The inhibitory effects of pudendal nerve stimulation on bladder overactivity in spinal cord injury dogs: is early stimulation necessary?

OBJECTIVE

To determine the inhibitory effects of pudendal nerve stimulation (5 Hz) on bladder overactivity at early and late stages of spinal cord injury in dogs.

MATERIALS AND METHODS

The study was performed in eight dogs with chronic spinal cord transection at the T9-T10 level. Group 1 (four dogs) underwent electrical stimulation of pudendal nerve one month after spinal cord transection. Group 2 (four dogs) underwent stimulation six months after spinal cord transection. The bladders were removed for histological examination of fibrosis after the stimulation.

RESULTS

The bladder capacity and the compliance were significantly increased (p < 0.05) by pudendal nerve stimulation in group 1, but not in group 2. The nonvoiding contractions were inhibited in both groups by electrical stimulation. Collagen fiber was increased, while elastic fiber was significantly decreased (p < 0.05) in group 2 when compared with group 1.

CONCLUSION

Pudendal nerve stimulation can increase the bladder capacity and compliance only during the early period before the bladder wall becomes fibrosit and can inhibit the nonvoiding contraction during two stages.