Tarsal Tunnel Syndrome – Causes, Symptoms, Diagnosis, Treatment and Ongoing care

Basics

Description

Tarsal tunnel syndrome is a compression neuropathy of the posterior tibial nerve as it passes under the flexor retinaculum in the medial ankle; a region commonly known as “the tarsal tunnel.”

Pregnancy Considerations

  • Tarsal tunnel syndrome can occur during pregnancy, typically secondary to local compression caused by fluid retention and volume changes.
  • Care usually is supportive until after delivery, because many cases resolve after pregnancy.

Epidemiology

Women are slightly more affected than men (56%). All postpubescent ages can be affected.

Risk Factors

Several authors have associated tarsal tunnel syndrome with certain occupations and activities, especially those that involve repetitive weight bearing on the foot and ankle, like jogging (1) or dancing (2).

Pathophysiology

  • Tarsal tunnel syndrome is caused by compression of the tibial nerve, resulting in decreased blood flow and ischemic damage.
  • Increased pressure in the confined space of the tarsal tunnel is caused by a variety of mechanisms, both mechanical and biochemical, all of which result in increased pressure on the posterior tibial nerve.
  • Chronic compression can destroy endoneurial microvasculature, leading to edema and eventually fibrosis and demyelination (3).

Etiology

  • The specific cause is identifiable in only 60–80% of patients (4); causes can be grouped into 3 categories: Trauma, space-occupying lesion, and deformity.
  • Most common causes include (4):
    • Trauma
    • Varicosities
    • Hindfoot varus or valgus
    • Fibrosis of the perineurium
  • Other causes of compression include ganglia, lipoma, neurilemmoma, inflammatory synovitis, pigmented villonodular synovitis, tarsal coalition, and accessory musculature.

Diagnosis

Frequently misdiagnosed because of poorly localized and variable symptoms

History

  • Often have history of trauma to foot, including trivial trauma that precipitated pain
  • Classically have pain and paresthesia on plantar aspect of foot
  • Pain usually worse with standing or activity
  • Pain can radiate proximally up medial leg (Valleix phenomenon) in 33% of patients with severe compression, or distally along path of involved nerves (4).
  • Some patients have substantial night pain, which may be related to venostasis.
  • Symptoms improve with rest, wearing loose footwear, and elevation.

Alert

Other neuropathies due to systemic causes such as diabetes, alcoholism, HIV, or drug reaction can present with similar symptoms.

Physical Exam

  • Perform a complete foot and ankle examination.
  • Foot alignment:
    • Examine for hindfoot varus or valgus abnormalities.
    • Exaggerating heel dorsiflexion, inversion, or eversion may reproduce symptoms by stretching or compressing the nerve.
  • Palpate the tarsal tunnel and course of the tibial nerve for:
    • Tenderness
    • Swelling consistent with a space-occupying lesion
  • Tinel sign: Percussion over the course of the tibial nerve may produce paresthesias and distal symptoms.
  • Cuff test: Using a pneumatic cuff to create a venous tourniquet may cause engorgement of varicosities and reproduce symptoms.
  • Compression test: Applying pressure to tarsal tunnel for 60 seconds may reproduce symptoms.
  • Sensory examination:
    • The MCN usually is spared, but numbness and altered sensation may be present in the distribution of the MPN or LPN.
    • 2-point discrimination is decreased early in the disease process.
  • Motor examination:
    • Intrinsic weakness is difficult to assess.
    • Rarely, weakness of toe plantarflexion may be present.
    • Atrophy of the abductor hallucis or abductor digiti minimi may be seen late in the disease process.

Diagnostic Tests & Interpretation

Lab

Routine laboratory tests can be used to rule out other conditions that may mimic tarsal tunnel syndrome, including diabetic neuropathy, thyroid dysfunction, or other systemic illnesses (5).

Imaging

  • Routine weight-bearing radiographs, followed by CT if necessary to assess for fracture or structural abnormality.
  • Consider evaluation of lumbar spine x-ray if “double-crush” (injury to lumbar nerve results in compensatory injury to posterior tibial nerve) (6) is suspected (5).
  • Magnetic resonance imaging (MRI): Can be helpful in assessing the tarsal tunnel for masses or other sources of nerve compression before surgery (4)
  • Ultrasound: Alternatively, ultrasound can be used to check for synovitis or ganglia (5).

Pediatric Considerations

  • MRI is recommended for evaluating pediatric tarsal tunnel syndrome because compression by a neoplastic mass is not uncommon.

Follow-Up & Special Considerations

Postoperative management includes:

  • Non-weight-bearing splint until incision heals (2–3 weeks), followed by progressively increased weight-bearing and range of motion exercises.
  • RICE protocol (rest, ice, compression, elevation) to limit swelling

Diagnostic Procedures/Surgery

Electrodiagnostic studies (4):

  • According to a systematic review in 2005, electromyography (EMG) can be used only to confirm the diagnosis of tarsal tunnel syndrome, as there is a large percentage of asymptomatic people with abnormal results.
  • It is important to evaluate for proximal nerve compression, including a lumbar radiculopathy or a double-crush phenomenon.

