What Is Tarsal Tunnel Syndrome, and How Is It Different From Sciatica?

Have you ever felt a burning or electric feeling in the sole of your foot, especially at night? Tarsal tunnel syndrome may be the cause. It is less well known than carpal tunnel syndrome in the wrist, but it works in a very similar way. A nerve gets trapped inside a tight space. The result is pain, tingling or numbness that can be hard to pin down.

What does tarsal tunnel syndrome feel like?

Tarsal tunnel syndrome usually causes burning, tingling or numbness in the sole of the foot, the heel or the underside of the toes. The symptoms often get worse after long periods of standing or walking. They can also flare up at night when you are resting.

Some people also notice that tapping the inner ankle with a finger brings back the tingling. Clinicians call this a positive Tinel's sign. It is one of the first things checked during a physical examination.

What causes tarsal tunnel syndrome?

Anything that raises the pressure inside the tarsal tunnel can press on the tibial nerve. The tarsal tunnel is a narrow space. The bones of your ankle form one side, and a tough band of tissue called the flexor retinaculum forms the other. When this space gets crowded, the nerve has nowhere to go.

Overpronation deserves special attention. If your foot rolls inward too far with every step, the tibial nerve is stretched over and over through the day. You can learn more about how foot position affects the whole chain in our guide to orthotics and overpronation.

How is tarsal tunnel syndrome different from sciatica?

The key difference is where the nerve is being pressed. In tarsal tunnel syndrome, the problem is local, right at the inner ankle. In sciatica, or more precisely lumbar radiculopathy, a nerve root in the lower back (often the S1 root) is irritated. The pain then travels all the way down the leg to the foot.

Both conditions can cause burning and numbness in the foot. But with sciatica you will usually feel pain or tightness that starts in the buttock or back of the thigh. It travels down the calf before it reaches the foot. With tarsal tunnel syndrome, the symptoms stay in the ankle and sole. Getting this difference right matters, because the treatment path is completely different.

Sometimes both problems are present at the same time. A pinched nerve higher up can change the way you walk. This shifts load onto the inner ankle and can worsen a tarsal tunnel that gave no trouble before. This is why looking at the whole chain matters.

How is tarsal tunnel syndrome diagnosed?

Diagnosis usually starts with a clinical examination, including Tinel's sign (tapping the nerve behind the inner ankle bone to bring back the tingling). After that, two main tests are used.

• Nerve conduction studies (NCS). These measure how quickly electrical signals travel along the tibial nerve. Slowing at the tarsal tunnel confirms the nerve is trapped.
• MRI of the ankle. An MRI can show cysts, swelling, varicose veins or other things taking up space inside the tunnel and pressing on the nerve.

Why does foot posture matter in tarsal tunnel syndrome?

Foot posture matters because flat feet and overpronation are among the most common mechanical causes of tarsal tunnel compression. When you lie down for a standard X-ray, gravity is taken away. Your arch may look normal, and the inner ankle looks relaxed. Only when you stand and carry your full body weight does the arch drop, the ankle roll inward and the tunnel narrow.

A standing whole-body assessment with ScanAlign standing EOS imaging captures the foot and ankle under real load. It uses about 90% less radiation than a standard X-ray, around ten times less. The image also shows the whole alignment chain, from feet to pelvis. This lets your clinician see whether a leg-length difference, pelvic tilt or knee angle is adding to the problem at the ankle.

This does not replace nerve conduction studies or MRI. It adds the posture picture that those tests cannot show. It helps clinicians understand why the nerve is being pressed, not just that it is.

What helps with tarsal tunnel syndrome?

Treatment depends on the underlying cause and how severe it is. ScanAlign is a diagnostic imaging clinic, so we do not provide treatment. However, your clinician may discuss the following options with you.

• Orthotic support. Custom insoles that support the arch can reduce the inward roll of the ankle and take pressure off the tibial nerve.
• Changing activity and rest. Cutting down on activities that bring on symptoms, along with ice and raising the foot, can ease inflammation.
• Physiotherapy. Nerve-gliding exercises, calf stretches and ankle-strengthening work may help.
• Medication. Anti-inflammatory painkillers or medicines aimed at nerve pain are sometimes prescribed by your doctor.
• Injection or surgery. In cases that do not settle, a specialist may consider a corticosteroid injection or surgery to release the flexor retinaculum.

Before you start treatment, or change the one you are on, it is worth getting a detailed diagnosis. Knowing whether the cause sits in the pelvis, the legs or the spine changes what will actually help.

Seek urgent help if you develop sudden, severe weakness in your foot, loss of feeling that is spreading quickly, or any loss of bladder or bowel control. These may point to a more serious nerve problem. Contact your doctor straight away or go to the nearest emergency department.

Frequently asked questions about tarsal tunnel syndrome