ULTRASOUND ENERGY FOR SELECTIVE NERVE STIMULATION

用于选择性神经刺激的超声波能量

• 批准号: 2885218
• 负责人: BRUCE C. TOWE
• 金额: $ 10.7万
• 依托单位: ARIZONA STATE UNIVERSITY-TEMPE CAMPUS
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-08-01 至 2001-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2885218
• 关键词: bioengineering /biomedical engineering; biomedical equipment development; laboratory rabbit; muscle strength; neuromuscular stimulator; neurophysiology; ultrasound

It is known that focused ultrasound energy in the 1-10 MHz medical diagnostic region of frequencies can stimulate bioelectrically excitable tissues such as nerves, brain tissue, and cardiac muscle cells. The reason for its effectiveness is thought to be due to pressure and stretch effects on cell membranes leading to intracellular sodium ion influx. Unfortunately, the bioelectric interaction mechanism of ultrasound with tissue at these frequencies is inefficient. At 7 MHz it requires relatively high ultrasound power levels to excite nerve, near tissue damage thresholds, and bulky transducers; therefore, this approach has seen little application. It has recently become possible however, to practically generate high frequency ultrasound in the 50-150 MHz region. A hypothesis of this work is that, for reasons based on both physiological theory as well as ultrasound physics, these relatively high frequencies should be much more effective in producing bioelectric stimulation effects. At the same time, high frequencies allow the use of millimeter-sized ultrasound transducers that can concentrate their energy in extremely small focal zones; near ten micron cellular dimensions. Ultrasound energy has a different interaction physics with excitable tissue than does electricity, leading to a number of unexplored possible advantages including the potential for less invasive stimulation as well as highly spatially selective stimulation of near cellular scale structures. The proposed work will compare high frequency ultrasound stimulation of peripheral nerve to that achieved by electrical stimulation using a rabbit model. Ultrasound functional activation of the sciatic nerve will be monitored by measuring developed hindleg muscle force and compared using muscle recruitment curves to that achieved by electrical activation. The work will evaluate the possibility of highly focal stimulation of individual nerve fibers in a bundle using the focal nature of ultrasound. Although very high frequency ultrasound has limited range in tissue, there are applications where small, potentially millimeter-order sized high frequency ultrasound transducers could be preferable to the use of conventional stimulating electrodes. In principle, improved and more effective ultrasound bioelectric-stimulation instrumentation could have broad utility in medical, biological, and electrophysiological studies.

众所周知，聚焦的超声能量在1-10 MHz的医学诊断频率范围内可以刺激生物电刺激的组织，如神经、脑组织和心肌细胞。其有效性的原因被认为是由于对细胞膜的压力和拉伸效应导致细胞内钠离子内流。不幸的是，在这些频率下，超声波与组织的生物电相互作用机制是无效的。在7 MHz下，它需要相对较高的超声功率水平来刺激神经、接近组织损伤阈值和笨重的换能器；因此，这种方法几乎没有应用。然而，最近已经有可能在50-150 MHz范围内实际产生高频超声。这项工作的一个假设是，基于生理学理论和超声波物理学的原因，这些相对较高的频率在产生生物电刺激效果方面应该更有效。同时，高频允许使用毫米尺寸的超声波换能器，这种换能器可以将能量集中在极小的焦点区域；接近10微米的细胞尺寸。超声能量与可兴奋组织的相互作用物理机制与电的不同，导致了许多未知的可能优势，包括更少侵入性刺激的可能性以及对近细胞尺度结构的高度空间选择性刺激。这项拟议的工作将在兔模型上比较高频超声波刺激周围神经和电刺激实现的效果。超声对坐骨神经的功能激活将通过测量发展的后腿肌力进行监测，并使用肌肉招募曲线与电激活实现的比较。这项工作将评估利用超声波的焦点性质对束中的单个神经纤维进行高度焦点刺激的可能性。尽管超高频超声在组织中的应用范围有限，但在某些应用中，小型的、可能是毫米级大小的高频超声换能器可能比使用传统的刺激电极更可取。从原理上讲，改进和更有效的超声生物电刺激仪器在医学、生物和电生理研究中可以有广泛的用途。