Triggered sacral neuromodulation to treat neurogenic detrusor overactivity based on algorithmic classification of bladder filling status from wireless pressure data.

Louis Stokes Cleveland Va Medical Center, Cleveland OH

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Abstract

Neurogenic detrusor overactivity (NDO) resulting from spinal cord injury or disorder (SCI/D) affects 80% of individuals with SCI/D. It is also associated with peripheral neurodegenerative conditions such as Parkinson’s disease, multiple sclerosis, diabetic neuropathy, or stroke. NDO causes urinary incontinence that profoundly impacts dignified, independent living, associates with numerous comorbidities and fall risk, and is a leading factor in functional decline among the elderly. Urinary incontinence contributes to social isolation and clinical depression and associates with military service and post-traumatic stress disorder in Veterans. Restoring urine storage is consistently cited as a high priority by individuals with NDO. Continuous SNM is an off-label treatment, which is effective for some individuals with NDO. Triggered sacral neuromodulation—in which SNM is applied only during the portion of the bladder fill cycle where NDO occurs—could show unique benefit in treatment in some individuals. While triggered SNM increased bladder capacity in sheep and rats, feasibility has not yet been demonstrated in humans with NDO. The primary goal of this research is to demonstrate the feasibility of increasing bladder capacity and reducing bladder filling pressures using triggered SNM in Veterans with NDO. This will expand on unique technologies developed by our team: the UroMonitor, the Context-Aware Threshold (CAT) algorithm, and the Application Specific Control Unit (ASCU). The UroMonitor is a small, transurethrally-inserted sensor that wirelessly transmits bladder pressure data. CAT is a wavelet-based algorithm that detects detrusor contractions from pressure data in real time. The ASCU is a modular neurostimulation platform supporting wireless communication and custom control software. We will modify and integrate these technologies to demonstrate the feasibility of automatically triggering SNM in Veterans. A secondary goal is to use the UroMonitor to determine bladder capacity, detrusor contraction rate, and filling pressures during a percutaneous SNM evaluation to identify individuals who respond to SNM therapy before a permanent implantation. Both translational goals will be accomplished through two Specific Aims (SA): SA1 will determine the change in bladder response to conditionally-triggered SNM during natural filling cycles after a two-week sacral neuromodulation evaluation phase in Veterans with NDO. In SA1a we will integrate a short-range radio and low-power algorithm processor into the ASCU to trigger percutaneous SNM under algorithm control. In SA1b we will develop and bench-validate a classification algorithm capable of triggering SNM based on adaptive detection of detrusor contractions. In SA1c we will apply triggered SNM using data transmitted from the UroMonitor to the ASCU. Triggered SNM will be applied for eight hours at three timepoints in the two-week percutaneous evaluation phase in eight Veterans. Voided urine volume, time between voids, and detrusor contraction frequency will be compared to determine change in conditional SNM response at the two timepoints and compared to baseline. Outcome measures will be measured from validated questionnaires, catheter-referenced bladder pressures, and collected voided urine. SA2 will determine change in bladder capacity, filling pressure, and detrusor contraction frequency during natural filling cycles throughout a two-week continuous sacral neuromodulation evaluation. In SA2a we will integrate adaptive antennas into the UroMonitor and develop an insertion tool for men and women. SA2b will demonstrate the feasibility of using the UroMonitor to characterize NDO symptoms (bladder capacity, filling pressure, and detrusor contraction rate) over several bladder filling/emptying cycles. Eight Veterans will receive standard, continuous percutaneous SNM for two weeks. NDO symptoms will be measured using the UroMonitor before SNM and after one and two weeks of continuous SNM. Accuracy of symptom quantification will be compared to standard catheter-based testing and validated urinary behavior questionnaires.