Electrical stimulation of the dorsal clitoral nerve reduces incontinence episodes in idiopathic faecal incontinent patients: a pilot study.

AIM: Faecal incontinence (FI) has a significant impact on quality of life. This study investigates whether stimulation of the dorsal genital nerve (DGN) improves FI symptoms. METHOD: Ten female patients suffering from idiopathic FI (median age 60 years) were included in the study. Stimulation was applied twice daily for 3 weeks at the maximal tolerable stimulation amplitude (pulse width, 200 µs; pulse rate, 20 Hz). Patients kept a 3-week bowel diary prior to stimulation, during stimulation and after the final stimulation. FI severity scores, FI Severity Visual-Analogue Score (VAS), FI Quality of Life Score (FIQL), sphincter function and rectal volume tolerance were assessed at baseline, immediately after stimulation and 3 weeks after stimulation. RESULTS: Nine patients completed the study. The Wexner score (P=0.027) and the St Mark's score (P=0.035) improved after stimulation in seven and six of the patients and improvement was maintained 3 weeks after stimulation (P=0.048 and P=0.049, respectively). The number of incontinent episodes was reduced in seven out of nine patients (P=0.025). Improvement was maintained for 3 weeks after stimulation (P=0.017). Subjective assessments of FI severity using the VAS score and the FIQl score did not improve during stimulation. Sphincter function and rectal volume tolerability were unaffected. CONCLUSION: DGN stimulation reduced the number of FI episodes in most patients suffering from idiopathic FI. Sphincter function and rectal volume tolerability were not affected. DGN stimulation may represent a new treatment for idiopathic FI.

Turning off sacral nerve stimulation does not affect gastric and small intestinal motility in patients treated for faecal incontinence.

AIM: Sacral nerve stimulation (SNS) reduces symptoms in up to 80% of patients with faecal incontinence (FI). Its effects are not limited to the distal colon and the pelvic floor. Accordingly, spinal or supraspinal neuromodulation have been suggested as part of the mode of action. The effect of SNS on gastric and small-intestinal motility was studied. METHOD: Using the magnet tracking system, MTS-1, a small magnetic pill was tracked twice through the upper gastrointestinal tract of eight patients with FI successfully treated with SNS. Following a randomized double-blind crossover design, the stimulator was either left active or was turned off for 1 week before investigations with MTS-1. RESULTS: The median (range) frequency of gastric con-tractions was 3.05 (2.83-3.40) per min during SNS and 3.04 (2.79?-3.76) per min without (P=NS). The median (range) frequency of contractions in the small intestine during the first 2h after pyloric passage was 10.005 (9.68-10.70) per min during SNS and 10.09 (9.79-10.29) per min without SNS (P=NS). The median (range) velocity of the magnetic pill during the first 2h in the small intestine was 1.6 (1.2-2.8) cm/min during SNS and 1.7 (0.8-3.7) cm/min without SNS (P=NS). Small-intestinal propagation mainly occurred during very fast movements (>15cm/min), accounting for 51% (42-60%) of the distance 3% (2-4%) of the time during SNS and for 53% (18-73%) of the distance 3% (1-8%) of the time without SNS (P=NS). CONCLUSION: Turning off SNS for 1week did not affect gastric or small-intestinal motility patterns.

Acute effect of electrical stimulation of the dorsal genital nerve on rectal capacity in patients with spinal cord injury.

