Tarsal Tunnel Syndrome (TTS) occurs when the posterior tibial nerve, running along the inside of the ankle, becomes compressed within the tarsal tunnel. This compression causes distinct neurological symptoms, most commonly numbness, burning, tingling, or shooting pain in the sole of the foot and toes. Because these sensations are common, they are frequently confused with other conditions affecting the lower leg and foot. Accurately diagnosing TTS is challenging because several common disorders can produce nearly identical pain patterns, often leading to misdiagnosis. Understanding the specific differences between TTS and its common mimics is essential for initiating the correct treatment plan.
Referred Pain from the Lower Back and Sciatic Nerve
One common source of pain mimicking Tarsal Tunnel Syndrome originates higher up in the body. This referred pain occurs when nerve roots in the lumbar spine are compressed or irritated, a condition known as lumbar radiculopathy or sciatica. The sciatic nerve branches into the tibial nerve that travels down to the foot.
Compression of these nerve roots, often due to a herniated disc or spinal stenosis, sends pain signals along the nerve pathway, making the foot the site of perceived pain. This proximal compression can imitate the tingling and burning sensations associated with localized entrapment in the ankle. Pain referred from the spine often includes symptoms in the buttock, hip, or thigh, which are not involved in true TTS.
Symptoms stemming from the lower back are often affected by changes in spinal posture rather than ankle movements. Sitting or bending the spine may aggravate referred pain. In contrast, true TTS symptoms are usually exacerbated by activities that increase pressure on the ankle, such as prolonged standing. Determining if the nerve distress is happening at the ankle (distal) or the spine (proximal) is crucial for correct treatment.
Generalized Peripheral Neuropathy
Generalized peripheral neuropathy involves systemic nerve damage that closely resembles Tarsal Tunnel Syndrome. Unlike TTS, which is a focal entrapment of a single nerve, neuropathy is a diffuse process damaging many peripheral nerves throughout the body. Diabetic neuropathy is the primary example, caused by chronically high blood sugar levels damaging small nerve fibers.
Peripheral neuropathy symptoms, including bilateral pain, tingling, and numbness, typically begin in the feet and progress upward in a characteristic “stocking-glove” distribution. This symmetry and gradual spread help differentiate it from the unilateral and localized nature of TTS. While diabetes can predispose a person to developing TTS, the systemic neuropathy presents differently.
Other causes of generalized nerve damage, such as chemotherapy or alcohol-related neuropathy, also produce similar sensations. In generalized neuropathy, sensory loss often dominates, whereas TTS often presents with a more acute, localized burning pain. Physicians must recognize that a patient with pre-existing systemic neuropathy may also develop a treatable focal nerve entrapment like TTS.
Local Tendon and Ligament Inflammation
Musculoskeletal conditions causing inflammation in the foot and ankle are frequently mistaken for Tarsal Tunnel Syndrome because they share the symptom of foot pain. These conditions involve soft tissue structures rather than nerve compression. Plantar Fasciitis, inflammation of the tissue on the bottom of the foot, is a major mimic, causing deep heel pain that can be confused with the deep ache sometimes felt with TTS.
The pain from Plantar Fasciitis is typically mechanical, meaning it is most severe with the first steps in the morning or after a period of prolonged rest. Posterior Tibial Tendonitis, inflammation of the tendon running alongside the tibial nerve, causes pain and swelling on the inside of the ankle. This localized tenderness can easily be misinterpreted as nerve compression within the adjacent tarsal tunnel.
The key distinction lies in the quality of the sensation. Inflammatory conditions primarily cause pain with specific movements or pressure, but lack true neurological symptoms. While TTS produces burning, tingling, and numbness, tendonitis and fasciitis cause a sharp, aching pain reproducible by pressing directly on the inflamed soft tissue.
Diagnostic Steps to Confirm Tarsal Tunnel Syndrome
A definitive diagnosis of Tarsal Tunnel Syndrome requires excluding mimics and confirming localized nerve compression. The initial physical examination includes provocative maneuvers, such as Tinel’s sign. Tapping over the tibial nerve behind the inner ankle bone elicits a shooting or tingling sensation in the foot. Reproducing the symptoms this way strongly suggests local nerve irritation.
Imaging studies, such as X-rays and Magnetic Resonance Imaging (MRI), are used to rule out structural causes of pain or nerve compression. An X-ray eliminates the possibility of a stress fracture or bone spur. An MRI can identify space-occupying lesions, such as a ganglion cyst or varicose vein, that might be directly pressing on the tibial nerve, helping pinpoint a mechanical cause of entrapment.
To objectively confirm the nerve’s functional status, a physician may order electrodiagnostic testing, including Nerve Conduction Velocity (NCV) and Electromyography (EMG). NCV measures the speed and strength of electrical signals traveling through the tibial nerve and its branches. A slowed signal or prolonged latency indicates focal compression at the ankle. This testing is often considered the gold standard for distinguishing a true entrapment neuropathy from a more generalized or proximal issue.