Aberrant Positioning of the Ulnar Nerve Found During Carpal Tunnel Release: A Case Report

Abstract

Introduction: Aberrant positioning of the ulnar nerve volar to the transverse carpal ligament is a rare anatomic variation.Case Presentation: We present the case of a 55-year-old female with unique ulnar nerve anatomy that was discovered introperatively during carpal tunnel release. The ulnar nerve was running directly adjacent to the median nerve in the distal forearm and as the median nerve traversed dorsal to the transverse carpal ligament (flexor retinaculum) to enter the carpal tunnel the ulnar nerve continued directly volar to this structure before angling towards Guyon’s Canal. The unique ulnar nerve anatomy was successfully identified, carefully dissected and managed with a successful patient outcome.Conclusion: Variations of the anatomy at the level of the carpal tunnel are rare but do exist. Awareness of these anatomic variations and adequate visualization of the ulnar nerve along with the surrounding structures is crucial to avoid iatrogenic injuries during carpal tunnel release.

Ulnar Nerve Neuropathy after Distal Radius Fracture Malunion. Uncommon Intra-Operative Findings and a Review of the Literature

“…Abnormal route of ulnar nerve has been described. It has been found to run directly adjacent to the median nerve in the distal forearm during carpal tunnel release surgery [20]. In a published analogous case, ulnar nerve exploration after distal radius fracture dorsally malunited, revealed that the nerve was in touch with the subcutaneous ulnar surface, fixxed by a fibrous tether 5 cm proximal to the ulno-carpal joint line suggesting an anatomical variation and not post-traumatic scarring.…”

Anatomical Variants of the Upper Limb Nerves: Clinical and Preoperative Relevance

“…Awareness of this anatomical variation and adequate visualization of the UN, along with the surrounding structures, is crucial to avoid iatrogenic injuries during carpal tunnel release. 48,49 There are also cases of aberrant transligamentous sensory branches of the UN entering the distal transverse carpal ligament. Hand surgeons should be aware of this anatomical variation because its location puts it at risk of iatrogenic injury during open and endoscopic carpal tunnel release.…”

“…Awareness of this anatomical variation and adequate visualization of the UN, along with the surrounding structures, is crucial to avoid iatrogenic injuries during carpal tunnel release. 48 49 …”