Electrical stimulation in the treatment of bladder dysfunction: technology update

Skin-inspired, sensory robots for electronic implants

Drawing inspiration from cohesive integration of skeletal muscles and sensory skins in vertebrate animals, we present a design strategy of soft robots, primarily consisting of an electronic skin (e-skin) and an artificial muscle. These robots integrate multifunctional sensing and on-demand actuation into a biocompatible platform using an in-situ solution-based method. They feature biomimetic designs that enable adaptive motions and stress-free contact with tissues, supported by a battery-free wireless module for untethered operation. Demonstrations range from a robotic cuff for detecting blood pressure, to a robotic gripper for tracking bladder volume, an ingestible robot for pH sensing and on-site drug delivery, and a robotic patch for quantifying cardiac function and delivering electrotherapy, highlighting the application versatilities and potentials of the bio-inspired soft robots. Our designs establish a universal strategy with a broad range of sensing and responsive materials, to form integrated soft robots for medical technology and beyond.

Real-time prediction of bladder urine leakage using fuzzy inference system and dual Kalman filtering in cats

The use of electrical stimulation devices to manage bladder incontinence relies on the application of continuous inhibitory stimulation. However, continuous stimulation can result in tissue fatigue and increased delivered charge. Here, we employ a real-time algorithm to provide a short-time prediction of urine leakage using the high-resolution power spectrum of the bladder pressure during the presence of non-voiding contractions (NVC) in normal and overactive bladder (OAB) cats. The proposed method is threshold-free and does not require pre-training. The analysis revealed that there is a significant difference between voiding contraction (VC) and NVC pressures as well as band powers (0.5-5 Hz) during both normal and OAB conditions. Also, most of the first leakage points occurred after the maximum VC pressure, while all of them were observed subsequent to the maximum VC spectral power. Kalman-Fuzzy method predicted urine leakage on average 2.2 s and 1.6 s before its occurrence and an average of 2.0 s and 1.1 s after the contraction started with success rates of 94.2% and 100% in normal and OAB cats, respectively. This work presents a promising approach for developing a neuroprosthesis device, with on-demand stimulation to control bladder incontinence.

[Functional-neurosurgical treatment options for functional pelvic floor disorders : Value of sacral neuromodulation]

BACKGROUND

Sacral neuromodulation is an established minimally invasive therapy indicated for the treatment of functional pelvic floor disorders. While it received its original US Food and Drug Administration (FDA) approval for the treatment of overactive bladder symptoms, it is now regarded as a therapeutic option to treat both urinary/fecal incontinence and retention. In addition, it has proven to be a valuable tool in the treatment of chronic pelvic pain, and preliminary results indicate a potential to elicit improvements in sexual functioning.

OBJECTIVE

This article serves to provide a summary of the therapy and its applications.

METHOD

Selective literature review.

RESULTS

Sacral neuromodulation implants allow for the controlled shifting of the autonomic control of bladder and rectum towards an inhibition or facilitation of voiding, dependent on the patient's needs and under the patient's control. At the same time and depending on the applied stimulation, the implants can interfere with the nerve's conduction of pain signals. This makes them a therapeutic option for pelvic pain that fails to respond to conventional treatment. Finally, there have been first reports suggesting improvements in sexual dysfunction under sacral neuromodulation, thus, potentially opening up a new line of therapy for those disorders.

DISCUSSION

Sacral neuromodulation is a flexible and efficient form of therapy for functional disorders of the pelvic floor. Specifically, the same intervention can treat seemingly contradictory disorders such as urinary/fecal incontinence and retention as well as chronic pain.

[Sacral Neuromodulation for Fecal Incontinence and Constipation: Evidence, Programming and Long-term Management]

BACKGROUND

Over the last two decades, sacral neuromodulation (SNM) has established its role in the treatment of functional pelvic organ-/pelvic floor disorders. Even though the mode of action is not fully understood, SNM has become the preferred surgical treatment of fecal incontinence.

METHODS AND RESULTS

A literature search was carried out on programming sacral neuromodulation and long-term outcomes in treating fecal incontinence and constipation.Sacral neuromodulation was found to be successful in the long term. Over the years, the spectrum of indications has expanded, and now includes patients presenting with anal sphincter lesions. The use of SNM for low anterior resection syndrome (LARS) is currently under clinical investigation. Findings of SNM for constipation are less convincing. In several randomised crossover studies, no success was demonstrated, even though it is possible that subgroups may benefit from the treatment. Currently the application cannot be recommended in general.The pulse generator programming sets the electrode configuration, amplitude, pulse frequency and pulse width. Usually pulse frequency and pulse width follow a default setting (14 Hz, 210 s), while electrode configuration and stimulation amplitude are adjusted individually to the patient need and perception of stimulation.Despite low infection rates and few electrode-/pulse generator dysfunctions, up to 65% of patients require surgical reintervention during long term follow-up - in 50% of cases because of battery depletion, which is an expected event. At least one reprogramming is necessary in about 75% of the patients during the course of the treatment, mostly because of changes in effectiveness, but rarely because of pain. Regular follow-up visits appear to be advisable.

