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Tomasz Poboży

Kategoria: Peripheral Nerves (EN)

English-language patient information about peripheral nerve compression, injury, neuropathic symptoms, ultrasound, electrodiagnostic testing and treatment.

  • Tarsal Tunnel Syndrome — What Causes Numbness in the Sole?

    Polish version

    Burning, tingling or numbness in the sole can result from compression of the tibial nerve or its branches within the tarsal tunnel, the space on the inner side of the ankle. These symptoms do not automatically mean tarsal tunnel syndrome, however. Similar complaints can arise from the lumbar spine, other peripheral nerves or structures within the foot. Diagnosis therefore depends on the history, clinical examination and appropriately selected tests rather than on any single investigation.

    The tarsal tunnel lies behind and below the medial malleolus. Tendons, blood vessels and the tibial nerve pass through it; the nerve then divides into branches supplying much of the sole. Symptoms can develop when the available space becomes restricted or when the nerve is compressed locally by another structure.

    Which symptoms fit tarsal tunnel syndrome?

    The most typical complaints are felt around the medial ankle and on the sole. Patients may describe burning, tingling, numbness, electric-shock sensations or shooting pain. Symptoms can radiate into the heel, arch or toes.

    • numbness or tingling mainly affects the sole rather than the top of the foot,
    • symptoms may worsen with prolonged standing, walking or running,
    • pressure or percussion behind the medial malleolus may reproduce tingling into the foot,
    • pain may feel burning or electrical rather than purely mechanical,
    • more advanced cases can produce sensory loss and, much less often, weakness of the small muscles of the foot.

    The symptom pattern alone is not enough for diagnosis. Tarsal tunnel syndrome can be confused with plantar fasciopathy, S1 radiculopathy and other neuropathies of the foot. Pain that is most prominent with the first steps in the morning and is centred at the medial heel may point instead toward plantar fascia overload.

    What can compress the tibial nerve?

    The cause is not always obvious. Reduced space within the tunnel may follow injury and scarring, bony changes, tendon-sheath inflammation, a ganglion or another space-occupying lesion. Varicose veins and other vascular abnormalities, accessory muscles and foot deformity that alters local mechanics have also been described.

    For that reason, the aim of assessment is not simply to label the problem as “nerve compression”, but—when possible—to identify what is causing the compression. This can directly influence treatment: a ganglion, post-traumatic scarring and a syndrome without a clear structural lesion are not managed in exactly the same way.

    How is the diagnosis made?

    The first step is to define the exact sensory distribution and how the symptoms are provoked. Examination includes sensation, strength, sites of tenderness, foot alignment and whether pressure or percussion over the tibial nerve behind the medial malleolus reproduces typical paraesthesia. At the same time, the clinician should look for evidence of another explanation such as lumbosacral radiculopathy or a generalised polyneuropathy.

    A review in EFORT Open Reviews emphasised that there is no single test that can diagnose tarsal tunnel syndrome with complete certainty. Clinical findings should be integrated with imaging and, where appropriate, nerve-conduction studies or electromyography.

    What can nerve ultrasound show?

    Ultrasound can trace the tibial nerve around the ankle and through the tarsal tunnel, assess its calibre and internal appearance, and look for a local cause of compression. It can also reveal neighbouring abnormalities such as a ganglion, tendon-sheath inflammation, selected vascular abnormalities, accessory muscles or post-traumatic change. A further advantage is dynamic assessment while the ankle moves or symptoms are provoked locally.

    Ultrasound is not a rule-out test. In a 2026 study of 26 feet with tarsal tunnel syndrome confirmed clinically and electrophysiologically, nerve ultrasound detected abnormalities with a sensitivity of about 65% when the commonly used nerve cross-sectional-area threshold of 11.8 mm² was applied. In other words, a normal ultrasound does not exclude tarsal tunnel syndrome.

    The same study noted that, when ultrasound was abnormal, nerve swelling was often seen within the tunnel itself rather than only just proximal to the presumed compression. This supports scanning the nerve over a sufficiently long segment and comparing its appearance within the tunnel with more proximal portions.

    Is EMG necessary?

    Nerve-conduction studies and electromyography can provide objective information about the function of the tibial nerve and its branches, and can help distinguish local compression from radiculopathy or polyneuropathy. Their sensitivity is also limited, however. A normal result should not automatically end the diagnostic process when the history and examination continue to strongly suggest an entrapment neuropathy.

    When are MRI or CT useful?

    MRI is particularly helpful when deeper tissues need more detailed assessment, a space-occupying lesion is suspected, or the clinical examination and ultrasound do not provide a clear answer. In a small surgical series, MRI identified the site of compression in 23 of 28 feet, but it did not always identify the specific cause, including some varices or small vascular branches compressing the nerve.

