Percutaneous electrical stimulation of sensory nerve fibers to improve motor function: applications in voiding dysfunction

The aim of this study was to describe the clinical applications of percutaneous electrical stimulation to sensory nerve fibers to improve motor function and its limitation. Semi-conditional dorsal penile nerve stimulation was used in this study to improve the storage function of the bladder in patient with spinal cord injury. The result of percutaneous electrical stimulation was compared with that of transcutaneous electrical stimulation. Seven subjects, who showed favourable results in suppression of bladder hyper-reflexia by transcutaneous, were tested using percutaneous electrical stimulation to compare the effect. For the transcutaneous stimulation surface electrodes with 1 cm diameters were used. The cathode and anode were placed, proximally and distally, respectively, on the dorsum of the penile shaft. For the percutaneous stimulation two sets of paired wire electrodes were placed in subcutaneous layer of dorsum of penile shaft, using guide needle. We applied dorsal penile nerve (DPN) stimulation using portable stimulator during the continuous bladder filling. Stimulation parameters were biphasic rectangular pulses of 25 Hz frequency, 250 μs pulse width. The 1 min stimulation was repeated to every reflex contraction during the cystometry. Immediate suppressive effect of DPN was analyzed. The infused volume of saline at the first and last reflex contraction during the percutaneous stimulation was not significantly different from that during the transcutaneous stimulation. The duration of suppression at the first and the last reflex contraction was not significantly different between two method of current delivery. The peak detrusor pressure (Pmax) were effectively suppressed by transcutaneous and percutaneous DPN stimulation. There were no statistically significant differences in baseline detrusor pressure (Pini), Pmax and suppressed pressure (Psup), between two stimulation techniques. Percutaneous electrical stimulation of neural pathway has definitive advantage compared with transcutaneous method. To get percutaneous stimulation into clinical practice, however, current limitation, such as, risk of infection, difficulties in placement to proper position, durability and affinity should be improved.