Restoration of micturition in patients with acontractile and hypocontractile detrusor by transurethral electrical bladder stimulation

[A review of intravesical treatment options in neuro-urology]

Neurogenic lower urinary tract dysfunction is caused by various disorders of the central and peripheral nervous system. This can result in several malfunctions of the storage and voiding phase, which are reflected in symptoms such as urgency, urinary incontinence, recurrent urinary tract infections and post-void residual urine. Reduced quality of life, impairment of the upper urinary tract, reduced employment opportunities and worsening of the symptoms of the underlying condition can be the consequences. Therefore, the primary goals of neuro-urology are to protect the upper urinary tract, maintain continence and improve the quality of life of those affected. To achieve these goals, different intravesical drug and electrophysical therapy options are available. These article addresses these intravesical therapy options as well as their indication and relevance in neuro-urology.

Effects of electroacupuncture on patients with chronic urinary retention caused by a lower motor neuron lesion: An exploratory pilot study

Chronic urinary retention (CUR) is defined as a non-painful bladder that remains palpable or percussible after the patient has passed urine. Acupuncture may decrease PVR and improve bladder function in patients with neurogenic CUR. The aim of this study was to preliminarily observe the effectiveness of electroacupuncture (EA) for patients with CUR caused by a lower motor neuron lesion and to provide some therapeutic data for further study.This study was a pilot study of 30 patients with CUR caused by a lower motor neuron lesion. Patients were treated with EA for 12 weeks with 36 sessions of EA.Responders were defined as participants with a decline in postvoid residual urine (PVR) volume after spontaneous urination of ≥50% from baseline. The proportion of responders, change in PVR volume from baseline after spontaneous urination, and the proportion of patients with severe difficulty with urination, who required assistance with bladder emptying and with stool retention, were measured at weeks 4, 8, and 12.Thirty patients were included in this study, and 23 completed 12 weeks of treatment. The proportion of responders at weeks 4, 8, and 12 was 6.67%, 28%, and 43.48%, respectively. Decrease in PVR volume, compared with baseline, was significant at all asessment timepoints. The proportion of patients with severe difficulty with urination, who required assistance with bladder emptying and with stool retention, decreased after treatment.EA is a potential treatment for improving bladder function in patients with CUR caused by a lower motor neuron lesion.

Underactive bladder: A review of the current treatment concepts

According to the International Continence Society standardization reports, underactive bladder (UAB) is a decrease in detrusor contraction and/or shortening of the contraction time, resulting in an incomplete and/or prolongation of the bladder emptying within the normal time frame. It has been indicated that idiopathic, neurogenic, myogenic, and iatrogenic factors play a role in the etiology. To make a diagnosis, it is absolutely necessary to perform a pressure-flow study. Treatment alternatives are generally based on the evacuation of the lower urinary tract, independent of the etiology. UAB treatments are listed under the headings of conservative methods and clean intermittent catheterization, pharmacotherapy (alpha-blockers, cholinesterase inhibitors, muscarinic agonists, prostaglandin E2, and acotiamide), surgical treatments (sacral nerve stimulation-electrical stimulation, injections into the external sphincter, surgeries to be performed for bladder outlet obstruction, reduction cystoplasty, and latissimus dorsi detrusor myoplasty), and stem cell and gene therapies. It is still controversial whether satisfactory success is achieved in the treatment of patients with UAB. Owing to the better understanding of the pathophysiology, future developments in the pharmaceutical industry, gene therapy, and biomedical applications are expected to close the gap in the treatment.

Current concepts of the acontractile bladder

The acontractile bladder (AcB) is a urodynamic-based diagnosis wherein the bladder is unable to demonstrate any contraction during a pressure flow study. Although it is often grouped with underactive bladder, it is a unique phenomenon and should be investigated independently. The purpose of the present review was to examine the current literature on AcB regarding its pathology, diagnosis, current management guidelines, and future developments. We performed a review of the PubMed database, classifying the evidence for AcB pathology, diagnosis, treatment, and potential future treatments. Over the 67 years covered in our review period, 42 studies were identified that met our criteria. Studies were largely poor quality and mainly consisted of retrospective review or animal models. The underlying pathology of AcB is variable with both neurological and myogenic aetiologies. Treatment is largely tailored for renal preservation and reduction of infection. Although future developments may allow more functional restorative treatments, current treatments mainly focus on bladder drainage. AcB is a unique and understudied bladder phenomenon. Treatment is largely based on symptoms and presentation. While cellular therapy and neuromodulation may hold promise, further research is needed into the underlying neuro-urological pathophysiology of this disease so that we may better develop future treatments.

