Anterior Tarsal Tunnel Syndrome




Abstract


Anterior tarsal tunnel syndrome is caused by compression of the deep peroneal nerve as it passes beneath the superficial fascia of the ankle. The most common cause of this compression is trauma to the dorsum of the foot. Severe, acute plantar flexion of the foot has been implicated in anterior tarsal tunnel syndrome, as has wearing tight shoes or squatting and bending forward, such as when planting flowers. The syndrome has also been associated with hypertrophy of the extensor hallucis brevis muscle in dancers. Anterior tarsal tunnel syndrome is much less common than is posterior tarsal tunnel syndrome. This entrapment neuropathy manifests primarily as pain, numbness, and paresthesias in the dorsum of the foot that radiate into the first dorsal web space; these symptoms may also radiate proximal to the entrapment, into the anterior ankle. No motor involvement occurs unless the distal lateral division of the deep peroneal nerve is affected.




Keywords

anterior tarsal tunnel, posterior tarsal tunnel, entrapment neuropathy, electormyography, nerve conduction testing, sports injury, dancer’s injury, Tinel sign, ultrasound guided injection, diagnostic sonography

 


ICD-10 CODE G57.50




Keywords

anterior tarsal tunnel, posterior tarsal tunnel, entrapment neuropathy, electormyography, nerve conduction testing, sports injury, dancer’s injury, Tinel sign, ultrasound guided injection, diagnostic sonography

 


ICD-10 CODE G57.50




The Clinical Syndrome


Anterior tarsal tunnel syndrome is caused by compression of the deep peroneal nerve as it passes beneath the superficial fascia of the ankle ( Fig. 124.1 ). The most common cause of this compression is trauma to the dorsum of the foot. Severe, acute plantar flexion of the foot has been implicated in anterior tarsal tunnel syndrome, as has wearing tight shoes or squatting and bending forward, such as when planting flowers ( Fig. 124.2 ). The syndrome has also been associated with hypertrophy of the extensor halluces brevis muscle in dancers ( Fig. 124.3 ). Anterior tarsal tunnel syndrome is much less common than is posterior tarsal tunnel syndrome.




FIG 124.1


The relationships of the medial malleolus, the tibial artery and nerve, and the flexor tendons of the ankle.

(From Kang HS, Ahn JM, Resnick D. MRI of the extremities: an anatomic atlas . 2nd ed. Philadelphia: Saunders; 2002:415.)



FIG 124.2


Anterior tarsal tunnel syndrome manifests as deep, aching pain in the dorsum of the foot, weakness of the extensor digitorum brevis, and numbness in the distribution of the deep peroneal nerve.



FIG 124.3


A, Preoperative right foot with identified dorsal hypertrophy of extensor hallucis brevis (EHB). B, Clinical photograph during grand plié at two (left) and five (right) months postoperatively and C, clinical photograph en pointe after return to dance at seven (left) and ten (right) months postoperatively.

(From Tennant JN, Rungprai C, Phisitkul P. Bilateral anterior tarsal tunnel syndrome variant secondary to extensor hallucis brevis muscle hypertrophy in a ballet dancer: a case report. Foot Ankle Surg. 2014;20(4):e56–e58.)




Signs and Symptoms


This entrapment neuropathy manifests primarily as pain, numbness, and paresthesias in the dorsum of the foot that radiate into the first dorsal web space; these symptoms may also radiate proximal to the entrapment, into the anterior ankle. No motor involvement occurs unless the distal lateral division of the deep peroneal nerve is affected. Nighttime foot pain analogous to that of carpal tunnel syndrome is often present. Patients may report that holding the foot in the everted position decreases the pain and paresthesias.


Physical findings include tenderness over the deep peroneal nerve at the dorsum of the foot. A positive Tinel sign just medial to the dorsalis pedis pulse over the deep peroneal nerve as it passes beneath the fascia is usually present ( Fig. 124.4 ). Active plantar flexion often reproduces the symptoms of anterior tarsal tunnel syndrome. Weakness of the extensor digitorum brevis may be present if the lateral branch of the deep peroneal nerve is affected.




FIG 124.4


Eliciting Tinel sign for anterior tarsal tunnel syndrome.

(From Waldman SD. Physical diagnosis of pain: an atlas of signs and symptoms. Philadelphia: Saunders; 2006:373.)




Testing


Electromyography (EMG) can distinguish lumbar radiculopathy and diabetic polyneuropathy from anterior tarsal tunnel syndrome. Plain radiographs are indicated in all patients who present with foot or ankle pain, to rule out occult bony disease ( Fig. 124.5 ). Magnetic resonance imaging (MRI) and ultrasound imaging of the ankle and foot are indicated if joint instability or a space-occupying lesion is suspected ( Figs. 124.6 and 124.7 ) Based on the patient’s clinical presentation, additional testing may be warranted, including a complete blood count, uric acid level, erythrocyte sedimentation rate, and antinuclear antibody testing. The injection technique described later serves as both a diagnostic and a therapeutic maneuver.


Sep 9, 2019 | Posted by in PAIN MEDICINE | Comments Off on Anterior Tarsal Tunnel Syndrome
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