Symptoms of tarsal tunnel syndrome
Tarsal tunnel syndrome refers to the irritation and/or compression of a nerve called the posterior tibial nerve.This nerve is found behind the ankle bone on the inner side of the foot. (Same side as the big toe) As the nerve travels in this area it runs through a small canal called the Tarsal Tunnel.
Symptoms of tarsal tunnel include:
1. Radiation, burning, or shooting pain on the bottom of the foot, along the arch and/or up into the leg
2. “Pins and needles” sensation to the bottom of the foot and into the toes
3. Disturbances in the perception of temperature (feelings of coldness)
4. Feeling like there is a tight band around the foot
5. Loss of sensation to the sole of the foot and/or heel
6. Pain getting worse with prolonged standing or walking
7. Rest and leg elevation can relieve symptoms
Causes of Tarsal Tunnel Syndrome
The main culprit of tarsal tunnel syndrome is the decrease in space in the tarsal tunnel, which results in compression of the posterior tibial nerve. There are multiple reasons that can cause narrowing of the tarsal tunnel.
1. As the tibial nerve travels behind the ankle bone, it goes through the tarsal tunnel, which is a narrow canal bordered by a sheath of tissue and the heel bone. As the tibial nerve goes through the tarsal tunnel, it usually splits into two nerves, the medial and lateral plantar nerves. If the tibial nerve splits into two nerves before entering the tarsal tunnel, it increases the number of structures going through the tarsal tunnel. This results in a relative decrease of space in the tunnel and compression of the nerve.
2. Several tendons and veins course through the tarsal tunnel with the tibial nerve. If these structures are enlarged or swollen the tibial nerve can be compressed.
3. Compression of the tibial nerve can also occur from bony prominences, spurs or fragments of bone in the tarsal tunnel.
4. Abnormal heel position with the heel positioned more inward or outward can stretch the tibial nerve or narrow tube of the tarsal tunnel again resulting in excessive pressure on the nerve.
Physical Examination in Tarsal Tunnel Syndrome
Tarsal tunnel syndrome can mirror other foot conditions, such as heel pain, arch pain, or neuropathy, therefore, the podiatrist may need to utilize various examination techniques, imaging modalities and electro diagnostic studies to diagnosis tarsal tunnel and syndrome. The podiatrist will tap along the course of tibial nerve to reproduce the shooting sensation often associated with tarsal tunnel syndrome. The podiatrist will also examine if there is any swelling along the tarsal tunnel and the medial arch because this may indicate a mass that may be in the tunnel. The podiatrist may also try to increase the pressure on the tibial nerve by turning the foot outward and up and holding this position for 5-10 seconds. This exam produces a narrowing the space of the tarsal tunnel and can recreate the patient’s symptoms. Heel and foot position may also be examined to determine if that may be the cause of tarsal tunnel compression. In order to determine which nerve branches are involved, a pin prick test may be applied to the sole of the foot to determine which areas of the foot have decreased sensation.
Diagnostic Studies in Tarsal Tunnel Syndrome
If a bony prominence is suspected as the cause of tarsal tunnel syndrome, the podiatrist may request X-ray imaging of the foot and ankle. For soft tissue masses or increase tendon size/swelling, MRIs may be requested as well. Ultrasound may also be utilized to determine the tibial nerve split or tendon pathology. If vein enlargement is suspected, the podiatrist may use a tourniquet wrapped above the tarsal tunnel to increase fluid accumulation in the veins. Other studies that may be ordered to study the function of the tibial nerve are nerve conduction studies or electromyography.
Non-Surgical Treatment of Tarsal Tunnel Syndrome
The podiatrist may recommend taping, bracing, orthotics, or shoe modifications to provide support to the feet and correct the heel position. Correcting the abnormal foot movement that may cause stretching and pressure in the tarsal tunnel may prove to relieve the symptoms of Tarsal Tunnel Syndrome. Icing and oral anti-inflammatory may be suggested to decrease swelling in the area.
Surgical Treatment of Tarsal Tunnel Syndrome
The main purpose of tarsal tunnel surgery is to release structures that may be putting pressure on the posterior tibial nerve or removing bone or soft tissue masses that may cause narrowing in the tarsal tunnel. The incision is made behind the ankle bone and in front of the Achilles tendon. During surgery, blunt surgical instruments are utilized in order to avoid damage to the nerves. The sheath of the tarsal tunnel is opened and the course of the tibial nerve and its branches are followed in order to remove any thickened structures and release any tight structures around the nerves. Following surgery, a bulky dressing is applied to the foot in order to decrease swelling. One week after surgery, simple motions of the ankle for 10-20 minutes twice a day may be recommended to prevent adhesions. After 2-3 weeks, sutures are removed and ambulation with tennis shoe may be allowed. The average time for most patients to begin exercise and full activity is 2-3 months after surgery. It is also important to note that tingling and pain may increase after surgery, and the pain and numbness may take up to one year or more to resolve