Tarsal tunnel syndrome refers to an entrapment neuropathy (tunnel syndrome) of the (posterior) tibial nerve or of its branches within the tarsal tunnel. This condition is analogous to carpal tunnel syndrome.

Clinical presentation

The most common symptoms are pain and paraesthesia in the toes, sole, or heel and the main finding at physical examination is the Tinel sign (distal paraesthesias produced by percussion over the affected portion of the nerve). Tarsal tunnel syndrome is usually unilateral.

Electromyography and nerve conduction studies are useful in confirming the diagnosis.

Pathology

Because the tarsal tunnel is a tight space, volume-occupying lesions can cause symptoms.

Aetiology

• idiopathic / no cause identified (40-50% cases) ^1,7

• ganglion cysts

• bone deformity after calcaneal fractures

• varicosities

• tenosynovitis of the flexor tendons

• tumours, e.g. schwannoma ⁶, lipoma

• accessory or hypertrophied abductor hallucis muscle

• synovial hypertrophy

• hindfoot valgus ¹

• pes planus

• post-traumatic fibrosis

• os trigonum ²

Radiographic features

Ultrasound

May be able to demonstrate the presence of some of the aetiological factors listed above.

MRI

MR imaging clearly depicts the bones, soft-tissue contents, and boundaries of the tarsal tunnel as well as the different pathologic conditions responsible for tarsal tunnel syndrome.

MR imaging can also aid in determining whether treatment should be conservative (e.g. tenosynovitis) or surgical (e.g. space-occupying lesions).

Treatment and prognosis

Conservative management - orthosis, local injection, anti-inflammatory medications, and tricyclic antidepressants (TCA).

Surgical management - decompressive surgery.

History and etymology

The term was first described by C Keck and S J S Lam in 1962 ³. 

See also

• medial ankle tendon mnemonic

• carpal tunnel syndrome

• sinus tarsi syndrome