Updated: 6/8/2021

Deep Peroneal Nerve Entrapment

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  • summary
    • Deep Peroneal Nerve Entrapment, also called Anterior Tarsal Tunnel Syndrome, is a rare compression neuropathy affecting the deep peroneal nerve, most commonly at the fibro-osseous tunnel formed by the inferior extensor retinaculum.
    • Diagnosis can be suspected clinically with dorsal foot pain with radiation to the 1st webspace and a positive Tinel's sign over the DPN.
    • Treatment is a trial of nonoperative management with shoe modifications. Surgical anterior tarsal tunnel release is indicated in patients with persistent symptoms who fail nonoperative management. 
  • Epidemiology
    • Incidence
      • rare
    • Demographics
      • adults of all ages and genders
    • Riisk factors
      • high heel use
      • compressive shoe wear
      • previous fracture
  • Etiology
    • Pathophysiology
      • site of compression
        • anterior leg/ankle/foot from 1 cm proximal to ankle joint proximally to talonavicular joint distally
      • position of compression
        • ankle inversion and plantar flexion (when traumatic)
      • pathoanatomy
        • intrinsic impingement
          • dorsal osteophytes over tibiotalar or talonavicular joints
          • other bony deformity (pes cavus, post-fracture)
          • ganglion cyst
          • tumor
          • tendinitis or hypertrophic muscle belly of EHL, EDL or TA
          • peripheral edema
        • extrinsic impingement
          • tight laces or ski boots
          • high heels (induces plantar flexion)
          • trauma (including recurrent ankle instability)
    • Associated conditions
      • pes cavus
      • fracture
        • navicular nonunion
      • talonavicular arthritis
      • systemic conditions causing peripheral edema
  • Anatomy
    • Anterior Tarsal Tunnel Anatomy
      • borders
        • superficial
          • inferior extensor retinaculum
        • deep
          • capsule of talonavicular joint
        • lateral
          • lateral malleolus
        • medial
          • medial malleolus
      • contents of anterior tarsal tunnel
        • EDL
        • EHL
        • Tibialis anterior
        • peroneus tertius
        • Deep peroneal nerve
          • within tunnel division of nerve between mixed (lateral) and sensory only (medial) occurs
        • dorsalis pedis artery and vein
  • Presentation
    • Symptoms
      • dysesthesia and paresthesias on dorsal foot
        • lateral hallux, medial second toe and first web space are most common locations
      • vague pain on dorsum of foot
    • Physical exam
      • motor
        • weakness or atrophy of EDB
      • sensory
        • decreased two-point discrimination
      • provocative tests
        • Tinel sign over course of DPN with possible radiation to first web space
        • exacerbation with plantar flexion and inversion (puts nerve on stretch)
        • relief of symptoms with injection of lidocaine (DPN nerve block)
  • Imaging
    • Radiographs
      • recommended views
        • lateral view of foot and ankle
      • findings
        • dorsal osteophytes
        • sequelae of prior fracture
    • CT
      • to define bony anatomy of canal
    • MRI
      • best for evaluation of mass lesions
  • Treatment
    • Nonoperative
      • shoe modifications
        • indications
          • first line of treatment
        • techniques
          • NSAIDs
          • PT (if ankle instability contributing)
          • injection
          • well padded tongue on shoe
          • alternative lacing configurations
          • full length rocker-sole steel shank
          • night splint (to prevent natural tendency for ankle to assume plantar flexion)
          • diuretic if chronic peripheral edema is implicated
    • Operative
      • surgical release of DPN by releasing inferior extensor retinaculum and osteophyte / ganglion resection
        • indications
          • failure of nonoperative treatment
          • symptoms of RSD are a contraindication to release
        • outcomes
          • 80% satisfactory
  • Technique
    • Surgical release of DPN by releasing inferior extensor retinaculum and osteophyte / ganglion resection
      • approach
        • S-shaped incision over dorsum of foot from ankle joint proximally to base of first and second metatarsals distally
      • decompression
        • start distal, identify nerve, and release both branches proximally (nerve lies lateral to EHL)
        • resect osteophytes, debulk hypertrophic muscle bellies
      • postoperative
        • no compressive shoe wear
  • Complications
    • Persistent symptoms following decompression
      • warn patient that recovery is prolonged
  • Prognosis
    • Recalcitrant cases may require surgery, which may yield 80% good to excellent results
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