Current pharmacological and surgical treatment of underactive bladder

Generally accepted guidelines are not yet available on the management of underactive bladder (UAB). Although the natural history of UAB is still not fully understood, observation may be an acceptable management option in patients with tolerable lower urinary tract symptoms and little risk of upper urinary tract damage. If needed, scheduled and double voiding may be recommended as an effective and safe add-on therapy. Parasympathomimetics have been widely used for the management of UAB, but the evidence does not support clinical benefit. The efficacy of alpha-blockers has also not yet been clearly demonstrated. However, selective alpha-blockers may help to enhance voiding efficiency and to decrease possible upper tract damage. Sacral neuromodulation is a surgical option for nonobstructive UAB approved by the Food and Drug Administration. However, the response rate of test stimulation is not high and the efficacy of permanent implants does not always coincide with that of test stimulation. Although surgery to reduce outlet resistance may be a viable option in UAB with presumed obstruction, surgery seems to have little role in those without obstruction. Latissimus dorsi detrusor myoplasty has shown promising results in restoring voluntary voiding in selected patients. The procedure requires a multidisciplinary team approach of urologists and plastic reconstructive experts. In summary, current treatments of UAB remain unsatisfactory. The multifactorial nature of UAB pathogenesis complicates the appropriate management for each patient. Future research to establish a more clinically relevant definition of UAB will be required to open new era of UAB management.

The management of neurogenic lower urinary tract dysfunction after spinal cord injury

The management of patients with neurogenic bladder has changed substantially over the past decades. Obtaining balanced lower urinary tract function has become possible in most patients, although, urological complications remain among the most serious complications these patients are likely to have and, even today, these can have a negative effect on quality of life. To this extent, patients with spinal cord injury (SCI) are likely to develop neurogenic bladder, and data are available on most aspects of neurogenic bladder in these patients. Data on physiology and pathophysiology form the basis of our understanding of patients' symptoms, and also provide a basis for the management of these patients. The use of conservative, and/or more invasive treatment measures, their complications and measures to prevent these complications, are all important clinical aspects that merit discussion. Considerable progress has been made in the urological management of patients with SCI over the past decades, but opportunities remain to make diagnosis more accurate and therapy more successful.

Effects of Physiotherapy in the Treatment of Neurogenic Bladder in Patients Infected With Human T-Lymphotropic Virus 1

OBJECTIVE

To evaluate the efficacy of physiotherapy for urinary manifestations in patients with human T-lymphotropic virus 1-associated lower urinary tract dysfunction.

METHODS

Open clinical trial was conducted with 21 patients attending the physiotherapy clinic of the Hospital Universitário, Bahia, Brazil. Combinations of behavioral therapy, perineal exercises, and intravaginal or intra-anal electrical stimulation were used.

RESULTS

The mean age was 54 ± 12 years and 67% were female. After treatment, there was an improvement in symptoms of urinary urgency, frequency, incontinence, nocturia, and in the sensation of incomplete emptying (P < .001). There was also a reduction in the overactive bladder symptom score from 10 ± 4 to 6 ± 3 (P < .001) and an increase in the perineal muscle strength (P <.001). The urodynamic parameters improved, with reduction in the frequency of patients with detrusor hyperactivity from 57.9% to 42.1%, detrusor-sphincter dyssynergia from 31.6% to 5.3%, detrusor hypocontractility from 15.8% to 0%, and detrusor areflexia from 10.5% to 0%, with positive repercussions in the quality of life in all patients.

CONCLUSION

Physiotherapy was effective in cases of human T-lymphotropic virus 1-associated neurogenic bladder, reducing symptoms, increasing perineal muscle strength, and improving urodynamic parameters and quality of life.

