Selective suppression of sphincter activation during sacral anterior nerve root stimulation

The purpose of this work was to electrically activate small-diameter motor fibers in the sacral anterior roots innervating the urinary bladder, without activating the large-diameter fibers to the sphincter. Quasitrapezoidal current pulses were applied through tripolar spiral nerve electrodes on selected anterior sacral roots during acute experiments on eight dogs, maintained under pentobarbital anesthesia. Pressures were recorded from the bladder and sphincter with catheter-mounted gauges. Stimulation with biphasic quasitrapezoidal pulses showed decrease in sphincter recruitment with increasing pulse amplitudes. The minimum current amplitude that resulted in maximum sphincter suppression was used to stimulate the roots with trains of 20 Hz pulses, with 60 mL of saline filling the bladder. Pressures were also recorded when 100 micros rectangular pulse trains at 20 Hz, both continuous and intermittent, were applied. Trains of stimuli were applied before and after dorsal root rhizotomy. Suppression of sphincter activation was defined to be a percentage, [(Maximum pressure -Minimum pressure)/Maximum pressure x100. The results from 22 roots in eight animals show that with single pulses, the average percentage suppression of sphincter activation was 76.3% (+/-14.0). The minimum current for maximum sphincter suppression was 1.29 mA (+/-0.62). The average bladder pressure evoked was 50 cm of water during pulse train stimulation, with no significant difference due to pulse type. With pulse trains, the sphincter pressures were significantly higher when the bladder was filled. Evacuation of fluid occurred in three animals with average flow rates of 1.0 mL/s.     

Sacral transcutaneous electrical nerve stimulation in the treatment of idiopathic faecal incontinence

Aim The aim of this study was to investigate the potential use of S3 transcutaneous electrical nerve stimulation (TENS) in the treatment of idiopathic faecal incontinence. Method Seventeen patients were treated by S3 TENS 2 h a day for 3 months. The outcome was evaluated by faecal incontinence severity index (FISI), faecal incontinence quality of life scale (FIQOL), 7‐day bowel diary, anorectal physiology, patients’ self‐reported impression of improvement, bowel control and satisfaction with treatment on a visual analogue scale. Results Seventeen patients (13 women) of mean age 67.2 years (52–80) were followed up for a mean of 19.7 months. The FISI improved in 69% after 3 months of TENS (P < 0.01), and all components of FIQOL improved. The number of incontinent episodes per week fell for incontinence to gas and stool (solid and/or liquid). There was no significant difference in the maximum resting pressure and squeeze pressure, but the mean rectal volume of first sensation (12.1 ml, P = 0.027) and first urge (25.0 ml, P = 0.054) fell, and the maximum tolerable volume (16.0 ml, P = 0.679) rose. The satisfaction score was ≥ 6/10 in all patients. Fifteen (88%) scored ≥ 6/10 for bowel control, and all patients scored ≥ 2 (scale: ?5 to +5) for their impression of improvement. Conclusion S3 transcutaneous electrical nerve stimulation seems to be a promising noninvasive method to treat faecal incontinence. However, further study is required.     

How sacral nerve stimulation works in patients with faecal incontinence

Aim Sacral nerve stimulation (SNS) reduces incontinence episodes and improves the quality of life of patients treated for faecal incontinence. However, the exact mechanism of action of this technique remains unclear. The present article reviews the pertinent neuroanatomy and neurophysiology related to SNS and provides explanations for potential mechanisms of action. Method A systematic review of the literature was performed for studies of the potential mechanisms of action of SNS, using MEDLINE, PubMed, Embase and the Cochrane Library. Articles dealing with the technique, adverse events and economic evaluations of SNS, as well as literature reviews, were excluded, except for reviews dealing with the mechanisms of action of SNS. The following inclusion criteria were used to select articles: (i) articles in English, (ii) randomized, double‐blinded, sham‐controlled studies, and (iii) cohort studies. Case–control studies or retrospective studies were cited only when randomized or cohort studies could not be found. Results We propose three hypotheses to explain the mechanism of action of SNS: (i) a somato‐visceral reflex, (ii) a modulation of the perception of afferent information, and (iii) an increase in external anal sphincter activity. Conclusion The mechanism of action of SNS in patients with faecal incontinence almost certainly depends on the modulation of spinal and/or supraspinal afferent inputs. Further research on humans and animals will be required to gain a better understanding of the mechanisms of action of SNS.     

