Effects of immediate sacral neuromodulation on bladder in rats with spinal cord hemisection-induced neurogenic bladder

OBJECTIVES: To establish a novel spinal cord hemisection-induced neurogenic bladder (SCHNB) rat model combined with sacral neuromodulation (SNM) and evaluate the immediate effects of SNM on bladder function and morphology in SCHNB. MATERIALS AND METHODS: Female Sprague-Dawley rats were randomly assigned to three groups: control, SCHNB, and SCHNB + SNM groups. Rats in control group underwent only T9-T10 laminectomy, SCHNB group received right T9-T10 spinal cord hemisection and electrode implantation without electrical stimulation, SCHNB + SNM group underwent the same procedure as SCHNB group but also received daily 3-hours SNM beginning on postoperative day 1 for 3 weeks. All rats subsequently underwent motor function assessment, bladder ultrasonography and cystography, cystometric testing, and histological analysis of spinal cord and bladder tissues. RESULTS: Ultrasonography revealed significantly increased post void residual in SCHNB group compared to control and SCHNB + SNM groups. Bladder weight in SCHNB group was significantly higher than in control and SCHNB + SNM groups. Cystometric analysis showed a shorter voiding contraction interval in SCHNB + SNM group than control group but longer than SCHNB group. During bladder filling, SCHNB group exhibited multiple uninhibited detrusor contractions, SCHNB + SNM group showed fewer uninhibited contractions and a lower maximum pressure. Histological examination revealed that compared to control and SCHNB + SNM groups, SCHNB group displayed disorganized bladder mucosal epithelium, disrupted and loosened lamina propria, tissue edema, and increased fibrosis. CONCLUSIONS: This model of SCHNB combined with SNM provides a new experimental platform for SNM research. Immediate SNM effectively inhibited bladder overactivity and partially improved functional and structural abnormalities of the bladder.