To assess whether the utilization of a motor response <3 volts during stage 1 neuromodulation results in better clinical outcomes compared to >4 volts in patients with overactive bladder or urinary retention.
An observational, retrospective, double cohort review was conducted of 339 female patients who had experienced medically recalcitrant overactive bladder symptoms or urinary retention. Between September 2001 and September 2014, both cohorts underwent successful Stage 1 to Stage 2 sacral neuromodulation placement. Group A included 174 women with motor response at ≤3 volts, and Group B evaluated 110 women with a motor response at ≥4 volts for medically recalcitrant overactive bladder. Group C compared 33 women with a motor response at ≤3 volts and Group D documented 22 women with a motor response at ≥4 volts for non-obstructive urinary retention. Patients completed 3-day voiding diaries, Urinary Distress Inventory-6, Incontinence Impact Questionnaire-7, and Patient Global Impression of Improvement Questionnaire.
Mean follow-up in months: Group A, 116.3±30.3 and Group B, 112±34.6 [p<0.354]; Group C, 150.5±20.4 and Group D, 145.8±17.2 [p<0.38]. Successful conversion of Stage 1 to Stage 2 showed statistically significant improvement for both <3-volt groups (Groups A & C). Group A had a 93.5% [174/186] conversion rate versus 72.3% [110/152, p<0.001] in Group B for overactive bladder symptoms. Group C had a 94% [34/36] conversion rate compared to Group D, with 70% [21/30, p<0.017] for urinary retention. Defined as a 50% or greater reduction in frequency, urgency, urgency incontinence, nocturia, and UDI-6 & IIQ-7, the success rate for Group A was 82.1% [143/174]; and for Group B was 63% [69/110, p<0.001]. Mean battery life improved in both < 3-volt cohorts [p<0.001]. Annual reprogramming sessions were reduced in Group A and Group C [p<0.001]. Subset ANOVA analysis demonstrated no statistical improvement in most patient outcomes when 1-volt subjects were compared to 2 and 3-volt cohorts. However, 32% of 1-volt patients [p<0.001] noted the onset of severe pelvic/perirectal pain and big toe plantar flexion movement with small increments in voltage [0.1-0.2 volts] during reprogramming. Only 7% of 2-volt and 1% of 3-volt patients experienced this complication.
Significant improvement was noted (up to 40%) in most clinical voiding parameters in the <3-volts patients for both overactive bladder and urinary retention. While less than 3- volts will still statistically improve patient outcomes, a voltage lower than 2 may elicit self-reprogramming pain with severe bellows and plantar flexion movement which may discourage patients from therapy adjustments. We recommend randomized, controlled trials to confirm these results. This article is protected by copyright. All rights reserved.
BJU international. 2018 Apr 10 [Epub ahead of print]
Serge Marinkovic, Joseph C Ford
Detroit Medical Center (DMC), Department of Urology, Harper Professional Building, 4160 John R Street. Suite 1017, Detroit, MI, 48201.