Treatment of neurogenic detrusor overactivity in spinal cord injured patients by conditional electrical stimulation

Automated closed-loop stimulation to inhibit neurogenic bladder overactivity

Individuals with spinal cord injury (SCI) usually develop neurogenic detrusor overactivity (NDO), resulting in bladder urgency and incontinence, and reduced quality of life. Electrical stimulation of the genital nerves (GNS) can inhibit uncontrolled bladder contractions in individuals with SCI. An automated closed-loop bladder neuromodulation system currently does not exist but could improve this approach. We have developed a custom algorithm to identify bladder contractions and trigger stimulation from bladder pressure data without need for abdominal pressure measurement. The goal of this pilot study was to test the feasibility of automated closed-loop GNS using our custom algorithm to identify and inhibit reflex bladder contractions in real time. Experiments were conducted in a single session in a urodynamics laboratory in four individuals with SCI and NDO. Each participant completed standard cystometrograms without and with GNS. Our custom algorithm monitored bladder vesical pressure and controlled when GNS was turned on and off. The custom algorithm detected bladder contractions in real time, successfully inhibiting a total of 56 contractions across all four subjects. There were eight false positives, six of those occurring in one subject. It took approximately 4.0 ± 2.6 s for the algorithm to detect the onset of a bladder contraction and trigger stimulation. The algorithm maintained stimulation for approximately 3.5 ± 1.7 s, which was enough to inhibit activity and relieve feelings of urgency. Automated closed-loop stimulation was well-tolerated and subjects reported that algorithm decisions generally matched with their perceptions of bladder activity. The custom algorithm automatically, successfully identified bladder contractions to trigger stimulation to inhibit bladder contractions acutely. Closed-loop neuromodulation using our custom algorithm is feasible, but further testing is needed refine this approach for use in a home environment.

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.

Control of Forelimb and Hindlimb Movements and Their Coordination during Quadrupedal Locomotion across Speeds in Adult Spinal Cats

Coordinating the four limbs is critical for terrestrial mammalian locomotion. Thoracic spinal transection abolishes neural communication between the brain and spinal networks controlling hindlimb/leg movements. Several studies have shown that animal models of spinal transection (spinalization), such as mice, rats, cats, and dogs recover hindlimb locomotion with the forelimbs stationary or suspended. We know less on the ability to generate quadrupedal locomotion after spinal transection, however. We collected kinematic and electromyography data in four adult cats during quadrupedal locomotion at five treadmill speeds before (intact cats) and after low-thoracic spinal transection (spinal cats). We show that adult spinal cats performed quadrupedal treadmill locomotion and modulated their speed from 0.4 m/sec to 0.8 m/sec but required perineal stimulation. During quadrupedal locomotion, several compensatory strategies occurred, such as postural adjustments of the head and neck and the appearance of new coordination patterns between the forelimbs and hindlimbs, where the hindlimbs took more steps than the forelimbs. We also observed temporal changes, such as shorter forelimb cycle/swing durations and shorter hindlimb cycle/stance durations in the spinal state. Forelimb double support periods occupied a greater proportion of the cycle in the spinal state, and hindlimb stride length was shorter. Coordination between the forelimbs and hindlimbs was weakened and more variable in the spinal state. Changes in muscle activity reflected spatiotemporal changes in the locomotor pattern. Despite important changes in the pattern, our results indicate that biomechanical properties of the musculoskeletal system play an important role in quadrupedal locomotion and offset some of the loss in neural communication between networks controlling the forelimbs and hindlimbs after spinal transection.

Targeting bladder function with network-specific epidural stimulation after chronic spinal cord injury

Profound dysfunctional reorganization of spinal networks and extensive loss of functional continuity after spinal cord injury (SCI) has not precluded individuals from achieving coordinated voluntary activity and gaining multi-systemic autonomic control. Bladder function is enhanced by approaches, such as spinal cord epidural stimulation (scES) that modulates and strengthens spared circuitry, even in cases of clinically complete SCI. It is unknown whether scES parameters specifically configured for modulating the activity of the lower urinary tract (LUT) could improve both bladder storage and emptying. Functional bladder mapping studies, conducted during filling cystometry, identified specific scES parameters that improved bladder compliance, while maintaining stable blood pressure, and enabled the initiation of voiding in seven individuals with motor complete SCI. Using high-resolution magnetic resonance imaging and finite element modeling, specific neuroanatomical structures responsible for modulating bladder function were identified and plotted as heat maps. Data from this pilot clinical trial indicate that scES neuromodulation that targets bladder compliance reduces incidences of urinary incontinence and provides a means for mitigating autonomic dysreflexia associated with bladder distention. The ability to initiate voiding with targeted scES is a key step towards regaining volitional control of LUT function, advancing the application and adaptability of scES for autonomic function.

Inhibition and Facilitation of the Spinal Locomotor Central Pattern Generator and Reflex Circuits by Somatosensory Feedback From the Lumbar and Perineal Regions After Spinal Cord Injury

Somatosensory feedback from peripheral receptors dynamically interacts with networks located in the spinal cord and brain to control mammalian locomotion. Although somatosensory feedback from the limbs plays a major role in regulating locomotor output, those from other regions, such as lumbar and perineal areas also shape locomotor activity. In mammals with a complete spinal cord injury, inputs from the lumbar region powerfully inhibit hindlimb locomotion, while those from the perineal region facilitate it. Our recent work in cats with a complete spinal cord injury shows that they also have opposite effects on cutaneous reflexes from the foot. Lumbar inputs increase the gain of reflexes while those from the perineal region decrease it. The purpose of this review is to discuss how somatosensory feedback from the lumbar and perineal regions modulate the spinal locomotor central pattern generator and reflex circuits after spinal cord injury and the possible mechanisms involved. We also discuss how spinal cord injury can lead to a loss of functional specificity through the abnormal activation of functions by somatosensory feedback, such as the concurrent activation of locomotion and micturition. Lastly, we discuss the potential functions of somatosensory feedback from the lumbar and perineal regions and their potential for promoting motor recovery after spinal cord injury.

