Irritation Induced Bladder Overactivity is Suppressed by Tibial Nerve Stimulation in Cats

Abstract

To investigate the effects of tibial nerve stimulation on bladder overactivity induced by acetic acid (AA) irritation. Cystometry was performed in 10 α-chloralose anesthetized female cats by infusing saline or AA through a urethral catheter that was secured by a ligature around the urethra. Intravesical infusion of 0.25% AA was used to irritate the bladder and induce bladder overactivity. Multiple cystometrograms (CMGs) were performed before, during, and after tibial nerve stimulation to determine the inhibitory effect on the micturition reflex. Infusion of 0.25% AA irritated the bladder, induced bladder overactivity, and significantly reduced the bladder capacity to about 20% of the control capacity measured during saline infusion. Tibial nerve stimulation at either low (5 Hz) or high (30 Hz) frequency significantly increased bladder capacity to about 40% of the saline control capacity when it was applied during AA infusion CMG. The amplitude of bladder contractions was smaller during AA irritation than during saline distention due to a significantly smaller bladder capacity. Tibial nerve stimulation at 5 Hz not only increased bladder capacity but also increased the amplitude of bladder contractions. Activation of somatic afferents in the tibial nerve of cats can partially reverse the bladder overactivity induced by intravesical administration of a chemical irritant that activates C-fiber afferent nerves. These data are consistent with clinical studies showing that tibial nerve neuromodulation is effective in treating overactive bladder symptoms.