Neuromodulation of the neural circuits controlling the lower urinary tract

Model-based analysis of the acute effects of transcutaneous magnetic spinal cord stimulation on micturition after spinal cord injury in humans

AIM

After spinal cord injuries (SCIs), patients may develop either detrusor-sphincter dyssynergia (DSD) or urinary incontinence, depending on the level of the spinal injury. DSD and incontinence reflect the loss of coordinated neural control among the detrusor muscle, which increases bladder pressure to facilitate urination, and urethral sphincters and pelvic floor muscles, which control the bladder outlet to restrict or permit bladder emptying. Transcutaneous magnetic stimulation (TMS) applied to the spinal cord after SCI reduced DSD and incontinence. We defined, within a mathematical model, the minimum neuronal elements necessary to replicate neurogenic dysfunction of the bladder after a SCI and incorporated into this model the minimum additional neurophysiological features sufficient to replicate the improvements in bladder function associated with lumbar TMS of the spine in patients with SCI.

METHODS

We created a computational model of the neural circuit of micturition based on Hodgkin-Huxley equations that replicated normal bladder function. We added interneurons and increased network complexity to reproduce dysfunctional micturition after SCI, and we increased the density and complexity of interactions of both inhibitory and excitatory lumbar spinal interneurons responsive to TMS to provide a more diverse set of spinal responses to intrinsic and extrinsic activation of spinal interneurons that remains after SCI.

RESULTS

The model reproduced the re-emergence of a spinal voiding reflex after SCI. When we investigated the effect of monophasic and biphasic TMS at two frequencies applied at or below T10, the model replicated the improved coordination between detrusor and external urethral sphincter activity that has been observed clinically: low-frequency TMS (1 Hz) within the model normalized control of voiding after SCI, whereas high-frequency TMS (30 Hz) enhanced urine storage.

CONCLUSION

Neuroplasticity and increased complexity of interactions among lumbar interneurons, beyond what is necessary to simulate normal bladder function, must be present in order to replicate the effects of SCI on control of micturition, and both neuronal and network modifications of lumbar interneurons are essential to understand the mechanisms whereby TMS reduced bladder dysfunction after SCI.

Interventions for Enuresis in Children and Adolescents: An Overview of Systematic Reviews

BACKGROUND

Enuresis is an involuntary and intermittent loss of urine during sleep, and its treatment can be done by pharmacological and non-pharmacological strategies.

OBJECTIVE

To conduct an overview to carry out a survey of the systematic reviews about treatment options for children/adolescents with enuresis.

METHODS

Databases used were Cochrane Library, PROSPERO, MEDLINE/PubMed, EMBASE, LILACS/BVS, PEDro, SciELO and Google Scholar. Any type of intervention for the treatment of enuresis in children/adolescents was selected by two independent researchers. Data extraction was done by two independent researchers. The risk of bias was assessed using Risk of Bias in Systematic Reviews (ROBIS) and A MeaSurement Tool to Assess Systematic Reviews (AMSTAR-2).

RESULTS

Seven systematic reviews were included. According to ROBIS, three reviews had a low risk of bias, while the others had a high risk of bias. Based on AMSTAR-2, four systematic reviews were of moderate quality, two were low quality, and one was critically low quality.

CONCLUSION

There is moderate confidence that the use of desmopressin plus an anticholinergic agent increases the chance of complete response compared to desmopressin alone. Neurostimulation may increase the risk of responses ≥50% and ≥90% compared to the control group. Likewise, it appears that electrical stimulation is superior to placebo about the chance of response ≥50%. In addition, there is clinical relevance in reducing enuresis episodes per week when neurostimulation is used compared to control groups.

Effect of magnetic therapy in bladder dysfunction and quality of life in paraplegic patients

BACKGROUND

Urinary dysfunction is linked to spinal cord injury (SCI). The quality of life (QoL) declines in both neurogenic bladder impairment and non-disordered patients.

OBJECTIVE

To ascertain the effectiveness of pulsed magnetic therapy on urinary impairment and QoL in individuals with traumatic incomplete SCI.

METHODS

This study included forty male paraplegic subjects with neurogenic detrusor overactivity (NDO) for more than one year following incomplete SCI between T6-T12. Their ages ranged from 20 to 35 and they engaged in therapy for three months. The subjects were divided into two groups of equal size. Individuals in Group I were managed via pulsed magnetic therapy once per week plus pelvic floor training three times a week. Individuals in Group II were managed with only three times a week for pelvic floor training. All patients were examined for bladder cystometric investigations, pelvic-floor electromyography (EMG), and SF-Qualiveen questionnaire.

RESULTS

There was a noteworthy increment in individuals in Group I in volume of bladder at first desire to void and maximum cystometric capacity, detrusor pressure at Qmax, and maximum flow rate. There was a momentous increment in Group I in measures of evaluation of EMG biofeedback. There was a notable rise in Group I in SF-Qualiveen questionnaire.

