are many other things in this small space and there is a ligament band that holds them all in place. In those with tarsal tunnel syndrome, this ligament is often overly tight, causing pressure on the nerve, leading to pain. This tightening of the ligament becomes worse in people with certain foot types, especially those with severely flat feet or very flexible feet. Other causes include varicose veins, enlarged or abnormally shaped muscles or tendons, a fatty growth called a lipoma, an enlargement of the nerve, as a result of ankle trauma (such as a fracture) and swelling due to exercise. There are certain medical conditions that have an increased risk of tarsal tunnel syndrome including Rheumatoid Arthritis, high cholesterol and low thyroid. In about 25% of cases, however, no cause can be identified.
The diagnosis is made with an exam by a foot and ankle specialist and some specialized tests performed by a neurologist. The diagnosis can also be aided by the use of MRI, which can show the varicose veins or other structures that are taking up too much space. The diagnosis can sometimes be difficult because tarsal tunnel syndrome can cause pain in various parts of the foot with an absence of pain in the ankle area.
Once the diagnosis is made there are conservative and surgical options, and treatment is focused on relieving the cause. Orthotics can help with this condition by taking pressure off of the nerve by realigning the joints (especially in those with flat feet) allowing the ligament band to be looser thus less tension on the nerve. Anti-inflammatory medications can help tremendously. A steroid injection can be given around the nerve to decrease inflammation (which is the cause of the pain). Various prefabricated and custom braces are also available to help support the ankle and put less pressure on the nerve. . If the condition is caused by varicose veins, compression stockings can help quite a bit. In many cases, however, tarsal tunnel syndrome requires surgical correction.
Surgical correction for tarsal tunnel syndrome consists of making an incision on the ankle and releasing the ligament that is putting pressure on the nerve. If there are an abnormal structures that are taking up space, such as varicose veins or abnormally large muscles or tendons, these are also removed during the procedure. Sometimes the nerve is wrapped with a special implant made of collagen, which helps to support the nerve and prevent continued pressure on it once healing occurs. The success rate with surgical correction of tarsal tunnel syndrome is high with approximately 90% of people having improvement or resolution of their pain.
The doctors at Advanced Foot and Ankle Center have specialized training and significant experience in the diagnosis and treatment of tarsal tunnel syndrome and many other nerve conditions.