Anorectal motility responses to selective stimulation of the ventral sacral nerve roots in an experimental model (original) (raw)
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Colorectal Disease, 2004
Background: Control of defaecation and continence may be lost in patients with spinal cord injury. Electrical stimulation of sacral nerve roots to promote defaecation simultaneously activates both the rectum and the external anal sphincter (EAS), and may actually obstruct defaecation. The aim of this study was to investigate whether the EAS could be blocked selectively by selective stimulation of the ventral sacral nerve roots, and whether activation of the rectum without activation of the EAS could be obtained by stimulation of the ventral sacral nerve roots. Methods: Selective electrical stimulation was performed using anodal blocking, a tripolar cuff electrode and monophasic rectangular current pulses applied to the sacral nerve roots in nine Göttingen minipigs. Results: Simultaneous responses in the rectum and the anal canal were observed in five animals, whereas only anal responses were noted in four. Variations in cross-sectional area and an increase in rectal pressure seemed to facilitate defaecation. Without blocking, the increase in anal canal pressure was 16-45 cmH 2 O. With blocking, this increase was abolished in seven and reduced to 3-6 cmH 2 O in two animals. Conclusion: Selective activation of the rectum is possible using an anodal block of somatic motor fibres. This technique holds promise in further development of electro-defaecation.
British Journal of Surgery, 1986
The motility responses of the sigmoid colon, rectum and external anal sphincter to sequential electrical stimulation of the anterior sacral roots (S,, S, and S,) were studied infive patients with traumatic spinal cord injury. Identical and reproducible results were obtained. S , stirnulation provoked isolated low-pressure colorectal contractions. S, stimulation initiated high-pressure colorectal motor activity which appeared peristaltic and was enhanced with repetitive stimuli. This response appeared to be frequency-dependent. S , stimulation increased colonic and rectal tone. External sphincter activity was stimulated in increasing order from S , to S,. These observations directly elucidate the central control of colorectal motility and may have implications in the treatment of severe constipation following spinal injury.
stimulation of sacral roots for electrodefecation results in simultaneous activation of the rectum and the external anal sphincter. The sphincter contraction hinders evacuation of the rectum. In this study anodal blocking has been used to reduce the activation of the external anal sphincter. Using a tripolar cuff electrode and monophasic rectangular current pulses in 7 acute minipigs experiments the pressure response in the anal canal was reduced more than 80 % in all animals compared to stimulation without blocking. The result confirms previous results from the bladder, in other species, in that selective small fibre activation can be obtained using an anodal block.
Spinal Cord, 2012
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 plasterelectrodes using an amplitude of twice the genito-anal reflex threshold (pulse width: 200 ms; 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%; P¼0.02) and 30 cmH 2 O (average decrease 4%; P¼0.03) above resting rectal pressure. Accordingly, rectal pressure-CSA relation was significantly reduced during stimulation at 20 (P¼0.03) and 30 cmH 2 O distension (P¼0.02). Conclusion: DGN Stimulation in patients with supraconal SCI results in an acute decrease of rectal CSA and the rectal pressure-CSA relation.
Gut, 1999
BACKGROUNDSome patients with faecal incontinence are not amenable to simple surgical sphincter repair, due to sphincter weakness in the absence of a structural defect.AIMSTo evaluate the efficacy and possible mode of action of short term stimulation of sacral nerves in patients with faecal incontinence and a structurally intact external anal sphincter.PATIENTSTwelve patients with faecal incontinence for solid or liquid stool at least once per week.METHODSA stimulating electrode was placed (percutaneously in 10 patients, operatively in two) into the S3 or S4 foramen. The electrode was left in situ for a minimum of one week with chronic stimulation.RESULTSEvaluable results were obtained in nine patients, with early electrode displacement in the other three. Incontinence ceased in seven of nine patients and improved notably in one; one patient with previous imperforate anus and sacral agenesis had no symptomatic response. Stimulation seemed to enhance maximum squeeze pressure but did n...
Neurogastroenterology & Motility, 2008
The extent and nature of colonic and anorectal motility responses to S2, S3, and S4 anterior nerve root stimulation were studied in seven paraplegic patients with a Brindley electromicturition sacral implant. After sequential S2, S3 and S4 stimulation wave height activity was increased above basal f r o m the transverse colon to the rectum. The mean motility index response to sequential stimulation was greatest at the splenicjlexure. The greatest peak wave height and mean motility index response to individual anterior nerue root stimulation was to S3, which could empty the left colon by a distal motility gradient. S4 anterior root stimulation increased the intrarectal pressure and also raised the anal canal pressure to high levels.
