Tarsal tunnel syndrome

Tarsal tunnel syndrome (TTS) is a rare neurological disorder of the foot associated with local sensory changes. Know all about this condition, including its possible causes, symptoms, diagnosis and treatment options.

Tarsal tunnel syndrome Definition

It is a type of compression neuropathy in the ankle and foot. In simple words, the condition represents a severe form of a neurological deficit due to squeezing of a nerve. It is generally abbreviated as TTS.

Medical experts also refer to this disorder by other names like:

Picture of Tarsal tunnel syndrome

Picture 1 – Tarsal tunnel syndrome

  • Posterior tibial nerve
  • Tibial nerve dysfunction

Tarsal tunnel syndrome Types

The disorder can be differentiated into two major types:

  • Anterior TTS
  • Distal TTS

Tarsal tunnel syndrome Symptoms

The primary manifestation of the condition is marked by frequent episodes of discomfort in the lower extremities of the body. The most distinguishing feature of this neuropathic condition is that the symptoms are unilateral. In rare cases, However, TTS could be bilateral. These are more pronounced at night and can cause sleep disruption. Affected patients normally complain of problems like:

  • Numbness and tingling in and around the ankles as well as on the sole of the foot
  • Severe ankle pain and burning sensation over the base of the foot and heel
  • Inflammation of the affected foot
  • Increased pain while standing, walking, running, or performing any other prolonged physical activity
  • Pain that shoots up into the leg, and down into the arch, heel and toes
  • “Pins and needles” feelings, especially at late evening
  • Weakness in the ankle
  • Loss of coordination in legs
  • Electric shock-like sensations
  • Tingling burning hot and cold sensations in the foot
  • Tenderness of the natural foot padding
  • Extreme pain with ankle dorsiflexion- action of bringing the top of the foot, upwards toward the body

Tarsal tunnel syndrome Causes

This painful condition of the foot is a result of a damaged tibial nerve – one of the major branches of the sciatic nerve that travels down the back of the leg and terminate into the foot. The nerve supplies the calf and foot muscles and facilitates conduction of nerve impulses as well as movement of the lower legs. Tarsal tunnel is a bony canal made up of seven bones, composing the ankle joint that provides a passage for the tibial nerve to the leg. This nerve splits into three different paths, in which one nerve continues to the heel while the other two join the bottom of the foot.

In the case of TTS, the nerve gets compressed and irritated, causing numbness, and tingling of the foot and toes. The nerve entrapment of the ankle prominently affects the plantar surface or bottom of the foot, causing sharp pain. The other regions of the foot can be highly affected depending on the degree of compression as well as involvement of the different branches of the nerve.

The flexor retinaculum, which is a strong, fibrous band forming the exterior region of the tarsal tunnel, has a limited ability to stretch so any weight bearing activity can lead to increased pressure and subsequent nerve damage. The blood supply to the foot gets severely hindered, giving rise to pain signals. The normal transmission of the impulses is reduced or blocked, owing to the damage incurred to the myelin sheath, an insulator of a nerve. In the course of time, fluid begins to accumulate in the foot and causes difficulty standing or walking. The muscles of the foot and leg and the number of fibers begin to decrease in size, resulting in numbness. A number of factors are responsible for exerting tremendous pressure on the tibial nerve, such as:

  • Trauma from repetitive work involving the ankle
  • Pregnancy
  • Osteoarthritis
  • Tenosynovitis
  • Post-traumatic ankle deformities
  • Cysts
  • Rheumatoid arthritis
  • Lipoma
  • Nerve ganglions
  • Exostosis or bone spurs
  • Ankle sprains or fractures
  • Varicose veins
  • Talonavicular coalition

Tarsal tunnel syndrome Diagnosis

The condition is suspected on the basis of recurrence of painful episodes of foot and ankle. The foot can be examined for swelling, tenderness or deformity. Tinel’s sign of TTS refers to tapping the skin overlying the affected tibial nerve to reproduce the sensations of tingling or “pins and needles” that travels into the foot and up the legs. Anomalies of the bones and joints of the ankle can be detected with X-ray tests. MRI scanning can identify any underlying lesions and evaluate the other possible causes of a compresses nerve. Ultrasound studies can aid in the diagnosis of ganglions or synovitis.

