Tarsal Tunnel Syndrome
Tarsal tunnel syndrome is a form of entrapment neuropathy in which the tibial nerve (or one of its terminal branches) is compressed within a narrow fibro-osseous “tunnel” along the posteromedial aspect of the ankle, beneath the flexor retinaculum. Chronic pressure leads to edema, reduced perfusion, impaired axonal transport, and progressive myelin/axonal changes, resulting in burning pain, numbness, or paresthesias in the sole of the foot.
Symptoms typically worsen with standing and walking and improve with rest. If compression remains untreated, there is a risk of permanent nerve injury. Therefore, accurate diagnosis (and exclusion of conditions that mimic these symptoms, such as lumbar radiculopathy or peripheral polyneuropathy) is essential, as is individualized management ranging from conservative measures to surgical decompression when there is proven entrapment with persistent functional impairment.
What is tarsal tunnel syndrome?
It is an entrapment of a peripheral nerve at the ankle, analogous (but less common) to carpal tunnel syndrome in the hand.
In tarsal tunnel syndrome, the tibial nerve or its terminal branches become compressed within a narrow channel formed by bone and connective tissue. Compression results in neuropathic pain (burning), paresthesias (tingling), or numbness in the sole of the foot.
Characteristically, symptoms worsen with weight bearing (walking, standing) and improve with rest. With prolonged compression, sensory loss and/or weakness may develop, typically in more advanced stages.
Where is the tarsal tunnel and which nerve is compressed?
The tarsal tunnel lies posterior to the medial malleolus and contains tendons, vessels, and the tibial nerve.
The tarsal tunnel is a fibro-osseous space along the posteromedial ankle. Its “roof” is formed by the flexor retinaculum, while the “floor” is composed of bone (tibia/talus/calcaneus).
The tibial nerve (terminal branch of the sciatic nerve) traverses the tunnel, where it divides into the medial and lateral plantar nerves. It often also gives rise to the medial calcaneal branch, which provides sensation to the posteromedial heel.
Simply put: when the anatomical space narrows or a mass/edema/fibrosis is present, the nerve is compressed and plantar symptoms develop.
Why does chronic compression cause nerve dysfunction?
Prolonged compression leads to edema, micro-ischemia, and progressive demyelination, with a risk of permanent nerve injury if unrelieved.
When a peripheral nerve is compressed within a confined anatomical space, edema develops first, along with a connective tissue response involving fibroblast proliferation and scar formation. This predisposes to reduced perfusion and disruption of axonal transport.
Chronic compression results in segmental demyelination and axonal thinning. Without timely decompression, the nerve may sustain permanent axonal injury.
This is why appropriate evaluation is critical: the better the functional status at the start of treatment, the more favorable the prognosis.
What are the most common causes and risk factors?
A reversible cause is often present (mass, tenosynovitis, deformity), while in other cases overuse or systemic factors predominate.
Common causes/mechanisms of entrapment:
- Mass lesions in the tarsal tunnel: ganglion cyst, lipoma, neurinoma/schwannoma, neuroma.
- Tenosynovitis of the flexor tendons (inflammation/edema).
- Fibrosis/scar tissue following ankle trauma or surgery.
- Osseous/mechanical factors: deformities (e.g., hindfoot valgus or varus), osteophytes, or congenital narrowing.
- Overuse: prolonged standing, hiking, long-distance running, demanding sports.
Systemic contributors may include diabetes mellitus, hypothyroidism, and inflammatory arthropathies.
What are the symptoms and how do patients usually describe them?
Typically described as burning or numbness in the sole that worsens with walking and improves with rest.
Common symptoms:
- Paresthesias or numbness along the medial ankle and plantar surface.
- Burning or dysesthesias in the distribution of the plantar branches.
- Worsening with standing/walking and relief with rest.
- Nocturnal pain in some patients.
- Less commonly, pain radiating proximally (anterior/medial leg).
Muscle weakness or atrophy of muscles innervated by the plantar nerves is typically a late finding.
Which conditions can mimic tarsal tunnel syndrome?
Accurate diagnosis requires exclusion of other causes of foot pain with different etiologies and treatments.
Common mimics include:
- Lumbar disc herniation/radiculopathy: radiating leg pain with possible neurological deficits (reflexes/strength). Confirmed with lumbar spine MRI when indicated.
- Spinal stenosis: low back pain with neurogenic claudication (often bilateral).
- Peripheral polyneuropathy: usually bilateral symptoms with systemic etiology (e.g., diabetes).
- Plantar fasciitis: heel pain primarily on first steps in the morning, with localized tenderness anterior to the calcaneal tubercle.
- Stress fracture: focal, sharp pain with point tenderness and difficulty with weight bearing.
The objective is to establish the correct diagnosis so that treatment can be effective.
How is the clinical examination performed (Tinel, provocation tests)?
Examination includes assessment of hindfoot alignment, identification of tender points, and symptom provocation with specific maneuvers.
In practice:
- Standing assessment: evaluation of hindfoot alignment (valgus/varus). Both deformities may stress the nerve (through traction or compression).
- Palpation of the tarsal tunnel for masses or focal tenderness.
- Tinel’s sign: percussion over the course of the tibial nerve posterior to the medial malleolus, reproducing “electric” sensations or paresthesias into the sole.
