You have probably heard of carpal tunnel syndrome. Carpal tunnel syndrome is a fairly common nerve entrapment syndrome affecting your wrist and hand. Tarsal tunnel syndrome is also a nerve entrapment syndrome, but it affects your ankle and foot.
Your posterior tibial nerve runs through a small space on the inside of your ankle, called the tarsal tunnel. There is a band of ligament there that helps connect your leg to your foot and protect the nerves and blood vessels that run through that small space behind the little bone that sticks out on your inner ankle. The ligament is thick and not very flexible.
If there is swelling in the area under the ligament, it puts pressure on the posterior tibial nerve as it runs through the tarsal tunnel. Pressure can be caused by anything that takes up space in the area, such as a tumor or mass, swelling due to injury, systemic disease like diabetes or rheumatoid arthritis, or swollen varicose veins. Sometimes a falling arch or flat foot will cause symptoms as well.
Symptoms are felt in the medial ankle and or the sole of the foot and vary with the person but commonly include:
• Vague pain
• Numbness or weakness
• Burning, tingling, or an electric shock sensation
• Shooting pain
Beginning a new exercise program can bring on symptoms, as can overuse related to standing and walking. Tarsal tunnel syndrome can slowly worsen, but it can also come on suddenly. It is important to get checked out by a health care provider if you have symptoms, because long-term pressure on the nerve can cause permanent dysfunction and nerve damage.
Diagnosis is done by physical exam, history of symptoms, and sometimes tests called electromyography (EMG) and nerve conduction velocity (NCV) study. The EMG measures how well the muscle responds to nerve impulses, and the NCV measures how long it takes an electrical impulse to travel down the nerve, so it can measure nerve dysfunction.
Conservative treatment often involves rest, icing, orthotics and wearing appropriate shoes, sometimes bracing, anti-inflammatory medications and injection of steroids into the area around the nerve to reduce inflammation.