Physiotherapy for human T-lymphotropic virus 1-associated myelopathy: review of the literature and future perspectives

Human T-lymphotropic virus 1 (HTLV-1) infection may be associated with damage to the spinal cord – HTLV-associated myelopathy/tropical spastic paraparesis – and other neurological symptoms that compromise everyday life activities. There is no cure for this disease, but recent evidence suggests that physiotherapy may help individuals with the infection, although, as far as we are aware, no systematic review has approached this topic. Therefore, the objective of this review is to address the core problems associated with HTLV-1 infection that can be detected and treated by physiotherapy, present the results of clinical trials, and discuss perspectives on the development of knowledge in this area. Major problems for individuals with HTLV-1 are pain, sensory-motor dysfunction, and urinary symptoms. All of these have high impact on quality of life, and recent clinical trials involving exercises, electrotherapeutic modalities, and massage have shown promising effects. Although not influencing the basic pathologic disturbances, a physiotherapeutic approach seems to be useful to detect specific problems related to body structures, activity, and participation related to movement in HTLV-1 infection, as well as to treat these conditions.

Clinical efficacy of intravesical electrostimulation on incomplete spinal cord patients suffering from chronic neurogenic non-obstructive retention: a 15-year single centre retrospective study

OBJECTIVE

To evaluate the clinical and urodynamic impact of intravesical electrostimulation (IVES) on incomplete spinal cord injury (SCI) patients suffering from chronic neurogenic non-obstructive urinary retention (N-NOR).

METHODS

One-hundred and two patients underwent at least 28 consecutive daily IVES sessions because objective evidence of detrusor acontractility instead of hypocontractility was detected. Diary entries written at various stages by each patient were compared (7 days before the IVES cycle, 15-21 days into the cycle and 7 days before its end). Responders were patients with a mean 50% reduction in both the number of daily catheterizations and post-void residual urine. Responders underwent further urodynamics at the end of the IVES cycle; patients experiencing first sensation of bladder filling, and the mean volume of first sensation of bladder filling per ml, Qmax ml s(-1), among others, were evaluated. Nineteen individuals who repeated another IVES round were included in this study.

RESULTS

Thirty-eight subjects (37.2%) responded to IVES and of those, 83.3% recovered the first sensation of bladder filling after the IVES round. Nineteen responders repeated IVES within 1 year, owing to loss of efficacy. They obtained similar voiding symptoms improvement and urodynamic results as after the first IVES cycle. A timespan of <2 years from SCI to IVES, and the presence of first sensation of bladder filling at baseline represented significant predictive parameters for IVES success (P<0.05) using χ(2)-test.

CONCLUSIONS

IVES represents a possible therapeutic option for incomplete SCI patients with N-NOR.

Can the use of different parameters and waveforms improve the results of intravesical electrical stimulation: a pilot study in the rat

AIM

Intravesical electrical stimulation (IVES) with square wave pulses, low frequencies and short pulse durations has been used for decades in diagnosis and treatment of lower urinary tract dysfunction. The results are not always satisfying. Several parameters have been studied before but not the use of other waveforms and the effect of electrical charge. This study compares the effect of changing waveforms, frequencies, pulse durations, amplitudes and derived parameters in IVES.

METHODS

IVES, performed in seven female Sprague-Dawley rats, was given for 10 sec with constant current unipolar square or sawtooth pulses with different pulse durations (10, 20, or 100 msec), frequencies (5, 20, or 10 Hz) and amplitudes (2, 4, 6, and 8mA). Bladder pressure was recorded. Electrical charge and power were calculated.

RESULTS

Stimulation with the same frequency, same pulse duration and same amplitude showed significantly higher maximal pressure rises (max DeltaP) for square wave (all P < 0.05). Stimulation with the same frequency, same pulse duration and same electrical charge, gave no different max DeltaP for both waveforms (all P > 0.05). The charge and power could be reduced without changing max DeltaP, by lowering frequencies and/or shortening pulse durations.

CONCLUSIONS

Sawtooth pulses are equally effective as square pulses for inducing detrusor contraction during IVES with the same electric charge. Frequency and pulse duration had, in this study, a minor influence on the efficacy of IVES. Lower frequency and/or shorter pulse duration results in lower charge and power without changing stimulation efficacy. This finding can be important for the battery life of implanted stimulators and for patient's comfort.