BACKGROUND: Constipation and fecal incontinence are considerable problems for most individuals with spinal cord injury (SCI). Neurogenic bowel symptoms are caused by several factors including abnormal rectal wall properties. Stimulation of the dorsal genital nerve (DGN) can inhibit bladder contractions and because of common innervation inhibitory effects are anticipated in the rectum too. Therefore, DNG could have a future role in the treatment of neurogenic fecal incontinence. AIM: To study the effect of acute DGN stimulation on the rectal cross sectional area (CSA) in SCI patients. METHODS: Seven patients with complete supraconal SCI (median age 50 years) were included. Stimulation was applied via plaster-electrodes using an amplitude of twice the genito-anal reflex threshold (pulse width: 200 µs; pulse rate: 20 Hz). A pressure controlled phasic (10, 20 and 30 cmH(2)O) rectal distension protocol was repeated four times with subjects randomized to stimulation during 1st and 3rd distension series or 2nd and 4th distension series. The rectal CSA and pressure were measured using impedance planimetry and manometry. RESULTS: All patients completed the investigation. Median stimulation amplitude was 51 mA (range 30-64). CSA was smaller during stimulation and differences reached statistical significance at distension pressures of 20 cmH(2)O (average decrease 9%; P = 0.02) and 30 cmH(2)O (average decrease 4%; P = 0.03) above resting rectal pressure. Accordingly, rectal pressure-CSA relation was significantly reduced during stimulation at 20 (P=0.03) and 30 cmH(2)O distension (P=0.02). CONCLUSION: DGN Stimulation in patients with supraconal SCI results in an acute decrease of rectal CSA and the rectal pressure-CSA relation.

The acute effect of dorsal genital nerve stimulation on rectal wall properties in patients with idiopathic faecal incontinence.

AIM: Faecal continence depends on several factors, including rectal wall properties. Stimulation of the dorsal genital nerve (DGN) can suppress bladder contraction and similar effects are anticipated for the rectum. In this study, the acute effect of DGN stimulation on the rectal cross-sectional area is investigated. METHOD: Ten female patients (median age 60 years) with idiopathic faecal incontinence were included in the study. Stimulation was applied via plaster electrodes with the maximum tolerable amplitude (pulse width was 200 µs at a pulse rate of 20 Hz). Three series of pressure-controlled phasic (10, 20 and 30 cm H(2) O) and stepwise (5-30 cm H(2) O in steps of 5 cm H(2) O) rectal distensions were conducted (unstimulated, stimulated, unstimulated), and the rectal cross-sectional area (CSA) was measured with impedance planimetry. RESULTS: All patients completed the investigation. The median stimulation amplitude was 21 (8.5-27) mA. Comparing stimulated with unstimulated phasic distension, there was no significant difference in the median rectal CSA. Comparing stimulated with unstimulated stepwise distension, there was no significant difference in the median rectal CSA. Neither the rectal pressure-CSA relationship (CSA/P(R) ) nor the rectal wall tension changed during stimulation. CONCLUSION: No acute effect on rectal CSA during pressure-controlled distension was demonstrated during DGN stimulation.

Minimal invasive electrode implantation for conditional stimulation of the dorsal genital nerve in neurogenic detrusor overactivity.

STUDY DESIGN: Experimental. OBJECTIVES: Electrical stimulation of the dorsal genital nerves (DGN) suppresses involuntary detrusor contractions (IDCs) in patients with neurogenic detrusor overactivity (DO). The feasibility of minimal invasive electrode implantation near the DGN and the effectiveness of conditional stimulation to suppress IDCs at different amplitudes in spinal cord injury (SCI) patients with DO were studied. SETTING: Radboud University Nijmegen MC, The Netherlands. METHODS: In eight healthy volunteers, a needle electrode was inserted from both a medial and lateral-to-midline site at the level of the pubic bone. Electrode insertion was guided by the genito-anal reflex (GAR) evoked by electrical stimulation and by sensation to this stimulation. In eight SCI patients with DO, the bladder was repeatedly filled and emptied partially in between. Conditional stimulation using a needle electrode was applied when an IDC was observed at urodynamics. Different amplitudes were used during each filling. Control cystometry was carried out before electrode insertion and after stimulation. RESULTS: The lateral implant approach was preferred, as it was easier to manoeuvre the needle along the pubic bone and fixate the needle. In SCI patients, the electrode was positioned successfully, and IDCs were suppressed (range 1-6 IDC suppressions) with conditional stimulation at maximum tolerable amplitude, except for one patient. Stimulation was less effective at lower amplitudes. Stimulation lowered the intensity of bladder sensations concomitant with IDC. CONCLUSION: The lateral-to-midline implant approach, in combination with GAR and sensation to stimulation, is feasible for electrode implantation near the DGN in SCI patients. Conditional stimulation effectively suppresses IDCs.