Ambulatory urodynamic monitoring assessment of dorsal genital nerve stimulation for suppression of involuntary detrusor contractions following spinal cord injury: a pilot study

STUDY DESIGN

A prospective interventional pilot study using within-individual comparisons.

OBJECTIVES

To assess the effect of dorsal genital nerve stimulation (DGNS) on urine-storage parameters in participants with spinal cord injury (SCI) and neurogenic detrusor overactivity (NDO) during natural bladder filling.

SETTING

The London Spinal Cord Injuries Centre at the Royal National Orthopaedic Hospital, Stanmore, UK.

METHODS

Ambulatory urodynamic monitoring (AUM) was carried out with and without DGNS, before and after a week of using DGNS at home. DGNS was applied on-demand by four participants with bladder sensation, and both continuously and intermittently by one participant with absent sensation. A Wilcoxon sign-rank test was used to test paired results of changes within an AUM session.

RESULTS

Urodynamic outcomes were improved using DGNS. Bladder capacity was increased from 244 ± 59 to 346 ± 61 ml (p = 0.0078), a mean change of 46 ± 25%. Maximum detrusor pressure was decreased from 58 ± 18 to 47 ± 18 cmH2O (p = 0.0156), a change of 17 ± 13%, and average peak detrusor pressure was decreased from 56 ± 16 to 31 ± 128 cmH2O (p = 0.0156), a mean reduction of 50 ± 19%. There was an increase in the number of detrusor contractions from the first involuntary detrusor contraction to a strong desire, urgency or incontinence, from 1.5 ± 1.4 to 4.3 ± 1.7, and an increase in time of 23 ± 22 min. There were no changes in baseline outcomes following home use of DGNS.

CONCLUSIONS

DGNS may be applied on-demand, intermittently or continuously, to increase bladder capacity, decrease storage pressures and provide extra time. Improvements were made in addition to existing antimuscarinic medication regimes.

Estimation of Bladder Pressure and Volume from the Neural Activity of Lumbosacral Dorsal Horn Using a Long-Short-Term-Memory-based Deep Neural Network

In this paper, we propose a deep recurrent neural network (DRNN) for the estimation of bladder pressure and volume from neural activity recorded directly from spinal cord gray matter neurons. The model was based on the Long Short-Term Memory (LSTM) architecture, which has emerged as a general and effective model for capturing long-term temporal dependencies with good generalization performance. In this way, training the network with the data recorded from one rat could lead to estimating the bladder status of different rats. We combined modeling of spiking and local field potential (LFP) activity into a unified framework to estimate the pressure and volume of the bladder. Moreover, we investigated the effect of two-electrode recording on decoding performance. The results show that the two-electrode recordings significantly improve the decoding performance compared to single-electrode recordings. The proposed framework could estimate bladder pressure and volume with an average normalized root-mean-squared (NRMS) error of 14.9 ± 4.8% and 19.7 ± 4.7% and a correlation coefficient (CC) of 83.2 ± 3.2% and 74.2 ± 6.2%, respectively. This work represents a promising approach to the real-time estimation of bladder pressure/volume in the closed-loop control of bladder function using functional electrical stimulation.

At-home genital nerve stimulation for individuals with SCI and neurogenic detrusor overactivity: A pilot feasibility study

OBJECTIVE

Neurogenic bladder dysfunction, including neurogenic detrusor overactivity (NDO) is one of the most clinically significant problems for persons with spinal cord injury (SCI), affecting health and quality of life. Genital nerve stimulation (GNS) can acutely inhibit NDO-related reflex bladder contractions and increase bladder capacity. However, it is unknown if GNS can improve urinary continence or help meet individuals' bladder management goals during sustained use, which is required for GNS to be clinically effective.

DESIGN

Subjects maintained voiding diaries during a one-month control period without stimulation, one month with at-home GNS, and one month after GNS. Urodynamics and quality of life assessments were conducted after each treatment period, and a satisfaction survey was taken at study completion.

SETTING

Subject screening and clinical procedures were conducted at the Louis Stokes Cleveland VA Medical Center. Stimulation use and voiding diary entries were conducted in subjects' homes.

PARTICIPANTS

Subjects included five men with SCI and NDO.

INTERVENTIONS

This study tested one month of at-home portable non-invasive GNS.

OUTCOME MEASURES

The primary outcome measure was leakage events per day. Secondary outcome measures included self-reported subject satisfaction, bladder capacity, and stimulator use frequency.

RESULTS

GNS reduced the number of leakage events from 1.0 ± 0.5 to 0.1 ± 0.4 leaks per day in the four subjects who reported incontinence data. All study participants were satisfied that GNS met their bladder goals; wanted to continue using GNS; and would recommend it to others.

CONCLUSIONS

Short term at-home GNS reduced urinary incontinence and helped subjects meet their bladder management goals. These data inform the design of a long-term clinical trial testing of GNS as an approach to reduce NDO.

Ambulatory urodynamic monitoring: state of the art and future directions

Urodynamic studies are a key component of the clinical evaluation of lower urinary tract dysfunction and include filling cystometry, pressure-flow studies, uroflowmetry, urethral function tests and electromyography. However, pitfalls of traditional urodynamics include physical and emotional discomfort, artificial test conditions with catheters and rapid retrograde filling of the bladder, which result in variable diagnostic accuracy. Ambulatory urodynamic monitoring (AUM) uses physiological anterograde filling and, therefore, offers a longer and more physiologically relevant evaluation. However, AUM methods rely on traditional catheters and pressure transducers and do not measure volume continuously, which is required to provide context for pressure changes. Novel telemetric AUM (TAUM) methods that use wireless, catheter-free, battery-powered devices to monitor bladder pressure and volume while patients carry out their daily activities are currently being investigated. TAUM devices under current development are innovating in the areas of remote monitoring, rechargeable energy sources, device deployment and retrieval and materials engineering to provide increased diagnostic accuracy and improved comfort for patients with incontinence or voiding dysfunction. These devices hold promise for improving the diagnosis and management of patients with lower urinary tract disorders.

