Hypothesis / aims of study
Sacral neuromodulation is an accepted treatment option for patients with idiopathic OAB or chronic nonobstructive urinary retention that is refractory to conservative treatment.  Since Food and Drug Administration approval in 1997 an increasing number of patients have been treated with SNM.
Nocturia, defined as nocturnal micturition with a frequency of at least once per night, is one of the most frequent lower urinary tract symptoms and often causes them to consult a physician. Nocturia is often bothersome and responsible for increased morbidity and mortality. In this study, we aimed to assess the effect of Sacral Neuro Modulation (SNM) during Percutaneous Nerve Evaluation (PNE) test on Nocturia
Study design, materials and methods
Patients received an Medtronic intestim device after showing a successful response to PNE or first stage tined lead screening tests. Success was defined as more than 50% improvement in at least 1 of the relevant voiding diary parameters compared to baseline. For OAB wet cases these parameters included a reduction in daily episodes of incontinence or pad use, and for OAB dry cases a reduction in the number of daily voids or an increase in voided volume per void.
Before the start of the protocol all patients completed a 3-day voiding diary to evaluate the effect of unilateral stimulation, which served as baseline measurement. PNE test was done to evaluate the effect of contralateral and bilateral stimulation. The stimulation electrode was placed in the contralateral S3 foramen. Sensory and motor responses were used to ensure correct lead positioning. The lead position that provoked an adequate response at the lowest possible amplitude was chosen to ensure that the lead was in close proximity to the nerve root. X-ray was done to verify lead position.
After implantation patients visited the outpatient clinic after 6 weeks, 6 months and yearly thereafter. In cases of decreased efficacy the impedance and battery life span were checked. Parameter settings were adjusted to restore efficacy. In cases of permanent loss of efficacy electrode position and cable integrity were checked using fluoroscopy.
We evaluated micturition diaries of 41 female patients who underwent a PNE test for the treatment of their Overactive bladder syndrome. Of these 41 patients, 40 had nocturia, defined as a micturition episode of one or more per night. Only patients suffering from nocturia were included in the study. Bladder diaries were kept for three days before and three days during the PNE test.
Interpretation of results
A reduction of nocturia occured in about 2/3 of all patients ondergoing a PNE test for OAB. In about 1/4 of all patients there was no change of nocturia episodes. Furthermore, in 6 cases, there was a non clinically significant deterioration of bladder function at night with 0.5 times more visits to the toilet per night (from 2.1 to 2.6 times per night), and in two cases (5%) a significant deterioration of one more nocturia episode per night occured.