Pudendal nerve stimulation attenuates bladder pain reflex responses in rat models of interstitial cystitis

Clinical reports suggest painful bladder disorders (PBD; e.g. interstitial cystitis) may benefit from neuromodulation of the pudendal nerve (PN). However, a systematic evaluation of this has not been carried out. Here we investigated the effect of PN stimulation on visceromotor reflex (VMR) responses to urinary bladder distension (UBD) in rat models of bladder hypersensitivity^1-3 due to 1) early-in-life bladder inflammation, 2) acute bladder inflammation, or 3) footshock-induced stress. Electrodes were placed under the PN bilaterally to deliver biphasic pulses (100 μs) at 3x motor threshold. PN stimulation for 10 min significantly attenuated the VMR to UBD (n=10, P<0.05) in rats which had received intravesical zymosan treatments early-in-life at all three frequencies tested (10 Hz, 50 Hz, 100 Hz). Inhibition was also observed using 10 Hz PN stimulation in rats receiving acute intravesical zymosan treatment as adults (n=8, p<0.05). Overall ANOVA revealed no significant effects of PN stimulation in the chronic stress or control groups. The presence of inhibitory effects of PN stimulation within the early-in-life inflammation group and smaller-but-significant effects in the acute bladder inflammation group suggest potential utility of PN stimulation in the treatment of PBD with inflammatory mechanisms. These findings suggest PN stimulation may be less efficacious for PBD when caused by psychological stress mechanisms. Clinical follow will better direct our understanding of this potentially useful therapy. (1. DeBerry J et al. J Pain, 11: 247-255, 2010. 2. DeBerry J et al. J Pain, 8: 914-923, 2007. 3. Robbins MT and Ness TJ. J. Pain 9: 991-998, 2008.) Supported by a grant from Medtronic, Inc.