The Safety of Irreversible Electroporation on Nerves Adjacent to Treated Tumors.

OBJECTIVES: To evaluate the safety of irreversible electroporation (IRE) on the sciatic nerve after IRE ablation of adjacent tumor.

METHODS: In this study, VX2 tumors were implanted adjacent to the sciatic nerves in 26 New Zealand white rabbits. The rabbits were divided into 3 groups 10 days after implantation, with 2 treatment groups of 10 rabbits each and a control group of 6 rabbits. In 1 of the treatment groups (IRE-S group), the rabbits underwent ablation with a single IRE application, and in the other group (IRE-D group) the rabbits underwent 2 IRE applications. IRE ablation was performed under ultrasonographic guidance. The 26 rabbits were euthanized as follows: half of the animals in each group on the seventh day and the rest on the 28th day after IRE ablation. The sciatic nerves were removed for histopathologic evaluation immediately after euthanasia. Sections from selected specimens were stained with hematoxylin and eosin and Masson's trichrome method for collagen; immunohistochemistry was performed for S100 and neurofilaments (markers for Schwann cells and axons, respectively). Clinical, radiologic, laboratory, and pathologic findings were analyzed.

RESULTS: The nerves from the IRE-S and IRE-D groups showed preserved endoneurial architecture and the presence of numerous small-caliber axons along with Schwann cell hyperplasia, consistent with axonal regeneration. The tumor lesions were completely necrosed. A fibrous scar was observed in the adjacent muscle tissue, confirming ablation at the site. Nerve damaged also showed in the control group for tumor advanced and no signs of repair; the tumor showed rapid progression.

CONCLUSION: The nerves adjacent to the tumor may undergo severe damage after IRE ablation, but their function and structure can return to normal in a short time. IRE ablation may be a feasible treatment option for tumors situated adjacent to nerves.