The effect of intravesical electrical stimulation on bladder function and synaptic neurotransmission in the rat spinal cord after spinal cord injury

OBJECTIVE

To investigate the effects of intravesical electrical stimulation (IVES) on bladder function and synaptic neurotransmission in the lumbosacral spinal cord in the spinalized rat, as the clinical benefits of IVES in patients with increased residual urine or reduced bladder capacity have been reported but studies on the mechanism of IVES have mainly focused on bladder A delta afferents in central nervous system-intact rats.

MATERIALS AND METHODS

In all, 30 female Sprague-Dawley rats were divided equally into three groups: normal control rats, sham-stimulated spinalized rats and IVES-treated spinalized rats. IVES was started 5 weeks after spinal cord injury (SCI) and was performed 20 min a day for 5 consecutive days. At 7 days after IVES, conscious filling cystometry was performed. Sections from the L6 and S1 spinal cord segments were examined for n-methyl-d-aspartic acid receptor 1 (NMDAR1) subunit and gamma-aminobutyric acid (GABA) immunoactivity.

RESULTS

In IVES-treated spinalized rats, the number and maximal pressure of nonvoiding detrusor contractions were significantly less than in sham-stimulated spinalized rats. The mean maximal voiding pressure was also lower in IVES-treated than in sham-stimulated spinalized rats. IVES significantly reduced the interval between voiding contractions compared with the untreated spinalized rats. There was an overall increase in NMDAR1 immunoactivity after SCI, which was significantly lower in IVES-treated spinalized rats. Immunoactivity of GABA after SCI was significantly lower than in the control group and was significantly higher in IVES-treated spinalized rats.

CONCLUSION

Our results suggest that IVES might affect voiding contractions in addition to inhibiting C-fibre activity and that IVES seems to have a more complex effect on the bladder control pathway. For synaptic neurotransmission in the spinal cord, IVES could possibly shift the balance between excitation and inhibition towards inhibition.

A review of non-invasive electro neuromodulation as an intervention for non-neurogenic bladder dysfunction in children

AIMS

The use of electrotherapeutics to improve filling and emptying dysfunction of the adult bladder has been well established, however the practice in children is less well known. The purpose of this review is to summarize the rationale behind the use of electro neuromodulation in children, examine the reported efficacy of the intervention for different presentations of dysfunction, and establish the current limitations to knowledge and practice.

MATERIALS AND METHODS

A modified systematic review was carried out on all Medline studies identified as considering the use of electrotherapy or neuromodulation in children with bladder problems. Literature relating to use of this approach in adults was also searched in order to present current understanding of the treatment rationale and modes of application.

RESULTS

A Medline search and handsearch of relevant conference proceedings revealed six studies of neuromodulation in children with non-neurogenic bladder dysfunction. There were no reports of the intervention in children with isolated pelvic floor dyssynergia, irritative symptoms, structural changes predisposing the pelvic floor to weakness, or monosymptomatic nocturnal enuresis. One report of the favorable effect of neuromodulation on gut dysmotility was identified. Study design and quality generated level 4 evidence. Positive post-intervention changes reported included: increased bladder capacity, decreased severity of urge, improved continence, and decrease frequency of urinary tract infection. Significant improvement in the urodynamic parameters of bladder compliance, number of uninhibited contractions, and bladder volume at first detrusor contraction were also reported.

CONCLUSIONS

There are clear benefits from the use of electroneuromodulation in children with differing forms of voiding dysfunction. The treatment approach is independent of cognitive and pharmacological therapy, is minimally invasive, and free of side effects. To date, there are no clinical variables that reliably predict efficacy of electrotherapy in the various presentations of over and under active detrusor, sphincter dyssynergia, or irritative symptoms.

Quest for standardisation of electrical sensory testing in the lower urinary tract: the influence of technique related factors on bladder electrical thresholds

AIMS

The aim of this study is to determine the influence of technique-related factors on bladder electrical thresholds in order to establish more standardisation in electrical sensory testing in the lower urinary tract (LUT).

METHODS

In 51 young healthy volunteers, electrical thresholds were determined in the bladder by using different techniques described in the literature. Within an individual, thresholds were repeatedly determined in the bladder while varying the position of the stimulating electrodes and the intravesical volume.

RESULTS

The height of bladder electrical thresholds is influenced by the position of the stimulating electrodes and the volume of the intravesical fluid at the time of the examination. By filling the bladder, the sensitivity of the bladder toward electrical stimulation can be increased.

