Arch Hand Microsurg.  2024 Dec;29(4):281-286. 10.12790/ahm.24.0040.

Successful recovery of anterior interosseous nerve palsy caused by blunt trauma at the forearm level: a case report

• Kim JW
• Koh SH
• Kim JS
• Lee DC
• Lee KJ
• Roh SY

• KMID: 2561380
• DOI: http://doi.org/10.12790/ahm.24.0040

Abstract

Anterior interosseous nerve syndrome (AINS) is typically characterized by dysfunction of the pure motor branch of the median nerve, primarily affecting the flexor pollicis longus and the flexor digitorum profundus (FDP) of the index finger, and occasionally involving the FDP of the middle finger and the pronator quadratus. Although various etiologies such as compressive neuropathy and isolated neuritis have been proposed, the most recent review describes AINS as a form of neuralgic amyotrophy. Its treatment remains a matter of debate; the most frequently discussed approach is conservative treatment followed by surgical intervention above the medial epicondyle level if recovery is not achieved. In the case described herein, a hematoma resulting from blunt trauma at the forearm level compressed the anterior interosseous nerve (AIN), with clinical features and diagnostic findings very similar to those of typical AINS. Early surgical removal of the hematoma led to complete recovery without complications. Despite the current understanding of AINS pathophysiology and treatment, this case emphasizes the need to consider the possibility of AIN palsy due to forearm lesions. We report on the clinical course and successful treatment of this case to highlight this important consideration.

Keyword

Wounds; nonpenetrating; Motor nerve; Forearm

Figure

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  Fig. 1. Preoperative photographs. (A) Flexion failure of the interphalangeal joint of the left thumb. (B) Flexion failure of the distal interphalangeal joint of the left index finger. (C) The patient was unable to form the ‘O’ sign.

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  Fig. 2. Preoperative magnetic resonance imaging T2-weighted images (A, axial view; B, coronal view) revealed a well-defined mass-like lesion. The size of the lesion is approximately 6.1×2.5×2.0 cm, with heterogeneous low signal intensity observed around the musculotendinous junction of the flexor digitorum profundus tendon (arrows), indicative of potential intramuscular hematoma.

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  Fig. 3. Intraoperative photographs. (A) An oval-shaped mass-like lesion, suspected to be an intramuscular hematoma, was found at the musculotendinous junction of the flexor digitorum profundus (FDP) tendon, with the muscle showing diffuse swelling. (B) Necrotic changes were observed in the FDP muscle of the index finger, along with a 40% tendon rupture at the musculotendinous junction. (C) It was confirmed that there were no visible injuries to the FPL tendon and the median nerve. The FDP2 tendon, which was dissected from the musculotendinous junction for tendon transfer, is also shown. *, FPL tendon; ▲, median nerve; •, FDP2 tendon. (D) A tendon transfer from FDP3 was performed to reconstruct FDP2.

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  Fig. 4. Serial improvement in the range of motion of the thumb interphalangeal joint over time (4, 7, 10, 12 weeks).

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  Fig. 5. (A) Improvement in the range of motion of the distal interphalangeal joint (arrow) of the index finger at 12 weeks after surgery. (B) The patient was able to achieve the "O" sign.

Reference

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