Tarsal tunnel syndrome
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Tarsal tunnel syndrome is a compression neuropathy of the tibial nerve or its terminal branches, developing in the fibro-osseous canal on the medial side of the ankle joint. Typical symptoms include burning, tingling, numbness, and pain radiating to the heel, sole, or toes. Symptoms often worsen during walking, prolonged standing, and sports activities. Causes may include trauma, swelling, foot deformity, a proliferative lesion, or chronic tissue overload. Diagnosis is based on the clinical presentation, neurological examination, provocative tests, as well as appropriately selected electrophysiological and imaging studies. Treatment depends on the source of compression, the duration of symptoms, and the degree of nerve damage.
Tarsal tunnel syndrome - why the nerve is compressed
The tarsal tunnel is located behind the medial malleolus. Its floor is formed by the talus and calcaneus bones, and its roof is formed by the flexor retinaculum, which is a strong band of connective tissue. The flexor muscle tendons, the posterior tibial artery and veins, and the tibial nerve run through this confined space. The nerve then divides into the medial plantar nerve, lateral plantar nerve, and calcaneal branches. The site of division and the course of the branches show significant anatomical variability, which affects the location of symptoms.
Pressure increases intracanal pressure, impedes venous outflow, and disrupts the nerve's microcirculation. Initially, reversible ischemia and impaired impulse conduction occur. Prolonged compression can damage the myelin sheath, and in advanced stages, the axons as well. The consequence is often chronic neuropathic pain, decreased sensation, and atrophy of the muscles innervated by the terminal branches of the nerve.
The most important causes include:
- injuries and their consequences, especially fractures, sprains, hematomas, scars, and ankle instability;
- space-occupying lesions, including ganglion cysts, lipomas, varicose veins, neuromas, nerve sheath tumors, and bone spurs;
- tenosynovitis, which increases the volume of structures running within the canal;
- hindfoot valgus and excessive pronation, causing stretching and dynamic irritation of the nerve;
- local or generalized edema, associated with trauma, venous insufficiency, inflammatory disease, or pregnancy;
- systemic diseases, such as diabetes, hypothyroidism, rheumatoid arthritis, and gout;
- repetitive strain, occurring during running, long walking, jumping, or working in a standing position.
In some cases, an identifiable anatomical cause remains difficult to point out. An idiopathic form is then diagnosed, after excluding other sources of neuropathy.
Tarsal tunnel syndrome - how it manifests
Positive sensory symptoms predominate: burning, stabbing, tingling, electric shock sensations, and paroxysmal pain. Symptoms usually begin behind the medial malleolus and radiate toward the sole, heel, or toes. The distribution of symptoms depends on the level of compression and the branch affected by the neuropathy. Pain may worsen in the evening, after prolonged walking, during running, and while maintaining the foot in a weight-bearing position.
Characteristic features include:
- paresthesia of the sole of the foot;
- hyperesthesia or decreased sensation of pain, touch, and temperature;
- burning pain in the medial ankle area and the arch of the foot;
- radiation to the heel, big toe, or lateral part of the sole;
- aggravation of symptoms during passive dorsiflexion and eversion of the foot;
- tenderness along the course of the tibial nerve;
- a positive Tinel's sign, meaning the elicitation of tingling by tapping the nerve;
- periodic cramps and a feeling of fatigue in the foot muscles.
Advanced neuropathy can lead to permanent sensory loss, weakness in toe flexion, and atrophy of the intrinsic foot muscles. Motor deficits occur less frequently and usually indicate significant or prolonged nerve damage.
The clinical picture partially resembles plantar fasciitis, diabetic neuropathy, lumbosacral radiculopathy, Baxter's nerve entrapment, Morton's disease, posterior tibial tendinopathy, or bone-related heel pain. For this reason, the location of the pain alone is only one element of the diagnosis.
Tarsal tunnel syndrome - who does it affect
Tarsal tunnel syndrome can occur at any age, but it is most commonly diagnosed in adults. Epidemiological data remain limited because diagnostic criteria vary between centers, and milder cases are sometimes attributed to other foot pain syndromes.
