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Anterior Interosseus Nerve Syndrome

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Other Names

  • Kiloh-Nevin Syndrome
  • AIN Compressive Neuropathy
  • AINS



  • Pathoanatomy
    • Most common site of compression is the tendinous edge of the deep head of the Pronator Teres
    • Also must consider
      • Proximal edge of the Flexor Digitorum Superficialis arch (the FDS arcade)
      • Gantzer's muscle (accessory head of the FPL muscle)
      • FDS or FDP accessory muscles
      • Arterial thrombosis (radial or ulnar artery have been implicated)
      • Lacertus fibrous
  • Etiology of the disease is controversial[1]
    • Traumatic etiologies:[2]
      • Supracondylar fractures,
      • Penetrating injuries and stab wounds
      • Cast fixation
      • Venipuncture
      • Complication of open reduction and internal fixation of fractures
    • Spontaneous etiologies:
      • Brachial plexus neuritis
      • Compartment syndrome
      • Compression neuropathy
  • Epidemiology
    • Represents <1% of upper extremity neuropathies[3]
  • Martin-Gruber Anastomosis
    • Anatomical variant in which AINM gives off branches to ulnar nerve, patients can then present with symptoms in ulnar nerve patterns

Risk Factors

Differential Diagnosis

Differential Diagnosis Wrist Pain

Differential Diagnosis Forearm Pain

Other Considerations

Clinical Features

  • General: Physical Exam Wrist
  • History
    • Poorly localized pain from forearm to anticubital fossa
    • The patient will not report any parasthesias
    • Inability to make "OK" sign
  • Physical Exam
    • This disease is characterized by motor deficits only, there are no sensory deficits
    • Weakness of index and thumb pincer movement
  • Special Tests
    • Pinch Test: Patient unable to hold sheet of paper between thumb and index finger



  • Standard Radiographs Wrist
  • 3 View radiographs typically acquired to evaluate for other etiologies
  • No role in diagnosis of atraumatic disease


  • Sensory nerve conduction studies of median nerve should be normal



  • N/A



  • Most patients improve with 6-12 weeks of relative rest and conservative care
  • Relative rest, especially from provocative activities
  • Splint elbow at 90° flexion
  • Physical Therapy
  • Medications including NSAIDS


  • Indications:
    • Failure of conservative measures
  • 75% of patients improve following surgery if clear space occupying lesion(need citation)
  • Procedure:
    • Surgical decompression of AIN

Return to Play

  • Needs to be updated


  • Motor weakness
  • Chronic pain

See Also


  1. Tyszkiewicz T, Atroshi I. Bilateral anterior interosseous nerve syndrome with 6-year interval. SAGE Open Med Case Rep. 2018;6:2050313X18777416.
  2. Akhondi, Hossein, and Matthew Varacallo. "Anterior Interosseous Syndrome." StatPearls [Internet]. StatPearls Publishing, 2018.
  3. Berger RA. Hand Surgery. Lippincott Williams & Wilkins. (2004) ISBN:0781728746
Created by:
John Kiel on 14 October 2019 18:05:24
Last edited:
13 October 2022 21:55:08