Neurogenic lower urinary tract dysfunction (NLUTD) is a common issue among stroke survivors. Research has demonstrated that they exhibit decreased cortical activity in response to bladder filling and emptying compared to healthy individuals. The use of Transcutaneous Spinal Cord Stimulation (TSCS) has emerged as a promising therapeutic alternative for managing NLUTD, resulting in a significant improvement in bladder function and a reduction in frequency, urgency, and incontinence episodes. 
Despite these positive outcomes, the effect of TSCS on micturition-associated brain activity (MABA) in stroke survivors has not yet been fully explored.  Therefore, this study aims to investigate where TSCS can lead to the normalization of MABA in stroke survivors by comparing the results with healthy individuals.

Simulations have suggested that a minimum of 12 subjects would be required to achieve 80% power at the individual voxel level to identify typical activations. In this prospective study, which was approved by our Institutional Review Board, informed consent was obtained from all participants. Twelve individuals with NLUTD received 12 weeks of TSCS to evaluate the effect of TSCS on MABA. Each participant underwent simultaneous fMRI and UDS before initiating TSCS and within 72 hours of completing the final TSCS session. An identical fMRI+UDS protocol was conducted in healthy subjects without LUTS. The BOLD signal intensity was detected during the period of maximum urgency (10 seconds preceding a detrusor contraction) using SPM. The results were compared between healthy controls and stroke survivors with NLUTS before and after TSCS with a significance level of p< 0.01 and cluster size >25 voxels. All models were adjusted for age and sex, and time from a stroke.

Before receiving TSCS therapy, stroke survivors exhibited reduced activation in several brain regions, including the right cerebellum, left putamen, right insula, right anterior cingulate gyrus, right precuneus, bilateral medial frontal gyri, and right superior frontal gyrus, compared to healthy controls. Interestingly, after receiving TSCS, there was no significant difference in BOLD signal intensity in these regions between stroke survivors and healthy controls. However, healthy controls continued to exhibit increased activation in the right precentral (motor cortex) and left postcentral (sensory cortex) gyri, left posterior cingulate, and left middle temporal gyrus even after TSCS.

These findings suggest that TSCS could potentially normalize MABA in stroke survivors with NLUTD, resulting in improved brain activation patterns in response to bladder filling and emptying. Despite these promising results, significant differences in BOLD signal were still present in several brain regions after TSCS, indicating that the neurosignature of stroke patients may not fully return to the healthy phenotype.

This study provides valuable insights into the mechanism  of TSCS therapy as a novel, non-invasivetherapy for neurogenic lower urinary tract dysfunction.

Continence 7S1 (2023) 100949
DOI: 10.1016/j.cont.2023.100949