The effects of botulinum-A toxin on bladder function and histology in spinal cord injured rats: is there any difference between early and late application?

Purpose: We explored the effects of early and late application of botulinum-A toxin (BTX-A) on reservoir function and histological bladder changes in spinal cord injured rats.

Materials And Methods: The study was done in 30 Sprague-Dawley rats randomly allocated into 5 groups. Group 1 of 6 rats underwent sham operation only. Group 2 of 6 rats underwent spinal cord transection. Group 3 of 6 rats underwent spinal cord transection followed by BTX-A application into the detrusor muscle 7 days later. Group 4 of 6 rats underwent spinal cord transection, followed by BTX-A application into the detrusor muscle 28 days later. Group 5 of 6 rats underwent spinal cord transection followed by saline injection into the detrusor muscle after 28 days. Spinal cord injury was created by transecting the cord at the T9 to T10 level. All rats underwent cystometric examination initially and on day 42 before sacrifice. The bladders were removed and examined histologically for fibrosis and hyperplasia.

Results: On cystometric examination BTX-A caused an improvement in baseline pressure, and the frequency and amplitude of uninhibited detrusor contractions (p <0.001). No significant differences were observed in maximal bladder capacity or urethral opening pressure (p >0.05). Histologically BTX-A led to decreased fibrosis and hyperplasia (p <0.001). No significant differences were found between histological or cystometric among the groups with respect to receiving BTX-A in the early and late periods (p >0.05).

Conclusions: BTX-A has a functional and histological healing effect on detrusor hyperreflexia subsequent to spinal cord injury in rats. Although administering BTX-A in the early period had better quantifiable functional and histological outcomes compared to the late period, the difference was not statistically significant.