CONCLUSION

Magnetic stimulation should be favored as beneficial adjunct to traditional therapy in the management of bladder impairment and enhancing QoL in individuals with SCI.

bTUNED: transcutaneous tibial nerve stimulation for neurogenic lower urinary tract dysfunction

OBJECTIVE

To present the protocol for a randomized controlled trial (RCT) evaluating the efficacy and safety of transcutaneous tibial nerve stimulation (TTNS) for refractory neurogenic lower urinary tract dysfunction (NLUTD).

STUDY DESIGN AND RESULTS

bTUNED (bladder and TranscUtaneous tibial Nerve stimulation for nEurogenic lower urinary tract Dysfunction) is an international multicentre, sham-controlled, double-blind RCT investigating the efficacy and safety of TTNS. The primary outcome is success of TTNS, defined as improvements in key bladder diary variables at study end compared to baseline values. The focus of the treatment is defined by the Self-Assessment Goal Achievement (SAGA) questionnaire. Secondary outcomes are the effect of TTNS on urodynamic, neurophysiological, and bowel function outcome measures, as well as the safety of TTNS.

CONCLUSIONS

A total of 240 patients with refractory NLUTD will be included and randomized 1:1 into the verum or sham TTNS group from March 2020 until August 2026. TTNS will be performed twice a week for 30 min during 6 weeks. The patients will attend baseline assessments, 12 treatment visits and follow-up assessments at the study end.

Mid-lumbar (L3) epidural stimulation effects on bladder and external urethral sphincter in non-injured and chronically transected urethane-anesthetized rats

Recent pre-clinical and clinical spinal cord epidural stimulation (scES) experiments specifically targeting the thoracolumbar and lumbosacral circuitries mediating lower urinary tract (LUT) function have shown improvements in storage, detrusor pressure, and emptying. With the existence of a lumbar spinal coordinating center in rats that is involved with external urethral sphincter (EUS) functionality during micturition, the mid-lumbar spinal cord (specifically L3) was targeted in the current study with scES to determine if the EUS and thus the void pattern could be modulated, using both intact and chronic complete spinal cord injured female rats under urethane anesthesia. L3 scES at select frequencies and intensities of stimulation produced a reduction in void volumes and EUS burst duration in intact rats. After chronic transection, three different subgroups of LUT dysfunction were identified and the response to L3 scES promoted different cystometry outcomes, including changes in EUS bursting. The current findings suggest that scES at the L3 level can generate functional neuromodulation of both the urinary bladder and the EUS in intact and SCI rats to enhance voiding in a variety of clinical scenarios.

Effects of dynamic body weight support on functional independence measures in acute ischemic stroke: a retrospective cohort study

BACKGROUND

Stroke remains a major public health concern in the United States and a leading cause of long-term disability in adults. Dynamic body weight support (DBWS) systems are popular technology available for use in clinical settings such inpatient rehabilitation. However, there remains limited studies in such inpatient settings that compare DBWS to standard of care (SOC) using real world outcome measures. For survivors of acute ischemic stroke, we determine if incorporating a dynamic body weight support (DBWS) system into inpatient therapy offers greater improvement than standard of care (SOC).

METHODS

A retrospective chart review included 52 individuals with an acute ischemic stroke admitted to an inpatient rehabilitation facility. Functional Independence Measure (FIM) data, specifically changes in FIM at discharge, served as the primary outcome measure. Patient cohorts received either therapies per SOC or therapies incorporating DBWS. Regardless of cohort group, all patients underwent therapies for 3 h per day for 5 days a week.

RESULTS

For both groups, a statistically and clinically significant increase in total FIM (P < 0.0001) was observed at discharge compared to at admission. Improvements for the DBWS group were significantly greater than the SOC group as evidenced by higher gains in total FIM (p = 0.04) and this corresponded to a medium effect size (Cohen's d = 0.58). Among FIM subscores, the DBWS group achieved a significant increase in sphincter control while all other subscore changes remained non-significant.

CONCLUSIONS

This preliminary evidence supports the benefit of using DBWS during inpatient rehabilitation in individuals who have experienced an acute ischemic stroke. This may be due to the greater intensity and repetitions of tasks allowed by DBWS. These preliminary findings warrant further investigations on the use of DBWS in inpatient settings.

Spinal cord injury is associated with changes in synaptic properties of the mouse major pelvic ganglion

Spinal cord injury (SCI) has substantial impacts on autonomic function. In part, SCI results in loss of normal autonomic activity that contributes to injury-associated pathology such as neurogenic bladder, bowel, and sexual dysfunction. Yet little is known of the impacts of SCI on peripheral autonomic neurons that directly innervate these target organs. In this study, we measured changes in synaptic properties of neurons of the mouse major pelvic ganglion (MPG) associated with acute and chronic SCI. Our data show that functional and physiological properties of synapses onto MPG neurons are altered after SCI, and differ between acute and chronic injury. After acute injury, excitatory post-synaptic potentials (EPSPs) show increased rise and decay time constants leading to overall broader and longer EPSPs, while in chronic injured animals EPSPs are reduced in amplitude and show faster rise and decay leading to shorter EPSPs. Synaptic depression and low pass filtering are also altered in injured animals. Lastly, cholinergic currents are smaller in acute injured animals, but larger in chronic injured animals relative to controls. These changes in synaptic properties are associated with differences in nicotinic receptor subunit expression as well. MPG CHRNA3 mRNA levels decreased after injury, while CHRNA4 mRNAs increased. Further, changes in the correlations of alpha- and beta-subunit mRNAs suggests that nicotinic receptor subtype composition is altered after injury. Taken together, our data demonstrate that peripheral autonomic neurons are fundamentally altered after SCI, suggesting that longer-term therapeutic approaches could target these neurons directly to potentially help ameliorate neurogenic target organ dysfunction.