CONCLUSIONS

Although the techniques to test electrical sensitivity have already proven to be a valuable tool in diagnosing the presence of neuropathy in the LUT, its full scope can only be evaluated after standardisation. Therefore, it is proposed that the position of the stimulating electrodes and the bladder volume at the time of the examination should be outlined in studies and standardised.

Intravesical electrical stimulation in the treatment of micturition dysfunction in children

AIMS

To evaluate the results of intravesical electrical stimulation (IVES) in an open prospective study to treat underactive detrusor in children. The treatment was offered as an alternative to clean intermittent catheterization (CIC).

METHODS

Forty-four children were included, 21 girls and 3 boys (6-16 years, md 10) with idiopathic, 9 girls and 11 boys (4-18 years; md 13) with neurogenic underactive detrusor. IVES was given by a catheter electrode in the bladder (cathode) with the anode attached to the suprapubic abdominal skin. Continuous stimulation at 20 or 25 Hz was delivered by battery powered stimulators giving unipolar square-wave pulses (0,2 or 0,7 ms). Stimulation intensity was adjusted individually according to the acceptance of the child (12-64 mA). IVES was initially given at the clinic but 18 children had additional treatment at home. Effect of treatment was monitored by micturiton/incontinence diary, reports of bladder sensation, recordings of urinary flow, residual volume and frequency of urinary tract infections.

RESULTS

The IVES-treatment was completed by 39/44 children. Long term normalization of the voiding (md 2,5 years follow up) was obtained for 20/24 children with idiopathic problems (83%) and 8/20 with neurogenic problems (40%). Another four had much improved bladder function. The neurogenic group required more stimulation sessions than the idiopathic group. Of those on CIC, 11/15 who completed IVES could discontinue the catheterization. The frequency of urinary tract infections and incontinence decreased significantly (P < 0.01).

CONCLUSIONS

It is concluded that IVES is a promising method to treat the underactive detrusor in children.

Study of the afferent nervous system and its evaluation in women with impaired detrusor contractility treated with bethanechol

OBJECTIVES

To study the effects of subcutaneous bethanechol on the afferent nervous system and correlate these with the efficiency of this treatment in women with impaired detrusor contractility and to evaluate whether patients likely to respond to bethanechol can be identified before treatment through sensation evaluation.

METHODS

Eighteen women with impaired detrusor contractility were given subcutaneous bethanechol for 10 days, and the flow pattern and postvoid residual urine volume were monitored. The afferent nervous system was studied before and after therapy by evaluating the sensation of filling during cystometry and by determining the bladder electrical perception threshold (EPT).

RESULTS

At the end of therapy, 61% voided without a postvoid residual volume. In these women, the sensation of filling and electrical sensitivity were significantly increased compared with before treatment. In women who still voided with a postvoid residual volume, the sensation of filling had increased to a lesser extent and no change in EPT was found. Women in whom bethanechol was unsuccessful had a higher pretreatment EPT than women who were successful. No such difference was found for the sensation of filling.

CONCLUSIONS

An increase in bladder sensitivity correlated with improvement in bladder emptying and can be evaluated by studying the sensation of filling and EPT. Patients likely to respond to bethanechol can be identified before treatment on the basis of the EPT level. Therefore, it would be valuable to initiate EPT measurement in the diagnosis of patients with impaired detrusor contractility.

Posterior tibial nerve stimulation in the treatment of urge incontinence

AIMS

The objective of this study was to evaluate the effect of posterior tibial nerve stimulation (PTNS) for treatment of urge incontinence.

METHODS

In a prospective multicentre study, 35 patients with complaints of urge incontinence underwent 12 weekly sessions of PTNS at one of five sites in the Netherlands and one site in Italy. Frequency/volume charts and I-QoL and SF-36 questionnaires were completed at 0 and 12 weeks. Success was analysed by using subjective and objective criteria. Overall subjective success was defined as the willingness to continue treatment, whereas objective success was defined as a significant decrease (to<50%) in total number of leakage episodes.

RESULTS

Twenty-two patients (63%) reported a subjective success. Twenty-four patients (70%) showed a 50% or greater reduction in total number of leakage episodes. Sixteen (46%) of these-patients were completely cured (i.e., no leakage episodes) after 12 sessions. Quality of life parameters improved significantly.