骶神经根周围囊肿的诊断及外科治疗

目的 探讨骶神经根周围囊肿的临床表现、影像学特点及外科治疗效果。方法 诊断22例骶管内神经根周围囊肿患者。对有明显症状的16例进行手术治疗。行病变部位后路椎板减压，13例囊肿切除，3例囊肿大部分切除，9例硬膜破裂神经根裸露采用胶原蛋白海绵覆盖。结果 MRI检查显示出椎管内神经根囊肿的形态，CT显示骶骨压迫性改变。16例切口均一期愈合，术后随访6个月～7年，平均2年9个月，患者术后腰骶疼痛、间歇跛行、骶神经症状均得到明显缓解，无感染病例，2例脑脊液漏1周内愈合。结论 骶管内神经周围囊肿临床上少见，容易误诊。MRI是最好的诊断方法，采用手术摘除囊肿和胶原蛋白海绵覆盖治疗，其治疗效果满意。     

Comparison of the efficacy and safety of sacral root magnetic stimulation with transcutaneous posterior tibial nerve stimulation in the treatment of neurogenic detrusor overactivity: an exploratory randomized controlled trial

BackgroundBoth repetitive sacral root magnetic stimulation (rSMS) and transcutaneous posterior tibial nerve stimulation (TTNS) have demonstrated clinical benefits for lower urinary tract dysfunction. However it still remains unclear that which method is more effective and safer to treat neurogenic detrusor overactivity (NDO).MethodsFrom December 2020 to December 2021, 50 patients (31 men and 19 women, aged 47.9±12.4 years) with NDO secondary to suprasacral spinal cord injury (SCI) were enrolled and randomly allocated to the rSMS or TTNS group based on a computer-generated random numbers table. The stimulation was applied continuously 5 times per week for 20 sessions. Urodynamic test was conducted at baseline and the day after the final 20th treatment session. The primary outcome was the individual change (Δ) in maximum cystometric capacity (MCC) from baseline to post-treatment. Secondary outcomes included changes (Δ) for the following parameters: volume at 1st involuntary detrusor contraction (1st IDCV), maximal detrusor pressure (Pdetmax), bladder compliance (BC), postvoid residual (PVR) volume, and bladder voiding efficiency (BVE). Additionally, adverse reactions including pain and skin irritation during stimulation were observed and recorded as safety outcomes.ResultsFinally 47 patients completed the study (23 in rSMS and 24 in TTNS group). A per-protocol (PP) analysis was performed, and Mann-Whitney U test and unpaired t-test were used for statistical analysis. Compared with the efficacy of TTNS, rSMS showed statistically greater ΔMCC [median +43 mL (IQR, 22–62 mL) vs. +20 mL (IQR, 15–25 mL), P=0.001, with a between-group difference of +22 mL (95% CI: +7 to +35 mL)] and ΔBVE [median +10.0% (IQR, 3.8–15.7%) vs. +3.5% (IQR, 0.0–7.8%), P=0.003, with a between-group difference of +5.9% (95% CI: +1.2% to +9.7%)]. No significant differences were found in Δ1st IDCV (P=0.40), ΔPdetmax (P=0.67), ΔBC (P=0.79) and ΔPVR (P=0.92) between the two groups. Meanwhile, patients exhibited high tolerance to both protocols, and no adverse reactions were observed.ConclusionsRSMS may be more effective to improve urodynamics in the treatment for NDO than TTNS, cause it led to a statistical improvement in bladder capacity and voiding efficiency, without any side effects. RSMS is thus worthy of further clinical promotion.Trial RegistrationChinese Clinical Trial Registry ChiCTR2100050663.     