Noninvasive spinal neuromodulation mitigates symptoms of idiopathic overactive bladder

Background

Overactive bladder (OAB) affects 12 to 30% of the world’s population. The accompanying urinary urgency, frequency and incontinence can have a profound effect on quality of life, leading to depression, social isolation, avoidance of sexual activity and loss of productivity. Conservative measures such as lifestyle modification and pelvic floor physical therapy are the first line of treatment for overactive bladder. Patients who fail these may go on to take medications, undergo neuromodulation or receive injection of botulinum toxin into the bladder wall. While effective, medications have side effects and suffer from poor adherence. Neuromodulation and botulinum toxin injection are also effective but are invasive and not acceptable to some patients.

Methods

We have developed a novel transcutaneous spinal cord neuromodulator (SCONE™^,) that delivers multifrequency electrical stimulation to the spinal cord without the need for insertion or implantation of stimulating electrodes. Previously, multifrequency transcutaneous stimulation has been demonstrated to penetrate to the spinal cord and lead to motor activation of detrusor and external urethral sphincter muscles. Here, we report on eight patients with idiopathic overactive bladder, who underwent 12 weeks of SCONE™ therapy.

Results

All patients reported statistically significant clinical improvement in multiple symptoms of overactive bladder, such as urinary urgency, frequency and urge incontinence. In addition, patients reported significant symptomatic improvements as captured by validated clinical surveys.

Conclusion

SCONE™ therapy represents the first of its kind therapy to treat symptoms of urgency, frequency and urge urinary incontinence in patients with OAB.

Trial registration

The study was listed on clinicaltrials.gov (NCT03753750).

Spinal interneurons of the lower urinary tract circuits

The storage and elimination of urine requires coordinated activity between muscles of the bladder and the urethra. This coordination is orchestrated by a complex system containing spinal, midbrain and forebrain networks. Normally there is a reciprocity between patterns of activity in urinary bladder sacral parasympathetic efferents and somatic motoneurons innervating the striatal external urethral sphincter muscle. At the spinal level this reciprocity is mediated by ensembles of excitatory and inhibitory interneurons located in the lumbar-sacral segments. In this review I will present an overview of currently identified spinal interneurons and circuits relevant to the lower urinary tract and will discuss their established or hypothetical roles in the cycle of micturition. In addition, a recently discovered auxiliary spinal neuronal ensemble named lumbar spinal coordinating center will be described. Sexual dimorphism and developmental features of the lower urinary tract which may play a significant role in designing treatments for patients with urine storage and voiding dysfunctions are also considered. Spinal cord injuries seriously damage or even eliminate the ability to urinate. Treatment of this abnormality requires detailed knowledge of supporting neural mechanisms, therefore various experiments in normal and spinalized animals will be discussed. Finally, a possible intraspinal mechanism will be proposed for organization of external urethral sphincter (EUS) bursting which represents a form of intermittent EUS relaxation in rats and mice.

A wireless spinal stimulation system for ventral activation of the rat cervical spinal cord

Electrical stimulation of the cervical spinal cord is gaining traction as a therapy following spinal cord injury; however, it is difficult to target the cervical motor region in a rodent using a non-penetrating stimulus compared with direct placement of intraspinal wire electrodes. Penetrating wire electrodes have been explored in rodent and pig models and, while they have proven beneficial in the injured spinal cord, the negative aspects of spinal parenchymal penetration (e.g., gliosis, neural tissue damage, and obdurate inflammation) are of concern when considering therapeutic potential. We therefore designed a novel approach for epidural stimulation of the rat spinal cord using a wireless stimulation system and ventral electrode array. Our approach allowed for preservation of mobility following surgery and was suitable for long term stimulation strategies in awake, freely functioning animals. Further, electrophysiology mapping of the ventral spinal cord revealed the ventral approach was suitable to target muscle groups of the rat forelimb and, at a single electrode lead position, different stimulation protocols could be applied to achieve unique activation patterns of the muscles of the forelimb.

Bladder and bowel responses to lumbosacral epidural stimulation in uninjured and transected anesthetized rats

Spinal cord epidural stimulation (scES) mapping at L5-S1 was performed to identify parameters for bladder and bowel inhibition and/or contraction. Using spinally intact and chronic transected rats of both sexes in acute urethane-anesthetized terminal preparations, scES was systematically applied using a modified Specify 5-6-5 (Medtronic) electrode during bladder filling/emptying cycles while recording bladder and colorectal pressures and external urethral and anal sphincter electromyography activity. The results indicate frequency-dependent effects on void volume, micturition, bowel peristalsis, and sphincter activity just above visualized movement threshold intensities that differed depending upon neurological intactness, with some sex-dependent differences. Thereafter, a custom-designed miniature 15-electrode array designed for greater selectivity was tested and exhibited the same frequency-dependent urinary effects over a much smaller surface area without any concurrent movements. Thus, select activation of autonomic nervous system circuitries with scES is a promising neuromodulation approach for expedient translation to individuals with SCI and potentially other neurologic disorders.

