Carpal Tunnel Syndrome: Compression by the Thenar Motor Branch

Abstract

Introduction: Carpal tunnel syndrome is predominantly idiopathic, with secondary causes being rare and anatomical etiologies being exceptionally uncommon. Variations of the thenar motor branch are rare, and its origin from the ulnar border of the median nerve is exceedingly rare. In this report, we describe a novel entity: median nerve compression caused by an anatomical variant of the thenar motor branch. A literature review was conducted. Case Presentation: A 47-year-old right-handed female tailor presented with bilateral severe carpal tunnel syndrome, confirmed by electromyography. Surgical exploration of the right hand via a mini-open approach revealed compression of the median nerve by an ulnar-sided thenar motor branch originating at the carpal tunnel level, directly compressing the affected nerve just after its passage. Following neurolysis, the patient experienced complete resolution of symptoms. Conclusion: This case underscores the importance of recognizing anatomical variations of the median nerve during carpal tunnel surgery. This case highlights the need to consider anatomical variations of the median nerve during carpal tunnel surgery. Careful dissection and thorough exploration of the nerve within the carpal tunnel are crucial to avoiding iatrogenic injury.