Limited value of bladder sensation as a trigger for conditional neurostimulation in spinal cord injury patients.

AIMS: Conditional stimulation of dorsal genital nerves suppresses undesired detrusor contractions (UDC) and consequently increases bladder capacity and prevents incontinence. No clinically applicable sensor exists for reliable bladder activity monitoring as a trigger for conditional stimulation. Primary objective of this study was to determine whether bladder sensation concomitant with UDC may be used for spinal cord injury (SCI) patients to trigger neurostimulation in daily life. METHODS: Nineteen male and 7 female SCI patients suspected of detrusor overactivity (DO) underwent conventional and 6-hr ambulatory urodynamics. Patients were instructed to do normal daily activities and to activate event buttons of the ambulatory recorder to mark events: physical activity, bladder sensation, micturition or intermittent catheterization, and urinary incontinence. Detection rate was defined as the number of recorded bladder sensation divided by the total number of recorded UDC during ambulatory urodynamics. RESULTS: Bladder sensation was reported by 73% of patients in daily life. Only 41% of patients had analyzable bladder sensation concomitant with UDC during ambulatory urodynamics. For ambulatory and conventional urodynamics, mean detection rates were 23% and 72%, respectively, with mean recording delays of 57 and 16 sec after UDC onset, respectively. CONCLUSIONS: Bladder sensation only occurs in a small group of SCI patients combined with a rather low detection rate and long reaction time. Therefore, bladder sensation as a trigger for conditional stimulation does not seem to be suitable for SCI patients with DO. Reliable techniques for chronic bladder activity monitoring are a prerequisite for successful clinical application of conditional stimulation.

Patient controlled versus automatic stimulation of pudendal nerve afferents to treat neurogenic detrusor overactivity.

PURPOSE: We investigated whether patients with neurogenic detrusor overactivity can sense the onset of bladder contraction and in turn suppress the contraction by electrical stimulation of the dorsal penile-clitoral nerve. MATERIALS AND METHODS: A total of 67 patients with different neurological disorders were recruited to undergo 3 filling cystometries. The first cystometry was done without stimulation. The second cystometry was performed with automatic controlled stimulation based on detrusor pressure. The third cystometry was done with patient controlled stimulation using a push button. RESULTS: Four females and 13 males underwent all 3 fillings. Compared to cystometry 1 average bladder capacity for cystometries 2 and 3 was 60% higher. Compared to peak pressure for cystometry 1 average peak pressure during suppressed contractions for cystometries 2 and 3 was 49% and 26% lower, respectively. The average delay of the onset of stimulation during cystometry 3 with respect to cystometry 2 was 5.7 seconds. CONCLUSIONS: The study shows that patient controlled genital nerve stimulation is as effective as automatic controlled stimulation to treat neurogenic detrusor overactivity. Thus, patient controlled stimulation is feasible in select patients, although patients must be trained in the technique.

Ano-rectal motility responses to pelvic, hypogastric and pudendal nerve stimulation in the Göttingen minipig.

UNLABELLED: We investigated the effect of efferent stimulation of the pelvic (PN), hypogastric (HGN) and pudendal (PuN) nerves on ano-rectal motility in Göttingen minipigs using an impedance planimetry probe. Changes in the rectal cross-sectional area (CSA) at five axial positions and pressures in the rectum and anal canal were investigated simultaneously. Pelvic nerve stimulation elicited a CSA decrease in the proximal part of the rectum and a simultaneous CSA increase in its distal part. Anal pressure also decreased. Hypogastric nerve and PuN stimulation elicited an increase in anal pressure, but no rectal response. Severing the HGN produced a persistent reduction in resting anal pressure, but no change was observed when the PN and the PuN were severed. Stimulation of the distal part of all three nerves produced a persistent response. Administration of phentolamine and pancouronium eliminated the response to stimulation of the HGN and the PuN, respectively. CONCLUSION: Rectal responses to PN stimulation vary more than previously suggested. The HGN has an excitatory effect on the internal anal sphincter, and the PuN on the external anal sphincter. However, the PuN plays no major role in maintaining basal anal pressure.

