Colucci Vincent, Strichartz Gary, Jolesz Ferenc, Vykhodtseva Natalia, Hynynen Kullervo
Department of Radiology, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA.
Ultrasound Med Biol. 2009 Oct;35(10):1737-47. doi: 10.1016/j.ultrasmedbio.2009.05.002. Epub 2009 Aug 3.
Minimally invasive applications of thermal and mechanical energy to selective areas of the human anatomy have led to significant advances in treatment of and recovery from typical surgical interventions. Image-guided focused ultrasound allows energy to be deposited deep into the tissue, completely noninvasively. There has long been interest in using this focal energy delivery to block nerve conduction for pain control and local anesthesia. In this study, we have performed an in vitro study to further extend our knowledge of this potential clinical application. The sciatic nerves from the bullfrog (Rana catesbeiana) were subjected to focused ultrasound (at frequencies of 0.661 MHz and 1.986 MHz) and to heated Ringer's solution. The nerve action potential was shown to decrease in the experiments and correlated with temperature elevation measured in the nerve. The action potential recovered either completely, partially or not at all, depending on the parameters of the ultrasound exposure. The reduction of the baseline nerve temperature by circulating cooling fluid through the sonication chamber did not prevent the collapse of the nerve action potential; but higher power was required to induce the same endpoint as without cooling. These results indicate that a thermal mechanism of focused ultrasound can be used to block nerve conduction, either temporarily or permanently.
将热能和机械能微创应用于人体解剖结构的特定区域，已在典型外科手术的治疗和恢复方面取得了重大进展。图像引导聚焦超声能够将能量完全无创地深入沉积到组织中。长期以来，人们一直对利用这种聚焦能量传递来阻断神经传导以控制疼痛和进行局部麻醉感兴趣。在本研究中，我们进行了一项体外研究，以进一步拓展我们对这种潜在临床应用的认识。对牛蛙（牛蛙属）的坐骨神经施加聚焦超声（频率为0.661兆赫兹和1.986兆赫兹）以及加热的林格氏液。实验表明神经动作电位降低，且与神经中测得的温度升高相关。根据超声暴露参数的不同，动作电位要么完全恢复、部分恢复，要么根本不恢复。通过在超声处理室中循环冷却液来降低基线神经温度，并不能防止神经动作电位的消失；但与不进行冷却相比，需要更高的功率才能达到相同的终点。这些结果表明，聚焦超声的热机制可用于暂时或永久阻断神经传导。
