摘要 脉冲射频( pulsed radiofrequency, PRF) 是利用间断发出的脉冲式电流在组织周围形成高电压, 并转化为热能; 脉冲射频从微观上对神经元的突触活性、细胞因子等有一定的影响, 而这与其在疼痛治疗中的作用有关。脉冲射频治疗技术具有创伤小、操作便捷、安全性高、效果好等特点, 目前在临床上广泛应用于慢性疼痛的治疗, 如椎间盘退行性病变引起的疼痛、带状疱疹后神经痛、颈源性头痛、三叉神经痛等。本文就这一领域的最新进展总结如下: 关键词: 脉冲射频; 慢性疼痛; 治疗中图分类号: 454.1 文献标识码: A 文章编号: 1005- 7234( 2007) 06- 0519- 03 Sluijte(r1997年) [1]提出了频( pulsed radiofrequency, PRF) 技术。脉冲射频是间断射频电流, 由射频仪间断发出的脉冲式电流传导至针尖的垂直前方的神经, 射频电流在神经组织附近形成高电压, 但在脉冲的间隙时间里组织的温度被扩散, 电极尖端温度不超过42℃。这种能量传递不可能通过蛋白凝固作用而破坏痛觉冲动传递的解剖基础, 更不会破坏运动神经功能。根据临床需要由医生选用不同直径、长短和形状的穿刺电极针, 当穿刺套针到达靶神经附近, 经射频仪的阻抗监测和电刺激试验, 准确地调节穿刺套针和温差电极的位置。然后应用38- 42℃的温度, 2- 8Hz 的频率和10- 30 毫秒/次的参数射频, 达到不破坏神经结构又能镇痛的作用。为此脉冲射频也称为非毁损射频。文献报告对禁忌行热凝毁损的神经性疼痛病人,可取得显著效果并且不出现神经热离断效应,术后不会出现感觉减 退、酸痛、灼痛和运动神经损伤。 脉冲射频的优势 1 危险小, 可经皮穿 刺操作, 甚至可用于门诊病人; 2 3 4 疼痛复发时可重复射频治疗, 同样有效。 鉴于PRF的安全性和有效性,在慢性疼痛的治疗领域越来越受到大家的重视。脉冲射频治疗疼痛的基础研究脉冲射频的作用机制研究, 目前有两种理论, 即神经毁损作用和射频电场的神经调节作用。前者指脉冲射频可能毁损一些细小的无髓纤维, 但随着研究的深入, 现在更趋于认为这只是脉冲射频的副反应, 而射频电场的生物学效应则成为关注的焦[2]。Higuchi·Y等[3]人在实验研究中发现, 脉冲射频作用于大鼠背根节,可以诱发脊髓背角Ⅰ、Ⅱ、Ⅳ板层神经元在c-fos 基因( 即早基因)上调,主要分布在脉冲射频的同侧;而假手术组和连续射频组只有脊髓背角I板层的少量神经元存在c- fos基因的上调。因为排除了温度效应和手术因素对实验的影响,作者推测是脉冲电流的波动诱发了脊髓神经元c-fos基因的表达,其波动的幅度是连续射频电流的40倍。有证据显示c-fos基因上调将导致基因表达的长时程改变,c-fos的表达被认为是脊髓产生某种长时程适应的信号因而作者认为这种长时程变化至少是脉冲射频临床效应的部分机制。VanZundert[4]在最近的研究中也发现PRF能激活c-fos基因的迟发性表达,在脉冲射频处理背根节7天后, 仍然在脊髓背角发现c-fos基因的上调, 作者由此认为脉冲射频的效应是持续的、长时程的;同时作者对脉冲射频效果有无时间累加效应进行初步的探讨,发现脉冲射频120秒和8min的实验结果并无差异。有人提出脉冲射频对背根节超微结构和邻近的脊神经前根没有破坏性影响, 脉冲射频使背根节P物质水平下调和脊髓P物质水平上调, 推测背根节脉冲射频可能通过背根节外周突抑制周围神经c纤维伤害性传入和刺激背根节中枢突激活脑干下行抑制系统产生镇痛作用的。 因此认为, 背根神经节脉冲射频的疗效好于肋间神经。Rozen[15]对腹股沟疝缝术后痛的患者进行了T12, L1和L2 的神经阻滞证实有效后, 分别进行T12, L1和L2 的脉冲射频治疗, 结果患者的疼痛减轻了75%- 100%, 而且疼痛的缓解持续了6- 9 个月,另外还有脉冲射频治疗肩痛[16, 17]、舌咽神经痛[18- 20]、枕大神经痛[21]、三叉神经痛[22, 23]的有关报道, 大家都认为脉冲射频对慢性疼痛的治疗是安全有效的。总之脉冲射频在疼痛治疗中的有效性越来越受到疼痛研究者的肯定, 但是它在疼痛治疗中的作用机制还有待于进一步研究。 参考文献: [1] Sluijter ME. 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