Sacral neuromodulation in congenital lumbo-sacral and traumatic spinal cord defects with neurogenic lower urinary tract symptoms: a single-center experience in children and adolescents

PURPOSE

This study evaluated sacral neuromodulation's effectiveness for managing refractory neuropathic lower urinary tract dysfunction in children and adolescents.

METHODS

Twenty-five children and adolescents underwent peripheral nerve evaluation test phase of sacral neuromodulation at our center. Thirteen (seven boys and six girls) cases suffered from neuropathic lower urinary tract dysfunction refractory to the maximum medical treatment. The test was done with temporary wire in all patients. Patients with more than 50% improvement in symptoms were chosen for the second stage of implantation of quadripolar tined lead and implantable pulse generator. Bowel transit symptoms were recorded before and after the surgery.

RESULTS

Eight patients (61.53%; five boys and three girls) had positive responses to the peripheral nerve evaluation test phase. They underwent implantation of permanent quadripolar tined lead and implantable pulse generator. The etiologies were lumbosacral myelomeningocele, occult spina bifida, partial sacral agenesis and incomplete spinal cord injury. Positive clinical response (> 50% improvement in symptoms) was achieved in seven (85%) at a mean follow-up of 14.25 months. Three patients became capable to stop clean intermittent catheterization (P =0.125). The 24-h pad test decreased from 484 to 78 g from before to after the surgery (P =0.043).

CONCLUSION

This clinical study on a small sample size of children and adolescents demonstrates positive results in short-term follow-up. However, as the procedure is still not approved officially, multicenter studies with more patients can prove the safety and efficacy of sacral neuromodulation in long term among this special group of patients.

Recent update on basic mechanisms of spinal cord injury

Spinal cord injury (SCI) is a life-shattering neurological condition that affects between 250,000 and 500,000 individuals each year with an estimated two to three million people worldwide living with an SCI-related disability. The incidence in the USA and Canada is more than that in other countries with motor vehicle accidents being the most common cause, while violence being most common in the developing nations. Its incidence is two- to fivefold higher in males, with a peak in younger adults. Apart from the economic burden associated with medical care costs, SCI predominantly affects a younger adult population. Therefore, the psychological impact of adaptation of an average healthy individual as a paraplegic or quadriplegic with bladder, bowel, or sexual dysfunction in their early life can be devastating. People with SCI are two to five times more likely to die prematurely, with worse survival rates in low- and middle-income countries. This devastating disorder has a complex and multifaceted mechanism. Recently, a lot of research has been published on the restoration of locomotor activity and the therapeutic strategies. Therefore, it is imperative for the treating physicians to understand the complex underlying pathophysiological mechanisms of SCI.

Genital nerve stimulation increases bladder capacity after SCI: A meta-analysis

BACKGROUND

Neurogenic detrusor overactivity (NDO) often results in decreased bladder capacity, urinary incontinence, and vesico-ureteral reflux. NDO can trigger autonomic dysreflexia and can impair quality of life. Electrical stimulation of the genital nerves (GNS) acutely inhibits reflex bladder contractions and can increase bladder capacity. Quantifying the effect of GNS on bladder capacity and determining what study factors and subject factors influence bladder capacity improvements will inform the design of clinical GNS interventions.

METHODS

We measured bladder capacity in 33 individuals with NDO, with and without GNS. These data were combined with data from seven previous GNS studies (n=64 subjects). A meta-analysis of the increase in bladder capacity and potential experimental factors was conducted (n=97 subjects total).

RESULTS

Bladder capacity increased 131±101 ml with GNS across subjects in all studies. The number of individuals whose bladder capacity was greater than 300 ml increased from 24% to 62% with GNS. Stimulus amplitude was a significant factor predicting bladder capacity gain. The variance of the bladder capacity gain significantly increased with increasing infusion rate. Other factors did not contribute to bladder capacity gain.

CONCLUSION

GNS acutely increases bladder capacity in individuals with NDO. The consistent increase in magnitude of bladder capacities across the eight studies, and the lack of dependence on individual-specific factors, provide confidence that GNS could be an effective tool for many individuals with NDO. Studies of the chronic effect of GNS on bladder control, with clinical measures such as urinary continence, are needed.

Genital nerve stimulation is tolerable and effective for bladder inhibition in sensate individuals with incomplete SCI

BACKGROUND

Neurogenic detrusor overactivity after spinal cord injury (SCI) causes urinary incontinence and reduces bladder capacity. Surface electrical genital nerve stimulation (GNS) acutely inhibits reflex bladder contractions. The stimulation amplitude selected for GNS is typically twice the amplitude that is required to evoke the pudendal-anal reflex. There is concern about the ability of persons with sensation to comfortably tolerate effective levels of GNS. The objective of this work is to determine if persons with incomplete SCI are able to tolerate acute GNS for bladder inhibition.

METHODS

Twenty-four subjects with neurogenic detrusor overactivity, SCI, and pelvic sensation were enrolled in this case series. The setting was the Spinal Cord Injury Service of a Veterans Affairs Medical Center. Primary outcome measures were sensation threshold and tolerable stimulation amplitude; secondary outcome measures were bladder capacity and bladder contraction inhibition.

RESULTS

GNS was tolerable up to 30±16 mA (range 8 mA to ≥60 mA) at amplitudes greater than twice the pudendal-anal (PA) reflex threshold, which was 8±5 mA (range 4 mA to 20 mA). Twelve subjects tolerated GNS at greater than twice the PA, six tolerated 1-1.5 times the PA, and five had no identifiable PA. GNS at tolerable amplitudes inhibited reflexive bladder contractions or increased bladder capacity 135±109 mL (n=23). GNS did not cause autonomic dysreflexia or intolerable spasticity.

CONCLUSIONS

GNS is tolerable at amplitudes that effectively inhibit neurogenic detrusor overactivity in individuals with pelvic sensation. GNS therefore is a tool with potential clinical applications for persons with preserved sensation.

