Does our limited knowledge of the mechanisms of neural stimulation limit its benefits for patients with overactive bladder? ICI-RS 2013

Response to tibial and sacral nerve modulation in overactive bladder: Is there any correlation?

OBJECTIVES

To assess the correlation between the response to transcutaneous tibial nerve stimulation (TTNS) and subsequent response to sacral nerve modulation (SNM) to treat overactive bladder (OAB).

MATERIALS AND METHODS

All patients who consecutively received TTNS followed by a two-stage SNM between January 2016 and June 2022 to treat OAB in two university hospital centers were included. The response to each therapy was evaluated with success defined by a 50% or greater improvement in one or more bothersome urinary symptoms from baseline. The primary endpoint was the statistical relationship between the response to TTNS and the response to SNM, assessed by logistic regression. Secondary endpoints were the statistical relationship between the response to TTNS and the response to SNM when controlling for gender, age (<57 years vs. >57 years), presence of an underlying neurological disease, and presence of DO, adding the factor and interaction to the previous regression model.

RESULTS

Among the 92 patients enrolled in the study, 68 of them were women (73.9%), and the median age was 57.0 [41.0-69.0] years. The success was reported in 22 patients (23.9%) under TTNS and 66 patients (71.7%) during the SNM test phase. There was no statistical correlation between response to TTNS and response to SNM in the overall population (confidence interval: 95% [0.48-4.47], p = 0.51). Similarly, there was no statistical correlation when controlling for age <57 years or ≥57 years, with p = 1.0 and p = 0.69, respectively. No statistical study could be conducted for the other subpopulations due to small sample sizes.

CONCLUSION

The response to TTNS does not predict the response to SNM in the treatment of OAB. TTNS and SNM should be considered as separate therapies, and the decision-making process for OAB treatment should take this into account.

Evolving types of pudendal neuromodulation for lower urinary tract dysfunction

Introduction

Sacral neuromodulation and posterior tibial nerve stimulation for lower urinary tract dysfunction (LUTD) and overactive bladder yield good and reliable results. However, neuromodulation research is continuously evolving because there is still need for more patient-friendly treatment options in the therapeutic management of LUTD. Pudendal neuromodulation (PNM) has been emerging as a promising alternative treatment option for the last few decades. The aim of this study is to review the current state of the art of PNM.

Material and methods

A wide literature search was conducted in the field of PNM using Medline through the PubMed database and Elsevier using the Scopus database; a critical review of the results was then carried out. PNM has been studied in its various possible aspects: percutaneous PNM, transrectal/transvaginal PNM, and both percutaneous and transcutaneous dorsal genital nerve stimulation.

Results

Each technique was found to result in promising improvements in different clinical outcomes, with some trials reporting even better results than sacral neuromodulation.

Conclusions

As a result of a comparison between the various PNM techniques with both sacral neuromodulation and posterior tibial nerve stimulation, we think that PNM should be seen as seriously promising, and we believe it will expand the treatment options for overactive bladder. Even though several studies accordingly showed PNM to be safe and effective, a systematic review and meta-analysis were not feasible. PNM in its various techniques is a promising treatment for LUTD. Nevertheless, further research is needed to include it in treatment algorithms.

Differences between brain responses to peroneal electrical transcutaneous neuromodulation and transcutaneous tibial nerve stimulation, two treatments for overactive bladder

OBJECTIVES

To compare brain responses to peroneal electrical transcutaneous neuromodulation (peroneal eTNM®) and transcutaneous tibial nerve stimulation (TTNS), two methods for treating overactive bladder (OAB), using functional magnetic resonance imaging (fMRI). The present study was not designed to compare their clinical efficacy.

MATERIALS AND METHODS

This study included 32 healthy adult female volunteers (average age 38.3 years (range 22-73)). Brain MRI using 3 T scanner was performed during three 8-min blocks of alternating sequences. During each 8-min block, the protocol alternated between sham stimulation (30 s) and rest (30 s) for 8 repeats; then peroneal eTNM® stimulation (30 s) and rest (30 s) for 8 repeats; then, TTNS stimulation (30 s) and rest (30 s) for 8 repeats. Statistical analysis was performed at the individual level with a threshold of p = 0.05, family-wise error (FWE)-corrected. The resulting individual statistical maps were analyzed in group statistics using a one-sample t-test, p = 0.05 threshold, false discovery rate (FDR)-corrected.