CONCLUSIONS

We conclude that posterior tibial nerve stimulation is an effective, minimally invasive option for treatment of patients with complaints of urge incontinence, as improvement was seen in subjective as well as objective parameters.

Posterior tibial nerve stimulation in the treatment of idiopathic nonobstructive voiding dysfunction

OBJECTIVES

To evaluate the effect of stimulation of the posterior tibial nerve in the treatment of voiding dysfunction.

METHODS

Thirty-nine patients with chronic voiding dysfunction necessitating clean intermittent catheterization were enrolled in a prospective multicenter trial in the Netherlands (n = 19) and Italy (n = 20). They underwent 12 weekly sessions of posterior tibial nerve stimulation. Frequency/volume charts, an incontinence quality-of-life instrument, and the MOS 36-item Short-Form Health Survey were completed at 0 and 12 weeks. Subjective success was defined by the patient's positive response resulting in a request to continue treatment. Efficacy was based on analysis of the frequency/volume charts comparing the baseline values with the data at 12 weeks. A reduction of 50% or more in total catheterized volume was considered as an objective success (primary outcome measurement).

RESULTS

Of the 39 patients, 23 (59%) chose to continue treatment. The frequency/volume charts showed a 50% decrease in total catheterized volume in 16 (41%) of 39 patients. Additionally, 10 patients (26%) noted a reduction of 25% to 50% in their total catheterized volume. For all patients, the total catheterized volume decreased by a mean of -228 mL (range -49 to -528). The incontinence quality-of-life instrument and Short-Form Health Survey parameters improved significantly.

CONCLUSIONS

Percutaneous stimulation of the posterior tibial nerve seems to be an effective, minimally invasive option worth trying in patients with idiopathic voiding dysfunction. Improvement was seen in objective micturition parameters, as well as in subjective quality-of-life data.

Does bladder tone influence sensation of filling and electro-sensation in the bladder? A blind controlled study in young healthy volunteers using bethanechol

PURPOSE

The influence of bladder tone on filling sensation and electro-sensation in the bladder was studied in young healthy volunteers.

MATERIALS AND METHODS

A total of 22 healthy volunteers 18 to 30 years old were included in our study, of whom 15 received a subcutaneous injection of 5 mg bethanechol and 7 received a subcutaneous injection of water to serve as randomly selected controls. In each group filling perception was evaluated during medium fill cystometry before and 25 minutes after injection. The bladder electrical threshold was determined in each group by constant current stimulation before and 25 minutes after injection.

RESULTS

In the study group there was a marked decrease in the volume at which various filling sensations occurred after bethanechol was given. The pressure at which all filling sensations were perceived was higher after bethanechol than at baseline cystometry. The electrical threshold decreased with bethanechol. In the control group no change was noted in the perception of filling or electro-sensation.

CONCLUSIONS

Bethanechol has a distinct influence on the filling sensation and on electrical bladder stimulation. Each sensation is sharpened after the administration of bethanechol. Several hypotheses are possible to explain these effects.

Intravesical electrostimulation in pediatric patients with spinal cord defects

PURPOSE

Creating a low pressure continent urinary storage mechanism for the pediatric patient with neurogenic bladder is difficult. Current therapy, which is enterocystoplasty with intermittent catheterization, is not an ideal solution. In an effort to optimize storage we used intravesical electrostimulation in patients with spinal cord defects.

MATERIALS AND METHODS

A retrospective review of all pediatric patients undergoing bladder stimulation was performed. Parameters reviewed included indication, patient age, initial age adjusted pressure specific bladder volume (less than 30 cm. H2O), initial leak point pressure, number of treatments, number of sessions per treatment, posttreatment age adjusted pressure specific bladder volume, voiding and continence status.

RESULTS

Records of all 44 patients treated were reviewed. Indications for treatment included decreasing bladder storage pressures in 24 cases, increased continence between catheterization in 13 and achieving volitional voiding in 7. Patients who became continent had similar age at initiation of treatment, number of treatments, number of sessions, initial leak point pressure and final age adjusted pressure specific bladder volume compared to nonresponders. Nonresponders required surgical intervention to achieve continence with safe storage pressures. Overall, 16% (7 of 44) of patients were continent with safe storage pressures at the completion of treatment and 9% (4 of 44) achieved pretreatment goals.

