Impact of Electrical Spinal Cord Stimulation on Lower Urinary Tract Dysfunction in Mice With Spinal Cord Injury.

Abstract

Purpose: We aimed to assess the effects of electrical stimulation of the L3-4 spinal cord containing the lumbar spinal coordinating center (LSCC) for neurogenic lower urinary tract dysfunction (NLUTD) in mice with spinal cord injury (SCI).

Methods: Male mice were divided into spinal cord intact (SI) and SCI groups. Two electrodes were placed over the epidural surface of the L3-4 spinal cord for electrical spinal cord stimulation (SCS). SCS was initiated when the intravesical pressure of voiding bladder contractions began rising. Cystometrograms (CMG) and external urethral sphincter (EUS)-electromyography (EMG) were recorded before, during and after SCS to examine the effects of SCS on CMG and EUS-EMG parameters in each group.

Results: In SI mice, significant differences in CMG parameters were not found after SCS compared to pre-SCS values. However, in SCI mice, the ratio of the voided volume to bladder filling volume was significantly higher after SCS compared to pre- SCS values (P<0.001). Additionally, SCI mice after SCS showed a significantly lower nonvoiding contraction number (P=0.017) and a shorter intercontraction interval (P=0.007) compared to those without SCS. EUS-EMG parameters in SI mice without and with SCS showed no significant differences in the ratio of active phases (AP) to silent phases (SP). In contrast, SCI mice with SCS had a significantly lower AP to SP ratio compared to those without SCS (P<0.001).

Conclusion: SCS applied to the L3-4 spinal cord can improve detrusor sphincter dyssynergia by increasing EUS relaxation to mitigate inefficient voiding as well as detrusor overactivity in SCI. Restoration of the LSCC function by SCS could be a therapeutic modality to improve NLUTD after SCI.