Conditional neuromodulation of neurogenic detrusor overactivity using transrectal stimulation in patients with spinal cord injury: A proof of principle study

AIMS

A proof of principle study of a novel wearable device to control neurogenic detrusor over-activity in eight male spinal cord injured subjects using conditional neuromodulation.

METHODS

Transrectal stimulation was delivered through the device in response to simultaneously recorded external anal sphincter (EAS) contraction as a marker for neurogenic detrusor overactivity (NDO). The effect of conditional neuromodulation on bladder capacity and maximum detrusor pressure was investigated in addition to reliability of dyssynergic sphincter contraction as a marker for NDO.

RESULTS

Conditional neuromodulation through the novel device showed a statistically significant increase in bladder capacity and reduction in maximum detrusor pressure in six male subjects with spinal cord injury (SCI). EAS activity was a reliable surrogate for detection of NDO.

CONCLUSIONS

It has been shown for the first time that conditional neuromodulation can be delivered and triggered via a single biocompatible device placed in the anal canal. The pudendal nerves lying in Alcock's canal were stimulated through the wall of the anal canal, and the dyssynergic activity of the EAS was used to detect NDO and trigger neuromodulation giving significant increases in bladder capacity and reduction in detrusor pressure in six male subjects with SCI.

Suburothelial Bladder Contraction Detection with Implanted Pressure Sensor

Aims

Managing bladder pressure in patients with neurogenic bladders is needed to improve rehabilitation options, avoid upper tract damage, incontinence, and their associated co-morbidities and mortality. Current methods of determining bladder contractions are not amenable to chronic or ambulatory settings. In this study we evaluated detection of bladder contractions using a novel piezoelectric catheter-free pressure sensor placed in a suburothelial bladder location in animals.

Methods

Wired prototypes of the pressure monitor were implanted into 2 nonsurvival (feline and canine) and one 13-day survival (canine) animal. Vesical pressures were obtained from the device in both suburothelial and intraluminal locations and simultaneously from a pressure sensing catheter in the bladder. Intravesical pressure was monitored in the survival animal over 10 days from the suburothelial location and necropsy was performed to assess migration and erosion.

Results

In the nonsurvival animals, the average correlation between device and reference catheter data was high during both electrically stimulated bladder contractions and manual compressions (r = 0.93±0.03, r = 0.89±0.03). Measured pressures correlated strongly (r = 0.98±0.02) when the device was placed in the bladder lumen. The survival animal initially recorded physiologic data, but later this deteriorated. However, endstage intraluminal device recordings correlated (r = 0.85±0.13) with the pressure catheter. Significant erosion of the implant through the detrusor was found.

Conclusions

This study confirms correlation between suburothelial pressure readings and intravesical bladder pressures. Due to device erosion during ambulatory studies, a wireless implant is recommended for clinical rehabilitation applications.

Minimizing a Wireless Passive LC-Tank Sensor to Monitor Bladder Pressure: A Simulation Study

In this simulation study, a wireless passive LC-tank sensor system was characterized. Given the application of continuous bladder monitoring, a specific system was proposed in terms of coil geometries and electronic circuitry. Coupling coefficients were spatially mapped by simulation, as a function of both coil distance, and longitudinal and transverse translation of the sensor relative to the antenna. Further, two interrogation schemes were outlined. One was an auto-balancing bridge for computing the sensor-system impedance. In this case, the theoretical noise limit of the analogue part of the system was found by simulations. As the full system is not necessary for obtaining a pressure reading from the sensor, a simplified circuit more suited for an implantable system was deduced. For this system, both the analogue and digital parts were simulated. First, the required ADC resolution for operating the system at a given coupling was found by simulations in the noise-free case. Then, for one selected typical operational point, noise was added gradually, and through Monte-Carlo type simulations, the system performance was obtained. Combining these results, it was found that it at least is possible to operate the proposed system for distances up to 12 mm, or equivalently for coupling coefficients above 0.005. In this case a 14 bit ADC is required, and a carrier SNR of 27 dB can be tolerated.

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.

Real-Time Classification of Bladder Events for Effective Diagnosis and Treatment of Urinary Incontinence

Diagnosis of lower urinary tract dysfunction with urodynamics has historically relied on data acquired from multiple sensors using nonphysiologically fast cystometric filling. In addition, state-of-the-art neuromodulation approaches to restore bladder function could benefit from a bladder sensor for closed-loop control, but a practical sensor and automated data analysis are not available. We have developed an algorithm for real-time bladder event detection based on a single in situ sensor, making it attractive for both extended ambulatory bladder monitoring and closed-loop control of stimulation systems for diagnosis and treatment of bladder overactivity. Using bladder pressure data acquired from 14 human subjects with neurogenic bladder, we developed context-aware thresholding, a novel, parameterized, user-tunable algorithmic framework capable of real-time classification of bladder events, such as detrusor contractions, from single-sensor bladder pressure data. We compare six event detection algorithms with both single-sensor and two-sensor systems using a metric termed Conditional Stimulation Score, which ranks algorithms based on projected stimulation efficacy and efficiency. We demonstrate that adaptive methods are more robust against day-to-day variations than static thresholding, improving sensitivity and specificity without parameter modifications. Relative to other methods, context-aware thresholding is fast, robust, highly accurate, noise-tolerant, and amenable to energy-efficient hardware implementation, which is important for mapping to an implant device.

