Sacral nerve stimulation and diurnal urine volume

Objectives: During a screening trial to determine candidacy for sacral nerv e stimulation (SNS), several patients were required to repeat the baseline dietary because of discrepancies in the 24-hour urine output before and aft er successful stimulation. This raised a question regarding the relationshi p between urine production and neuromodulation. A more complete diary analy sis of patients affected by urgency/frequency and/or urge incontinence was therefore carried out to evaluate the possibility of a direct modulatory in fluence of SNS on urine production. Methods: Voiding diaries of 40 patients (37 females and 3 males, average age 39.4 years) who underwent SNS were ev aluated. Voiding diaries were obtained at baseline, during and after periph eral nerve evaluation (PNE) and after permanent implantation. Results: Ther e was an increase in the average volume/ void during PNE in 39 patients. Tw enty-four-hour urine volume during PNE was statistically greater than that at baseline. Volume/void and diurnal volume were also significantly greater in follow-up periods after permanent implantation. Conclusion: SNS appears to influence not only bladder function but also urine production. Increase in volume/void is paralleled by an increase in 24-hour urine output. The m echanism is unclear, but it is consistent with an altered release of antidi uretic hormone. This observation reflects the direct refractory involvement of the hypothalamus in micturition.