Podhajsky Ronald J, Sekiguchi Yasufumi, Kikuchi Shinichi, Myers Robert R
Valleylab, Tyco Healthcare, Boulder, CO, USA.
Spine (Phila Pa 1976). 2005 May 1;30(9):1008-13. doi: 10.1097/01.brs.0000161005.31398.58.
Experimental histologic study of the effects of radiofrequency (RF) or convective heating of the rat dorsal root ganglion or sciatic nerve to 42 degrees C.
To determine whether treatment causes neuropathologic changes in an effort to explore the mechanisms and safety of pulsed RF pain therapy.
Clinical data suggest that low temperature pulsed RF energy delivered to the DRG is a safe and effective form of therapy for low back pain. However, the mechanism by which this treatment modifies pain is unclear.
A total of 118 Sprague-Dawley rats were divided into five groups for different RF and thermal treatments. All treatments increased tissue temperature to 42 degrees C. Treatments of the DRG included pulsed RF, continuous RF, and conductive heat. The generator output was increased until 42 degrees C was obtained in the tissue and was then maintained for 120 seconds. As a positive control, some rat sciatic nerves were treated with continuous RF lesions at 80 degrees C. Animals were killed for histologic study at 2, 7, or 21 days after treatment. Tissue was fixed in gluteraldehyde and embedded in plastic resin for detailed light microscopic neuropathologic evaluation.
The methods used to heat the tissue to 42 degrees C caused no significant difference in pathology. However, subclinical changes included endoneurial edema caused by alterations in the function of the blood-nerve barrier, fibroblast activation, and collagen deposition. Tissue returned to normal conditions by 7 days in nerve and 21 days in the DRG. These minor structural changes observed at the light microscopic level in normal animals do not exclude the possibility that there would be nonstructural changes in gene expression or cytokine upregulation in injured tissue. Lesions at 80 degrees C caused consistent thermal injury characterized by Wallerian degeneration of nerve fibers.
The data support the hypothesis that pulsed RF treatment does not rely on thermal injury of neurologic tissue to achieve its effect.
对大鼠背根神经节或坐骨神经进行射频（RF）或对流加热至42摄氏度效果的实验性组织学研究。
确定治疗是否会引起神经病理变化，以探索脉冲射频疼痛治疗的机制和安全性。
临床数据表明，传递至背根神经节的低温脉冲射频能量是治疗腰痛的一种安全有效的疗法。然而，这种治疗改善疼痛的机制尚不清楚。
总共118只Sprague-Dawley大鼠被分为五组进行不同的射频和热疗。所有治疗均将组织温度升至42摄氏度。对背根神经节的治疗包括脉冲射频、连续射频和传导热。增加发生器输出，直到组织温度达到42摄氏度，然后维持120秒。作为阳性对照，一些大鼠坐骨神经用80摄氏度的连续射频损伤处理。在治疗后2、7或21天处死动物进行组织学研究。组织固定于戊二醛中，包埋于塑料树脂中进行详细的光镜神经病理评估。
将组织加热至42摄氏度的方法在病理学上无显著差异。然而，亚临床变化包括血神经屏障功能改变引起的神经内膜水肿、成纤维细胞活化和胶原沉积。神经组织在7天内恢复正常，背根神经节在21天内恢复正常。在正常动物光镜水平观察到的这些轻微结构变化并不排除在损伤组织中基因表达或细胞因子上调存在非结构变化的可能性。80摄氏度的损伤导致一致的热损伤，其特征为神经纤维的华勒氏变性。
数据支持脉冲射频治疗不依赖神经组织热损伤来实现其效果这一假说。