Temporary Sacral Nerve Stimulation Alters Rectal Sensory Function: A Physiological Study
Diseases of the Colon & Rectum, 2011
BACKGROUND: The indications for sacral nerve stimulation are increasing, but the mechanism remains poorly understood. OBJECTIVE: This study aimed to examine the effect of sacral nerve stimulation on rectal compliance and rectal sensory function. DESIGN: This was a prospective study. SETTINGS: This study took place at a university teaching hospital. PATIENTS: Twenty-three consecutive consenting patients (22 female; median age, 49 y) undergoing temporary sacral nerve stimulation for fecal incontinence were prospectively studied. Clinical response was assessed by the use of bowel diaries and Wexner scores. MAIN OUTCOME MEASURES: Anal manometry, rectal compliance, volume and pressure thresholds to rectal distension (barostat), and rectal Doppler mucosal blood flow were measured before and at the end of stimulation. RESULTS: Sixteen patients (70%) had a favorable clinical response. Median anal squeeze pressures increased with stimulation from 40 (range, 6-156) cmH 2 O to 64 (range, 16-243) cmH 2 O. Median rectal compliance did not significantly change with stimulation (prestimulation: 11.5 (range, 7.9-21.8) mL/mmHg, poststimulation: 12.4 (range, 6.2-22) mL/mmHg, P ϭ .941). Rectal wall pressures associated with urge (baseline: 15.4 (range, 11-26.7) mmHg, poststimulation: 19 (range, 11.1-42.7) mmHg, P ϭ .054) and maximal tolerated thresholds (baseline: 21.6 (8.5-31.9) mmHg, poststimulation: 27.1 (14.3-43.3) mmHg, P ϭ .023) significantly increased after stimulation. Rectal Doppler mucosal blood flow did not significantly change with stimulation (baseline: 125.8 (69.9-346.8), poststimulation: 112.4 (50.2-404.1), P ϭ .735). Changes in anal resting pressure and rectal wall pressures with stimulation were evident only in responders; however, changes in anal squeeze pressures were evident in both responders and nonresponders. LIMITATIONS: The study reports results following shortterm stimulation in a small but homogenous group of patients. A larger long-term study will follow. CONCLUSION: Temporary sacral nerve stimulation does not change rectal compliance, but is associated with significant changes to the pressure thresholds of rectal distension. This, together with the observation that outcome is not related to sphincter integrity, supports the hypothesis of an afferent-mediated mechanism of action.
Archives of Physical Medicine and Rehabilitation, 1993
Aims: Transcutaneous electrical stimulation of the dorsal penile/clitoral nerve (DPN) has been shown to suppress detrusor contractions in patients with neurogenic detrusor overactivity (NDO). However, the long-term use of surface electrodes in the genital region may not be well tolerated and may introduce hygienic challenges. The aim of this study was to assess whether electrical stimulation of the sacral dermatomes could suppress detrusor contractions in multiple sclerosis (MS) patients with NDO, hereby providing an alternative to DPN stimulation. Materials and Methods: A total of 14 MS patients (8 M, 6 F) with low bladder capacity (<300 ml) and a recent urodynamic study showing detrusor overactivity incontinence participated in the study. Three successive slow fill cystometries (16 ml/min) were carried out in each patient. The first filling served as control filling where no stimulation was applied. In the second and third filling electrical stimulation of either the DPN or sacral dermatomes was applied automatically whenever the detrusor pressure exceeded 10 cmH 2 O. Results: The control filling showed detrusor overactivity in 12 of the 14 patients. In 10 of the 12 patients one or more detrusor contractions could be suppressed with DPN stimulation. Electrical stimulation of the sacral dermatomes failed to suppress detrusor contractions in all patients. Conclusions: Although therapeutic effects may be present from stimulation of the sacral dermatomes, we were unable to demonstrate any acute effects during urodynamics. For this reason stimulation of the sacral dermatomes is not an option in a system that relies on the acute suppression of a detrusor contraction.
Neurourology and urodynamics, 2006
Individuals with spinal cord injury or neurological disorders may develop bladder contractions at low volumes (neurogenic detrusor overactivity), which can lead to significant health problems. Present devices can inhibit unwanted contractions through continuous electrical stimulation of sensory nerves, but do not enable conditional stimulation only at the onset of bladder contractions. The objectives of this study were to determine the relationship between the electrical activity of external anal sphincter (EAS) and bladder pressure during neurogenic detrusor contractions and to determine whether EAS activity could be used to detect the onset of bladder contractions.
Neurogastroenterology & Motility, 2008
The effect of the Brindley stimulator on pelvic jloor function has been studied in seven paraplegic subjects by standard manometric, radiologic, and electrophysiologic methods. There was no d@erence in the maximum resting pressure in the anal canal between the stimulated group and paraplegic subjects without sacral stimulators acting as controls. The f a l l in pressure in response to the rectosphinteric rejlex as a percentage of the original resting pressure was signGcantly less, indicating a proportional effect on the external sphincter. There was less descent of the pelvic jloor at rest in the stimulated group, but no dgerence in the pudendoanal re3ex latency, motor unit potential duration, or resting electromyogram activity of the external anal sphincter. The maximum resting pressure in the anal canal, the pudendoanal rejlex response amplitude, and the external anal sphincter electromyogram activity increased, however, with the duration of the implant. The S4 root had the dominant effect on the pelvic jloor, with decreasing effects f r o m the S3 and S2 roots on the pressure and integrated electromyogram activity generated by the external anal sphincter. The anorectal angle had not changed at rest in the group with the stimulator, but S4 root stimulation made it more acute than S 3 or S2 root stimulation. The results suggest profound effects of S4 anterior root stimulation on the pelvicjloor with additional effects of S3 and S2 anterior roots on pelvic. .function.