- Provocation maneuver: maximal external rotation of the foot followed by dorsiflexion of the ankle for 10–15 seconds typically exacerbates symptoms.
- Plantar sensation may be normal in early stages. Motor weakness is usually a late finding.
Which investigations are required (X-rays, MRI, EMG/NCV) and what do they show?
Tests are selected individually to document entrapment and exclude alternative diagnoses.
- Weight-bearing X-rays of the foot/ankle: demonstrate deformities (e.g., valgus/varus) or osseous causes.
- Ankle/tarsal tunnel MRI: particularly useful for identifying masses, tenosynovitis, ganglion cysts, inflammation, and pathology within the tunnel.
- Electrodiagnostic testing (EMG/NCV): helps differentiate from lumbar radiculopathy or polyneuropathy. Sensory conduction studies are usually more sensitive than motor studies, and comparison with the contralateral side is helpful.
A normal EMG/NCV does not categorically exclude tarsal tunnel syndrome. Diagnosis remains primarily clinical, with imaging particularly valuable when a mass or mechanical cause is suspected.
What conservative treatments are available and for how long should they be tried?
The goal of conservative care is to reduce irritation/edema and remove precipitating factors that compress the nerve.
Common options:
- Activity modification: avoidance of prolonged standing/walking or activities that exacerbate symptoms.
- Footwear/orthotics: arch support and correction of mechanical loading.
- Physiotherapy: mobilization, stretching, off-loading techniques, and strengthening as indicated.
- Anti-inflammatory medications (when appropriate) and management of contributory factors (e.g., weight, metabolic issues).
- Targeted injections/blocks in selected cases when focal inflammation or severe pain is documented.
When symptoms are significant and the clinical picture is compatible, a structured trial of conservative therapy is typically pursued for 3–6 months, with reassessment of function and pain.
When is surgery considered and what is the goal of the operation?
Surgery is considered in patients with persistent, function-limiting symptoms and documented entrapment that does not respond to conservative management.
Surgical evaluation is warranted when:
- Symptoms remain persistent and disabling despite appropriate conservative treatment for 3–6 months.
- There are clear clinical findings (e.g., positive Tinel’s sign, provocation tests) and/or supportive imaging/electrodiagnostic evidence.
- A mass is present within the tarsal tunnel or there is post-traumatic/post-surgical scarring suspected as the cause.
- Progressive neurological deficits develop (e.g., worsening sensory loss, late weakness).
The goals of surgery are:
- Division/release of the flexor retinaculum and fibrous bands compressing the nerve.
- External neurolysis of the tibial nerve and its branches, with careful identification of their course.
- Excision of causative lesions (e.g., ganglion, mass) responsible for compression.
Internal neurolysis is generally avoided, as it may increase the risk of perineural fibrosis and recurrence. Success depends on complete decompression extending to the medial and lateral plantar branches when required.
What should I expect after decompression – recovery & symptom course?
Recovery is gradual: the objective is reduction of neuropathic pain and restoration of function, with realistic expectations.
After surgical decompression, meticulous wound care is followed by gradual return to weight bearing. Full weight bearing often begins after 2–4 weeks, depending on the protocol, healing, and individual factors.
Relief of burning/paresthesias may be immediate in some patients, while in others it is progressive, as the nerve requires time to recover. In chronic cases with long-standing symptoms, improvement may be incomplete.
Unfavorable prognostic factors include long symptom duration, established motor deficits, extensive scarring of the tarsal tunnel, and inadequate surgical decompression.
Frequently asked questions & when should you seek specialist advice?
Is tarsal tunnel syndrome the same as plantar fasciitis?
No. Plantar fasciitis is primarily mechanical heel pain (often on the first steps in the morning), whereas tarsal tunnel syndrome produces neuropathic symptoms (burning/numbness) in the sole.
If my EMG/NCV is normal, does that mean I do not have tarsal tunnel syndrome?
Not necessarily. Electrodiagnostic studies are helpful, but a normal result does not exclude the diagnosis. Clinical findings and imaging (especially MRI when a mass is suspected) are critical.
When is it reasonable to proceed to surgery?
When symptoms are persistent and limiting despite a structured 3–6-month trial of conservative therapy and there is supportive clinical/imaging evidence or strong clinical suspicion of entrapment.
Could my symptoms be coming from my lower back rather than the ankle?
Yes. Lumbar radiculopathy can produce foot symptoms. For this reason, we evaluate pain distribution, neurological findings, and when needed obtain lumbar spine MRI and/or EMG/NCV.
At Neuroknife, assessment follows a structured protocol: detailed history, examination focused on mechanical factors (hindfoot alignment/loading), clinical tests (Tinel/provocation), and targeted imaging (weight-bearing radiographs, MRI when indicated), ensuring that management is precise, individualized, and realistic.
When should you seek specialized evaluation?
If you experience burning/numbness in the sole that worsens with walking, night pain, or if symptoms persist despite footwear changes/orthotics/physiotherapy, targeted evaluation for tibial nerve entrapment is important.
In the presence of progressive sensory loss, new weakness, or suspicion of a mass in the region, assessment should be prompt to reduce the risk of permanent neurological injury.
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