Improvements in Bladder Function Following Activity-Based Recovery Training With Epidural Stimulation After Chronic Spinal Cord Injury

Spinal cord injury (SCI) results in profound neurologic impairment with widespread deficits in sensorimotor and autonomic systems. Voluntary and autonomic control of bladder function is disrupted resulting in possible detrusor overactivity, low compliance, and uncoordinated bladder and external urethral sphincter contractions impairing storage and/or voiding. Conservative treatments managing neurogenic bladder post-injury, such as oral pharmacotherapy and catheterization, are important components of urological surveillance and clinical care. However, as urinary complications continue to impact long-term morbidity in this population, additional therapeutic and rehabilitative approaches are needed that aim to improve function by targeting the recovery of underlying impairments. Several human and animal studies, including our previously published reports, have documented gains in bladder function due to activity-based recovery strategies, such as locomotor training. Furthermore, epidural stimulation of the spinal cord (scES) combined with intense activity-based recovery training has been shown to produce volitional lower extremity movement, standing, as well as improve the regulation of cardiovascular function. In our center, several participants anecdotally reported improvements in bladder function as a result of training with epidural stimulation configured for motor systems. Thus, in this study, the effects of activity-based recovery training in combination with scES were tested on bladder function, resulting in improvements in overall bladder storage parameters relative to a control cohort (no intervention). However, elevated blood pressure elicited during bladder distention, characteristic of autonomic dysreflexia, was not attenuated with training. We then examined, in a separate, large cross-sectional cohort, the interaction between detrusor pressure and blood pressure at maximum capacity, and found that the functional relationship between urinary bladder distention and blood pressure regulation is disrupted. Regardless of one’s bladder emptying method (indwelling suprapubic catheter vs. intermittent catheterization), autonomic instability can play a critical role in the ability to improve bladder storage, with SCI enhancing the vesico-vascular reflex. These results support the role of intersystem stimulation, integrating scES for both bladder and cardiovascular function to further improve bladder storage.

Dynamic body-weight support to boost rehabilitation outcomes in patients with non-traumatic spinal cord injury: an observational study

Background

Dynamic body-weight support (DBWS) may play an important role in rehabilitation outcomes, but the potential benefit among disease-specific populations is unclear. In this study, we hypothesize that overground therapy with DBWS during inpatient rehabilitation yields greater functional improvement than standard-of-care in adults with non-traumatic spinal cord injury (NT-SCI).

Methods

This retrospective cohort study included individuals diagnosed with NT-SCI and undergoing inpatient rehabilitation. All participants were recruited at a freestanding inpatient rehabilitation hospital. Individuals who trained with DBWS for at least three sessions were allocated to the experimental group. Participants in the historical control group received standard-of-care (i.e., no DBWS). The primary outcome was change in the Functional Independence Measure scores (FIM_gain).

Results

During an inpatient rehabilitation course, participants in the experimental group (n = 11), achieved a mean (SD) FIM_gain of 48 (11) points. For the historical control group (n = 11), participants achieved a mean (SD) FIM_gain of 36 (12) points. From admission to discharge, both groups demonstrated a statistically significant FIM_gain. Between groups analysis revealed no significant difference in FIM_gain (p = 0.022; 95% CI 2.0–22) after a post hoc correction for multiple comparisons. In a secondary subscore analysis, the experimental group achieved significantly higher gains in sphincter control (p = 0.011: 95% CI 0.83–5.72) with a large effect size (Cohen’s d 1.19). Locomotion subscores were not significantly different (p = 0.026; 95% CI 0.37–5.3) nor were the remaining subscores in self-care, mobility, cognition, and social cognition.

Conclusions

This is the first study to explore the impact of overground therapy with DBWS on inpatient rehabilitation outcomes for persons with NT-SCI. Overground therapy with DBWS appears to significantly improve functional gains in sphincter control compared to the standard-of-care. Gains achieved in locomotion, mobility, cognition, and social cognition did not meet significance. Findings from the present study will benefit from future large prospective and randomized studies.

Brain functional network alterations caused by a strong desire to void in healthy adults: a graph theory analysis study

PURPOSE

This resting-state functional magnetic resonance imaging (fMRI) study determined the functional connectivity (FC) changes and topologic property alterations of the brain functional network provoked by a strong desire to void in healthy adults using a graph theory analysis (GTA).