CONCLUSION

Sacral neuromodulation can be considered to be a safe and effective long-term therapy of fecal incontinence. To optimise the therapeutic effect, a structured follow-up regime is advisable.

Application of the first rechargeable sacral neuromodulation system for treatment of neurogenic lower urinary tract dysfunction in China: a case report

Neurogenic lower urinary tract dysfunction (NLUTD) is caused by nervous system lesions and characterized by impaired micturition and urinary incontinence. The goal of treatment is to manage these symptoms, improve quality of life, prevent urinary tract infections, and maintain urinary function. Pelvic floor muscle training and medication are commonly used for treating it. Sacral neuromodulation (SNM) has been used in the treatment of NLUTD for >20 years worldwide, and its effectiveness and safety have been verified. Several countries have begun using a rechargeable SNM system, whereas the current sacral SNM system used in China is non-rechargeable. A 29-year-old man with persistent voiding dysfunction for >20 years presented with progressive symptoms 1 year ago. He was admitted to our hospital in August 2022 for a rechargeable SNM system implantation. The patient underwent a video-urodynamic examination and the Short Form of a Urinary Quality of Life Questionnaire (SF-Qualiveen) before and 1 month after surgery. The video-urodynamic examination showed that the maximum bladder capacity significantly increased after surgery, bladder compliance improved, the phenomenon of uninhibited bladder contraction during filling decreased, and urine leakage was reduced. The SF-Qualiveen score showed the patient's quality of life significantly improved. To our knowledge, this is the first case of a rechargeable SNM system implantation in China, which shows that it is safe and effective. More clinical cases and long-term observation are still needed. In conclusion, a rechargeable SNM system has significance for health and the economy and has a broad clinical application prospect.

Effects of electroacupuncture on bladder dysfunction and the expression of PACAP38 in a diabetic rat model

Objective: To explore the effects and the possible mechanism of electroacupuncture (EA) on diabetic bladder dysfunction (DBD) in streptozotocin-high fat diet (STZ-HFD) induced type 2 diabetes mellitus (T2DM) rats. Methods: The experiment was divided into Control, diabetic bladder dysfunction, electroacupuncture, and Sham electroacupuncture group. After 8 weeks of electroacupuncture intervention, the body mass, 24 h urine volume, intraperitoneal glucose tolerance test (IPGTT), and urodynamics were detected. After the wet weight of the bladder was detected, the hematoxylin-eosin (HE), Masson's trichrome, and TUNEL were used to analyze histological changes. The PACAP38 expressions in the bladder were detected by Real-time PCR and Western blot. Results: Compared to the Control group, the bladder wet weight, 24 h urine volume, blood glucose, maximum bladder capacity, bladder compliance, bladder wall thickness, the smooth muscle/collagen ratio, and apoptosis rate of the diabetic bladder dysfunction group were significantly increased. Moreover, the body mass and leak point pressure were significantly reduced. Compared with the Sham electroacupuncture group, the bladder wet weight, maximum bladder capacity, bladder compliance, bladder wall thickness, and apoptosis rate of the electroacupuncture group were significantly reduced. In contrast, the leak point pressure was increased. The PACAP38 mRNA and PACAP38 protein expression of the diabetic bladder dysfunction group were significantly lower than the Control group, while electroacupuncture treatment could upregulate PACAP38 mRNA levels and PACAP38 protein expression of diabetic bladder dysfunction model rats. Conclusion: electroacupuncture could ameliorate bladder dysfunction in the diabetic bladder dysfunction model rats by reversing bladder remodeling, which might be mainly mediated by regulating the PACAP38 level.