    CT has less value for assessing the nerve itself, but it can be useful when a bony cause is suspected—for example deformity, an osteophyte, a consequence of fracture or another osseous abnormality whose anatomy matters for treatment planning.

    What else should be considered?

    Burning or numbness in the foot does not always originate in the tarsal tunnel. Depending on the distribution and character of symptoms, the differential diagnosis includes S1 radiculopathy, polyneuropathy, plantar fasciopathy, stress fracture and more distal focal neuropathies of the foot. Forefoot pain and tingling that radiate into adjacent toes, especially in tight footwear, may suggest Morton’s neuroma instead.

    How is tarsal tunnel syndrome treated?

    Treatment depends mainly on the cause and on the degree of nerve dysfunction. When there is no progressive neurological deficit and no clear lesion that requires removal, management usually starts non-operatively: reducing the loading that reproduces symptoms, modifying footwear or using an orthotic when appropriate, treating pain, and addressing relevant mechanical factors of the foot.

    An injection around the tarsal tunnel may be considered in selected patients, particularly when a local inflammatory component or swelling is suspected. Because the nerve and vessels lie close together, ultrasound guidance allows direct control of needle position. This is not, however, a universal treatment for every tibial neuropathy.

    When does an orthopaedic surgeon consider surgery?

    Surgical decompression is considered mainly when clinically important symptoms persist despite appropriate non-operative treatment and there is credible evidence that the nerve is actually being compressed within the tarsal tunnel. The indication is stronger when a specific cause can be identified, such as a ganglion, post-traumatic scar or another space-occupying lesion.

    Reported rates of good surgical outcomes vary widely. The result cannot be promised on the basis of one positive provocative test or one ultrasound image. Better outcomes have been reported when symptoms have been present for a shorter time, the cause of compression is clear and the clinical findings are concordant. Long-standing neuropathy with established nerve damage may not fully recover even after the compression has been removed.

    Which symptoms need faster assessment?

    • progressive weakness of the toes or foot muscles, especially with a new gait disturbance,
    • rapidly worsening or extensive sensory loss after a recent ankle injury,
    • marked swelling after injury accompanied by increasing pain and numbness,
    • a cold, pale or blue foot or other signs of impaired blood flow,
    • fever, redness, warmth and increasing swelling suggesting infection,
    • numbness affecting both feet or multiple limb regions, which may indicate a generalised problem rather than compression of one local nerve.

    What is the practical takeaway?

    Tarsal tunnel syndrome is worth considering when burning, tingling and numbness mainly affect the sole and relate to the region behind the medial malleolus. The key is to establish whether the symptoms truly fit tibial nerve compression and, where possible, identify the cause. Ultrasound can be very useful, but a normal scan does not exclude neuropathy. Likewise, an isolated abnormal EMG or MRI finding should not be interpreted without clinical correlation.

    Back to: Foot and Ankle Conditions

    See also: Peripheral Nerves

    References

    • Holtz B-O, Ceanga M, Behnert A, Marquardt R, Geis C, Axer H. Nerve Ultrasound for the Diagnosis of Tarsal Tunnel Syndrome: Findings in 26 Clinically and Electrophysiologically Confirmed Feet. J Clin Med. 2026;15(5):1699. DOI: 10.3390/jcm15051699.
    • Rodríguez-Merchán EC, Moracia-Ochagavía I. Tarsal tunnel syndrome: current rationale, indications and results. EFORT Open Rev. 2021;6(12):1140–1147. DOI: 10.1302/2058-5241.6.210031.
    • de Souza Reis Soares O, Duarte ML, Brasseur J-L. Tarsal Tunnel Syndrome: An Ultrasound Pictorial Review. J Ultrasound Med. 2022;41(5):1247–1272. DOI: 10.1002/jum.15793.
    • Kim K, Kokubo R, Isu T, Nariai M, Morimoto D, Kawauchi M, Morita A. Magnetic Resonance Imaging Findings in Patients with Tarsal Tunnel Syndrome. Neurol Med Chir (Tokyo). 2022;62(12):552–558. DOI: 10.2176/jns-nmc.2022-0118.

    This information is educational and does not replace an individual medical consultation.

    Content prepared by: Tomasz Poboży - orthopaedic surgeon.

  • Radial Tunnel Syndrome — Lateral Elbow Pain Without Numbness

    Polska wersja

    Radial tunnel syndrome can cause deep pain on the outer side of the elbow and upper forearm, usually without numbness in the fingers. The symptoms often resemble tennis elbow, but tenderness is typically located several centimetres below the lateral epicondyle. Diagnosis requires caution because no single test can confirm the syndrome on its own.

