The injury of recurrent laryngeal nerve and thyroid regeneration after irreversible electroporation ablation of most part of thyroid gland—an experimental study on swine model

To study the thyroid regeneration and injury of recurrent laryngeal nerve after irreversible electroporation (IRE). 12 pigs were divided into three groups: six pigs underwent IRE, other pigs were used as controls. IRE was performed near tracheoesophageal groove, to ablate most part of thyroid gland. Parathyroid and thyroid function, recurrent laryngeal nerve injury and thyroid computed tomography (CT) imaging were regularly investigated. The histopathology results were analyzed to detect thyroid regeneration. Masson's trichrome method for collagen and immunohistochemistry were performed for Soluble protein-100 (S100) and neurofilaments on nerve section. In IRE group, there were no symptoms of recurrent laryngeal nerve-related injury. No abnormalities of recurrent laryngeal nerve were shown on hematoxylin-eosin (HE) staining, Masson's trichrome staining, Neurofilament (NF) staining and S100 staining. There were no significant changes for thyroid and parathyroid function in all pigs. Immediately after IRE, CT showed hypoattenuation in the ablated thyroid gland and it became swelling. 14 days after IRE, thyroid CT showed hetergenous attenuation in the electroporation zone, and the size and attenuation of thyroid gland were normal after two months. There was cell apoptosis in the thyroid gland after IRE. Seven and 14 days after IRE, there was fragmentation of nucleus within the follicle, and some follicles were empty. Two months later, complete regeneration of thyroid tissue was shown. IRE was shown to be both effective and safe with complete regeneration of thyroid tissue and preservation of the function and structure of the recurrent laryngeal nerve.