Identification of c-kit-positive cells in the uterus.
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Action Potentials↗
Biomedical subjects
O El-Sibai
Publications and source records attributed to O El-Sibai.
Overactive corpus cavernosum: a novel cause of erectile dysfunction.
Our recording of the electromyographic (EMG) activity of the corpus cavernosum (CC) in 59 patients with erectile dysfunction (ED) revealed 18 patients who had elevated electric activity, which presumably points to heightened tone of the CC smooth muscles. We investigated the hypothesis that this elevated EMG activity and muscular tone of the CC could be the cause of ED. The study comprised the said 18 subjects with the hypertonic CC muscles as study group (42.6 +/- 5.3 SD years), 15 healthy volunteers (41.8 +/- 5.1 SD years) and 15 patients (41.6 +/- 5.5 SD years) with ED who had not recorded elevated tone of the CC muscles as control group. The EMG activity was registered in the flaccid, erectile and detumescent phases by two electrodes inserted into the CC. Electrocavernosography (ECG) of healthy volunteers recorded in the flaccid phase showed regular slow waves (SW) and random action potentials (APs). The wave variables declined significantly in the erection phase (P < 0.01). In the study group, the SW variables in the flaccid phase increased significantly (P < 0.05) compared with the healthy volunteers and the rhythm was irregular. Erection did not occur with sildenafil but with intracavernosal injection of papaverine, which led to decline of the SW variables (P < 0.05). The control ED group exhibited in the flaccid phase diminished SW variables (P < 0.05) compared with the healthy volunteers. On erection with sildenafil administration, the SW variables showed significant reduction (P < 0.05). CC hypertonicity or 'overactive CC' was identified as a possible cause of ED. An elevated EMG activity of the CC muscle fibres in the flaccid phase presumably denotes hypertonicity of these fibres and their failure to relax to effect erection. The cause of elevated CCEMG activity and presumed muscle hypertonicity is unknown and could be functional or organic. Erection was produced by intracavernosus injection of papaverine and not by sildenafil. This condition of 'overactive CC' should be considered in the diagnosis of ED. However, further studies in the pathogenesis of the condition are warranted.
Action Potentials↗
Videodefecography: a study of the rectal motile pattern.
The mechanism of rectal motility has remained largely obscure. Recently, by recording rectal electromechanical activity, we identified the rectal motility pattern as occurring in a "mass squeeze" manner. In the current communication, rectal motility was studied by means of videodefecography. The study comprised 28 healthy volunteers (18 men, 10 women; mean age 37.6+/-11.8 years). Evacuation dynamics were studied and registered using a videocassette tape with a high-resolution recorder. The rectum showed no peristaltic or segmentation activity at rest. When the subject was asked to evacuate, a contraction wave started at the rectosigmoid junction (RSJ) and spread aborally. The upper rectum appeared to contract producing anal canal opening and the closure of the RSJ; after rectal evacuation, the anal canal closed and the RSJ opened. The rectal contraction wave was repeated as long as the rectum still contained barium paste. The subjects strained prior to the start of each contraction wave. Some waves did not effect rectal evacuation. These "incomplete" waves started at the mid- or lower rectum and were followed by "complete" waves that produced evacuation. In five of 28 subjects, rectal intussusception occurred during rectal contraction. A small anterior rectocele occurred in another two subjects during rectal contraction. Videodefecography revealed that upon rectal distension with barium paste, a contraction wave, initiated at the RSJ, effected reflex RSJ closure and anal canal opening. The wave spread aborally, "squeezing" the rectal contents towards the opened anal canal. Two types of contraction waves were observed: "complete" which produced rectal evacuation, and "incomplete" which failed to effect evacuation. Physiologic intussusception or rectocele were seen in a few subjects.
Adult↗
Study of the effect of straining on the bulbocavernosus muscle with evidence of a straining-bulbocavernosus reflex and its clinical significance.