Influence of implantation on the electrochemical properties of smooth and porous TiN coatings for stimulation electrodes.

OBJECTIVE: To determine whether changes in electrochemical properties of porous titanium nitride (TiN) electrodes as a function of time after implantation are different from those of smooth TiN electrodes. APPROACH: Eight smooth and 8 porous TiN coated electrodes were implanted in 8 rats. Before implantation, voltage transients, cyclic voltammograms and impedance spectra were recorded in phosphate buffered saline (PBS). After implantation, these measurements were done weekly to investigate how smooth and porous electrodes were affected by implantation. MAIN RESULTS: The electrode capacitance of the porous TiN electrodes decreased more than the capacitance of the smooth electrodes due to acute implantation under fast measurement conditions (such as stimulation pulses). This indicates that protein adhesion presents a greater diffusion limitation for counter-ions for the porous than for the smooth electrodes. The changes in electrochemical properties during the implanted period were similar for smooth and porous TiN electrodes, indicating that cell adhesion poses a similar diffusion limitation for smooth and porous electrodes. SIGNIFICANCE: This knowledge can be used to optimize the porous structure of the TiN film, so that the effect of protein adhesion on the electrochemical properties is diminished. Alternatively, an additional coating could be applied on the porous TiN that would prevent or minimize protein adhesion.

Biofouling resistance of boron-doped diamond neural stimulation electrodes is superior to titanium nitride electrodes in vivo.

OBJECTIVE: The goal of this study was to assess the electrochemical properties of boron-doped diamond (BDD) electrodes in relation to conventional titanium nitride (TiN) electrodes through in vitro and in vivo measurements. APPROACH: Electrochemical impedance spectroscopy, cyclic voltammetry and voltage transient (VT) measurements were performed in vitro after immersion in a 5% albumin solution and in vivo after subcutaneous implantation in rats for 6 weeks. MAIN RESULTS: In contrast to the TiN electrodes, the capacitance of the BDD electrodes was not significantly reduced in albumin solution. Furthermore, BDD electrodes displayed a decrease in the VTs and an increase in the pulsing capacitances immediately upon implantation, which remained stable throughout the whole implantation period, whereas the opposite was the case for the TiN electrodes. SIGNIFICANCE: These results reveal that BDD electrodes possess a superior biofouling resistance, which provides significantly stable electrochemical properties both in protein solution as well as in vivo compared to TiN electrodes.

Propulsive activity induced by sequential electrical stimulation in the descending colon of the pig.

UNLABELLED: This work was performed to study electrically induced contractions in the descending colon of pigs. Contractions were monitored using impedance planimetry and manometry. The luminal pressure, cross-sectional area (CSA), latency and velocity of CSA decrease were compared when using 3 ms, 9, 12, 15 or 30 mA pulses at 10 Hz for 10 s, and 15 mA, 0.03, 0.3 or 3 ms pulses at 10 Hz for 10 s. Stimulation was performed prior and after the application of N(G)-nitro-L-arginine methyl ester (L-NAME) and atropine. In the untreated colon, contraction was always of an 'off' type. A current increase from 9 to 30 mA increased the pressure. An increase of pulse duration from 0.03 to 3 ms shortened the latency, accelerated contraction and increased pressure. By sequential stimulation, contractions were coordinated to propel semi-fluid and solid luminal contents. L-NAME increased the magnitude of CSA decrease. Atropine induced inhibitory effects on contractions elicited by 3 ms pulses and abolished contractions induced by 0.03 and 0.3 ms pulses. IN CONCLUSION: (i) electrical stimulation evokes'off' colon contractions, which can be coordinated to result in propulsion; (ii) the best combination for current and pulse duration to induce propulsive contractions is 15 mA and 3 ms; (iii) nitrergic and cholinergic pathways mediate responses to electrical stimulation.