MATERIALS AND METHODS

Thirty-four healthy, right-handed subjects filled their bladders by drinking water. The subjects were scanned under an empty bladder and a strong desire to void states. The Pearson's correlation coefficients were calculated among 90 brain regions in the automated anatomical labeling (AAL) atlas to construct the brain functional network. A paired t test (P < .05, after false discovery rate [FDR] correction) was used to detect significant differences in the FC, topologic properties (small-world parameters [gamma, sigma], C_p, L_p, E_glob, E_loc, and E_nodal) between the two states in all subjects.

RESULTS

Both the two states showed small-world network properties. The clustering coefficient (C_p) and local efficiency (E_loc) in the whole brain network decreased, while the FC within the default mode network (DMN) increased during the strong desire to void compared with the empty bladder state. Moreover, an increased nodal efficiency (E_nodal) was detected in the basal ganglia (BG), DMN, sensorimotor-related network (SMN), and visual network (VN).

CONCLUSION

We detected FC changes and topologic property alterations in brain functional networks caused by a strong desire to void in healthy and suggest that the micturition control may be a process dominated by DMN and coordinated by multiple sub-networks (such as, BG, SMN, and VN), which could serve as a baseline for understanding the pathologic process underlying bladder dysfunction and be useful to improve targeted therapy in the future.

Spinal cord stimulation for the restoration of bladder function after spinal cord injury

Spinal cord injury (SCI) results in the inability to empty the bladder voluntarily, and neurogenic detrusor overactivity (NDO) and detrusor sphincter dyssynergia (DSD) negatively impact both the health and quality of life of persons with SCI. Current approaches to treat bladder dysfunction in persons with SCI, including self-catheterisation and anticholinergic medications, are inadequate, and novel approaches are required to restore continence with increased bladder capacity, as well as to provide predictable and efficient on-demand voiding. Improvements in bladder function following SCI have been documented using a number of different modalities of spinal cord stimulation (SCS) in both persons with SCI and animal models, including SCS alone or SCS with concomitant activity-based training. Improvements include increased volitional voiding, voided volumes, bladder capacity, and quality of life, as well as decreases in NDO and DSD. Further, SCS is a well-developed therapy for chronic pain, and existing Food And Drug Administration (FDA)-approved devices provide a clear pathway to sustainable commercial availability and impact. However, the effective stimulation parameters and the appropriate timing and location of stimulation for SCS-mediated restoration of bladder function require further study, and studies are needed to determine underlying mechanisms of action.

A Urodynamic Comparison of Neural Targets for Transcutaneous Electrical Stimulation to Acutely Suppress Detrusor Contractions Following Spinal Cord Injury

Objectives

To assess and compare the effect of transcutaneous Dorsal Genital Nerve Stimulation (DGNS), Tibial Nerve Stimulation (TNS), Sacral Nerve Stimulation (SNS), and Spinal Stimulation (SS) on Neurogenic Detrusor Overactivity (NDO) and bladder capacity in people with Spinal Cord Injuries (SCI).

Materials and Methods

Seven male participants with supra-sacral SCI were tested. Standard cystometry (CMG) was performed to assess bladder activity at baseline and with stimulation applied at each site. This was conducted over four separate sessions. All stimulation was monophasic, 15 Hz, 200 μS pulses and applied at maximum tolerable amplitude. Results were analysed against individual control results from within the same session.

Results

Dorsal Genital Nerve Stimulation increased bladder capacity by 153 ± 146 ml (p = 0.016) or 117 ± 201%. DGNS, TNS and SNS all increased the volume held following the first reflex contraction, by 161 ± 175, 46 ± 62, and 34 ± 33 ml (p = 0.016, p = 0.031, p = 0.016), respectively. SS results showed small reduction of 33 ± 26 ml (p = 0.063) from baseline bladder capacity in five participants. Maximum Detrusor Pressure before leakage was increased during TNS, by 10 ± 13 cmH₂O (p = 0.031) but was unchanged during stimulation of other sites. DGNS only was able to suppress at least one detrusor contraction in five participants and reduced first peak detrusor pressure below 40 cmH₂O in these 5. Continuous TNS, SNS, and SS produced non-significant changes in bladder capacity from baseline, comparable to conditional stimulation. Increase in bladder capacity correlated with stimulation amplitude for DGNS but not TNS, SNS or SS.

Conclusion

In this pilot study DGNS acutely suppressed detrusor contractions and increased bladder capacity whereas TNS, SNS, and SS did not. This is the first within individual comparison of surface stimulation sites for management of NDO in SCI individuals.

