Sacral neuromodulation of nociceptive bladder overactivity in cats.

Abstract

AIMS: To investigate the effects of electrical stimulation of sacral dorsal/ventral roots on irritation-induced bladder overactivity, reveal possible different mechanisms under nociceptive bladder conditions, and establish a large animal model of sacral neuromodulation. METHODS: Intravesical infusion of 0.5% acetic acid (AA) was used to irritate the bladder and induce bladder overactivity in cats under &#x3b1;-chloralose anesthesia. Electrical stimulation (5, 15, or 30&#x2009;Hz) was applied to individual S1-S3 dorsal or ventral roots at or below motor threshold intensity. Repeated cystometrograms (CMGs) were performed with/without the stimulation to determine the inhibition of bladder overactivity. RESULTS: AA irritation induced bladder overactivity and significantly (P&#x2009;<&#x2009;0.05) reduced the bladder capacity to 62.6&#x2009;&#xb1;&#x2009;11.7% of control capacity measured during saline CMGs. At threshold intensity for inducing reflex twitching of the anal sphincter or toe, S1/S2 dorsal root stimulation at 5&#x2009;Hz but not at 15 or 30&#x2009;Hz inhibited bladder overactivity and significantly (P&#x2009;<&#x2009;0.05) increased bladder capacity to 187.3&#x2009;&#xb1;&#x2009;41.6% and 155.5&#x2009;&#xb1;&#x2009;9.7% respectively, of AA control capacity. Stimulation of S3 dorsal root or S1-S3 ventral roots was not effective. Repeated stimulation of S1-S3 dorsal root did not induced a post-stimulation inhibition. CONCLUSIONS: This study established a cat model of sacral neuromodualation of nociceptive bladder overactivity. The results revealed that the mechanisms underlying sacral neuromodulation are different for nociceptive and non-nociceptive bladder activity.