Perineural air injection as a means of prevention of thermal injury of the sciatic nerve during radio frequency ablation: a preliminary experimental study in rabbits.

Objective: The purpose of this study was to determine whether perineural air injection before radio frequency (RF) ablation of thigh muscles can minimize thermal injury to the sciatic nerve.

Methods: Eighteen percutaneous RF ablation procedures were performed in the thighs of 9 rabbits (control, n = 9, right thigh; experimental, n = 9, left thigh) with an internally cooled electrode (1-cm active tip). In the control group, the tip of the electrode was located in posterior muscles 5 mm away from the sciatic nerve before ablation. In the experimental group, sonographically guided air injection into the perineural space was performed just before ablation. Animals were killed 7 days after ablation, and the presence or absence of pathologic changes of the sciatic nerves (axonal necrosis, myelin digestion, endoneurial fibrosis, perineurial fibrosis, and dystrophic calcification) in both groups were compared under an optical microscope.

Results: Perineural air injection was achieved successfully with a single puncture in all rabbits in the experimental group. All of the pathologic findings were observed much more frequently in the control group, and the differences in the frequencies of axonal necrosis and myelin digestion of the sciatic nerve between the groups were clinically significant (P < .05).

Conclusions: Perineural air injection may be useful for reducing the frequency of thermal injury during RF ablation of lesions adjacent to nerves.