ABSTRACT
Objective To evaluate the damage to the brochial plexus produced by pulsed radiofrequency (PRF)and radiofrequency thermocoagulation(RFTC).Methods Fifty-five male Wistar rats weighing 250-300 g were randomly divided into 3 groups:groupⅠPRF(n=25):groupⅡRFTC(n=25)and groupⅢnormal control(n=5).The animals were anesthetized with intraperitoneal chloral hydrate.The left brochial plexus was exposed and PRF or RFTC was applied to the left brochial plexus.The voltage and current of the minimal stimulation which elecited muscle twitching and the impedance before and after operation were recorded in group PRF and RFTC.The nerve function was scored according to Tarloo(0=flaccid paresis,5=normal gait)before and at 3d after operation.The animals were killed and the left brachial plexus was removed immediately and at 1, 7,14,30 d after operation(n=5 at each time point)for determination of histopathological changes using microscope.Results The impedance and Tarlov score were significantly decreased after operation as compared to the baseline values before operation in group RFTC and were also significantly lower than in group PRF. Microscopic examination showed that the myelinated nerve fibers exhibited Wallerian degeneration and axon regeneration and the cytochondria in cylindraxile were severely injured or disappeared in group RFTC.The myelinated nerve fibers and the cytochondria in cylindraxile were significantly less injured after operation in group PRF than in group RFTC and returned to normal at 7 d and 30 d respectively.Conclusion The injury to brachial plexus produced by PRF is slighter than that produced by RFTC.