Symptoms and causes
Tarsal tunnel syndrome
The carpal tunnel of the ankle — except that here, unlike the wrist, a treatable lump is found often enough that skipping the scan is a real mistake.
Written by the Managing Neuropathy editorial team under the direction of Dr. Tom Biernacki, DPM, FACFAS · Clinical review pending · Last updated 7 September 2026
The short answer. The tibial nerve passes behind the bump on the inside of your ankle through a tunnel roofed by a tough band of tissue. Squeezed there, it produces burning, tingling and numbness in the sole — usually in one foot, usually worse with standing and walking, often worse at night. That one-sidedness is the main thing separating it from a general neuropathy. Because a discrete space-occupying cause is found in a substantial share of cases, imaging is more useful here than in most nerve entrapments.
Where the tunnel is, and what is in it
Run your finger down the bony bump on the inside of your ankle and curve backwards toward the heel. Under your finger is the tarsal tunnel: a fibro-osseous channel roofed by the flexor retinaculum. Sharing that space are three tendons, an artery and vein, and the tibial nerve, which divides within or just beyond the tunnel into the branches that supply the sole — including the branch that goes on to become Baxter’s nerve in the heel.
It is a rigid roof over a crowded space. Anything that takes up room, or any position that stretches and compresses the nerve, has somewhere to make trouble.
What it feels like
- Burning, tingling or electric pain in the sole, sometimes into the toes, sometimes into the heel.
- Numbness on the bottom of the foot. Note what is not numb: the skin over the top of the foot is supplied by different nerves, so it is usually spared.
- Worse with standing, walking and by the end of the day, better with rest and elevation.
- Night pain that gets people out of bed to walk about or hang the foot down.
- Pain travelling upward into the calf when the tunnel is tapped — a recognized feature of nerve compression.
- Usually one foot. Bilateral tarsal tunnel syndrome exists but should raise the question of whether a general polyneuropathy is the real diagnosis.
The discriminators
| Feature | Tarsal tunnel syndrome | Polyneuropathy | Plantar fasciitis |
|---|---|---|---|
| Sides | Usually one | Both, symmetric | Either |
| Shape | Sole of the foot; top of the foot spared | Stocking, toes worst | Focal, under the heel |
| Timing | Worse with activity and at night | Worse at night and at rest | Worst on the first steps of the morning |
| Tapping behind the inner ankle | Reproduces the symptoms, sometimes shooting up the leg | Usually not | Usually not |
| Character | Burning, electric | Burning, numb | Sharp, tearing |
The wider symptom map is here, and the spine is the other impostor worth excluding.
What causes it
This is the part that makes tarsal tunnel different from most entrapments, because a specific, findable, fixable cause turns up far more often than people expect.
- Something occupying the space: a ganglion cyst, enlarged veins, a lipoma, an accessory muscle, a nerve sheath tumour, or bone from an old fracture or arthritis.
- Foot shape. A flat foot with the heel rolled outward puts the nerve under tension every step. This is one of the most common contributors and one of the most treatable without surgery.
- Trauma: ankle fracture, severe sprain, or scarring after surgery.
- Systemic conditions that swell soft tissue or make nerves vulnerable — diabetes, inflammatory arthritis, an underactive thyroid, pregnancy.
- Nothing identifiable, in a meaningful minority.
A diabetes footnote worth stating plainly. A nerve already under metabolic stress tolerates compression poorly, so people with diabetes get entrapments more readily. That means someone can have a symmetric diabetic polyneuropathy in both feet and a compressed tibial nerve in one. If one foot is markedly worse than the other, that asymmetry does not fit a polyneuropathy and deserves its own examination rather than being folded into the existing diagnosis.
How it is assessed
Tapping over the tunnel to see whether symptoms are reproduced; holding the ankle in the position that maximally narrows the tunnel — foot turned out and pulled up, toes extended — and waiting to see whether symptoms appear; mapping exactly where sensation is altered, and confirming the top of the foot is spared.
Hindfoot position under load is part of the diagnosis and cannot be judged on a couch.
Ultrasound or MRI to look for a cyst, a mass, enlarged veins or an accessory muscle. Finding one changes both the treatment and the expected result.