The bulbocavernosus muscle (BCM) surrounds the vaginal introitus and covers the vestibular bulb. Its role in erection is known. However, as it surrounds the vaginal introitus, it may also have a role in intravaginal pressure regulation and in the pathogenesis of uterovaginal prolapse. We investigated the effect of increased intra-abdominal pressure (IAP) on the BCM, aiming to assess its possible function in supporting the uterus, vagina and anorectum. The intrarectal (representative of the IAP) and intravaginal pressures were measured by manometric catheters in 19 healthy women volunteers (mean age 46.2 +/- 10.4 years). The EMG activity of the BCM and its response to straining at different pressures were recorded by a concentric needle electrode. Two types of straining were tested: sudden momentary and slow sustained. The procedure was repeated in 11 of the women after individual anesthetization of the BCM, rectum and vagina. Sudden straining (coughing) produced a significant increase in intrarectal ( P<0.0001) and intravaginal ( P<0.0001) pressure as well as BCM EMG activity. Slow straining effected a similar but lower response: the BCM responded gradually with pressure elevation, whereas the latency exhibited a gradual decrease. The BCM did not react to straining after individual anesthetization of the BCM, vagina and rectum, but did respond to saline administration. The results were reproducible. BCM contraction on straining postulates a reflex relationship, which we call the 'straining-bulbocavernosus reflex'. We hypothesized that this reflex is evoked by straining and results in BCM contraction and closure of the vaginal introitus. The vagina is believed to become a closed cavity, counteracting the increased intra-abdominal pressure and the uterine tendency to prolapse. The high pressure in the closed vaginal cavity presumably supports the rectovaginal septum against the high intrarectal pressure, and is suggested to share in the prevention of rectocele. The role of BCM in the pathogenesis of uterovaginal prolapse and rectocele needs further study.
Adult↗
Cauterization-plication operation in the treatment of complete rectal prolapse.
The current communication presents a simple technique for treatment of complete rectal prolapse (CRP). The study included 28 patients presenting with CRP (mean age, 36.4 years; 4 children 2-12 years; 17 female and 11 males). Fourteen patients had fecal incontinence. With the patient under general anesthesia in lithotomy position, the prolapsed rectum was pulled outside the anal canal, the mucosa was cauterized in vertical lines and the exposed muscle layer was plicated by 2/0 coated Vicryl sutures. Posterior levatorplasty was done in 14 adult patients in whom the length of prolapsed segment was more than 10 cm and who were incontinent due to a wide levator hiatus. The postoperative follow up was 31.6+/-14.8 months (mean+/-SD). Five had postoperative mucosal prolapse and one had recurrence 3 months of operation. Mucosal plication was performed for the five patients and the operation was redone for the recurrent patient. Fecal impaction, stricture and fistula formation were not encountered. The technique is simple, easy and with minimal complications.
Adolescent↗
Study of the levator ani muscle in the multipara: role of levator dysfunction in defecation disorders.
The levator ani muscle (LAM) shares in the mechanism of defecation and urination as well as in visceral support. Levator dysfunction occurs in conditions of chronic straining or increased intra-abdominal pressure. Studies have shown that the gravid uterus, by virtue of its weight and associated increased intraabdominal pressure, might disturb the levator function. It is postulated that this effect is augmented with repeated pregnancies. The current study investigated the functional activity of the LAM in 50 multipara, 30 primipara and 20 nullipara (controls). The 50 multipara (age 46.4 years, 4-7 deliveries) were divided into group A (28 women with normal deliveries) and group B (22 women with a prolonged 2nd stage of labour). Of the 30 primipara (age 44.2 years) 18 had normal delivery (group A) and 12 prolonged 2nd stage of labour (group B). The mean age of the nullipara was 45.3+/-7.6. The LAM activity at rest and on contraction was recorded. The rectal and anal canal pressure response to LAM stimulation was also registered. In group A of the multipara, the LAM EMG activity at rest was similar to (P>0.05), and on contraction lower (P<0.05) than the LAM EMG of the controls (nullipara). Group B exhibited a lower activity at rest and on contraction (P<0.01, both). Primipara group A had a resting and contractile EMG activity similar to the controls, while group B showed diminished activity in both conditions (P<0.05, both) which was significantly higher (P<0.05, P<0.01, respectively) than that of group B multipara. The rectal pressure in the multipara and primipara did not differ from the nullipara (P>0.05, both). In groups A and B of multiparous women, the anal canal pressure at rest was significantly lower and on LAM contraction significantly higher than that of nullipara. Group A of the primipara showed no significant difference against the controls, while group B exhibited a decline at rest (P<0.05) and no difference on LAM contraction (P>0.05). In conclusion, levator dysfunction might occur in the parous women. It was more common in the multipara than the primipara and in particular those with a history of a prolonged 2nd stage of labour. Levator dysfunction may lead to constipation and faecal or urinary incontinence as a result of pudendal neuropathy and the development of pudendal canal syndrome.
Adult↗
Role of the sigmoid colon in the defecation mechanism with evidence of sigmoido-anal inhibitory and ano-sigmoid excitatory reflex.
