Objectives: During a screening trial to determine candidacy for sacral nerve stimulation (SNS), several patients were required to repeat the baseline dietary because of discrepancies in the 24-hour urine output before and after successful stimulation. This raised a question regarding the relationship between urine production and neuromodulation. A more complete diary analysis of patients affected by urgency/frequency and/or urge incontinence was therefore carried out to evaluate the possibility of a direct modulatory influence 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 evaluated. Voiding diaries were obtained at baseline, during and after peripheral nerve evaluation (PNE) and after permanent implantation.
Results: There was an increase in the average volume/void during PNE in 39 patients. Twenty-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 mechanism is unclear, but it is consistent with an altered release of antidiuretic hormone. This observation reflects the direct refractory involvement of the hypothalamus in micturition.