Low-Intensity Ultrasound Tibial Nerve Stimulation Suppresses Bladder Activity in Rats
Zitian He, Qinggang Liu, Ruiyao Yang, Yongheng Zhou, Xin Liu, Han Deng, Huiling Cong, Yixi Liu, Limin Liao
Neuromodulation: Technology at the Neural Interface 2025, 28, 95-102 · 10.1016/j.neurom.2024.06.005
Abstract
Background and objective Noninvasive neuromodulation, particularly through low-intensity ultrasound, holds promise in the fields of neuroscience and neuro-engineering. Ultrasound can stimulate the central nervous system to treat neurologic disorders of the brain and activate peripheral nerve activity. The aim of this study is to investigate the inhibitory effect of low-intensity ultrasonic tibial nerve stimulation on both the physiological state and the overactive bladder (OAB) model in rats. Materials and methods A total of 28 female Sprague-Dawley rats were used in this study. Continuous transurethral instillation of 0.9% normal saline into the bladder was initially performed to stimulate physiological bladder activity. Subsequently, a solution containing 0.3% acetic acid dissolved in saline was instilled to induce rat models of OAB. The study comprised two phases: initial observation of bladder response to low-intensity ultrasound (1 MHz, 1 W/cm 2 , 50% duty cycle) in seven rats; subsequent exploration of ultrasound frequency (3 MHz) and intensity (2 W/cm 2 and 3 W/cm 2 ) effects in 21 rats. The intercontraction intervals (ICIs) were the primary outcome measure. Histologic analysis of tibial nerves and surrounding muscle tissues determined safe ultrasound parameters. Results Low-intensity ultrasound tibial nerve stimulation significantly inhibited normal and OAB activity. Ultrasound stimulation at 1 MHz, 1 W/cm 2 , with a 50% duty cycle significantly prolonged the ICI in both normal (p 2 and 1 MHz frequency with a 50% duty cycle, ultrasound stimulation significantly prolonged the ICI in both normal (p 2 ultrasound intensity also significantly extended the ICI in both normal (p 0.05). Low-intensity ultrasound tibial nerve stimulation did not influence baseline pressure, threshold pressure, or maximum pressure. In addition, a latency period in bladder reflex inhibition was induced by low-intensity ultrasound tibial nerve stimulation in some rats. Histologic analysis indicated no evident nerve or muscle tissue damage or abnormalities. Conclusions This study confirmed the potential of transcutaneous ultrasound tibial nerve stimulation to improve bladder function. According to the findings, the ultrasonic intensities ranging from 1 to 3 W/cm 2 and frequencies of 1 MHz and 3 MHz are both feasible and safe treatment parameters. This study portended the promise of low-intensity ultrasound tibial nerve stimulation as a treatment for OAB and provides a basis and reference for future clinical applications.
Abstract via europepmc.
Exposures
Exposure 1: Transcutaneous ultrasound tibial nerve stimulation, varying frequency and intensity
Target: tibial nerve — “tibial nerve”
Device: other named manufacturer · Shenzhen Dongdixin Technology Co, Ltd · NU-TEK UT1041 ✓
| Waveform | pulsed | |
|---|---|---|
| Fundamental frequency (kHz) | 1,000, 3,000swept | ✓✓✓ |
| Pulse duration (ms) | not reported | |
| Pulse repetition frequency (Hz) | not reported | |
| Duty cycle (%) | 50 | ✓✓✓ |
| Sonication duration (s) | 300 | ✓✓✓ |
| Free-field pressure (kPa) | not reported | |
|---|---|---|
| Free-field Isppa (W/cm²) | not reported | |
| Free-field Ispta (W/cm²) | not reported | |
| In-situ estimate | not reported | |
| In-situ pressure (kPa) | not reported | |
| In-situ Isppa (W/cm²) | not reported | |
| In-situ Ispta (W/cm²) | not reported | |
| Isppa, domain unspecified (W/cm²) | 1, 2, 3swept | ✓✓✓⚑ |
The transducer probe was placed ~1 cm above the inner ankle over the tibial nerve. A frequency group compared 1 MHz vs 3 MHz (both 1 W/cm2, 50% duty cycle); an intensity group compared 2 W/cm2 vs 3 W/cm2 (both 1 MHz, 50% duty cycle). Ultrasound was administered for 5 minutes after voiding contractions, with 30-minute baseline and 60-minute (saline) or 25-minute (0.3% acetic acid/OAB) post-stimulation cystometry recordings.
Flags from extraction
exposures[0].unspecified_domain.isppa_w_cm2— The paper reports plain 'W/cm2' intensities (1, 2, 3 W/cm2) without stating whether these are spatial-peak pulse-average (Isppa) or spatial-peak temporal-average (Ispta) values; the Discussion explains the general Isppa/Ispta distinction but does not say which one was used for the stimulation settings, so domain/metric is uncertain.n_sessions_per_subject— Each rat underwent a continuous experimental protocol including ultrasound stimulation during both saline (physiological) and 0.3% acetic acid (OAB) bladder instillation, but the paper does not state this as a discrete number of stimulation sessions.device.family— The NU-TEK UT1041 is a named commercial ultrasound stimulator (Shenzhen Dongdixin Technology) that does not match any of the specific listed manufacturer families, so it is coded as commercial_other.