Tarsal Tunnel Syndrome
What is Tarsal Tunnel Syndrome?
The tarsal tunnel is a fibrous passageway along the inner side of the ankle that contains the tibial nerve, which is one of two major nerves of the leg and foot. It is responsible for sensation to the bottom of the foot and toes. The tibial nerve also controls the small muscles between the bones of the foot. In Tarsal Tunnel Syndrome, the fibrous passageway for the tibial nerve can become narrower along the inner side of the ankle and lead to compression of the nerve.
What are the symptoms of Tarsal Tunnel Syndrome?
With continued compression of the tibial nerve, patients can develop pain, numbness, and tingling of the bottom of the foot and toes. Without the ability to feel, patients may unknowingly and repeatedly injure the bottom their foot and toes. In long-standing or severe circumstances, tibial nerve compression can lead to weakness and loss of muscle mass between the bones of the foot. This may manifest as curling or clawing of the toes. Sometimes patient interpret this weakness as clumsiness while walking. Symptoms may worsen with prolonged standing, walking, exercising, or during sleep.
What causes Tarsal Tunnel Syndrome?
Risk factors for Tarsal Tunnel Syndrome include patients with “flat” feet and fallen arches that places the nerve on stretch, diabetes, arthritis, and a prior history of ankle sprains or trauma. The common factor in these conditions is that they all lead to increased swelling in the fibrous passageway and decreased space for the tibial nerve. In this situation, the nerve remains in continuity but is its outer lining and blood supply can be damaged by the pressure caused by this tight passageway. In response, scar tissue replaces the natural outer insulation of the nerve, called myelin. Myelin is critical in speeding the transmission of electrical signals to the muscle to cause contractions or from the skin to the brain to produce feeling. With scar replacing myelin, electrical signals cannot easily travel across the nerve
How is Tarsal Tunnel Syndrome diagnosed?
Tarsal Tunnel Syndrome can generally be diagnosed by the history of symptoms and by physical exam looking for signs of numbness along the bottom of the foot/toes, curling of the toes or loss of muscle mass in the foot, and for evidence of nerve inflammation (Tinel’s and scratch-collapse tests). During the Tinel’s test, the skin over the tarsal tunnel is tapped and the patient is asked if there are any signs of tingling or electrical shocks traveling to the bottom of the foot or toes. For the scratch-collapse test, the patient performs resisted shoulder external rotation exercises. The test is considered positive if the affected inner ankle is lightly scratched and the patient momentarily collapses while performing resisted shoulder external rotation. In situations where the diagnosis is unclear, a nerve conduction and muscle study can be ordered to obtain more information on the health of the tibial nerve and its muscles
What are the treatments for Tarsal Tunnel Syndrome?
Treatment of Tarsal Tunnel Syndrome begins with rest, splinting the ankle in the neutral position, custom shoe inserts or custom shoes for better arch support, non-steroidal anti-inflammatory drugs to reduce the swelling and inflammation, diet and exercise in obese patients, and strict glucose control in diabetics. If these measures fail to eliminate the patient’s persistent pain, numbness, and/or muscle weakness, a tarsal tunnel release is recommended. In this procedure, a nerve decompression / neurolysis is performed of the tibial nerve through a small incision along the inner side of the ankle and along the bottom of the foot. The goal is to provide space for the nerve and its blood supply, giving it a chance to regenerate. Doing so in a timely fashion should lead to speedier electrical signals and return of movement, feeling, and function.
What happens after surgery for Tarsal Tunnel Syndrome?
Tarsal tunnel release is generally a 1-hour procedure that can be performed under general anesthesia. After the completion of surgery, the ankle is wrapped in a soft, bulky dressing. Following a 1-2-hour recovery period, patients are discharged home the same day on Tylenol, Motrin, and sometimes on a short course of narcotics. Light walking activity (partial weight bearing) is encouraged when comfortable for the patient, though some patients prefer using crutches until the bulky dressing and bandages are removed. One week after surgery, patients may take off their bandages and get the incision wet. At this point, full walking activity is permitted. Six weeks after surgery, patients may resume running. With mild and/or intermittent symptoms, relief of numbness, tingling, and pain is often immediate. With long-standing or severe cases, relief of symptoms and return of muscle function may be more gradual and over the course of many months.