Sacral nerve stimulation (SNS) implantation is a minimally invasive procedure which has current FDA approval for urinary urge incontinence, urgency-frequency syndrome and non-obstructive urinary retention, and has been available in the United States since 1997. The SNS delivers non-painful, mild electrical pulses to the sacral nerves to modulate the reflexes that influence the bladder, sphincter, and pelvic floor to improve or restore normal voiding function. While SNS has been shown to have efficacy for the aforementioned conditions, the exact mechanism of action is unknown, but it is believed to work primarily through the somatic afferent system in promoting inhibitory reflex pathways to facilitate urine storage. The degree of stimulation is thought to be at a level that only evokes a sensory and not a motor response; however this has not been tested.