Tarsal Tunnel Syndrome
What Is the Tarsal Tunnel?
Thetarsal tunnel is a narrow space that lies on the inside of the anklenext to the ankle bones. The tunnel is covered with a thick ligament(the flexor retinaculum) that protects and maintains the structurescontained within the tunnel—arteries, veins, tendons, and nerves. Oneof these structures is the posterior tibial nerve, which is the focusof tarsal tunnel syndrome.
What Is Tarsal Tunnel Syndrome?
Tarsal tunnel syndrome isa compression, or squeezing, on the posterior tibial nerve thatproduces symptoms anywhere along the path of the nerve running from theinside of the ankle into the foot.
Tarsal tunnel syndrome is similar to carpal tunnel syndrome, whichoccurs in the wrist. Both disorders arise from the compression of anerve in a confined space.
Tarsal tunnel syndrome is caused by anything that produces compression on the posterior tibial nerve, such as:
- A person with flat feet is at risk for developing tarsal tunnelsyndrome, because the outward tilting of the heel that occurs with“fallen” arches can produce strain and compression on the nerve.
- An enlarged or abnormal structure that occupies space within thetunnel can compress the nerve. Some examples include a varicose vein,ganglion cyst, swollen tendon, and arthritic bone spur.
- An injury, such as an ankle sprain, may produce inflammation andswelling in or near the tunnel, resulting in compression of the nerve.
- Systemic diseases such as diabetes or arthritis can cause swelling, thus compressing the nerve.
Patients with tarsal tunnel syndrome experience one or more of the following symptoms:
- Tingling, burning, or a sensation similar to an electrical shock
- Pain, including shooting pain
Symptoms are typically felt on the inside of the ankle and/or on thebottom of the foot. In some people, a symptom may be isolated and occurin just one spot. In others, it may extend to the heel, arch, toes, andeven the calf.
Sometimes the symptoms of the syndrome appear suddenly. Often theyare brought on or aggravated by overuse of the foot, such as inprolonged standing, walking, exercising, or beginning a new exerciseprogram.
It is very important to seek early treatment if any of the symptomsof tarsal tunnel syndrome occur. If left untreated, the conditionprogresses and may result in permanent nerve damage. In addition,because the symptoms of tarsal tunnel syndrome can be confused withother conditions, proper evaluation is essential so that a correctdiagnosis can be made and appropriate treatment initiated.
The foot and ankle surgeon will examine the footto arrive at a diagnosis and determine if there is any loss of feeling.During this examination, the surgeon will position the foot and tap onthe nerve to see if the symptoms can be reproduced. He or she will alsopress on the area to help determine if a small mass is present.
Advanced imaging studies may be ordered if a mass is suspected or ifinitial treatment does not reduce the symptoms. Studies used toevaluate nerve problems—electromyography and nerve conduction velocity(EMG/NCV)—may be ordered if the condition shows no improvement withnon-surgical treatment.
A variety of treatment options, often used in combination, are available to treat tarsal tunnel syndrome. These include:
- Rest. Staying off the foot prevents further injury and encourages healing.
- Ice. Apply an ice pack to the affected area, placinga thin towel between the ice and the skin. Use ice for 20 minutes andthen wait at least 40 minutes before icing again.
- Oral medications. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, help reduce the pain and inflammation.
- Immobilization. Restricting movement of the foot by wearing a cast is sometimes necessary to enable the nerve and surrounding tissue to heal.
- Physical therapy. Ultrasound therapy, exercises, and other physical therapy modalities may be prescribed to reduce symptoms.
- Injection therapy. Injections of a local anestheticprovide pain relief, and an injected corticosteroid may be useful intreating the inflammation.
- Orthotic devices. Custom shoe inserts may beprescribed to help maintain the arch and limit excessive motion thatcan cause compression of the nerve.
- Shoes. Supportive shoes may be recommended.
- Bracing. Patients with flatfoot or those with severesymptoms and nerve damage may be fitted with a brace to reduce theamount of pressure on the foot.
When is Surgery Needed?
Sometimes surgery is the bestoption for treating tarsal tunnel syndrome. The foot and ankle surgeonwill determine if surgery is necessary and will select the appropriateprocedure or procedures based on the cause of the condition.