Peroneal Electric Transcutaneous NeuroModulation (eTNM®): A Novel Method for the Treatment of the Overactive Bladder

Overactive bladder syndrome (OAB) is a prevalent medical problem with a significant impact on the quality of life of the affected individuals. Pharmacotherapy is considered the main treatment method, although it is discontinued in a significant proportion of patients due to inefficacy or associated side effects. If pharmacotherapy fails, patients can undergo peripheral neuromodulation of the somatic nerves of the lower limb or sacral neuromodulation; however, neither of these represents an ideal therapeutic tool. The Peroneal electric Transcutaneous NeuroModulation (Peroneal eTNM^®), based on the selective stimulation of the peroneal nerve, is the new fully noninvasive neuromodulation method intended to treat OAB. The URIS^® neuromodulation system, engineered to provide Peroneal eTNM^®, consists of the URIS^® device, URIS^® active electrodes, and the biofeedback foot sensor (BFS). The unique design of the URIS^® device and URIS^® active electrodes allows for the use of a low voltage and current during neuromodulation, which significantly reduces the unpleasant sensations. The BFS allows for precise localization of the active electrodes and for continuous adjustment of the voltage and frequency to achieve the optimal therapeutic effect. The URIS^® system adopts several principles of telemedicine, which makes it compatible with the US Food and Drug Administration (FDA) and European Union (EU) regulations for home-based use. This article describes both the Peroneal eTNM^® method and the URIS^® neuromodulation system, including its technical specifications and data from laboratory testing. Preclinical and early clinical data demonstrate the feasibility of this new method for noninvasive OAB treatment and possible implications for clinical practice.

The Frequency-Dependence of Pre- and Postganglionic Nerve Stimulation of Pig and Rat Bladder

PURPOSE

The urinary bladder generates phasic contractions via action potentials generated in pre- and then postganglionic neurons. Whilst the frequency-dependence of postganglionic neurons to generate contractions has been quantified, the dynamic range of preganglionic neurons is less clear and if intramural ganglia exert frequency-dependent modulation of transmission between pre- and postganglionic neurons. The phosphodiesterase type 5 inhibitor sildenafil reduces neurotransmitter release from postganglionic fibres to detrusor smooth muscle and an additional question was if there was also a preganglionic action. This study aimed to compare the frequency range of bladder contractile activation by pre- and postganglionic stimulation in pig and rat bladders and if sildenafil exerted additional preganglionic actions.

METHODS

An arterially-perfused ex vivo pig bladder preparation was used for preganglionic (pelvic nerve) and mixed pre-and postganglionic (direct bladder wall) stimulation at 36°C and postganglionic mediated contractions achieved by field-stimulation of in vitro isolated detrusor strips. With rats, pelvic nerve stimulation was carried out in vivo and postganglionic stimulation also with isolated detrusor strips.

RESULTS

All contractions were abolished by 2% lignocaine indicating they are nerve-mediated. Stimulation targets were verified with hexamethonium that completely abolished pelvic nerve responses by had no effect on detrusor strips; responses to mixed bladder wall stimulation were partially reduced. The frequency-dependence of contractile activation was similar whether by pre- or postganglionic stimulation in both pigs and rats. Sildenafil reduced contractions to preganglionic stimulation significantly more than to postganglionic stimulation. Mixed pre- and postganglionic stimulation were reduced by an intermediate extent.

CONCLUSION

Intramural ganglia offer no frequency-dependent modulation under the experimental conditions used here and the sildenafil data are consistent with multiple sites of action underlying generation of bladder contractions. A translational aspect of these findings is discussed in terms of setting stimulation parameters for neuromodulation protocols.

[Therapeutic effects of sacral neuromodulation on detrusor underactivity]

OBJECTIVE

To evaluate the effects of sacral neuromodulation (SNM) on detrusor underactivity (DUA).

METHODS

From December 2019 to April 2020, 6 patients with DUA who had been treated with SNM were assessed retrospectively. The average age was 58 years (46-65 years), with 3 males and 3 females. All the patients were diagnosed with DUA by urodynamics examination. Obstruction of bladder outlet was excluded through the cystoscopy. No patient had the history of neurological disease. All the patients were placed with the bladder colostomy tube before SNM. One female patient accepted the trans-urethral resection of bladder neck. Two male patients accepted the trans-urethral resection of prostate. All the 3 patients had no improvement of void symptom after the urethral operation. Before SNM, the average 24 h times of voiding was 23.8 (18-33), average volume of every voiding was 34.2 mL (10-50 mL), average residual volume was 421.7 mL (350-520 mL). The preoperative and postoperative 24 h urine frequency, average voided volume, and average residual urine volume were compared respectively.

