The tarsal tunnel is a narrow space that is on the inside of the ankle. The tunnel is covered with a thick ligament (flexor retinaculum) that protects and maintains the structures contained within the tunnel (arteries, veins, tendons, and nerves). The nerve (tibial nerve), which is the main source of tarsal tunnel syndrome. Tarsal tunnel syndrome is a compression (tightening or squeezing) of the tibial nerve that produces symptoms anywhere along the path of the nerve running from the inside of the ankle into the foot.
Tarsal tunnel syndrome is very similar to carpal tunnel syndrome, which occurs in the wrist. Both of these disorders occur due to compression of a nerve in a confined (small) space.
Causes
Compression on the tibial nerve is related to the cause, for example:
- Flat feet are risk factors for developing tarsal tunnel syndrome, due to the outward tilting/position of the heel that occurs when the arch falls. This can further produce strain and compression on the nerve.
- An enlarged structure that occupies space within the tarsal tunnel can compress the nerve. For example: varicose veins, ganglion cysts, swollen tendons, and/or arthritic bone spurs.
- An injury (i.e. Ankle sprain) can produce inflammation and swelling in or adjacent to the tunnel, resulting in compression of the nerve.
- Systemic diseases such as diabetes or arthritis can cause swelling, thus compressing the nerve.
At times the cause may be idiopathic (unknown) without any specific pathology compressing the nerve.
Frequently patients will present with heel pain and similar symptoms as plantar fasciitis (i.e. pain on the bottom of the heel, pain in the arch, pain in the morning). This is due to a communicating nerve from the main tibial nerve that runs adjacent to the plantar fascia. At times the tarsal tunnel symptoms can be masked during the treatment of the heel pain (rest, ice, injection, night splint, physical therapy, shoe wear modification, inserts) however, the symptoms do not subside and often times return more abruptly and robust.
Symptoms
- Tingling, burning (sensation similar to an electrical shock)
- Numbness
- Shooting pain
Symptoms are felt on the inside of the ankle and/or on the bottom of the foot towards the toes. At times the symptoms may shoot or extend to the calf.
At time the symptoms appear suddenly. Other times they are aggravated by overuse of the foot, such as in prolonged standing, walking, exercising, or even beginning a new exercise program.
Diagnosis
In diagnosing Tarsal Tunnel Syndrome your surgeon will examine the foot to determine if there is any loss of feeling and/or sensation. During the exam, your surgeon will position the foot in (inverted) and out (everted) and tap on the nerve to see if the symptoms (i.e. burning, tingling, shooting) can be reproduced. Your surgeon will also press on this area to determine if a small mass is present.
Advanced imaging studies may be ordered if a mass is suspected or if initial treatment does not reduce the symptoms. An electromyography and nerve conduction velocity (EMG/NCV) will be ordered to evaluate the extent of the tarsal tunnel syndrome and also to rule out other neurogenic problems. An MRI may also be ordered to determine the extent of the pathology (i.e. space occupying lesion) as well as determine surgical planning should surgery be warranted.
Treatments
Non Surgical Treatment
Treatment approaches for Tarsal Tunnel Syndrome are based on the severity of the symptoms and the confirmation of the diagnosis with an EMG/NCV and/or MRI. Conservative treatment options are encouraged prior to surgical intervention and include:
- Immobilization/Rest. Immobilization may involve the use of a short leg cast or removable walking boot to reduce the strain and forces on the tarsal tunnel to enable the nerve and surrounding tissue to heal.
- Ice. Putting an ice pack on your heel for 20 minutes several times a day helps reduce inflammation. Place a thin towel between the ice and your foot/ankle; do not apply ice directly to the skin.
- Medications. Oral nonsteroidal anti-inflammatory drugs (NSAIDs) may be prescribed to reduce pain and inflammation. Oral Gabapentin (Neurontin) in low doses may be utilized to remove the pain and discomfort associated with the compressed nerve. At times a topical Gabapentin may be prescribed if the patient cannot take oral NSAIDs or Gabapentin due to drug interactions or medical conditions.
- Physical therapy. Ultrasound therapy, exercises, and other physical therapy modalities may be prescribed to reduce symptoms.
- Orthotic devices. Custom or over the counter orthotic devices that fit into your shoe help correct the underlying structure of the foot and stabilize the arch to limit excessive motion that can compress the nerve.
- Shoes. Supportive or custom shoes may be recommended.
- Bracing. Patients with flatfoot or those with severe symptoms and nerve damage may be fitted with a brace to reduce the amount of pressure on the foot.
- Avoid barefoot. When you walk without shoes, you put increase strain and stress on your plantar fascia.
Surgery
If non-surgical approaches fail to relieve the compressed nerve and symptoms of tarsal tunnel syndrome, surgery may be necessary. Your surgeon will discuss the surgical approach to release the compressed nerve as well as address the heel pain that often accompanies the tarsal tunnel syndrome.
Surgery is typically an outpatient procedure (day surgery) and scheduled at your convenience.
A splint or boot will be placed on your surgical foot/ankle after surgery. No weight to the surgical foot/ankle is advised until your surgeon encourages weight bearing (typically 2-4 weeks post surgery).