Influence of variable nerve fibre geometry on the excitation and blocking threshold. A simulation study.

The aim of the study was to investigate how variable fibre geometry influences the excitation and blocking threshold of an undulating peripheral nerve fibre. The sensitivity of the excitation and blocking thresholds of the nerve fibres to various geometric and stimulation parameters was examined. The nerve fibres had a spiral shape (defined by the undulation wavelength, undulation amplitude and phase), and the internodal length varied. Diameter-selective stimulation of nerve fibres was obtained using anodal block. Simulation was performed using a two-part simulation model: a volume conductor model to calculate the electrical potential distribution inside a tripolar cuff electrode and a model of a peripheral undulating human nerve fibre to simulate the fibre response to stimulation. The excitation threshold of the undulating fibres was up to 100% higher than the excitation threshold of the straight fibres. When a nerve was stimulated with long pulses, which are typically applied for anodal block (> 400 micros), the blocking threshold of the undulating fibres was up to four times higher than the blocking threshold of the straight fibres. Dependencies of the excitation threshold on geometric and stimulation parameters were the same as for a straight fibre. Dependencies of the blocking threshold on geometric and stimulation parameters were different compared with a straight fibre. Owing to the fibre undulation and variable internodal length, the blocking threshold and the minimum pulse duration to obtain anodal block were generally different in the proximal and distal directions. Owing to variable fibre geometry, the excitation threshold varied by up to +/- 40% of the mean value, and the blocking threshold varied by up to +/- 60 % of the mean value. Owing to undulation, the blocking threshold of large fibres could be higher than the blocking threshold of small-diameter fibres, even if they had the same geometry. The results indicate that, during skeletal muscle stretching and contracting or during variation in joint angle, the excitation and blocking thresholds of the nerve fibres change owing to variations in fibre geometry. A straight fibre model could be too simple for modelling the response of peripheral nerve fibres to electrical stimulation.

Selective stimulation of sacral nerve roots for bladder control: a study by computer modeling.

The aim of this study was to investigate theoretically the conditions for the activation of the detrusor muscle without activation of the urethral sphincter and afferent fibers, when stimulating the related sacral roots. Therefore, the sensitivity of excitation and blocking thresholds of nerve fibers within a sacral root to geometric and electrical parameters in tripolar stimulation using a cuff electrode, have been stimulated by a computer model. A 3-D rotationally symmetrical model, representing the geometry and electrical conductivity of a nerve root surrounded by cerebrospinal fluid and a cuff was used, in combination with a model representing the electrical properties of a myelinated nerve fiber. The electric behavior of nerve fibers having different diameters and positions in a sacral root was analyzed and the optimal geometric and electrical parameters to be used for sacral root stimulation were determined. The model predicts that an asymmetrical tripolar cuff can generate unidirectional action potentials in small nerve fibers while blocking the large fibers bidirectionally. This result shows that selective activation of the detrusor may be possible without activation of the urethral sphincter and the afferent fibers.

Different pulse shapes for selective large fibre block in sacral nerve roots using a technique of anodal block: an experimental study.

The aim of this study was experimentally to investigate whether it is possible to reduce the charge per phase that is applied during selective large fibre block. Sacral roots in pigs were stimulated. Sacral roots contain large somatic nerve fibres and small parasympathetic nerve fibres. Large nerve fibres that innervate the external urethral and external anal sphincters were selectively blocked using a technique of anodal block. In that way, selective activation of the detrusor muscle and the rectum innervated by parasympathetic fibres could be obtained. The square stimulation pulse was replaced with three different pulse shapes that had the same duration as the square pulse and consisted of a depolarising prepulse and a blocking part of the pulse. Compared with the square pulse, the charge per phase needed for anodal block could be reduced with all three pulse shapes. Maximum reduction of the charge per pulse was 17+/-6%. A lower charge might make anodal block safer in long-term applications.