RESULTS

During peroneal eTNM®, TTNS, and sham stimulations, we recorded activation in the brainstem, bilateral posterior insula, bilateral precentral gyrus, bilateral postcentral gyrus, left transverse temporal gyrus, and right supramarginal gyrus. During both peroneal eTNM® and TTNS stimulations, but not sham stimulations, we recorded activation in the left cerebellum, right transverse temporal gyrus, right middle frontal gyrus, and right inferior frontal gyrus. Exclusively during peroneal eTNM® stimulation, we observed activation in the right cerebellum, right thalamus, bilateral basal ganglia, bilateral cingulate gyrus, right anterior insula, right central operculum, bilateral supplementary motor cortex, bilateral superior temporal gyrus, and left inferior frontal gyrus.

CONCLUSIONS

Peroneal eTNM®, but not TTNS, induces the activation of brain structures that were previously implicated in neural control of the of bladder filling and play an important role in the ability to cope with urgency. The therapeutic effect of peroneal eTNM® could be exerted, at least in part, at the supraspinal level of neural control.

Magnetic resonance image connectivity analysis provides evidence of central nervous system mode of action for parasacral transcutaneous electro neural stimulation - A pilot study

INTRODUCTION

Parasacral transcutaneous electriconeural stimulation (pTENS) is a common treatment modality for patients with overactive bladder (OAB). Its mechanism of effectiveness has yet to be elucidated. Recent studies with fMRI in adults with implanted sacral nerve stimulators impute its effectiveness on changes in the brain involving the anterior cingulate cortex (ACC) and prefrontal cortex (PFC).

AIM

The study set out to evaluate brain connectivity utilizing functional MRI to the outline the mechanism of action of pTENS in the brain.

METHODS

Ten adult volunteers without urinary tract symptoms underwent fMRI. Electrodes were placed on the skin at sacral level (S2) (Experimental Stimulation - pTENS) and on the right scapular region (Sham Stimulation - sTENS). Stimulation was done twice on each site for 6 min at a frequency of 10 Hz and pulse width of 260 μs and intensity determined by the motor threshold. A 6 min resting state fMRI was also done twice as control. Functional connectivity data was acquired during each state (resting, pTENS and sTENS). Standard functional connectivity preprocessing was performed. Seed connectivity was examined to investigate changes in ACC functional connectivity between the stimulations and resting-state conditions. Significance was assessed at p < 0.05 corrected for multiple comparisons.

RESULTS

For all conditions (pTENS, sTENS, and rest), standard patterns of ACC connectivity were detectable with strong connectivity between the ACC and subcortical regions and between the ACC and the frontal lobe. Functional connectivity between ACC seed and the dorsal lateral prefrontal cortex (DLPFC) was significantly increased during pTENS compared to rest. sTENS did not increase connectivity between the ACC seed and DLPFC when compared to rest.

DISCUSSION

Preliminary results indicate that ACC is a major site of activation during pTENS. Increased connectivity between ACC and DLPFC may be a possible mechanism of pTENS effectiveness, which appears to be specific to pTENS compared to sTENS. This study is limited to the small size at this time which prevents further investigation at other sites in the brain.

CONCLUSIONS

The study confirms our original aim which was to define if parasacral TENS actually has a central effect.

Do Failure of Posterior Tibial Nerve Stimulation Precludes to Use Sacral Neuromodulation in Patient With Overactive Bladder?

Purpose

To evaluate the outcomes of sacral neuromodulation (SNM) after failure of transcutaneous posterior tibial nerve stimulation (TPTNS) in patients with overactive bladder (OAB).

Methods

A retrospective study was conducted in 3 university hospitals and included all patients with OAB and treated with SNM after TPTNS had been tried between October 2008 and May 2018. The primary endpoint was the proportion of definitive SNM device implantation in patients with 50% objective and/or subjective improvement after a test period (stage 1). The secondary outcomes of interest were changes of the number of diurnal voids and nocturia episodes per 24 hours between the end of TPTNS and the end of stage 1.

Results

Overall, 28 of the 43 patients included achieved at least 50% objective and/or subjective improvement during stage 1 and underwent an Interstim II implantation (65.1%). The mean daytime frequency decreased significantly from 10.3/day at the end of TPTNS to 7.8 diurnal voids/day at the end of SNM stage 1 (P=0.01). The mean number of nocturia episodes decreased from 2.5/night at the end of TPTNS to 2.1/night at the end of stage 1, but this did not reach statistical significance (P=0.18). There was no other parameter significantly associated with response to SNM

Conclusions

SNM might improve OAB symptoms in most patients who experienced no or poor efficacy with TPTNS. History of failed TPTNS should not preclude the use of SNM in OAB patients.

Successful treatment of urodynamic detrusor over-activity in a young patient with Myasthenia gravis using pretibial nerve stimulation with follow-up to two years

We report a rare case of Myasthenia gravis and overactive bladder successfully treated with pretibial nerve stimulation.