Effect of radiofrequency of different temperatures and durations on motor conduction velocity of rat sciatic nerve

Objective To evaluate the effect of radiofrequency of different temperatures and durations on sciatic nerve motor conduction velocity (MCV). Methods The bilateral sciatic nerve of 70 adult SD rats was dissected and exposed to radiofrequency ablation of different temperatures (30, 50, 55, 60, and 70 ℃) and durations. The nerves were also exposed to increasing ablation temperatures from 30 ℃ to 50 ℃ with an increment of 5 ℃ (60 s at each temperature), and the changes in the MCV parameters were observed. Results The MCV parameters of rat sciatic nerve underwent significant changes following the radiofrequency exposures (P0.05) except for the exposure at 55 ℃ for 10 s. Below the temperature of 55 ℃, the MCV showed no obvious correlation to the exposure time for the group. For the nerves exposed to radiofrequency of 55 ℃, the latency was not correlated to the exposure time within 30 s, and data could be obtained from 55 s group; with these exceptions, the latency was found to positively while the negative phase wave inversely correlated to the exposure time. With fixed exposure time of 60 s, the MCV parameters were positively correlated to the ablation temperature (below 50 ℃). Failure of MCV measurement occurred following exposures to 55 ℃ for 50 s (or longer) or to 60 ℃ (or higher) for 10 s. Conclusion Low-temperature radiofrequency (below 50 ℃) produces definite effects on the MCV of rat sciatic nerve, and the effects are not associated with the exposure time, the mechanism of which remains unclear. At a given temperature, the ablation for sufficiently long durations can result in complete block of the MCV. At higher temperatures, radiofrequency exposure cause obvious nerve conduction block.