Modelling selective activation of small myelinated nerve fibres using a monopolar point electrode.

The aim of this study is to investigate theoretically the possibility for activation of small myelinated nerve fibres without activating larger ones when stimulating a nerve fibre bundle using a monopolar point electrode. Therefore, the sensitivity of excitation and blocking threshold currents of nerve fibres to fibre diameter, electrode-fibre distance and pulse duration has been simulated by a computer model. A simple infinite, homogeneous volume conductor and a cathodal point source were used in combination with a model representing the electrical properties of a myelinated nerve fibre. The results show that selective activation of small myelinated fibres may be possible in a region at some distance from the electrode.

Potential distribution and single-fibre action potentials in a radially bounded muscle model.

In modelling the electrical behaviour of muscle tissue, we used to employ a frequency-dependent volume conductor network model, which was infinitely extended in all directions. Equations in this model could be solved using a finite-difference approach. The most important restriction of this model was the fact that no boundary effects could be incorporated. Analytical models of muscle tissue normally do not have this disadvantage, but in those models the microscopic structure of muscle tissue cannot be taken into account. In the paper, we present a combined numerical/analytical approach, which enables the study of potential distributions and SFAPs in simulated microscopic muscle tissue in which the influence of the muscle boundary has been considered. We considered muscle models with radii of 1.5 mm and 10 mm. Both models were compared with an unbounded network model. In the model with a radius of 1.5 mm we varied the position of the active fibre relative to the muscle surface. It appeared that in most cases the presence of a boundary had a considerable effect on the potential distribution. An increase in the peak-to-peak value of the SFAP amplitude up to 300 per cent was noticed when the active fibre was positioned 500 microns beneath the muscle surface in a model with a radius of 1.5 mm.

An implant for chronic selective stimulation of nerves.

An implantable stimulator system has been developed for nerve stimulation. The system is capable of stimulating selectively, either by fibre position, fibre size or by sending action potentials in one direction only, based on the use of nerve cuffs. The stimulator produces either quasi-trapezoidal current pulses, to allow anodal blocking, or conventional rectangular-shaped current pulses, of amplitude 20 microA to 5 mA (in 20 microA steps) with duration of 16 micros to 1 ms (in 8 micros steps). For safety, both active and passive charge balancing is used. The amplitude of the active charge-balancing phase can be varied between 1/7 and 1/47 of the pulse amplitude. During manufacture, each implant is customised so as to drive either 6 quasi-tripolar (dipolar), 4 tripolar or 2 pentapolar cuffs. Possible applications of the device are: improved defaecation and bladder voiding after spinal cord injury, by stimulation of the sacral motor roots; neuromodulation to reduce hyperreflexia without concomitant muscle contractions; in stroke patients, to enable balanced inversion-eversion while dorsiflexing the ankle by stimulating the peroneal nerve. It may also be used in chronic animal experiments.This paper describes the implant system, its hardware and communication protocol, and shows results from in vitro tests of the device and the first acute anodal-blocking experiments in pigs.

Bladder and urethral responses to pelvic nerve stimulation in the pig.

