Inhibition of bladder overactivity by stimulation of feline pudendal nerve using transdermal amplitude‐modulated signal (TAMS)

What's known on the subject? and What does the study add? It is known that direct stimulation of pudenal nerve using a cuff electrode can inhibit normal bladder activity. This study further indicates that overactive bladder activity can be inhibited using non-invasive skin surface electrodes and a transdermal amplitude-modulated signal (TAMS). OBJECTIVE •  To develop a non-invasive neuromodulation method targeting the pudendal nerve. MATERIALS AND METHODS •  Bladder overactivity induced by acetic acid (AA) irritation was partially suppressed by electrical stimulation of the pudendal nerve in α-chloralose anaesthetized cats using a transdermal amplitude-modulated signal (TAMS). RESULTS •  During cystometrography (CMG), intravesical infusion of 0.25% AA significantly decreased the mean (se) bladder capacity to 28.8 (5.9)% of the capacity measured during saline infusion. •  The TAMS stimulation inhibited AA-induced bladder overactivity at 5, 7 and 10 Hz, and significantly increased the mean (se) bladder capacity to 61.8 (9.9)%, 51.3 (14.5)%, 53.6 (14.9)%, respectively, of the control capacity during saline infusion, whereas stimulation at 20–40 Hz had no effect. •  Under isovolumetric conditions at a bladder volume ranging between 130 to 160% of the bladder capacity measured during AA infusion, TAMS stimulation at all frequencies (5–40 Hz) significantly suppressed the irritation-induced rhythmic bladder contractions, reduced the area under the bladder pressure curve, and decreased the frequency of bladder contractions. However, the amplitude of rhythmic bladder contractions was only significantly decreased at stimulation frequencies of 5–20 Hz. •  At bladder volumes above the AA control capacity, TAMS stimulation with frequencies of 20–30 Hz had an excitatory effect, resulting in large amplitude (>25 cmH2O) bladder contractions. CONCLUSIONS •  TAMS stimulation targeting the cat pudendal nerve can inhibit C-fibre afferent-mediated bladder overactivity. •  Thus, clinical research seems warranted to explore the usefulness of this technology for patients with overactive bladder symptoms.