Electrical management of neurogenic lower urinary tract disorders

Management of lower urinary tract dysfunction (LUTD) in neurological diseases remains a priority because it leads to many complications such as incontinence, renal failure and decreased quality of life. A pharmacological approach remains the first-line treatment for patients with neurogenic LUTD, but electrical stimulation is a well-validated and recommended second-line treatment. However, clinicians must be aware of the indications, advantages and side effects of the therapy. This report provides an update on the 2 main electrical stimulation therapies for neurogenic LUTD - inducing direct bladder contraction with the Brindley procedure and modulating LUT physiology (sacral neuromodulation, tibial posterior nerve stimulation or pudendal nerve stimulation). We also describe the indications of these therapies for neurogenic LUTD, following international guidelines, as illustrated by their efficacy in patients with neurologic disorders. Electrical stimulation could be proposed for neurogenic LUTD as second-line treatment after failure of oral pharmacologic approaches. Nevertheless, further investigations are needed for a better understanding of the mechanisms of action of these techniques and to confirm their efficacy. Other electrical investigations, such as deep-brain stimulation and repetitive transcranial magnetic stimulation, or improved sacral anterior root stimulation, which could be associated with non-invasive and highly specific deafferentation of posterior roots, may open new fields in the management of neurogenic LUTD.

Extradural implantation of sacral anterior root stimulator in spinal cord injury patients

AIMS

To evaluate the efficacy and complications of extradural sacral anterior root stimulation (SARS) implantation in patients with neurogenic detrusor overactivity (NDO) resulting from spinal cord injury (SCI).

MATERIALS AND METHODS

A retrospective study was conducted between 2009 and 2013, on consecutive patients with NDO associated with SCI that underwent SARS implantation. We evaluated those factors related to clinical symptoms such as urinary infection rate, erections, and episodes of autonomic dysreflexia. Data from cystometric bladder capacity (CBC) and post-void residual (PVR) volume were also analyzed.

RESULTS

Of the 104 patients included in the study, 95 (91%) patients were men with a mean (standard deviation) (SD) age of 38 (10) years. Mean (SD) time between the onset of SCI and the SARS was 78.2 (59.0) months. At baseline, 95 (91%) patients had urinary infections as compared with 16 (15%) after treatment, P < 0.001. The percentage of patients that had urinary incontinence was significantly higher at baseline than that observed after SARS, 100% versus 14%, respectively, P < 0.001. Similar results were obtained regarding dysreflexia, P < 0.001. After SARS, the mean (SD) bladder capacity was 362 (108) ml and 98 (94%) patients had a bladder capacity greater than 400 ml. As regard to the adverse effects, six patients (6%) required a suburethral mesh implant and two (2%) patients had an infection, 4 and 5 months after SARS, respectively.

CONCLUSIONS

Extradural implantation of SARS seems to be an effective and safe procedure in patients with spinal cord injury and neurogenic detrusor overactivity. Neurourol. Urodynam. 35:970-974, 2016. © 2015 Wiley Periodicals, Inc.

Management and rehabilitation of neurologic patients with lower urinary tract dysfunction

Diverse lower urinary tract problems arise in neurologic disease, caused by dysfunctions of the bladder and outlet, both during urine storage and voiding. Most neurologic diseases cause some lower urinary tract dysfunction (LUTD), and the type of dysfunction is related to the location of the nervous system lesion. Clinical evaluation requires identification of risk factors for major morbidity, particularly renal dysfunction, and mechanisms underlying symptoms. A holistic approach is needed to cover influential aspects (e.g., cognitive function, mobility, and urinary tract infections) and related issues (e.g., sexual function, bowel function, and autonomic dysreflexia), requiring a multidisciplinary team. Comprehensive history and examination are supported by a bladder diary, urinalysis, and renal assessment, supplemented by urodynamic tests. The simplest classification of neurogenic LUTD describes both bladder and sphincter function, cataloging each structure as normal, overactive, or underactive. Treatment aims to protect life expectancy and improve quality of life, noting the possibility of neurologic disease progression and comorbid disorders. Conservative measures include fluid advice and assessment of suitable containment products. Urine storage can be improved with antimuscarinic medications, bladder injections with botulinum neurotoxin A, and less established methods such as nerve stimulation, intravesical instillations, and beta-3 agonist. For severe storage dysfunction, sacral neuromodulation or surgery to improve reservoir function, increase outlet resistance, or divert the urinary tract may be needed. Voiding is usually replaced by intermittent or indwelling catheterization, which has largely superseded triggered reflex voiding, bladder expression, or sphincterotomy. Treatment selection is hampered by a limited, low-quality evidence base.

Iatrogenic urological triggers of autonomic dysreflexia: a systematic review

STUDY DESIGN

This is a systematic review.

OBJECTIVE

The objective of this study was to review the literature on iatrogenic urological triggers of autonomic dysreflexia (AD).

SETTING

This study was conducted in an international setting.

METHODS

A systematic review was conducted from PubMed search using AD/ autonomic hyperreflexia and spinal cord injury (SCI). Studies selected for review involved iatrogenic urological triggers of AD in individuals with SCI, including original articles, previous practice guidelines, case reports and literature reviews. Studies that did not report AD or blood pressure (BP) assessments during urological procedures were excluded.

RESULTS

Forty studies were included for analysis and categorized into four groups: (1) urodynamics and cystometry; (2) cystoscopy and transurethral litholapaxy; (3) extracorporeal shock-wave lithotripsy (ESWL); and (4) other procedures. During urodynamics, the incidence of AD ranged from 36.7% to 77.8%. The symptomatic rate ranged from 50% to 65%, with AD symptoms seen predominantly in cervical SCI patients. The studies imply no consensus regarding the relationship between AD, neurogenic detrusor overactivity and detrusor sphincter dyssynergia. Without anesthesia, the majority of individuals develop AD during cystoscopy, transurethral litholapaxy and ESWL. The effectiveness of different anesthesia methods relies on blocking the nociceptive signals from the lower urinary tract (LUT) below the level of the neurological lesion. Other iatrogenic urological triggers were commonly associated with bladder filling.

CONCLUSION

The LUT triggers of episodes of AD are often associated with iatrogenic urological procedures. AD was more prevalent in cervical SCI than in thoracic SCI. To detect this potential life-threatening complication following cervical and high thoracic SCI, routine BP monitoring during urological procedures is highly recommended.

