Tarsal tunnel syndrome: A type of compression neuropathy (nerve disease due to compression of the nerve) in the ankle and foot.
Tarsal tunnel syndrome (TTS) is similar to the better-known carpal tunnel syndrome (CTS) caused by compression and irritation of the median nerve within the carpal tunnel, a bony canal in the palm side of the wrist that provides passage for the median nerve to the hand. The irritation of the median nerve is specifically due to pressure from the transverse carpal ligament.
Anatomy similar to that of the wrist and hand exists in the ankle and foot. Tarsal is a word from Latin which means ankle. The tarsal tunnel refers to the canal formed between the medial malleolus (part of the ankle bone, this is the bump on the inside of the ankle) and the flexor retinaculum (a band of ligaments that stretches across the foot). Inside the tarsal tunnel are the nerves, arteries, and tendons that provide movement and flexibility to the foot. The sensory nerve in the ankle, the tibial nerve, passes through the tarsal tunnel and can be compressed and irritated causing numbness and tingling of the foot and toes as this nerve provides sensation to the bottom of the foot. Tarsal tunnel syndrome has also been called posterior tibial neuralgia. This condition is far less common than carpal tunnel syndrome (CTS).
Both CTS and TTS are usually due to trauma from repetitive work involving the wrist and ankle, respectively. Other factors predisposing to TTS include obesity, pregnancy, hypothyroidism, arthritis, and diabetes, flat feet or fallen arches, an enlarged or abnormal structure lie a cysts or a bone spur, or swelling secondary to ankle sprain.
The symptoms of TTS include a shooting pain in the foot, numbness, burning and tingling of the bottom of the foot and toes, a "pins and needles" feeling at night, feelings of weakness in the ankle and incoordination.
The diagnosis of TTS is suspected based on symptoms, supported by signs on comprehensive physical examination, imaging (X-ray, CT or MRI scans), and nerve conduction testing.
The treatment of TTS depends on the severity of symptoms and the underlying cause. Early TTS is usually treated by modification of activities, orthotic devices, a removable ankle brace and anti-inflammatory medicines. Caught early, TTS is reversible. If numbness and pain continue in the foot and toes, a cortisone injection into the tarsal tunnel can help. Surgery is only indicated if other treatments have failed. In advanced TTS, particularly with profound weakness and muscle atrophy (wasting), surgery is done to avoid permanent nerve damage.
The surgical procedure is called a tarsal tunnel release. It relieves the pressure exerted on the nerve within the tarsal tunnel. This surgical procedure is performed via a small incision using conventional surgery or a fiberoptic scope (endoscopic tarsal tunnel repair).