Effects of low-intensity extracorporeal shock wave on bladder and urethral dysfunction in spinal cord injured rats.

Abstract

To investigate the effects of low-intensity extracorporeal shock wave therapy (LiESWT) on bladder and urethral dysfunction with detrusor overactivity and detrusor sphincter dyssynergia (DSD) resulting from spinal cord injury (SCI). At 3 weeks after Th9 spinal cord transection, LiESWT was performed on the bladder and urethra of adult female Sprague Dawley rats with 300 shots of 2Hz and an energy flux density of 0.12mJ/mm2, repeated four times every 3 days, totaling 1200 shots. Six weeks postoperatively, a single cystometrogram (CMG) and an external urethral sphincter electromyogram (EUS-EMG) were simultaneously recorded in awake animals, followed by histological evaluation. Voiding efficiency significantly improved in the LiESWT group (71.2%) compared to that in the control group (51.8%). The reduced EUS activity ratio during voiding (duration of reduced EUS activity during voiding/EUS contraction duration with voiding + duration of reduced EUS activity during voiding) was significantly higher in the LiESWT group (66.9%) compared to the control group (46.3%). Immunohistochemical examination revealed that fibrosis in the urethral muscle layer was reduced, and S-100 stained-positive area, a Schwann cell marker, was significantly increased in the urethra of the LiESWT group. LiESWT targeting the urethra after SCI can restore the EUS-EMG tonic activity during voiding, thereby partially ameliorating DSD. Therefore, LiESWT is a promising approach for treating bladder and urethral dysfunction following SCI.