Delayed Repair of Severed Thenar Branch with Transligamentous Variation after Open Carpal Tunnel Release

Abstract

A 49-year-old female patient with carpal tunnel syndrome at both hands was performed open carpal tunnel release. 4 months later, on the left hand, severance of the thenar branch was found by electromyography. On the 138th day, re-exploration was performed for direct nerve repair. During exploration, we identified the transligamentous variation of recurrent motor branch. Direct nerve repair was successful. At 6 months after direct repair, the nerve function began to return. At 2 years after direct repair, the nerve function has almost returned. There are some variations on the recurrent motor branch. And we overlooked transligamentous variation when we perform more decompression around the median nerve. It is important that recognize variations of thenar branch when we perform carpal tunnel release for not occurrence of severance of thenar branch.

Combined hypothenar fat pad flap and delayed neurorrhaphy for transected thenar branch during carpal tunnel release

“…At eight months post-surgery, we observed an improvement in all physiotherapeutic parameters. In comparison to the thenar motor branch repair by Lee (2019), we already observed the start of nerve function return during the first follow-up, two months postoperatively [5] . Their patient received a direct thenar motor branch repair 138 days after transection, without a hypothenar fat pad flap or other nerve coverage and nerve function started to return at six months [5] .…”

Repair of severed recurrent thenar branch of median nerve after open carpal tunnel release

“…The thenar function was eventually restored in both patients. In the case reported by Lee et al in 2019, direct nerve repair of severance of the thenar branch accompanied by transligamentous variation of recurrent motor branch was performed at 138 days after open CTR, and the nerve function almost returned two years later [3] . During the first operation, they performed additional dissection of loose connective tissue around the median nerve for more decompression effect of the median nerve after TCL release during the surgical procedure.…”

“…However, an anatomical understanding of median nerve variation is essential for successful decompression. Although iatrogenic injury of the thenar branch after CTR has not been reported in many since its first report in 1985, it can cause serious damage to the patient [2] , [3] . We report a case of severed recurrent thenar branch of the median nerve discovered through nerve conduction examination in a patient with suspected thenar branch damage after CTR surgery.…”