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Tarsal Tunnel Syndrome

Richard A. Zell, M.D.

Tarsal Tunnel Syndrome is a less common condition caused by the compression of the tibial nerve in the tarsal tunnel. This condition is akin to Carpal Tunnel Syndrome of the upper extremity in which the median nerve is compressed by the transverse carpal ligament in the wrist. In Tarsal Tunnel Syndrome, the tibial nerve is compressed by the flexor retinaculum behind and distal to the medial malleolus. The compression of the tibial nerve can be caused by: a lipoma, ganglion, bony exostosis or neoplasm within the tarsal tunnel. Other causes of compression include: a plexus of veins or an accessory flexor digitorum longus muscle. The condition can be associated with a flatfoot or valgus position of the heel.

Patients with Tarsal Tunnel Syndrome complain of ankle pain that radiates along the plantar side of the foot and sometimes up into the calf. Other patients report parathesias or foot numbness. Physical exam can demonstrate a positive Tinel sign behind the medial malleolus. Other patients have increased pain with manual compression over the tarsal tunnel. Some patients may have atrophy of the foot. Two point discrimination tests may be abnormal on the plantar aspect of the foot.

EMG and nerve conduction tests can be helpful in the diagnosis of Tarsal Tunnel Syndrome. A recent study reported that 81% of patients with tarsal tunnel syndrome had abnormal EMG studies. An MRI is a useful study in the work up of patient with Tarsal Tunnel Syndrome as it can be used to identify space-occupying structures within the tarsal canal as well as the specific site of compression of the tibial nerve.

Many patients improve with rest, NSAIDS and possibly orthotics. Surgery is recommended for patients with persistent symptoms and a space-occupying lesion within the tarsal canal. During a Tarsal Tunnel Release an incision is made along the medial aspect of the ankle and the tibial nerve and its branches are decompressed. The cause of the compression is removed i.e. the venous plexus surrounding the nerve or the ganglion compressing the nerve is removed.