ラットを用いた高周波熱凝固法によるNeuropathic Pain Modelに関する研究

Abstract

Background : The mechanisms of neuropathic pain are not clearly understood which are characterized by various different kinds abnormal sensation ; hence the author attempted to elucidate a novel pain model that is produced by radiofrequency neurolysis in rats. Methods : Bilateral sciatic nerves of 30 wister rats (7-8 weeks) were exposed and blocked with heat (neurolysis) under pentobarbital anesthesia. Right sciatic nerves were treated at 50℃ for 45 sec. (N=10), 60℃ for 45 sec. (N=10), 70℃ for 45 sec. (N=10) respectively ; left sciatic nerves were not treated as a sham. Rats were placed in plastic cages for behavioral testing ; posture of neurolyzed extremity, responses to spontaneous nociceptive pain and radiant heat impinged on plantar surface of hind paw. To examine neuropathologic change in sciatic nerves that were harvested after neurolysis, light microscopic sections were stained with toluidine blue. Results : Average autotomy scores were remarked during nerve reconstruction in 60℃ and 70℃ neurolysis but no significant difference was found between sham and operated paws in 50℃neurolysis. In micrographs of nerves removed 7 days after neurolysis, endoneural edema was prominent and the destruction of myelinated fibers could be seen. Conclusion : It was demonstrated that this model of neuropathic pain with radiofrequency neurolysis revealed partially similar, partially different results compared with previous models, and suggested that an optimal radiofrequency neurolysis in rats was 60℃ for 45 sec. that developed in recovery course of nerve injury.