An increased risk particularly applies to:
- runners, dancers, and individuals performing repetitive movements that stress the ankle joint;
- patients after fractures and sprains of the medial malleolus region;
- individuals with hindfoot valgus, flatfoot (pes planovalgus), or ankle instability;
- workers spending many hours standing;
- pregnant women and individuals prone to lower limb edema;
- patients with diabetes, inflammatory joint diseases, hypothyroidism, or obesity;
- individuals with tumors, cysts, dilated veins, or scars within the tarsal tunnel.
Diabetes requires a particularly thorough evaluation. A patient may have coexisting generalized polyneuropathy and local tibial nerve compression. Similarly, bilateral symptoms suggest the need to analyze systemic, metabolic, and neurological causes. Unilateral symptoms are more often associated with local trauma, deformity, or a space-occupying lesion.
Tarsal tunnel syndrome - how to diagnose
The diagnosis is clinical and requires a combination of medical history, foot examination, and supplementary tests. A single test has limited diagnostic value, which is why the concordance of several independent findings is the most reliable.
The examination includes the assessment of sensation, muscle strength, reflexes, gait, limb alignment, and hindfoot position. The physician looks for swelling, deformity, a scar, a palpable mass, and dilated vessels. Tinel's sign supports the diagnosis, especially when tapping the nerve evokes typical radiation to the sole. The dorsiflexion-eversion test involves stretching the canal structures for a dozen or so seconds. Reproduction of the paresthesias familiar to the patient indicates nerve irritation.
Tests are selected according to the probable cause:
- electroneurography and electromyography assess conduction in the tibial nerve, plantar nerves, and foot muscles; a normal result may occur in cases of mild or intermittent compression;
- high-resolution ultrasonography shows the nerve, its cross-section, tendons, vessels, and proliferative lesions, while a dynamic examination allows the assessment of structural behavior during movement;
- magnetic resonance imaging precisely visualizes soft tissues, muscle denervation, cysts, tumors, abnormal vessels, and tenosynovitis;
- radiography or computed tomography are used to assess deformities, the consequences of fractures, and bone changes;
- laboratory tests help detect diabetes, thyroid disorders, inflammatory, and metabolic diseases.
Differential diagnosis should also take into account the examination of the lumbar spine, the vascular system, and the remaining nerves of the lower limb.
Tarsal tunnel syndrome - how to treat
Management is determined based on the cause, severity of symptoms, and the presence of neurological deficits. Conservative treatment is usually the first stage in overload, inflammatory, and biomechanical cases. It includes temporary restriction of activities that aggravate symptoms, footwear modification, orthotics correcting overpronation, ankle joint stabilization, and pharmacotherapy selected by a physician. Ultrasound-guided corticosteroid injection can reduce local inflammation, but requires precision due to the proximity of the nerve and vessels.
Physiotherapy may include:
- exercises improving foot and lower limb alignment control;
- strengthening of the tibialis posterior muscle and short muscles of the foot;
- graded tibial nerve gliding exercises;
- mobilization of the ankle joint and soft tissues;
- correction of training loads, gait, and movement patterns;
- gentle stretching of the gastrocnemius and soleus calf muscles.
At Ambasada Urody, procedures are available that, following medical diagnosis, can serve a supportive function: physiotherapy and manual therapy, myofascial therapy, therapeutic massage, deep tissue massage, sports massage, and INDIBA Med used in pain and injury therapy. Manual work should avoid direct, heavy compression of the nerve, and its goal is to improve biomechanics, mobility, and load tolerance. Manual lymphatic drainage, pressotherapy, and Icoone Med drainage may be considered in the presence of coexisting edema only after determining its cause and ruling out vascular contraindications. These procedures are complementary and do not themselves eliminate the anatomical obstruction in the tarsal tunnel.
Surgical treatment is considered in the case of a tumor, cyst, bone deformity, progressive sensory loss, muscle weakness, or persistent symptoms despite properly conducted conservative therapy. The procedure involves transecting the flexor retinaculum and releasing the nerve along with its branches. The outcome depends primarily on accurate diagnosis, the identified cause of compression, the duration of neuropathy, and the degree of axonal damage. Prolonged compression and nerve fibrosis reduce the chances of a full recovery of function.
