Genital nerve stimulation for modulating the lower urinary tract functions in subjects with spinal cord injury

Abstract

Neurogenic bladder, a condition associated with spinal cord injury (SCI), is characterized by uninhibited bladder contractions in response to bladder filling; these contractions reduce bladder capacity and urinary continence. Few studies have investigated the amplitude-dependent effects of dorsal genital nerve stimulation (GNS) on the inhibition of bladder hyperreflexia in subjects with SCI. The present study aimed to determine the acute effects of the GNS intensity changes on bladder capacity gain in SCI subjects with neurogenic detrusor overactivity. A cystometric measurement was used to assess the effects of continuous GNS on bladder capacity during bladder filling. The cystometric trials were in a randomized sequence of cystometric fills without and with continuous GNS at stimulation intensities ranged 1–4 times of threshold (1–4 T). Our data revealed that the average bladder capacity significantly increased to 34%–70% of the control value in response to a stimulation amplitude ranging from 1.6 to 3.2 T, and stimulation amplitude and bladder capacity were significantly linearly correlated ( R = 0.89). In addition, the average bladder compliance also increased because of GNS. This study demonstrates that the stimulation amplitude was positively correlated with bladder capacity gain in subjects with SCI in acute GNS experiments. These results could aid in developing an advanced neural prosthesis to restore bladder function in clinical settings.