End-to-Side Nerve Repair: Current Concepts and Future Perspectives

Peripheral nerves injuries are extremely debilitating and have been a perennial challenge to the reconstructive surgeon. End-to-side (ETS) neurorrhaphy is a potential strategy for treating nerve lesions without usable proximal nerve stump. A number of interesting clinical and experimental studies have been carried out on ETS nerve repair during the first years of the 20th century. End-to-side nerve repair was then almost abandoned for more than 50 years. The rediscovery of ETS nerve repair was attributed to the experimental work of Viterbo. Two mechanisms have been suggested for axonal regeneration: terminal and collateral sprouting. While in collateral sprouting axonal outgrowth occurs along the length of the uninjured axons, in terminal sprouting, axonal regeneration takes place at the distal most aspect of either injured or uninjured axons. Clinical experience with ETS nerve repair includes management of upper extremity nerve injury, facial reanimation, reconstruction after tumor ablation, and the prevention of neuroma formation. The aim of this review article was 2-fold: (1) overviewing the most interesting experimental investigations and clinical studies published so far; (2) calling for more basic research on ETS nerve repair indicating the several unanswered questions that this concept asks to the microsurgical community.