Feasibility of Self-administered Neuromodulation for Neurogenic Bladder in Spinal Cord Injury

Development of a Sham Protocol to Investigate Transcutaneous Tibial Nerve Stimulation in Randomised, Sham-Controlled, Double-Blind Clinical Trials

Transcutaneous tibial nerve stimulation (TTNS) is a promising treatment for neurogenic lower urinary tract symptoms. However, the evidence is limited due to a general lack of randomised controlled trials (RCTs) and, also, inconsistency in the sham and blinding conditions. In the context of much-needed RCTs, we aimed to develop a suitable sham-control protocol for a clinical setting to maintain blinding but avoid meaningful stimulation of the tibial nerve. Three potential electrode positions (lateral malleolus/5th metatarsal/plantar calcaneus) and two electrode sizes (diameter: 2.5 cm/3.2 cm) were tested to determine which combination provided the optimal sham configuration for a TTNS approach, based on a visible motor response. Sixteen healthy volunteers underwent sensory and motor assessments for each sham configuration. Eight out of them came back for an extra TTNS visit. Sensory thresholds were present for all sham configurations, with linear regression models revealing a significant effect regarding electrode position (highest at plantar calcaneus) but not size. In addition, motor thresholds varied with the position-lowest for the 5th metatarsal. Only using this position and 3.2 cm electrodes attained a 100% response rate. Compared to TTNS, sensory and motor thresholds were generally higher for the sham configurations; meanwhile, perceived pain was only higher at the lateral malleolus. In conclusion, using the 5th metatarsal position and 3.2 cm electrodes proved to be the most suitable sham configuration. Implemented as a four-electrode setup with standardized procedures, this appears to be a suitable RCT protocol for maintaining blinding and controlling for nonspecific TTNS effects in a clinical setting.

Efficacy of peripheral electrical nerve stimulation on improvements of urodynamics and voiding diary in patients with neurogenic lower urinary tract dysfunction: a systematic review and meta-analysis

BACKGROUND

Peripheral electrical nerve stimulation is a routinely recommended treatment for non-neurogenic overactive bladder but has not been approved for patients with neurogenic lower urinary tract dysfunction (NLUTD). This systematic review and meta-analysis was to elucidate the efficacy and safety of electrostimulation and thus provide firm evidence for treating NLUTD.

MATERIALS AND METHODS

We systematically performed the literature search through PubMed, Web of Science, and Cochrane Library databases in March 2022. The eligible studies were identified across the inclusion criteria and the data on urodynamic outcomes, voiding diary parameters, and safety was collected to quantitatively synthesize the pooled mean differences (MDs) with 95% CIs. Subgroup analyses and sensitivity analyses were subsequently used to investigate the possible heterogeneity. This report was achieved in accordance with the preferred reporting items for systematic reviews and meta-analyses statement.

RESULTS

A total of 10 studies involving 464 subjects and 8 studies with 400 patients were included for systematic review and meta-analysis, respectively. The pooled effect estimates indicated that electrostimulation could significantly improve urodynamic outcomes, including maximum cystometric capacity (MD=55.72, 95% CI 15.73, 95.72), maximum flow rate (MD=4.71, 95% CI 1.78, 7.65), maximal detrusor pressure (MD=-10.59, 95% CI -11.45, -9.73), voided volume (MD=58.14, 95% CI 42.97, 73.31), and post-void residual (MD=-32.46, 95% CI -46.63, -18.29); for voiding diary parameters, patients undergoing electrostimulation showed lower MDs of incontinence episodes per 24 h (MD=-2.45, 95% CI -4.69, -0.20) and overactive bladder symptom score (MD=-4.46, 95% CI -6.00, -2.91). In addition to surface redness and swelling, no stimulation-related severe adverse events were reported else.

CONCLUSIONS

The current evidence demonstrated that peripheral electrical nerve stimulation might be effective and safe for managing NLUTD, whereas more reliable data from large-scale randomized controlled trials are necessary to strengthen this concept.

Transcutaneous Electrical Stimulation for Neurogenic Bladder Dysfunction Following Spinal Cord Injury: Meta-Analysis of Randomized Controlled Trials

OBJECTIVES

To assess the efficacy of transcutaneous electrical nerve stimulation (TENS) for neurogenic bladder dysfunction secondary to spinal cord injury (SCI).

MATERIALS AND METHODS

A systematic search of MEDLINE, EMBASE, Web of Science, Scopus, and Cochrane libraries up to February 2021 was performed using PRISMA methodology. All randomized controlled trials (RCTs) that studied TENS for neurogenic bladder in a SCI population were included. The primary outcomes of interest were maximum cystometric capacity (MCC) and maximum detrusor pressure (Pdet). Meta-analysis was conducted with RevMan v5.3.

RESULTS

Six RCTs involving 353 participants were included. Meta-analysis showed that TENS significantly increased MCC (standardized mean difference 1.11, 95% confidence interval [CI] 0.08-2.14, p = 0.03, I²  = 54%) in acute SCI. No benefits were seen for maximum Pdet. TENS was associated with no major adverse events.

CONCLUSIONS

TENS may be an effective, safe intervention for neurogenic bladder dysfunction following SCI. Further studies are essential to confirm these results and more work is required to determine optimal stimulation parameters and duration of the treatment.

The long-lasting post-stimulation inhibitory effects of bladder activity induced by posterior tibial nerve stimulation in unanesthetized rats

Tibial nerve stimulation (TNS) is one of the neuromodulation methods used to treat an overactive bladder (OAB). However, the treatment mechanism is not accurately understood owing to significant differences in the results obtained from animal and clinical studies. Thus, this study was aimed to confirm the response of bladder activity to the different stimulation frequencies and to observe the duration of prolonged post-stimulation inhibitory effects following TNS. This study used unanesthetized rats to provide a closer approximation of the clinical setting and evaluated the changes in bladder activity in response to 30 min of TNS at different frequencies. Moreover, we observed the long-term changes of post-stimulation inhibitory effects. Our results showed that bladder response was immediately inhibited after 30 min of 10 Hz TNS, whereas it was excited at 50 Hz TNS. We also used the implantable stimulator to observe a change in duration of the prolonged post-stimulation inhibitory effects of the TNS and found large discrepancies in the time that the inhibitory effect lasted after stimulation between individual animals. This study provides important evidence that can be used to understand the neurophysiological mechanisms underlying the bladder inhibitory response induced by TNS as well as the long-lasting prolonged post-stimulation effect.