CONCLUSIONS

While some high risk patients were spared surgery due to intravesical electrostimulation, most were not. Spontaneous voiding to completion at safe pressures was not achieved. We were unable to clarify before treatment which patients would benefit from intravesical electrostimulation.

Modulation of the micturition reflex pathway by intravesical electrical stimulation: an experimental study in the rat

Intravesical electrical stimulation (IVES) is used clinically to improve bladder evacuation in patients with inadequate micturition contractions. The procedure involves field stimulation of Adelta bladder mechanoreceptor afferents resulting in a prolonged enhancement of the micturition reflex. The aim of the present experimental study in the rat was to identify the site for this neuromodulation, whether it was due to sensitization of bladder mechanoreceptors, to enhancement of transmission in the central micturition reflex pathway, or to improved effectiveness of the peripheral motor system of the bladder. The experiments were performed on female rats, anesthetized by alpha-chloralose. Multi-unit afferent or efferent activity was recorded from bladder pelvic nerve branches during repeated cystometries before and after IVES. The specific antagonist CPPene was used to block central glutaminergic receptors of NMDA type. Micturition threshold volume decreased significantly after IVES. The afferent threshold volume, peak response, and pressure sensitivity were unchanged as were the peak efferent activity and bladder contractility. There was no efferent activity until just before the micturition contraction. The IVES-induced decrease in micturition threshold was blocked by prior administration of the NMDA (N-methyl-D-aspartic acid) antagonist CPPene (3-(2-carboxypiperazin-4-yl)-1-propenyl-1-phosphonic acid). The findings indicate that the IVES-induced modulation of the micturition reflex is due to an enhanced excitatory synaptic transmission in the central micturition reflex pathway. The observed modulation may account for the clinical beneficial effect of IVES treatment.

Prolonged enhancement of the micturition reflex in the cat by repetitive stimulation of bladder afferents

1. Prolonged modulation of the parasympathetic micturition reflex was studied in cats anaesthetized by alpha-chloralose. Reflex discharges were recorded from a thin pelvic nerve filament to the bladder and evoked by stimulation of the remaining ipsilateral bladder pelvic nerves or urethral branches of the pudendal nerve. 2. Stimulation of bladder or urethral afferents at Adelta intensity evoked micturition reflexes with a latency of 90-120 ms. Such reflexes were much enhanced following repetitive conditioning stimulation of the same afferents at 20 Hz for 5 min. 3. The reflex enhancement lasted more than 1 h after the conditioning stimulation. The effect was not prevented by a preceding complete transection of the sympathetic supply to the bladder. A prolonged suppression of the reflex was obtained after conditioning stimulation of afferents in the dorsal clitoris nerves. 4. It is proposed that the prolonged modulations of the micturition reflex represent physiological adaptive processes, which preserve a flawless function of the bladder during life. The observations provide a theoretical explanation for the beneficial effect of electric nerve stimulation in patients with voiding disorders.

Optimal conditions for the long-term modulation of the micturition reflex by intravesical electrical stimulation: an experimental study in the rat

OBJECTIVE

To determine whether induced bladder contractions influence the modulation by intravesical electrical stimulation (IVES) of the micturition reflex in anaesthetized rats, and to identify the optimal IVES frequency and duration.

MATERIALS AND METHODS

Seventy-six adult female rats, anaesthetized by alpha-chloralose. were divided into four groups to study the effect of: (i) IVES in combination with bladder contractions; (ii) bladder contractions alone; (iii) IVES frequency; and (iv) IVES duration. IVES was administered using a catheter electrode in the bladder. The effect of various IVES procedures was evaluated by determining the micturition threshold volume obtained from repeated cystometries before and after stimulation.

RESULTS

Administering IVES with standard parameters induced a significant decrease in the micturition threshold volume for about an hour. There was no difference in outcome between IVES with the bladder filled and contracting during the stimulation or empty and not contracting. Imposed bladder contractions per se had no effect on the micturition threshold volume. IVES at low frequencies (< or = 20 Hz) had a better modulatory effect than higher frequencies and the optimum duration of IVES was 5 min.

CONCLUSIONS

Evoked bladder contractions did not improve the IVES-induced modulation of the micturition reflex. These findings might help to improve the clinical application of the IVES procedure.