Non-Invasive Activation of Cervical Spinal Networks after Severe Paralysis

Paralysis of the upper extremities following cervical spinal cord injury (SCI) significantly impairs one's ability to live independently. While regaining hand function or grasping ability is considered one of the most desired functions in tetraplegics, limited therapeutic development in this direction has been demonstrated to date in humans with a high severe cervical injury. The underlying hypothesis is that after severe cervical SCI, nonfunctional sensory-motor networks within the cervical spinal cord can be transcutaneously neuromodulated to physiological states that enable and amplify voluntary control of the hand. Improved voluntary hand function occurred within a single session in every subject tested. After eight sessions of non-invasive transcutaneous stimulation, combined with training over 4 weeks, maximum voluntary hand grip forces increased by ∼325% (in the presence of stimulation) and ∼225% (when grip strength was tested without simultaneous stimulation) in chronic cervical SCI subjects (American Spinal Injury Association Impairment Scale [AIS] B, n = 3; AIS C, n = 5) 1-21 years post-injury). Maximum grip strength improved in both the left and right hands and the magnitude of increase was independent of hand dominance. We refer to the neuromodulatory method used as transcutaneous enabling motor control to emphasize that the stimulation parameters used are designed to avoid directly inducing muscular contractions, but to enable task performance according to the subject's voluntary intent. In some subjects, there were improvements in autonomic function, lower extremity motor function, and sensation below the level of the lesion. Although a neuromodulation-training effect was observed in every subject tested, further controlled and blinded studies are needed to determine the responsiveness of a larger and broader population of subjects varying in the type, severity, and years post-injury. It appears rather convincing, however, that a "central pattern generation" phenomenon as generally perceived in the lumbosacral networks in controlling stepping neuromodulator is not a critical element of spinal neuromodulation to regain function among spinal networks.

Using EMG to deliver lumbar dynamic electrical stimulation to facilitate cortico-spinal excitability

BACKGROUND

Potentiation of synaptic activity in spinal networks is reflected in the magnitude of modulation of motor responses evoked by spinal and cortical input. After spinal cord injury, motor evoked responses can be facilitated by pairing cortical and peripheral nerve stimuli.

OBJECTIVE

To facilitate synaptic potentiation of cortico-spinal input with epidural electrical stimulation, we designed a novel neuromodulation method called dynamic stimulation (DS), using patterns derived from hind limb EMG signal during stepping.

METHODS

DS was applied dorsally to the lumbar enlargement through a high-density epidural array composed of independent platinum-based micro-electrodes.

RESULTS

In fully anesthetized intact adult rats, at the interface array/spinal cord, the temporal and spatial features of DS neuromodulation affected the entire lumbosacral network, particularly the most rostral and caudal segments covered by the array. DS induced a transient (at least 1 min) increase in spinal cord excitability and, compared to tonic stimulation, generated a more robust potentiation of the motor output evoked by single pulses applied to the spinal cord. When sub-threshold pulses were selectively applied to a cortical motor area, EMG responses from the contralateral leg were facilitated by the delivery of DS to the lumbosacral cord. Finally, based on motor-evoked responses, DS was linked to a greater amplitude of motor output shortly after a calibrated spinal cord contusion.

CONCLUSION

Compared to traditional tonic waveforms, DS amplifies both spinal and cortico-spinal input aimed at spinal networks, thus significantly increasing the potential and accelerating the rate of functional recovery after a severe spinal lesion.

Activation of the spinal neuronal network responsible for visceral control during locomotion

It has been established that stepping of the decerebrate cat was accompanied by involvement of the urinary system: external urethral sphincter (EUS) and detrusor muscle activation, as well as the corresponding increase of the intravesical pressure. Detrusor and EUS evoked EMG activity matched the limbs locomotor movements. Immunohistochemical labeling of the immediate early gene c-fos expression was used to reveal the neural mechanisms of such somatovisceral interconnection within the sacral neural pathways. Study showed that two locomotor modes (forward and backward walking) had significantly different kinematic features. Combining the different immunohistochemical methods, we found that many c-fos-immunopositive nuclei were localized within several visceral areas of the S2 spinal segment which matched the sacral parasympathetic nucleus and dorsal gray commissure. Cats stepping backward had 4-fold more c-fos-immunopositive nuclei within the ventrolateral part of the sacral parasympathetic nucleus apparently correspondent to the "lateral band" contained cells controlling bladder function. The present work provides the direct evidences of visceral neurons activation depending on the specific of locomotor pattern and confirms the somatovisceral integration carrying out on the spinal cord level.

Intra- and inter-resting-state networks abnormalities in overactive bladder syndrome patients: an independent component analysis of resting-state fMRI

PURPOSE

This study aims to determine whether intra-network and inter-network brain connectivities are altered using an independent component analysis (ICA).

METHODS

Resting-state functional MRI (rs-fMRI) data were acquired from 26 patients with OAB and 28 healthy controls (HC). Eleven resting-state networks (RSNs) were identified via ICA. General linear model (GLM) was used to compare intra-network FC and inter-network FC of RSNs between the two groups. Pearson correlation analyses were performed to investigate the relationship between the identified RSNs and clinical variables.

RESULTS

Compared with HC, the OAB group showed abnormal FC within the sensorimotor-related network (SMN), the dorsal attention network (DAN), the dorsal visual network (dVN), and the left frontoparietal network (LFPN). With respect to inter-network interactions, decreased FC was detected between the SMN and the anterior default mode network (aDMN).

CONCLUSION

This study demonstrated that abnormal FC between RSNs may reflect the altered resting state of the brain-bladder network. The findings of this study provide complementary evidence that can help further understand the neural substrates of the overactive bladder.

