The Effects of Clipping on Thoracic Sympathetic Nerve in Rabbits: Early and Late Histopathological Findings

Background The clipping of the thoracic sympathetic nerve, which has been a technique used for approximately the past 10 years, has rapidly become popular because of its "bring-back" claim. However, the information regarding the mechanism behind this claim is based on investigator's comments and has not been proven by objective research, such as the histopathological examination of the clipped nerve and/or ganglion. We aimed to evaluate sympathetic regeneration and degeneration after clip removal. Methods The rabbits were divided into two groups with six rabbits per group. For the first group (group A), the sympathetic chain was clipped using two titanium clips, and a right thoracotomy was made at the T4 and T5 levels. For the second group (group B), the animals were also operated on, which was similar to the rabbits in group A. At the end of a 48-hour follow-up period, the clips were removed after a second operation. The rabbits in group B were followed for 45 days and sympathetic nerves were also examined histopathologically. Results In group A, hemorrhage, fibrinous material, polymorphonuclear leukocyte infiltration, and acute inflammation with fat necrosis were observed in and around the sympathetic ganglia and trunk. Loss of nuclei and vacuolization in some sympathetic ganglia cells were also observed. These findings demonstrated severe degeneration of the sympathetic ganglia and trunk. For group B, microscopic examination revealed a loss of sympathetic ganglion cells as well as fibrosis within and around the ganglia. No signs of regeneration were detected and the progression of nerve degeneration was observed. Conclusions The clips used in our study were shown to cause the degeneration of neural structures within 2 days. At the end of the 45 days following the removal of the clips, progressive, degenerative changes radiating along the axons of the sympathetic cells were seen.