    Where is the nerve compressed?

    Around the elbow, the radial nerve divides into a superficial branch and a deep branch, which continues as the posterior interosseous nerve. The deep branch passes through a tunnel formed by muscles and fibrous bands in the proximal forearm. The region of the supinator muscle is one of the more common sites of compression.

    Pain is the dominant feature in radial tunnel syndrome. Clear finger drop or wrist drop suggests a more significant motor lesion of the posterior interosseous nerve or radial nerve and warrants more prompt investigation.

    Which symptoms can suggest radial tunnel syndrome?

    • deep, dull or burning pain on the lateral side of the elbow and upper forearm,
    • tenderness usually 3–5 cm below the lateral epicondyle of the humerus,
    • pain aggravated by forearm supination, gripping or repetitive hand work,
    • pain with resisted middle-finger extension or resisted supination,
    • usually no typical numbness of the skin of the hand or fingers.

    Radial tunnel syndrome or tennis elbow?

    In tennis elbow, maximal tenderness is usually directly over the lateral epicondyle at the origin of the wrist extensors. In radial tunnel syndrome, the most painful point is more often distal to the epicondyle, along the course of the nerve. The two problems can coexist, and a single provocative test does not settle the diagnosis.

    How is it diagnosed?

    Clinical examination

    The location of pain, muscle strength, sensation, range of motion of the neck and elbow, and reproduction of symptoms during specific resisted movements are all important. The differential diagnosis includes extensor tendinopathy, radiocapitellar joint disease, cervical radiculopathy and radial nerve compression at another level.

    EMG and nerve conduction studies

    Electrophysiological studies may be normal in a typical pain-dominant radial tunnel syndrome. They are more useful when there is objective weakness and the clinician needs to assess a motor nerve lesion or distinguish the problem from radiculopathy.

    Ultrasound and MRI

    Ultrasound can show the course of the nerve, changes in its calibre, compression by a cyst or another lesion, and can provide dynamic assessment. MRI can help identify a space-occupying lesion and signs of muscle denervation. Normal imaging, however, does not exclude a clinical pain syndrome.

    How does treatment begin?

    Management usually starts by reducing repetitive movements that provoke pain, particularly forceful gripping, forearm supination and work with the elbow extended. Ergonomic modification, graded exercise, soft-tissue treatment and work on mobility and strength may help, provided the programme does not continually provoke symptoms.

    Analgesic or anti-inflammatory medication can be used in appropriately selected patients. A targeted injection is sometimes used diagnostically or therapeutically, but evidence for durable benefit is limited. Ultrasound guidance improves control of needle placement, although technical accuracy alone does not confirm the diagnosis.

    When does an orthopaedic surgeon consider surgery?

    Surgical decompression may be considered in selected patients with well-documented, persistent pain despite appropriately conducted non-operative treatment, or when compression by a specific structure has been demonstrated. Outcomes are not uniformly predictable. A systematic review published in 2026 highlighted substantial variation in diagnostic criteria and surgical techniques, making it difficult to identify a single best operative approach.

    Red flags

    Prompt assessment is warranted for new finger or wrist drop, progressive grip weakness, sensory loss after injury, marked swelling or deformity of the elbow, worsening pain with fever and redness, or signs of impaired circulation in the hand. These findings should not be attributed simply to “overuse.”

    Back to: Peripheral Nerves

    See also: Elbow Conditions

    References

    • Wolf JM, Patel R, Ghosh K. Radial Tunnel Syndrome: Review and Best Evidence. J Am Acad Orthop Surg. 2023;31(15):e667–e674. DOI: 10.5435/JAAOS-D-23-00314.
    • Levina Y, Dantuluri PK. Radial Tunnel Syndrome. Curr Rev Musculoskelet Med. 2021;14:205–213. DOI: 10.1007/s12178-021-09703-w.
    • Raymond B, Cueto RJ, Mazudie Ndjonko LC, et al. Clinical Outcomes of Operative Management for Radial Tunnel Syndrome According to Surgical Approach: A Systematic Review. Hand (N Y). 2026;21(1):24–31. DOI: 10.1177/15589447251315761.

    This information is educational and does not replace an individual medical consultation.

    Content prepared by: Tomasz Poboży - orthopaedic surgeon.

  • Painful Surgical Scar — Could It Be a Neuroma?

    A sharply localised burning, stabbing or electric-shock-like pain in or next to a surgical scar can come from an irritated or trapped cutaneous nerve and, in some cases, from a painful neuroma. Not every tender scar is a neuroma, however. Normal healing, infection, implant-related problems, local tissue overload and complex regional pain syndrome must also be considered.