RESULTS

Totally 6 patients underwent SNM with stage Ⅰ procedure. The operation time for stage Ⅰ procedure was 62-135 min (average 90 min). After an average follow-up of two weeks, stage Ⅱ procedure was performed on responders. Four patients accepted stage Ⅱ procedure (conversion rate 66.7%), the other two patients refused the stage Ⅱ procedure because the urine frequency did not reach the satisfied level. But all the patients had the improvement of residual urine volume. For the 4 patients at the follow-up of 10-15 months, the improvement of void was still obvious. For the all patients after stage Ⅰ procedure, the average 24 h urine frequency reduced to 13.5 times (9-18 times, P < 0.001), the average voided volume increased to 192.5 mL (150-255 mL, P < 0.001), and the average residual urine volume reduced to 97.5 mL (60-145 mL, P < 0.001). No adverse events, such as wound infection or electrode translocation were detected during an average follow-up of 11.3 months. Only one of the 4 patients who received the stage Ⅱ procedure did the intermittent catheterization for one time each day.

CONCLUSION

SNM provides a minimal invasive approach for the management of DUA.

Triboelectric Nanogenerators for Therapeutic Electrical Stimulation

Current solutions developed for the purpose of in and on body (IOB) electrical stimulation (ES) lack autonomous qualities necessary for comfortable, practical, and self-dependent use. Consequently, recent focus has been placed on developing self-powered IOB therapeutic devices capable of generating therapeutic ES for human use. With the recent invention of the triboelectric nanogenerator (TENG), harnessing passive human biomechanical energy to develop self-powered systems has allowed for the introduction of novel therapeutic ES solutions. TENGs are especially effective at providing ES for IOB therapeutic systems given their bioconformability, low cost, simple manufacturability, and self-powering capabilities. Due to the key role of naturally induced electrical signals in many physiological functions, TENG-induced ES holds promise to provide a novel paradigm in therapeutic interventions. The aim here is to detail research on IOB TENG devices applied for ES-based therapy in the fields of regenerative medicine, neurology, rehabilitation, and pharmaceutical engineering. Furthermore, considering TENG-produced ES can be measured for sensing applications, this technology is paving the way to provide a fully autonomous personalized healthcare system, capable of IOB energy generation, sensing, and therapeutic intervention. Considering these grounds, it seems highly relevant to review TENG-ES research and applications, as they could constitute the foundation and future of personalized healthcare.

A general framework for automatic closed-loop control of bladder voiding induced by intraspinal microstimulation in rats

Individuals with spinal cord injury or neurological disorders have problems in voiding function due to the dyssynergic contraction of the urethral sphincter. Here, we introduce a closed-loop control of intraspinal microstimulation (ISMS) for efficient bladder voiding. The strategy is based on asynchronous two-electrode ISMS with combined pulse-amplitude and pulse-frequency modulation without requiring rhizotomy, neurotomy, or high-frequency blocking. Intermittent stimulation is alternately applied to the two electrodes that are implanted in the S2 lateral ventral horn and S1 dorsal gray commissure, to excite the bladder motoneurons and to inhibit the urethral sphincter motoneurons. Asynchronous stimulation would lead to reduce the net electric field and to maximize the selective stimulation. The proposed closed-loop system attains a highly voiding efficiency of 77.2-100%, with an average of 91.28 ± 8.4%. This work represents a promising approach to the development of a natural and robust motor neuroprosthesis device for restoring bladder functions.

Multiple magnetic resonance imaging in patients with implanted sacral nerve stimulator

AIM

The aim of this study was to assess possible impacts of multiple magnetic resonance imaging (MRI) scans on the function of InterStim™ sacral neurostimulator systems (SNS; Medtronic Inc.) devices and on patient's safety.

METHODS

Over the course of 17 years, a total of 16 patients required 72 MRI examinations in various parts of the body. Each time an MRI was performed, the implanting urologist evaluated the SNS device function and deactivated the implant before the scan. Patients were monitored continuously during and after the procedure. After the MRI session, the site of the implanted device was examined, and the SNS device was reactivated.

RESULTS

None of the patients experienced pain or discomfort during or after the MRI scan. Impedances and stimulation amplitudes were recorded before and after MRI and showed no statistically significant changes regarding implant function. Micturition-time charts after MRI procedures were compared with previous records and showed no deviations either. No negative consequences of multiple MRIs have been observed.

CONCLUSION

This is the first report of patients successfully undergoing multiple MRI scans despite a previously implanted SNS. Sixteen patients underwent more than one MRI scan, with no negative effect on the functional outcome of SNS or negative side effects for the patients.

New Technologies and Applications in Sacral Neuromodulation: An Update

Recently rechargeable devices have been introduced for sacral neuromodulation (SNM) with conditional safety for full-body magnetic resonance imaging (MRI). Currently a recharge-free SNM device represents the standard implant; however, it is only approved for MRI head scans. As further new technologies with broader MRI capabilities are emerging, the advantages as well as disadvantages of both rechargeable versus recharge-free devices will be briefly discussed in this commentary from the perspective of patients, healthcare professionals, and providers.