title: Acute and subacute effects of irreversible electroporation on nerves: experimental study in a pig model.
abstract: OBJECTIVE
  To evaluate whether irreversible electroporation (IRE) has the potential to damage nerves in a porcine model and to compare histopathologic findings after IRE with histopathologic findings after radiofrequency ablation (RFA).
  
  
  METHODS
  This study was approved by the institutional animal care and use committee. Computed tomography (CT)-guided IRE of 11 porcine sciatic nerves was performed in nine pigs, and histopathologic analysis was performed on the day of ablation or 3, 6, or 14 days after ablation. In addition, acute RFA of six porcine sciatic nerves was performed in six pigs that were harvested on the day of ablation. All nerves and associated muscles and tissues were assessed for histopathologic findings consistent with athermal or thermal injury, respectively, such as axonal swelling, axonal fragmentation and loss, Wallerian degeneration, inflammatory infiltrates, Schwann cell proliferation, and coagulative necrosis. The percentage of fascicles affected was recorded.
  
  
  RESULTS
  All nerves had an axonal injury. The percentage of affected nerve fascicles after IRE was 50%-100%. Axonal swelling and perineural inflammatory infiltrates were detectable at every time point after ablation. Axonal fragmentation and loss, macrophage infiltration, and Schwann cell proliferation were found 6 and 14 days after ablation. Distal Wallerian axonal degeneration was observed 14 days after ablation. The endoneurium and perineurium architecture remained intact in all cases. RFA specimens at the day of ablation revealed acute coagulative necrosis associated with intense basophilic staining of extracellular matrix, including collagen of the perineurium and epineurium consistent with thermal injury.
  
  
  CONCLUSIONS
  IRE has the potential to damage nerves and may result in axonal swelling, fragmentation, and distal Wallerian degeneration. However, preservation of endoneurium architecture and proliferation of Schwann cells may suggest the potential for axonal regeneration. In contrast, RFA leads to thermal nerve damage, causing protein denaturation, and suggests a much lower potential for regeneration.
authors.affiliation: Department of Radiology, Memorial Sloan-Kettering Cancer Center, 1275 York Ave, New York, NY 10065, USA.
authors.forename: Helmut
authors.initials: H
authors.lastname: Schoellnast
authors.forename: Sebastien
authors.initials: S
authors.lastname: Monette
authors.forename: Paula C
authors.initials: PC
authors.lastname: Ezell
authors.forename: Ajita
authors.initials: A
authors.lastname: Deodhar
authors.forename: Majid
authors.initials: M
authors.lastname: Maybody
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Erinjeri
authors.forename: Michael D
authors.initials: MD
authors.lastname: Stubblefield
authors.forename: Gordon W
authors.initials: GW
authors.lastname: Single
authors.forename: William C
authors.initials: WC
authors.lastname: Hamilton
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Solomon
mesh_terms: D000818:Animals; D017115:Catheter Ablation / Q000009:adverse effects / Q000379:methods*; D018274:Electroporation / Q000379:methods*; D023421:Models, Animal; D015641:Radiography, Interventional; D012584:Sciatic Nerve / Q000293:injuries*; D013552:Swine; D014057:Tomography, X-Ray Computed