End-to-side anastomosis of transected nerves to prevent neuroma formation.

Neuroma can be painful and physically and psychologically disabling. Among the many methods of treatment available, one of the more successful is centrocentral nerve union with an autologous graft. However, it cannot be used in small nerves that lack two fascicles. This study evaluated neuroma prevention in an end-to-side anastomosis, a new technique applicable to all nerves. The lateral branch of the right sciatic nerve in 20 rats was transected at the midthigh level. The proximal segment was looped back to the main nerve and an end-to-side epineural anastomosis was performed. The lateral branch of the left sciatic nerve was transected to serve as a control, and the proximal nerve stump was closed by interrupted epineural sutures. The animals were sacrificed 12 weeks after the operation. Histologic analysis of specimens from the 12 controls showed neuroma formation. Specimens from 12 side-to-end anastomoses contained regenerated nerve tissues and formed smaller masses compared with that of the controls. The regenerated tissues at the anastomoses were orientated more orderly than were tissues from the controls in 75% of cases. The differences were statistically significant. Electron microscopic study on specimens from the remaining eight controls showed the presence of abundant large abnormal myelinated fibers (10-15 microns) with thick irregular myelin sheaths scattered among smaller myelinated fibers (2-10 microns) that had thin myelin sheaths. In the remaining eight end-to-side anastomoses, large abnormal myelinated fibers were absent. The myelinated fibers were 2 to 10 microns in diameters and had a normal appearance with thin myelin sheaths. End-to-side anastomosis formed a smaller mass of regenerated nerve tissues. Ultrastructurally they were formed better and orientated more orderly resembling normal nerve.