    What is a postoperative neuroma?

    When a nerve is cut or significantly injured, its fibres attempt to regenerate. If they cannot reconnect with the distal segment, a disorganised bulb of regenerating nerve tissue may form at the nerve end. This is a traumatic neuroma. Similar symptoms can also occur when a nerve remains anatomically continuous but becomes tethered in dense scar tissue or repeatedly irritated during movement.

    Which symptoms suggest neuropathic scar pain?

    • a very small, clearly defined point of maximal tenderness within or next to the scar;
    • burning, stabbing, shooting or electric-shock-like pain;
    • pain radiating along a nerve distribution when one specific point is pressed or tapped;
    • numbness, hypersensitivity or pain from light contact such as clothing;
    • symptoms aggravated by stretching the scar, moving the nearby joint, footwear or a brace pressing on the area.

    During the first weeks after surgery, local tenderness, a small patch of numb skin and altered sensation may improve gradually without additional treatment. A neuroma becomes more likely when the pain has a distinctly neuropathic quality, persists or worsens, and can be reproduced consistently by pressing one focal point.

    How is it investigated?

    What does an orthopaedic surgeon assess during examination?

    The scar itself is examined together with the distribution of sensory change, muscle strength and the expected course of the nerve. The clinician may also check whether tapping the painful point reproduces radiating symptoms. It is useful to know whether the nerve could have been cut, mobilised or placed at risk during the original operation.

    High-resolution nerve ultrasound

    High-resolution ultrasound can demonstrate focal nerve enlargement, loss of continuity, tethering to scar tissue and the relationship to tendons, implants or vessels. Dynamic examination may show whether movement stretches or displaces the symptomatic segment. A normal ultrasound does not completely exclude pain arising from a very small cutaneous nerve branch.

    Other tests

    MRI, including MR neurography in selected cases, may be helpful for deeper lesions. Nerve conduction studies and electromyography are more useful when pain is accompanied by muscle weakness or sensory loss in the territory of a larger peripheral nerve. A selective local anaesthetic injection can sometimes help test whether a particular nerve segment is generating the pain, but the result still needs to be interpreted in the context of the full examination.

    How are painful scars and neuromas treated?

    Treatment depends on the time since surgery, the severity of symptoms and whether the nerve is thought to be divided, tethered or temporarily irritated. Early management may include protecting the area from pressure, gradual desensitisation, scar mobility work and appropriate medical treatment for neuropathic pain. Aggressive massage directly over a very painful focal point before the diagnosis is clear can aggravate symptoms.

    Selected patients may benefit from diagnostic or therapeutic injections, sometimes performed under ultrasound guidance. Evidence for hydrodissection and other injection-based techniques remains limited, so these procedures should not replace an effort to identify the underlying pain mechanism.

    Surgery may be considered when pain is persistent, well localised, functionally important and has not improved with appropriate conservative treatment. Options include freeing a nerve from scar tissue, excising a neuroma and protecting or reconstructing the nerve end. The technique depends on the anatomy and on whether meaningful nerve continuity can be restored; no procedure guarantees complete relief.

    When is urgent assessment needed?

    Do not assume that worsening scar pain is a neuroma if the wound is hot, red or draining, if fever develops, swelling is increasing rapidly, or pain suddenly becomes much more severe. New or progressive muscle weakness, widespread numbness, a cold or pale limb, or severe pain associated with marked colour or temperature change and swelling of the whole region also require prompt assessment. Sudden neurological weakness should be investigated without delay.

    Key point

    A painful neuroma is one possible cause of persistent scar pain after surgery, but the diagnosis requires a consistent symptom pattern, clinical examination and—when appropriate—imaging or a diagnostic block. Treatment is most useful when it targets a specific mechanism rather than simply attempting to “break up” the scar.

    References

    1. Zhou L, Huo T, Zhang W, et al. New techniques and methods for prevention and treatment of symptomatic traumatic neuroma: a systematic review. Front Neurol. 2023;14:1086806. DOI: 10.3389/fneur.2023.1086806.
    2. Hendrickson NR, McDonald JR, Kennedy SA, et al. Treatment of Postsurgical Neuroma in Foot and Ankle Surgery. Foot Ankle Orthop. 2023;8(3). DOI: 10.1177/24730114231188125.
    3. Grimm A, Décard BF, Athanasopoulou I, et al. Nerve Ultrasound in Traumatic and Iatrogenic Peripheral Nerve Injury. Diagnostics. 2021;11(1):30. DOI: 10.3390/diagnostics11010030.

    Polish version · For Patients

    Content prepared by: Tomasz Poboży - orthopaedic surgeon.