Electrical stimulation for the treatment of lower urinary tract dysfunction after spinal cord injury

Electrical stimulation for bladder control is an alternative to traditional methods of treating neurogenic lower urinary tract dysfunction (NLUTD) resulting from spinal cord injury (SCI). In this review, we systematically discuss the neurophysiology of bladder dysfunction following SCI and the applications of electrical stimulation for bladder control following SCI, spanning from historic clinical approaches to recent pre-clinical studies that offer promising new strategies that may improve the feasibility and success of electrical stimulation therapy in patients with SCI. Electrical stimulation provides a unique opportunity to control bladder function by exploiting neural control mechanisms. Our understanding of the applications and limitations of electrical stimulation for bladder control has improved due to many pre-clinical studies performed in animals and translational clinical studies. Techniques that have emerged as possible opportunities to control bladder function include pudendal nerve stimulation and novel methods of stimulation, such as high frequency nerve block. Further development of novel applications of electrical stimulation will drive progress towards effective therapy for SCI. The optimal solution for restoration of bladder control may encompass a combination of efficient, targeted electrical stimulation, possibly at multiple locations, and pharmacological treatment to enhance symptom control.

The role of electrical stimulation techniques in the management of the male patient with urgency incontinence

PURPOSE OF REVIEW

Overactive bladder affects 10-27% of men, a significant portion of whom report urge urinary incontinence that is inadequately treated with first-line and second-line treatments. There is thus a substantial need to critically evaluate the alternative means of clinical management.

RECENT FINDINGS

This review presents the current evidence for the use of sacral neuromodulation and percutaneous tibial nerve stimulation in the treatment of men with urge incontinence, as well as evaluates the financial implications of these treatments. Other alternative modes of electrical stimulation for urge incontinence are also briefly reviewed.

SUMMARY

Both sacral neuromodulation and percutaneous tibial nerve stimulation prove to be viable, durable options for treating patients with refractory urge incontinence. Alternative modes of stimulation are also beginning to show promise.

Neurogenic bladder and disc disease: a brief review

OBJECTIVE

Neurogenic bladder refers to morphofunctional alterations of the bladder-sphincter complex secondary to central or peripheral neurological lesions. Discal etiology can be suggested by clinical observation in patients complaining of classical lower back pain, but not excluded even without musculoskeletal pain. This review provides a brief overview of associations between neurogenic bladder and disc disease, analyzing neuroanatomy, pathophysiology, clinical and urodynamic findings. Therapy is reviewed focusing on etiological treatments.

METHODS

The literature search was performed on PubMed, Medline and Google scholar using the following keywords: 'neurogenic bladder', 'disc herniation', 'disc prolapse', 'disc protrusion', 'cauda equina syndrome', 'treatment', 'surgery', 'urodynamic', either alone or in combination using 'AND' or 'OR'. The reference lists of articles retrieved were examined to capture other potentially relevant articles. The search was restricted to articles published between 1970 and 2012. Seventy-nine papers were found, but only 42 were reviewed and summarized.

FINDINGS

The literature reviewed confirmed correlations between neurogenic bladder and disc disease. Approximately 40% of patients with lumbar disc disease have abnormal urodynamic testing, and an even larger proportion complain of voiding symptoms. The most common urodynamic finding is detrusor areflexia, but underactive or overactive detrusor can also be observed. Electromyography can show perineal floor muscle innervation abnormalities. Chronic nervous damage induces reduction of bladder sensitivity and detrusor atrophy. An overdistension of the bladder follows, with global and circumferential thinning of the bladder wall. Overactive detrusor is related to early nerve roots stretching causing an irritative state responsible for overstimulation and neurogenic overactivity. Detrusor hypertrophy is the anatomical deformation correlated.

CONCLUSIONS

Benefits for neurogenic bladder obtained through disc disease treatment should be studied in more detail, especially conservative therapies, not yet discussed in literature. Spine surgery effectiveness on voiding function should be valued in the light of the latest surgical techniques, considering the controversial results reported after laminectomy.

Dorsal genital nerve stimulation in patients with detrusor overactivity: a systematic review

This study evaluates the outcome of trials to stimulate the dorsal genital nerve (DGN) in patients with lower urinary tract dysfunction. The aim of most studies was to suppress detrusor overactivity in patients with overactive bladder (OAB) syndrome by DGN stimulation. A literature search was performed using Pub Med, Web of Science, and Scopus databases (1980 to April 2012) for clinical trials of DGN stimulation in patients with detrusor overactivity. Seventeen studies were found in the literature. In the studies, different patterns of DGN stimulation were applied. The patterns were either continuous, conditional, or semi-conditional; on an acute or on a chronic basis. DGN stimulation lead to improvement of bladder capacity and reduction in urgency and/or incontinence episodes in many patients. The outcomes of conditional stimulation were comparable to continuous stimulation with respect to improvement of bladder capacity. The publications give evidence that DGN stimulation increases bladder capacity and suppresses involuntary detrusor contractions. Implantable DGN stimulation electrodes can open the way for more prolonged studies in larger patient groups to assess the effectiveness of chronic DGN stimulation in patients with OAB syndrome. Chronic DGN stimulation seems to be of value in the management of OAB syndrome.

Comparison of neural targets for neuromodulation of bladder micturition reflex in the rat

Spinal nerve (SN) stimulation inhibits the bladder rhythmic contraction (BRC) in anesthetized rats. This preparation was used to study the effects of electrical stimulation of the tibial nerve (TN) and the dorsal nerve of the clitoris (DNC) on BRC. Stimulation of the TN and DNC for 10 min produced a frequency- and intensity-dependent attenuation of the frequency of bladder contractions. As observed with the SN, 10-Hz stimulation of either TN or DNC produced the greatest degree of inhibition, with lower or higher frequencies being either less efficacious or inactive. In contrast to the prolonged inhibition produced by SN stimulation, both TN and DNC stimulation produced “short” lasting inhibition of bladder contractions and the maximal inhibition occurred during stimulation. TN stimulation was effective over only a narrow range of current intensities [3–4 × motor threshold current for inducing a toe twitch ( Tmot)] and only at a frequency of 10 Hz. Stimulation of TN at 10 Hz, 3 × Tmot inhibited BRC to 23% of control. Ten-hertz DNC stimulation at 2 × TEAS, the threshold current for evoking a reflex anal sphincter contraction, decreased the frequency of contractions to 4% of control. Although compared with the respective threshold current the BRC response was more sensitive to DNC compared with TN stimulation, the absolute current required to reduce BRC using DNC stimulation appeared to be higher. Comparing the effects of TN and DNC stimulation to our previous results with SN stimulation, SN stimulation produces the largest duration and efficacy of bladder inhibition.