Pathological Findings

At the time of surgical exploration, the following may be found:

  • Focal swelling, scarring, or nerve abnormalities
  • A pathologic source of compression

Differential Diagnosis

  • Peripheral neuropathies (diabetes, alcoholism, HIV, or drug related)
  • Inflammatory arthritis (rheumatoid arthritis) (7)
  • Morton’s neuroma
  • Metatarsalgia
  • Subtalar joint arthritis
  • Tibialis posterior tendinitis/dysfunction
  • Plantar fasciitis
  • Plantar callosities
  • Peripheral vascular disease
  • Lumbar radiculopathy
  • Proximal injury or compression of the tibial branch of the sciatic nerve

Treatment

Conservative management is recommended, except for tarsal tunnel syndrome of acute onset or in the setting of a known space-occupying lesion:

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  • Rest/immobilization
  • Taping and bracing
  • Orthotics or shoe modification
  • Anti-inflammatories (steroid injections vs nonsteroidal anti-inflammatory drugs)
  • Medications to alter neurogenic pain (antidepressants, antiepileptic drugs, nerve blocks)
  • Physical therapy for desensitization (stretching, ultrasound, massage, icing)
  • Physical therapy to strengthen the intrinsic and extrinsic muscles of the foot and to restore the medial longitudinal arch
  • Compression stockings to decrease swelling
  • Weight loss in obese patients

Medication

Initially, nonoperative management is recommended, except for acute tarsal tunnel syndrome or in the setting of a known space-occupying lesion (excluding synovitis):

  • Rest/immobilization
  • Orthotics
  • Anti-inflammatories, including steroid injections and nonsteroidal drugs
  • Medications that alter neurogenic pain (tricyclic antidepressants, antiepileptic drugs, nerve blocks)
  • Physical therapy (desensitization)
  • Compression stockings
  • Weight loss

Surgery/Other Procedures

  • Surgery is indicated (3,4,8):
    • If nonoperative measures fail following a 3–6-month trial
    • In the setting of acute tarsal tunnel syndrome
    • If a space-occupying lesion is identified
  • The surgical outcome is dependent on technique and postoperative management. Ability to achieve a good to excellent outcome ranges from 50–95%.

Ongoing Care

Patient Education

An outline of the conservative care modalities available should be presented. Use of each of these therapies will depend on patient circumstance. A decision about surgical intervention should be made with a clear understanding of limitations of this treatment and the potential adverse outcomes.

Prognosis

The most symptomatic improvement with surgery is expected for (4):

  • Young patients
  • Short duration of symptoms
  • Localized space-occupying lesion identified (8)
  • No motor neuron involvement
  • Surgical outcomes are dependent on technique and postoperative management.

Complications

  • The main adverse outcome is unsuccessful surgical intervention: No improvement, partial/incomplete improvement, or temporary improvement with recurrence of symptoms (4)
  • Causes for a failed tarsal tunnel release:
    • Incorrect diagnosis
    • Incomplete release
    • Adhesive neuritis (external scar formation)
    • Intraneural damage (systemic disease, direct nerve injury)
    • Failure to treat all sources of nerve compression in a double-crush phenomenon
  • Electrodiagnostic studies are rarely helpful in determining the cause of a failed tarsal tunnel release.
  • Revision surgery results are poorer than for the primary surgical release.

References

1. Shapiro BE, Preston DC. Entrapment and compressive neuropathies. Med Clin North Am.2009;93:285–315, vii.

2. Kennedy JG, Baxter DE. Nerve disorders in dancers. Clin Sports Med. 2008;27:329–34.

3. Dellon AL. The four medial ankle tunnels: a critical review of perceptions of tarsal tunnel syndrome and neuropathy. Neurosurg Clin N Am. 2008;19:629–48.

4. Lau JT, Daniels TR. Tarsal tunnel syndrome: a review of the literature. Foot Ankle Int. 1999;20:201–9.

5. Franson J, Baravarian B. Tarsal tunnel syndrome: a compression neuropathy involving four distinct tunnels. Clin Podiatr Med Surg. 2006;23:597–609.

6. Upton AR, McComas AJ, et al. The double crush in nerve entrapment syndromes. Lancet.1973;2:359–62.

7. Campbell WW, Landau ME. Controversial entrapment neuropathies. Neurosurg Clin N Am.2008;19:597–608.

8. Sung KS, Park SJ, et al. Short-term operative outcome of tarsal tunnel syndrome due to benign space-occupying lesions. Foot Ankle Int. 2009;30:741–5.

Additional Reading

Allen JM, Greer BJ, Sorge DG, et al. MR Imaging of Neuropathies of the Leg, Ankle, and Foot. Magn Reson Imaging Clin N Am. 2008;16:117–31.

Cimino WR. Tarsal tunnel syndrome: review of the literature. Foot Ankle. 1990;11:47–52.

Patel AT, Gaines K, Malamut R, et al. Usefulness of electrodiagnostic techniques in the evaluation of suspected tarsal tunnel syndrome: an evidencebased review. Muscle Nerve. 2005;32:236–40.

See Also (Topic, Algorithm, Electronic Media Element)

Algorithm: Foot Pain

Codes

ICD9

355.5 Tarsal tunnel syndrome

Snomed

47374004 tarsal tunnel syndrome (disorder)

Clinical Pearls

  • Tinel sign: Percussion over the course of the tibial nerve produces paresthesias and distal symptoms over the plantar aspect of the foot (most sensitive and specific test) (3).
  • Conservative management is recommended, except for tarsal tunnel syndrome of acute onset or in the setting of a known space-occupying lesion.
  • EMG abnormality alone cannot be used to diagnose tarsal tunnel syndrome; may only be used to confirm clinical diagnosis.

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