Preserved finger flexion following high median nerve transection: a rare case report and review of literature.

Background: High-level complete transection of the median nerve will impair the flexion function and sensation of the thumb and index finger, and will also result in weakened wrist flexion strength. In rare cases, atypical clinical manifestations may arise, potentially due to ulnar-to-median nerve anomalies, such as Marinacci communication (MC), or the function of muscles directly innervated by ulnar nerve branches.

Case Presentation: A 52-year-old male sustained a chainsaw injury to his left elbow and forearm, resulting in complete transection of the median nerve. Despite this, he retained partial finger flexion, with muscle strength reaching grade IV in the 3rd-5th fingers on postoperative day one. Marinacci communication, a rare anatomical variant, may explain the preserved motor function in the absence of direct nerve continuity. Electrophysiological studies are key to diagnosing MC, which can influence recovery after nerve injuries. In this case, preserved flexion function suggests the presence of MC. Greater awareness and understanding of this communication are essential for accurate diagnosis and treatment planning.

Conclusion: There exists a low-probability anatomical variation in the forearm concerning the ulnar and median nerves. This case contributes further to our understanding of the clinical presentation of hand function following high median nerve transection. It also provides valuable evidence for further exploration of the physiological aspects of never communication.