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.

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.

Semiconditional electrical stimulation of pudendal nerve afferents stimulation to manage neurogenic detrusor overactivity in patients with spinal cord injury

Objective

To evaluate the effect of semiconditional electrical stimulation of the pudendal nerve afferents for the neurogenic detrusor overactivity in patients with spinal cord injury. Forty patients (36 males, 4 males) with spinal cord injury who had urinary incontinence and frequency, as well as felt bladder contraction with bladder filling sense or autonomic dysreflexic symptom participated in this study.

Method

Patients with neurogenic detrusor overactivity were subdivided into complete injury and incomplete injury groups by ASIA classification and subdivided into tetraplegia and paraplegia groups by neurologic level of injury. Bladder function, such as bladder volumes infused to the bladder until the first occurrence of neurogenic detrusor overactivity (V_ini) and the last contraction suppressed by electrical stimulation (V_max) was measured by water cystometry (CMG) and compared with the results of each subgroup.

Results

Among the 40 subjects, 35 patients showed neurogenic detrusor overactivity in the CMG study. Among these 35 patients, detrusor overactivity was suppressed effectively by pudendal nerve afferent electrical stimulation in 32 patients. The infusion volume until the occurrence of the first reflex contraction (V_ini) was 99.4±80.3 ml. The volume of saline infused to the bladder until the last contraction suppressed by semiconditional pudendal nerve stimulation (V_max) was 274.3±93.2 ml, which was significantly greater than V_ini. In patients with good response to the pudendal nerve afferent stimulation, the bladder volume significantly increased by stimulation in all the patients.

Conclusion

In this study, semiconditional electrical stimulation on the dorsal penile afferent nerve could effectively inhibit neurogenic detrusor overactivity and increase bladder volume in patients with spinal cord injury.

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.

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.

Surgical access for electrical stimulation of the pudendal and dorsal genital nerves in the overactive bladder: a review

PURPOSE

The anatomy of the pudendal nerve and its nerve branches, especially the dorsal nerve of the penis and clitoris (dorsal genital nerves), and the clinical application of electrical stimulation of these nerves in patients with overactive bladder syndrome and detrusor overactivity are reviewed.

MATERIALS AND METHODS

A literature search was performed using the PubMed® database and reference lists of relevant studies to obtain articles concerning the anatomy as well as the electrical stimulation of the pudendal nerve and its nerve branches in patients with overactive bladder syndrome.

RESULTS

According to the anatomy, electrical stimulation of the pudendal nerve and the dorsal genital nerves to suppress involuntary detrusor contractions is possible at several sites along their course from the sacral nerves to the penis or clitoris. The nerves are accessible by minimally invasive percutaneous methods. Stimulation of the pudendal nerve and dorsal genital nerves effectively increases bladder capacity, and inhibits involuntary detrusor contractions and overactive bladder symptoms.

CONCLUSIONS

More clinically applied studies are recommended for stimulation of the dorsal genital nerves to assess its value and feasibility because most studies have been performed in an acute and experimental setting. The preferred type of electrode is not known, but if wire electrodes can be implanted and fixated well by a minimally invasive procedure, cuff electrodes are not necessary. Before deciding on continuous or conditional stimulation, chronic clinical studies are recommended because acute studies remain inconclusive. The feasibility of conditional stimulation depends on the availability of a reliable and clinically applicable detrusor activity sensor.

Clinical results of a brindley procedure: sacral anterior root stimulation in combination with a rhizotomy of the dorsal roots

The Brindley procedure consists of a stimulator for sacral anterior-root stimulation and a rhizotomy of the dorsal sacral roots to abolish neurogenic detrusor overactivity. Stimulation of the sacral anterior roots enables micturition, defecation, and erections. This overview discusses the technique, selection of patients and clinical results of the Brindley procedure. The Brindley procedure is suitable for a selected group of patients with complete spinal cord injury and detrusor overactivity. Overall, the Brindley procedure shows good clinical results and improves quality of life. However, to remain a valuable treatment option for the future, the technique needs some adequate changes to enable analysis of the implanted parts, to improve revision techniques of the implanted parts, and to abolish the sacral dorsal rhizotomy.

Spinal cord injury markedly altered protein expression patterns in the affected rat urinary bladder during healing stages

The influence of spinal cord injury (SCI) on protein expression in the rat urinary bladder was assessed by proteomic analysis at different time intervals post-injury. After contusion SCI between T9 and T10, bladder tissues were processed by 2-DE and MALDI-TOF/MS at 6 hr to 28 days after SCI to identify proteins involved in the healing process of SCI-induced neurogenic bladder. Approximately 1,000 spots from the bladder of SCI and sham groups were visualized and identified. At one day after SCI, the expression levels of three protein were increased, and seven spots were down-regulated, including heat shock protein 27 (Hsp27) and heat shock protein 20 (Hsp20). Fifteen spots such as S100-A11 were differentially expressed seven days post-injury, and seven proteins including transgelin had altered expression patterns 28 days after injury. Of the proteins with altered expression levels, transgelin, S100-A11, Hsp27 and Hsp20 were continuously and variably expressed throughout the entire post-SCI recovery of the bladder. The identified proteins at each time point belong to eight functional categories. The altered expression patterns identified by 2-DE of transgelin and S100-A11 were verified by Western blot. Transgelin and protein S100-A11 may be candidates for protein biomarkers in the bladder healing process after SCI.

