Effects of high‐intensity focused ultrasound on nerve conduction

Abstract

The effects of various exposures (intensity, duration) of high-intensity focused ultrasound (HIFU) on sciatic nerve conduction were investigated in vivo in rats. The objective was to identify HIFU exposures that produce biological effects ranging from partial to complete conduction block, indicating potential use of HIFU as an alternative to current clinical methods of inducing nerve conduction block. In the study, 26 nerves were exposed and treated with 5-s applications of 5.7-MHZ HIFU with acoustic intensities of 390, 2,255, 3,310, and 7,890 W/cm(2) (spatial peak, temporal peak). Compound muscle action potentials (CMAPs), in response to electrical stimulation of the nerve proximal to the HIFU site, were recorded from the plantar foot muscles immediately before and after HIFU treatment and 2 and 4 h after treatment. Furthermore, a preliminary long-term investigation was performed on 27 nerves with the same four sets of HIFU parameters. CMAPs were measured at the survival endpoint for each animal (7 or 28 days after treatment). For nerves treated with the three lower exposures, CMAPs decreased initially within 4 h or 7 days after HIFU treatment and then recovered to their baseline level at 28 days after treatment. For the highest exposure, however, CMAPs remained absent even 28 days after treatment. These exposure-dependent effects of HIFU on nerve function suggest its future potential as a novel treatment for severe spasticity and pain.

Noninvasive Renal Denervation for Resistant Hypertension Using High-Intensity Focused Ultrasound

“…An ultrasound-mediated nerve conduction block can be achieved with lower acoustic energy dose, suggesting that the nerve fibers may be highly sensitive to HIFU energy. 10 Therefore, the HIFU may offer benefit to RDN by an efficient and direct heating generation at the target nerves.…”

Nerve conduction block in diabetic rats using high-intensity focused ultrasound for analgesic applications

“…Our findings support a previous study showing that the CAPs of normal rat sciatic nerves were partly and temporarily blocked at low exposure (390 W cm 22 , 5 s, 5.7 MHz). 8 The degree of suppression of the HIFU-treated diabetic nerves was less than that of the control nerves, and the duration from suppression to recovery was relatively long.…”

“…5 6 Furthermore, HIFU has also been applied to suppress nerve conduction and was able to produce a complete and temporary conduction block of bullfrog sciatic nerves in vitro, 7 whilst in rats CMAPs in plantar foot muscles were partly and temporarily blocked by HIFU. 8 However, additional investigations of the effects of HIFU on neuropathic nerves are required. In addition, previous data described the effects on sensory and motor nerves together; thus, the influence of HIFU on sensory nerves alone is uncertain.…”

High-intensity focused ultrasound: past, present, and future in neurosurgery

“…15,25,26,70,86 Other studies have demonstrated activation of neural tissue, both peripherally and in the CNS. 32,50,81 These effects have been postulated to occur as a result of mechanical stimuli (reversible) and thermal ablation (potentially irreversible).…”