Tarsal Tunnel Syndrome
Tarsal tunnel syndrome, also known as posterior tibial neuralgia, is a disorder of the foot that may result in significant pain. The tarsal tunnel, the canal that runs between the inner ankle and the band of ligaments that stretch across the foot, houses several vital arteries, nerves and tendons, which provide flexibility to the foot. Since the walls of this tunnel consist of either bone or tough fibrous material through which these blood vessels, tendons and nerves have to pass, the inflexibility of the walls may create a problem.
In tarsal tunnel syndrome, abnormal pressure is exerted on the tibial nerve, the nerve that provides sensation to the bottom of the foot, pushing the nerve painfully against the rigid wall of the tarsal tunnel. This can happen for a variety of reasons when any tissue in the area becomes inflamed and enlarged, causing symptoms ranging from tingling to numbness. As the tunnel narrows, the pain may worsen.
Causes of Tarsal Tunnel Syndrome
Anything that causes the tarsal tunnel to narrow can result in tarsal tunnel syndrome. Reasons for such narrowing of the passage may include an enlarged adjacent muscle, varicose veins, an arterial aneurysm, a ganglion cyst, a bone spur or excessive scar tissue. Risk factors for the disorder may include:
- Being age 30 and older
- Having flat feet
- Having arthritis or diabetes
- Having vascular disease
- Having lower back pain
Being an athlete or suffering an injury of the foot or ankle may also be a risk factor in developing this condition.
Symptoms of Tarsal Tunnel Syndrome
The primary symptoms of tarsal tunnel syndrome may include pain, tingling, numbness and other sensations, such as feelings of heat or cold or electrical shocks along the tibial nerve. These sensations may be experienced anywhere along the nerve, including in the toes, feet or lower legs. Such discomfort may be worse after prolonged standing and may improve with rest. Patients with tarsal tunnel syndrome may also experience tendon inflammation and swelling of the foot or lower leg.
Diagnosis of Tarsal Tunnel Syndrome
A simple diagnostic test for tarsal tunnel syndrome is the Tinel's sign test. During this procedure, the tibial nerve is tapped and the patient with this condition experiences electrical sensations or a pins-and-needles feeling in the affected area. Other diagnostic tests administered for tarsal tunnel syndrome may include a nerve conduction test, an electromyogram (EMG) and an MRI scan. The MRI scan is typically administered if the presence of a cyst or benign tumor is suspected.
Treatment of Tarsal Tunnel Syndrome
There are a variety of treatments for mild to moderate tarsal tunnel syndrome, which may include:
- Resting the foot
- Wearing well-fitted shoes
- Wearing orthotics for support and to limit excess motion
- Receiving corticosteroid or anesthetic injections
- Taking nonsteroidal anti-inflammatory drugs (NSAIDs)
- Wearing compression stockings or a cast to restrict movement
- Taking vitamin B supplements
- Doing foot exercises
When these treatments do not provide relief, surgery may be considered to relieve pressure on the tibial nerve. During such a procedure, an incision is made into the ankle to relieve pressure on the tibial nerve. Benign tumors, cysts and scar tissue, if present, may be removed at the same time to increase the space in the tibial tunnel. This surgical procedure is quite similar to the procedure performed on the wrist for carpal tunnel syndrome. It is typically performed with the patient under local, epidural, spinal or general anesthesia, depending on the complexity of the condition. It can sometimes be performed endoscopically with equally good results.