Multiple pudendal sensory pathways reflexly modulate bladder and urethral activity in patients with spinal cord injury

PURPOSE

Electrical stimulation of pudendal afferents can evoke reflex bladder contractions with relaxation of the external urethral sphincter in cats. This voiding reflex is mediated by pudendal sensory fibers innervating the penile and prostatic urethra that engage spinal and spinobulbospinal micturition pathways, respectively. However, clinical translation of this potential therapy in individuals with spinal cord injury is limited by the lack of evidence showing analogous reflex mechanisms in humans. We investigated excitatory pudendal-to-bladder reflexes in 7 individuals with chronic spinal cord injury.

MATERIALS AND METHODS

We recorded isovolumetric bladder pressure and perineal electromyogram in response to intraurethral electrical stimulation at varying amplitudes and frequencies.

RESULTS

Selective electrical stimulation of the proximal (29.7 ± 11.6 cm H(2)O) and distal urethral (23.3 ± 9.28 cm H(2)O) segments evoked sustained reflex bladder contractions in different subsets (3 each) of participants. In contrast, the corresponding reflex perineal electromyogram revealed a differential activation pattern between proximal and distal intraurethral stimulation (normalized electromyogram of 1.3 ± 0.2 and 0.3 ± 0.1, respectively, p <0.05).

CONCLUSIONS

To our knowledge we report the first clinical evidence of 2 independent excitatory pudendal-to-bladder reflex pathways, which in turn differentially modulate efferent pudendal output. Each reflex mechanism involves complex interaction of multiple sensory inputs and may provide a neural substrate to restore micturition after spinal cord injury.

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.

Conditional and continuous electrical stimulation increase cystometric capacity in persons with spinal cord injury

AIMS

Individuals with spinal cord injury (SCI) exhibit neurogenic detrusor overactivity (NDO) causing high intravesicle pressures and incontinence. The first aim was to measure changes in maximum cystometric capacity (MCC) evoked by electrical stimulation of the dorsal genital nerve (DGN) delivered either continuously or conditionally (only during bladder contractions) in persons with SCI. The second aim was to use the external anal sphincter electromyogram (EMG(EAS)) for real-time control of conditional stimulation.

METHODS

Serial filling cystometries were performed in nine volunteers with complete or incomplete supra-sacral SCI. Conditional stimulation was delivered automatically when detrusor pressure increased to 8-12 cmH(2)O above baseline. MCCs were measured for each treatment (continuous, conditional, and no stimulation) and compared using post-ANOVA Tukey HSD paired comparisons. Additional treatments in two subjects used the EMG(EAS) for automatic control of conditional stimulation.

RESULTS

Continuous and conditional stimulation increased MCC by 63 +/- 73 ml (36 +/- 24%) and 74 +/- 71 ml (51 +/- 37%), respectively (P < 0.05), compared to no stimulation. There was no significant difference between MCCs for conditional and continuous stimulation, but conditional stimulation significantly reduced stimulation time (174 +/- 154 sec, or 27 +/- 17% of total time) as compared to continuous stimulation (469 +/- 269 sec, 100% of total time, P < 0.001). The EMG(EAS) algorithm provided reliable detection of bladder contractions (six of six contractions over four trials) and reduced stimulation time (21 +/- 8% of total time).

CONCLUSIONS

Conditional stimulation generates increases in bladder capacity while substantially reducing stimulation time. Furthermore, EMG(EAS) was successfully used as a real-time feedback signal to control conditional electrical stimulation in a laboratory setting.

Intraurethral activation of excitatory bladder reflexes in persons with spinal cord injury

Electrical activation of an excitatory reflex between sensory fibers in the pudendal nerve and the bladder has been demonstrated in cats and is a potential means of restoring micturition function in persons with spinal cord injury. We investigated the clinical feasibility of activating this reflex to restore bladder function in persons with spinal cord injury by using intraurethral electrical stimulation to activate pudendal sensory fibers innervating the urethra. Excitatory bladder responses (contractions) were evoked by trains of electrical pulses applied to either the proximal (29.7 +/- 11.6 cmH2O) or distal (30.2 +/- 11.6 cmH2O) segment of the urethra. The results indicate that an excitatory reflex between pudendal nerve afferents and the bladder exists in humans with spinal injury and may provide a substrate for restoring micturition function.

Urodynamic profile in myelopathies: A follow-up study

Aims:

To study the significance of filling cystometry in assessment and management of neurogenic bladder in myelopathies and correlate neurological recovery and bladder management in the follow up.

Study Design:

Retrospective analysis of reports of filling cystometry in patients with traumatic and non-traumatic myelopathy.

Setting:

Neuro-rehabilitation unit of a tertiary care university hospital.

Methods:

The study was carried out between September 2005 and June 2006 and included all subjects with myelopathy who underwent filling cystometry. ASIA impairment scale was used to assess neurological status during admission as well as in the follow up. Bladder management was advised based on the cystometric findings. Neurological recovery and mode of bladder management were correlated during the follow up after a minimum of 6 months.

Results:

Fifty-two subjects (38 males, 14 females), mean age 33.26 ± 14.66 years (10–80) underwent filling cystometry. Twenty patients had cervical, 24 had thoracic and 8 had lumbar myelopathy. Cystometric findings were overactive detrusor observed in 43 patients, (21 had detrusor sphincter dyssynergia (DSD), 22 without DSD) and areflexic/underactive detrusor in 9. Post-void residual (>15% of voided urine) was significant in 27 patients. Twenty-three patients (44%) reported for follow up (16 males, 7 females) after a mean duration of 9.04 ± 2.44 months (6–15 months). Neurological recovery was seen in 61% cases, while 1 patient showed deterioration. Only 26% patients reported change in bladder management during follow up. Correlation between neurological recovery and bladder management was found to be insignificant (P > 0.05) using spearman correlation co-efficient.

Conclusions:

Filling cystometry is valuable for assessment and management of neurogenic bladder after myelopathy. No significant relationship was observed between neurological recovery and neurogenic bladder management in the follow up in the present study.