Ultra-High Frequency Spinal Nerve Neuromodulation for Improving Bladder Continence: Implications for Overactive Bladder Management

Objective: Ultrahigh frequencies (UHF) have been shown to selectively suppress the sensory pathway with a rapid onset and prolonged effect compared with low frequencies. Few studies have explored the feasibility of UHF electrical stimulation in treating overactive bladder. This study aimed to investigate whether bladder overactivity could be inhibited by UHF stimulation at the L6 nerve root. Materials and Methods: Female Sprague-Dawley rats (n = 12) were divided into two groups: sham and UHF groups. Bladder overactivity was induced by continuous intravesical infusion of 0.5 acetic acid (AA). UHF L6 nerve root stimulation (500 kHz, 20 mA for 5 minutes) was applied to the rats in the UHF group. To investigate the effects of the treatment, intravesical pressure was recorded by cystometrography during continuous transvesical infusion, with volume threshold (VT) and intercontraction interval (ICI) used to conduct the investigation. Results: Bladder overactivity was successfully developed in all rats with a significant decrease of median VT and ICI to 83.7 and 86.4, respectively. UHF stimulation of the L6 nerve root was able to counteract the AA effect by significantly increasing median VT and ICI to 220 and 36.1, respectively; these effects persisted for two hours. There was a significant difference in the effects of UHF electrical stimulation between the sham and UHF groups (p < 0.05). Conclusion: This preliminary study provides evidence for UHF stimulation of the L6 spinal nerve root, analogous to the sacral nerve root in humans, as a potential alternative neuromodulation technique to suppress bladder overactivity.