Emergence of Epidural Electrical Stimulation to Facilitate Sensorimotor Network Functionality After Spinal Cord Injury

BACKGROUND

Traumatic spinal cord injury (SCI) disrupts signaling pathways between the brain and spinal networks below the level of injury. In cases of severe SCI, permanent loss of sensorimotor and autonomic function can occur. The standard of care for severe SCI uses compensation strategies to maximize independence during activities of daily living while living with chronic SCI-related dysfunctions. Over the past several years, the research field of spinal neuromodulation has generated promising results that hold potential to enable recovery of functions via epidural electrical stimulation (EES).

METHODS

This review provides a historical account of the translational research efforts that led to the emergence of EES of the spinal cord to enable intentional control of motor functions that were lost after SCI. We also highlight the major limitations associated with EES after SCI and propose future directions of spinal neuromodulation research.

RESULTS

Multiple, independent studies have demonstrated return of motor function via EES in individuals with chronic SCI. These enabled motor functions include intentional, controlled movement of previously paralyzed extremities, independent standing and stepping, and increased grip strength. In addition, improvements in cardiovascular health, respiratory function, body composition, and urologic function have been reported.

CONCLUSIONS

EES holds promise to enable functions thought to be permanently lost due to SCI. However, EES is currently restricted to scientific investigation in humans with SCI and requires further validation of factors such as safety and efficacy before clinical translation.

Epidural Spinal Cord Stimulation Acutely Modulates Lower Urinary Tract and Bowel Function Following Spinal Cord Injury: A Case Report

Regaining control of autonomic functions such as those of the cardiovascular system, lower urinary tract and bowel, rank among the most important health priorities for individuals living with spinal cord injury (SCI). Recently our research provided evidence that epidural spinal cord stimulation (ESCS) could acutely modulate autonomic circuits responsible for cardiovascular function after SCI. This finding raised the question of whether ESCS can be used to modulate autonomic circuits involved in lower urinary tract and bowel control after SCI. We present the case of a 32-year-old man with a chronic motor-complete SCI (American Spinal injury Association Impairment Scale B) at the 5^th cervical spinal segment. He sustained his injury during a diving accident in 2012. He was suffering from neurogenic lower urinary tract and bowel dysfunction. Epidural stimulation of the lumbosacral spinal cord immediately modulated both functions without negatively affecting the cardiovascular system. Specifically, the individual's bowel function was assessed using different pre-set configurations and stimulation parameters in a randomized order. Compared to the individual's conventional bowel management approach, ESCS significantly reduced the time needed for bowel management (p = 0.039). Furthermore, depending on electrode configuration and stimulation parameters (i.e., amplitude, frequency, and pulse width), ESCS modulated detrusor pressure and external anal sphincter/pelvic floor muscle tone to various degrees during urodynamic investigation. Although, ESCS is currently being explored primarily for restoring ambulation, our data suggest that application of this neuroprosthetic intervention may provide benefit to lower urinary tract and bowel function in individuals with SCI. To fully capitalize on the potential of improving lower urinary tract and bowel function, further research is needed to better understand the neuronal pathways and identify optimal stimulation configurations and parameters.

Effect of 5-HT2A receptor antagonist ketanserin on micturition in male rats

OBJECTIVES

This study aimed to investigate the effects of ketanserin on micturition mediated via the 5-HT_2A receptor in the motoneuron nucleus of the Lumbosacral cord, as reflected in high frequency oscillations (HFOs) of intravesical pressure and the external urethral sphincter electromyogram (EUS-EMG) in anesthetized male rats. METHODS：: Male Sprague-Dawley rats were used. Cystometry and EUS-EMG were performed in all rats under urethane anesthesia to examine the variations after successive intrathecal (i.t.) administration of various doses of ketanserin into the lumbosacral cord. Immunofluorescence staining and Western blotting were made to observe the distribution of 5-HT2 A and -2C receptors in the lumbosacral cord motor neurons.

RESULTS

Compared to the controls, ketanserin-treated rats showed a declined trend of dose-dependent manner in the HFOs, in accordance with the variation of EUS-EMG, while decreased micturition volume, voiding efficiency, and increased post-void residual volume was only observed at the dose of 0.1 mg/kg. The effects of ketanserin on the HFO and EUS-EMG activity were partially or completely reversed by the 5-HT_2A/2C receptor agonist, DOI. Meanwhile, immunofluorescence staining and Western blot analysis showed that immunoreactivity of 5-HT_2A receptor was higher than that of 5-HT_2C, labeling in the lumbosacral cord motoneurons.

CONCLUSIONS

The intrathecally administrated 5-HT_2A receptor antagonist ketanserin can weaken the EUS bursting activity, decrease HFOs, and reduce voiding efficiency as dose dependently. The effects of ketanserin on micturition may be mainly mediated via the 5-HT_2A receptors in the motoneuron nucleus of the lumbosacral cord.