截瘫后经马尾骶神经根重建自控性膀胱功能

目的 通过对截瘫患马尾骶神经根的桥接来改善膀胱功能,建立起自控性膀胱。方法 将2例截瘫后患行切断15前根,两例行L5-S2前根的桥接。结果 2例患近期表现为膀胱容量增大,顺应性提高,远期有敲击跟腱后引发排尿．最大尿流率11．0mL/s。结论 建立“腱反射—脊髓中枢—膀胱”的人工反射弧途径来达到重建自控性膀胱功能是可行的。     

Sacral anterior root stimulation: Prerequisites and indications

An intact sacral reflex arc, or at least an intact second motor-neuron and a detrusor being able to contract, are the two prerequisites for implanting an anterior sacral root stimulator. Transrectal electrostimulation or direct needle stimulation of the sacral roots may reveal if patients despite absent or only weak detrusor contractions on routine investigation are suitable. Patients with a complete midthoracic paraplegia are the ideal candidates, but tetraplegics also benefit. Patients with incomplete lesions and preserved pain sensations are suitable provided that they can undergo posterior sacral root rhizotomy. Non-traumatic spinal cord lesions follow the same rules, provided that the type of lesion does not allow recovery and is not progressive. Myelomeningocele patients may be suitable provided that the pathoanatomy of the sacral roots permits the operation (may be possible only in thoracolumbar myelomeningocele). Vesico-uretero-renal reflux is no contraindication; it may even be a strong indication, if a low compliance bladder or high detrusor contractions are the main reasons for it. In most patients the procedure should or must be combined with posterior sacral root rhizotomy in order to normalize a low compliance, to abolish spontaneous reflex contractions, and to achieve continence. The benefit of following these rules is reflected in our own series of 30 patients. In all of them the operation has improved considerably the quality of life and no patient so far has regretted the operation.     

The Effect of sacral nerve stimulation on uterine activity: a pilot study

Introduction  Sacral nerve stimulation (SNS) is a treatment for consecutive therapy resistant faecal incontinence or constipation. Little is known about the effects of SNS on uterocervical function. Therefore, it is advised to turn off the stimulator during pregnancy or to wait with permanent implantation of the stimulator until family completion. Diagnostic ultrasound provides an, non‐invasive, opportunity to study various aspects of uterine activity. The purpose of this pilot study was to assess the influence of SNS on endometrial waves of the nonpregnant uterus by ultrasound recordings. Method Six patients with an implanted SNS were included. Ultrasound recordings were performed with the stimulator turned off and in three stimulation frequencies. Uterine activity is described as wave frequency and wave direction. Results All three premenopausal patients showed endometrial activity with the stimulator turned off. This activity was maintained with the stimulator turned on in two patients, but disappeared in one patient. All three postmenopausal patients had no endometrial activity with the stimulator turned off. In one patient there was activity with the stimulator turned on at a frequency of 21 Hz. Conclusion We have shown some effect of SNS on uterine activity. In premenopausal women we discovered that SNS seems to exhibit no effect or an inhibitory effect rather than an excitatory effect on uterine activity. Based on the preliminary results of this study, we can not recommend any guidelines for SNS usage during conception and pregnancy. A larger study in premenopausal women with SNS is needed to investigate the significance of these changes.     

Predictive factors for successful sacral nerve stimulation in the treatment of faecal incontinence: results of trial stimulation in 200 patients

Aim Sacral nerve stimulation (SNS) has a place in the treatment algorithm for faecal incontinence (FI). However, after implantation, 15–30% of patients with FI fail to respond for unknown reasons. We investigated the effect of SNS on continence and quality of life (QOL) and tried to identify specific predictive factors of the success of permanent SNS in the treatment of FI. Method Two hundred consecutive patients (six men; median age = 60; range 16–81) underwent permanent implantation for FI. The severity of FI was evaluated by the Cleveland Clinic Score. Quality of life was evaluated by the French version of the American Society of Colon and Rectal Surgeons (ASCRS) quality of life questionnaire (FIQL). All patients underwent a preoperative evaluation. After permanent implantation, severity and QOL scores were reevaluated after six and 12 months and then once a year. Results The severity scores were significantly reduced during SNS (P = 0.001). QOL improved in all domains. At the 6‐month follow‐up, the clinical outcome of the permanent implant was not affected by age, gender, duration of symptoms, QOL, main causes of FI, anorectal manometry or endoanal ultrasound results. Only loose stool consistency (P = 0.01), persistent FI even though diarrhoea was controlled by medical treatment (P = 0.004), and low stimulation intensity (P = 0.02) were associated with improved short‐term outcomes. Multivariate analysis confirmed that loose stool consistency and low stimulation intensity were related to a favourable outcome. Conclusion Stool consistency and low stimulation intensity have been identified as predictive factors for the short‐term outcome of SNS.     