The signs of a nerve injury can be confirmed by a nerve conduction velocity test. The rate of speed or velocity of electrical impulses as they course down a nerve can be measured by using the test. This is usually conducted by using surface patches that are attached to the skin over the damaged nerve at various locations. Here, one electrode stimulates the nerve with a mild electrical impulse while the other records the resulting electrical activity. The distance between the electrodes and the time taken for the impulses to travel between the electrodes determines the nerve conduction velocity. The rate of transmission of nerve impulses through the tarsal tunnel is relatively slow in patients with TTS. Intravenous insertion of needle electrodes in an electromyogram (EMG) test can record the electrical activity of the muscle that is innervated by the tibial nerve. Abnormal spontaneous activity might indicate some nerve and/or muscle damage.

Tarsal tunnel syndrome Differential Diagnosis

It is essential for physicians to use a series of well-known tests to exclude the possibility of presence of other conditions that could mimic TTS. Some of these disorders include:

  • Achilles tendonitis
  • Calcaneal stress fractures
  • Plantar fasciitis
  • Heel pad atrophy

Tarsal tunnel syndrome Treatment

The initial method of treatment involves proper rest, use of arch supports and wider shoes, alternate application of cold and heat compresses, and immobilization of the foot in a splint. Orthotics works for individuals with a deformed foot. Non-steroidal anti-inflammatory drugs, such as Anaprox, work effectively in cases of inflammation and severe pain. Cortisone injections into the tarsal tunnel can alleviate the pain and numbness in the foot. Ultracet, Neurontin and Lyrica, duloxetine and tricyclic antidepressants are the other drugs frequently prescribed by physicians. Early orthopedic intervention for ankle fracture reduces the length of hospital stay. Surgical method is considered only in the case of irreversible nerve and muscle damage. The procedure is performed via a small incision using conventional surgery or an endoscopic technique. Here, the tibial nerve is identified and decompressed or released through surgical excision of the flexor retinaculum. In this way, the pressure exerted on the nerve is reduced to a great extent within the tarsal tunnel.

Tarsal tunnel syndrome Exercises

TTS patients should develop strength and endurance in the muscles of the foot by performing a few exercises correctly and consistently. These involve:

Toe press

The steps involved in this exercise to hasten healing are as follows:

  • Place your feet flat on the floor.
  • Press the toes downward and hold for a count of three.
  • Do not curl your toes during this workout.

Toe spread

The stepwise directions for this workout are given below:

  • Spread your toes as wide as possible, with your feet flat on the floor.
  • Hold the stretch for a few seconds.
  • Pull the toes back.

Toe lift

Patients must abide by the following steps to improve the condition of the affected foot:

  • Stand straight and shift your weight towards the heels of the feet.
  • Lift your toes up toward the ceiling.
  • Release the toes and bring them back to the floor.

Sitting calf stretch

This is a flexibility exercise performed to loosen the leg muscles and reduce stress on the ankle. The steps for this important workout are as follows:

  • Sit down with your knees kept straight.
  • Loop a towel around the ball of the foot.
  • Slowly pull the towel back until you feel your upper calf stretch.
  • Hold this stretch for 20 seconds and relax.

Standing calf stretch

The different steps for this workout are as follows:

  • Place your hands on a wall.
  • Put your affected foot behind the other while pointing your toes forward.
  • Keep your back leg straight and slowly bend the front knee until you feel the calf stretch.
  • Hold the stretch for 20 seconds and relax.

Tarsal tunnel syndrome Prognosis

The outlook following a medical treatment is normally good as patients respond well to the conservative measures. The outcome is quite satisfactory in the case of a surgical operation. However, residual weakness can occur in a few individuals.

Tarsal tunnel syndrome Risk factors

Individuals with severe flat foot/feet deformity are at an increased risk of developing TTS. This condition can also result from a lower back problem that pinches the tibial nerve. In addition to these medical ailments, the neuropathic pain also prevails in patients with health issues like:

Image of Tarsal tunnel syndrome

Picture 2 – Tarsal tunnel syndrome Image

  • Obesity
  • Diabetes
  • Alcoholism
  • Vitamin deficiencies

With adherence to various conventional treatment measures, Tarsal tunnel syndrome usually subsides within a few days. Physical therapy sessions are advisable for patients who have undergone surgery. In order to achieve early recovery, patients should withdraw activities that demand repetitive use of the ankles.

References:

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001796/

http://en.wikipedia.org/wiki/Tarsal_tunnel_syndrome

http://orthopedics.about.com/cs/footproblems/a/tarsaltunnel.htm

http://emedicine.medscape.com/article/1236852-overview

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