They can support the diagnosis and are useful for identifying a background polyneuropathy, but a normal study does not exclude tarsal tunnel syndrome. This is a diagnosis made mainly on history and examination.
Treatment
Most people are managed without surgery, and the order matters.
- Correct the mechanics. An orthosis that controls hindfoot valgus and supports the arch takes tension off the nerve and is the single most useful non-surgical measure when foot shape is contributing. Shoes with a firm heel counter do the same job. Fit criteria are here.
- Reduce the load temporarily — activity modification, and occasionally a period of immobilisation for a flare.
- Physiotherapy, including nerve gliding work and calf flexibility.
- Anti-inflammatories or an injection around the tunnel, which can both settle symptoms and support the diagnosis.
- Medication for neuropathic pain where the pain is clearly nerve-type. Options here.
- Surgical release of the retinaculum, with removal of any mass, when conservative care has failed. Results are reported as considerably better when a specific compressing lesion is identified beforehand — which is the practical argument for scanning rather than operating on a hunch.
Get seen promptly for these
Weakness or a change in the shape of the foot, particularly clawing of the toes, which suggests motor fibers are involved and that waiting is costly. A rapidly enlarging lump behind the inner ankle. Symptoms that appeared after an injury and are worsening. Any skin breakdown on a foot with reduced sensation. And numbness that has spread to both feet, which points away from a local entrapment and toward something that needs blood tests.
Common questions
Is tarsal tunnel syndrome the same as plantar fasciitis?
No. Plantar fasciitis is a problem of the fascia at the heel and classically hurts most on the first steps of the morning. Tarsal tunnel is nerve compression at the inner ankle, burns rather than tears, and typically worsens through the day. They can coexist, and stubborn heel pain deserves a look at both — along with Baxter’s nerve.
Can it go away on its own?
Symptoms triggered by a temporary swelling, a period of unusual activity or pregnancy often settle. Symptoms driven by foot shape or by a mass will not resolve until the cause is addressed.
Why is my scan normal if the nerve is trapped?
Because imaging is looking for a structural cause, and in a proportion of cases there is not one — the compression comes from position and tension rather than from a lump. A normal scan makes a mass unlikely; it does not exclude the diagnosis.
Is surgery worth it?
It can be, in well-selected cases that have exhausted conservative treatment. The selection is what matters: the best outcomes are reported where a clear compressing structure was identified, and the least predictable where the diagnosis was uncertain and no cause was found.
Both my feet burn. Could this still be it?
Possible but less likely. Bilateral symptoms should first prompt a search for a generalised cause — glucose, B12, thyroid, alcohol, medication — before two separate entrapments are assumed. The classification is here.
Related reading
Types of neuropathy · Baxter’s neuropathy · The full symptom list · Back pain versus nerve pain · Foot drop · Numb toes and the pattern
Sources and further reading: Published reviews and surgical series on tarsal tunnel syndrome, including the frequency of space-occupying lesions and their relationship to outcome after release. American College of Foot and Ankle Surgeons clinical guidance on heel and nerve pain. American Academy of Neurology guidance on electrodiagnostic assessment of focal neuropathies and its limitations at the ankle.
This page is general education and is not a diagnosis or a treatment plan. Clinical review by Dr. Biernacki is pending; the review date will be shown here once complete.
For our Michigan neighbors
One burning foot is
a different problem.
Asymmetric nerve pain deserves an examination that includes the ankle, the hindfoot under load, and a decision about imaging. Dr. Biernacki is a double board-certified foot and ankle surgeon.
Everywhere else, take this page to your own clinician.
Dr. Tom Biernacki, DPM, FACFAS is a double board-certified foot and ankle surgeon (ABFAS and ABPM) and a Fellow of the American College of Foot & Ankle Surgeons. He is the founder of Balance Foot & Ankle in Howell and Bloomfield Township, Michigan, where peripheral neuropathy, diabetic foot risk and loss of protective sensation are part of his weekly clinic. His patient education videos have drawn more than 950,000 subscribers on YouTube. He writes Managing Neuropathy to put the explanation he gives in the exam room in front of the people who cannot get to one — including when a product is worth buying and when it is not.