Reverse End-to-Side Nerve Transfer for Severe Ulnar Nerve Injury: A Western Canadian Multicentre Prospective...

Area of Science:

• Neurosurgery
• Peripheral Nerve Injury
• Regenerative Medicine

Background:

• Reverse end-to-side (RETS) nerve transfer is increasingly used for severe high ulnar nerve injuries.
• Reported outcomes for RETS nerve transfers have been inconsistent, necessitating further investigation.
• The "babysitting effect" in nerve regeneration remains incompletely understood.

Purpose of the Study:

• To evaluate the "babysitting effect" by comparing anterior interosseous nerve (AIN) RETS transfer with nerve decompression alone.
• To compare outcomes of AIN RETS transfer with end-to-end (ETE) nerve transfer to understand the source of regenerating axons.
• To assess the clinical efficacy and regenerative capacity of RETS nerve transfer in severe ulnar nerve injuries.

Main Methods:

• A comparative study involving 62 patients with severe ulnar nerve injury across four Canadian centers.
• Electrophysiology (compound muscle action potentials) and functional assessments (key pinch, Semmes-Weinstein monofilaments) were utilized.
• Patients were followed for 3 years post-surgery to evaluate nerve fiber regeneration and functional recovery.

Main Results:

• No crossover reinnervation from the AIN to the abductor digiti minimi muscle was observed in the RETS group.
• No significant improvement in electrophysiological measures or pressure detection thresholds was noted in RETS or decompression groups.
• Significant improvement in key pinch strength was observed in the RETS group compared to controls (P < .05).

Conclusions:

• Unlike end-to-end transfers, RETS nerve transfers did not demonstrate measurable crossover regeneration in this study.
• The extent of reinnervation following RETS transfer was comparable to nerve decompression alone.
• The findings challenge the current justifications for utilizing RETS nerve transfer, suggesting a need for re-evaluation.