Non-invasive Neuromodulation of Spinal Cord Restores Lower Urinary Tract Function After Paralysis

It is commonly assumed that restoration of locomotion is the ultimate goal after spinal cord injury (SCI). However, lower urinary tract (LUT) dysfunction is universal among SCI patients and significantly impacts their health and quality of life. Micturition is a neurologically complex behavior that depends on intact sensory and motor innervation. SCI disrupts both motor and sensory function and leads to marked abnormalities in urine storage and emptying. Current therapies for LUT dysfunction after SCI focus on preventing complications and managing symptoms rather than restoring function. In this study, we demonstrate that Transcutaneous Electrical Spinal Stimulation for LUT functional Augmentation (TESSLA), a non-invasive neuromodulatory technique, can reengage the spinal circuits' active in LUT function and normalize bladder and urethral sphincter function in individuals with SCI. Specifically, TESSLA reduced detrusor overactivity (DO), decreased detrusor-sphincter dyssynergia (DSD), increased bladder capacity and enabled voiding. TESSLA may represent a novel approach to transform the intrinsic spinal networks to a more functionally physiological state. Each of these features has significant clinical implications. Improvement and restoration of LUT function after SCI stand to significantly benefit patients by improving their quality of life and reducing the risk of incontinence, kidney injury and urinary tract infection, all the while lowering healthcare costs.

Assessment and management of acute spinal cord injury: From point of injury to rehabilitation

CONTEXT

Spinal cord injury (SCI) is a devastating condition that can lead to significant neurological impairment and reduced quality of life. Despite advancements in our understanding of the pathophysiology and secondary injury mechanisms involved in SCI, there are currently very few effective treatments for this condition. The field, however, is rapidly changing as new treatments are developed and key discoveries are made.

METHODS

In this review, we outline the pathophysiology, management, and long-term rehabilitation of individuals with traumatic SCI. We also provide an in-depth overview of emerging therapies along the spectrum of the translational pipeline.

EVIDENCE SYNTHESIS

The concept of "time is spine" refers to the concept which emphasizes the importance of early transfer to specialized centers, early decompressive surgery, and early delivery of other treatments (e.g. blood pressure augmentation, methylprednisolone) to affect long-term outcomes. Another important evolution in management has been the recognition and prevention of the chronic complications of SCI including respiratory compromise, bladder dysfunction, Charcot joints, and pressure sores through directed interventions along with early integration of physical rehabilitation and mobilization. There have also been significant advances in neuroprotective and neuroregenerative strategies for SCI, many of which are actively in clinical trial including riluzole, Cethrin, stem cell transplantation, and the use of functional electrical stimulation.

CONCLUSION

Pharmacologic treatments, cell-based therapies, and other technology-driven interventions will likely play a combinatorial role in the evolving management of SCI as the field continues to evolve.

The Role of Functional Neuroanatomy of the Lumbar Spinal Cord in Effect of Epidural Stimulation

In this study, the neuroanatomy of the swine lumbar spinal cord, particularly the spatial orientation of dorsal roots was correlated to the anatomical landmarks of the lumbar spine and to the magnitude of motor evoked potentials during epidural electrical stimulation (EES). We found that the proximity of the stimulating electrode to the dorsal roots entry zone across spinal segments was a critical factor to evoke higher peak-to-peak motor responses. Positioning the electrode close to the dorsal roots produced a significantly higher impact on motor evoked responses than rostro-caudal shift of electrode from segment to segment. Based on anatomical measurements of the lumbar spine and spinal cord, significant differences were found between L1-L4 to L5-L6 segments in terms of spinal cord gross anatomy, dorsal roots and spine landmarks. Linear regression analysis between intersegmental landmarks was performed and L2 intervertebral spinous process length was selected as the anatomical reference in order to correlate vertebral landmarks and the spinal cord structures. These findings present for the first time, the influence of spinal cord anatomy on the effects of epidural stimulation and the role of specific orientation of electrodes on the dorsal surface of the dura mater in relation to the dorsal roots. These results are critical to consider as spinal cord neuromodulation strategies continue to evolve and novel spinal interfaces translate into clinical practice.

Cell biology of spinal cord injury and repair

Spinal cord injury (SCI) lesions present diverse challenges for repair strategies. Anatomically complete injuries require restoration of neural connectivity across lesions. Anatomically incomplete injuries may benefit from augmentation of spontaneous circuit reorganization. Here, we review SCI cell biology, which varies considerably across three different lesion-related tissue compartments: (a) non-neural lesion core, (b) astrocyte scar border, and (c) surrounding spared but reactive neural tissue. After SCI, axon growth and circuit reorganization are determined by neuron-cell-autonomous mechanisms and by interactions among neurons, glia, and immune and other cells. These interactions are shaped by both the presence and the absence of growth-modulating molecules, which vary markedly in different lesion compartments. The emerging understanding of how SCI cell biology differs across lesion compartments is fundamental to developing rationally targeted repair strategies.

Generalized convulsive seizures are associated with ketamine anesthesia in a rhesus macaque (Macaca mulatta) undergoing urodynamic studies and transcutaneous spinal cord stimulation

A female rhesus macaque developed two episodes of generalized convulsions during transcutaneous spinal cord stimulation (TSCS) and urodynamic studies under ketamine anesthesia. The seizures took place in the absence of active TSCS and bladder pressure elevation. Ketamine anesthesia remains the primary risk factor for the convulsions during these experimental procedures.