Urinary bladder control by electrical stimulation: Review of electrical stimulation techniques in spinal cord injury

Evacuation of urine in paraplegics without the need for catheters would be possible when voiding could be induced by eliciting a bladder contraction. A challenging option to obtain detrusor contraction is electrical stimulation of the detrusor muscle or its motor nerves. This article reviews the 4 possible stimulation sites where stimulation would result in a detrusor contraction: the bladder wall, the pelvic nerves, the sacral roots, and the spinal cord. With respect to electrode application, sacral root stimulation is most attractive. However, in general, sacral root stimulation results in simultaneous activation of both the detrusor muscle and the urethral sphincter, leading to little or no voiding. Several methods are available to overcome the stimulation-induced detrusor-sphincter dyssynergia and allow urine evacuation. These methods, including poststimulus voiding, fatiguing of the sphincter, blocking pudendal nerve transmission, and selective stimulation techniques that allow selective detrusor activation by sacral root stimulation, are reviewed in this paper.     

经皮电刺激促进腓总神经损伤后神经再生的临床研究

目的证实经皮电刺激对周围神经(本文选择腓总神经)完全损伤后神经再生的促进作用,并探讨最佳的电刺激的参数、波形优化组合等治疗方案。方法对30例腓总神经完全损伤患者,随机分为电刺激组和对照组,每组15例,在行神经缝合术后,各组同时服用神经营养药物治疗,电刺激组在术后4周石膏拆除后加用电刺激治疗。经过方波和变频波的交替使用,之后均使用变幅脉冲波+肌肉训练波,并适度增加肌肉训练波的治疗时间。术后随访内容:术后6个月进行足趾伸屈力,神经电生理检测。结果电刺激组的临床肌力与肌电图结果均优于对照组,两组差异有统计学意义(P<0.05)。电刺激组的肌力恢复时间与肌电图恢复时间也明显短于对照组,两组差异有统计学意义(P<0.05)。结论经皮电刺激治疗具有促进受损周围神经再生和传导功能恢复的作用,并且能减少受损骨骼肌的萎缩,尤其对电刺激仪的工作参数、电流波形进行优化组合后,可获得更好的疗效。     

c-Fos expression in the spinal cord after acute sacral segmental nerve stimulation

AIMS: Sacral nerve stimulation (SNS) can provide subjective and objective relief of pelvic pain and chronic voiding symptoms, but its mechanism is poorly understood. It is well known that a noxious stimulus applied to one part of the body can reduce the response to a subsequent stimulus elsewhere in the body. This phenomenon, known as diffuse noxious inhibitory controls (DNIC), seems to be the mechanism by which pain can be reduced by concurrent noxious stimulation. METHODS: On the basis of the DNIC concept, we investigated the expression of a protein product of proto-oncogene c-Fos (c-Fos) in the rat spinal cord after acute electrical stimulation of the sacral segmental nerve with or without lower urinary tract irritation. Adult male Sprague-Dawley rats were treated either by sacral nerve stimulation (SNS) from the S1 sacral foramen or chemical irritation of the lower urinary tract (LUT) or both. Rats were perfused transcardially, and spinal cords were removed and processed for c-Fos immunohistochemistry. c-Fos expression in the central nervous system was detected by immunohistochemistry by using the avidin-biotin technique. The number of c-Fos-positive cells and their locations in the spinal cord were evaluated. RESULTS: SNS and LUT irritation resulted in significant increases in c-Fos-positive cells in L6 and S1 spinal segments. In the animals treated by SNS and LUT irritation, counts of c-Fos-positive cells in L6 and S1 segments were significantly smaller than expected. Distribution and number of c-Fos-positive cells in rats that received SNS and LUT irritation were almost the same as those induced by SNS alone in the S1 segment. CONCLUSIONS: SNS alone caused a near maximal response in c-Fos expression such that adding LUT irritation did not cause a linear increase in c-Fos. Subsequent LUT irritation could not induce additional expression of c-Fos within the spinal cord.