OBJECTIVE: The aim of our study of the pig was to investigate the responses of smooth muscle of the bladder and the urethral sphincter to preganglionic parasympathetic stimulation, and to assess the effect on the lower urinary tract of IV administration of alpha,beta-methylene-ATP. MATERIALS AND METHODS: In seven anaesthetised female pigs, the responses to repeated 20 s pelvic nerve stimulations before and after IV administration of 0.02 mg/kg alpha-beta-methylene-ATP, and the responses to the drug itself, were recorded in the bladder and the urethra separately. RESULTS: In the urethral high-pressure zone, pre-stimulation pressure was a mean of 61+/-11 cmH2O. During pelvic nerve stimulation, urethral pressure declined by 48+/-9 cmH2O, while the bladder pressure increased to 30+/-18 cmH2O. The rate of pressure changes during the first 3 s of stimulation (initiation of voiding) was larger in the urethra than in the bladder (urethral pressure decrease: 13.0+/-3.1 cmH2O/s, bladder pressure increase: 3.2+/-2.5 cmH2O/s). Administration of alpha,beta-methylene-ATP was followed by a significant but temporary enlargement in the bladder response to pelvic nerve stimulation to 36+/-20 cmH2O, p = 0.028, n = 7, but no change in urethral response. CONCLUSIONS: At least 80% of the urethral pre-stimulation pressure was exerted by the smooth muscle. The synergic activation of the detrusor and the urethral smooth muscle in response to preganglionic parasympathetic nerve stimulation was controlled by the peripheral nerves or by the neuromuscular transmission. Administration of alpha,beta-methylene-ATP increased the bladder response to pelvic nerve stimulation without changing the urethral response.

Detecting the onset of urinary bladder contractions using an implantable pressure sensor.

This study investigates whether signals obtained from an implantable pressure sensor placed in the urinary bladder wall could be used to detect the onset of bladder contractions. The sensor assembly was custom made using a small piezoresistive sensor die. The die was mounted on ceramic substrate (8 mm × 8 mm) and encapsulated in silicone by a two-part moulding process. The final sensor was lens shaped with a diameter of 13.6 mm and height of 2.0 mm. Experiments were performed in six pigs that had one or more sensors placed in the bladder wall. An external reference sensor was used to simultaneously monitor intravesical pressure via a transurethral catheter. Bladder contractions were evoked by unilateral electrical stimulation of the pelvic nerve. Onset latency was computed using both signals. In addition, the correlation between wall pressure and intravesical pressure was calculated. On average, the onset latency was - 307 ms using the wall sensors compared to the intravesical pressure, i.e., the detection occurred earlier using the wall sensors than the intravesical sensor. In 91 of 114 recordings the correlation coefficient was above 0.90. In conclusion, the implantable sensor performs similar to the reference sensor when used to detect the onset of bladder contractions.

Urethral sphincter EMG-controlled dorsal penile/clitoral nerve stimulation to treat neurogenic detrusor overactivity.

The goal of this study was to investigate whether real-time external urethral sphincter (EUS) EMG-controlled dorsal genital nerve (DGN) stimulation can suppress undesired detrusor bladder contractions in patients with both neurogenic detrusor overactivity (NDO) and detrusor sphincter dyssynergia (DSD). Detrusor pressure (Pdet) and EUS EMG were recorded in 12 neurogenic patients who underwent two filling cystometries. The first one was without stimulation and was intended to confirm the NDO and DSD and to set the EMG detection threshold. The second one was with real-time EMG-controlled stimulation of DGNs. Two detection methods were analyzed to detect bladder contractions. The first method was a Kurtosis-scaled root mean square (RMS) detector and was used on-line. The second was a simple RMS detector and was used off-line. Of 12 patients included, 10 patients showed both NDO and DSD. In nine of these ten patients relevant EMG concomitant to detrusor activity was detected and stimulation could suppress at least one detrusor contraction. The second filling compared to the first one showed an increase of 84% in bladder capacity (p = 0.002) and a decrease of 106% in Pdet (p = 0.002). Nine false-positive detections occurred during the ten fillings with electrical stimulation. The mean increases of both time and Pdet between stimulation and bladder contraction onsets for method 1 were 1.8 s and 4 cmH(2)O and for method 2 were 0.9 s and 2 cmH(2)O, respectively. This study shows that EUS EMG can be used in real time to detect the onset of a bladder contraction. In combination with DGN stimulation has been shown to be feasible to suppress undesired bladder contractions and in turn to increase bladder capacity in subjects with both NDO and DSD.