In spite of voluminous literature that has been written on defecation, the exact mechanism has not yet been fully cleared up. The current study investigated the effect of sigmoid colon (SC) distension on anal motile activity and of anal distension on SC motility. Sixteen healthy volunteers (age 36.2 +/- 11.6 SD years, 10 men) were studied. The SC was distended by a balloon in 10 ml increments of CO2, and the anal, rectal and SC pressure response was recorded before and after their individual anesthetization. The anal, rectal and SC pressure response to anal distension in increments of 2 ml of CO2 was also registered. SC distension with big volumes (mean 86.2 +/- 1.9 ml) effected a SC pressure increase (p<0.05) and no rectal pressure response (p>0.05); the balloon was expelled to the exterior. Distension of the anesthetized SC caused no SC, rectal or anal pressure response (p>0.05, p>0.05, p>0.05, respectively); the response returned after the anesthetic effect had waned. SC distension while the rectum had been anesthetized, affected a significant SC pressure rise as well as an anal pressure decrease and balloon expulsion to the exterior. Anal balloon distension produced a significant pressure rise of the SC (p<0.001) and rectum (p<0.01). Distension of the anesthetized rectal neck (anal canal) caused no SC or rectal pressure response (p>0.05, p>0.05, respectively); response returned after the anesthetic effect had disappeared. SC distension appears to effect anal dilatation while anal distension causes SC contraction. This reciprocal action is suggested to be reflex and mediated through the "sigmoido-anal inhibitory reflex" and the "ano-sigmoid excitatory reflex". These 2 reflexes are believed to keep the SC contracting and the rectal neck dilated until complete SC evacuation occurs. The study seemingly negates the role of rectal distension as a prerequisite for balloon expulsion.
Adult↗
Electric activity of the rectosigmoid canal and its relation to rectal and sigmoid electric activity: an evidence of a sphincteric function of the rectosigmoid canal.
We have previously demonstrated that the rectosigmoid junction is more than a junction: it is a segment with a mean length of 2.8 cm which we termed the 'rectosigmoid canal' (RSC). Our data support the existence of a physiologic and anatomic sphincter at the RSC which regulates the passage of stools from the sigmoid colon (SC) to the rectum (R). In view of its sphincteric action we investigated the hypothesis that the RSC has a higher electric activity than that of the SC and R. The tests were performed during repair of huge incisional hernia in 11 subjects (age 46.7(12.5 years; 8 women). The electric activity was recorded by means of 2 monopolar electrodes applied to each of the SC, RSC and R. The RSC was then anesthetized with xylocaine and the electric activity of SC, RSC and R was recorded after 10 minutes and one hour. The test was repeated using saline instead of xylocaine. The SC, RSC and R exhibited electric activity in the form of pacesetter potentials (PPs) and action potentials (APs). The PPs were monophasic in the SC and triphasic in the RSC and R. The frequency, amplitude and conduction velocity of the waves recorded from the RSC and R had higher readings (p<0.05) than those from the SC. The RSC and R showed a similar frequency and conduction velocity, but the RSC had a higher amplitude (p<0.05). Ten minutes after RSC anesthetization, electric waves were recorded from the SC but not from the RSC or R; electric activity returned one hour after anesthetization. Saline injection of the RSC did not affect the electric activity of the RSC, SC or R. The electric wave pattern and parameters of the RSC and R differed from those of the SC, suggesting that they are evoked by 2 different pacemakers. The similarity in pattern, frequency and conduction velocity of electric waves of RSC and R supposedly denotes that the rectal waves are a continuation of those of the RSC and that both are evoked by a single pacemaker located in the RSC. The higher amplitude of the RSC waves may be due to the thicker RSC musculosa in comparison to that of the SC and R and may by itself be an evidence of the sphincteric function of the RSC.
Adult↗
Study of the mechanism underlying the difference in motility between the large and small intestine: the "single" and "multiple" pacemaker theory.
The common movement of the small intestine (SI) is peristalsis and of the large intestine (LI) are giant migrating contractions. The mechanism underlying the difference in the type of motility between the SI and LI is yet to be elucidated; the current communication investigated this point. 7 pigs (4 male) were anesthetized, abdomen opened and a balloon-ended catheter was introduced into the right colon through ileotomy. Balloon was filled in increments of 10 ml of saline and the EMG activity of the colonic longitudinal and circular muscle layers was recorded before and after myotomy performed between 2 of the 3 electrodes fixed to the colon. The balloon was then withdrawn, located in the terminal ileum and distended in increments of 2 ml; the ileal EMG activity was registered before and after myotomy done between 2 of the 3 electrodes applied to the ileum. The LI showed slow waves or pacesetter potentials (PPs) and action potentials (APs) which had the same frequency, amplitude and conduction velocity from the 3 electrodes of the same animal. The waves were recorded from the longitudinal and not the circular muscle coat. Upon LI distension, the electric activity increased and was recorded also from the circular muscle. At 40-50 ml distension, the balloon was dispelled to the transverse colon. Electric activity from SI was similar to that of the LI, but was not the same from the 3 electrodes; it diminished aborally. It increased with increasing balloon distension until, at 8-10 ml distension, the balloon moved slowly aborally. Electric waves were recorded proximally but not distally to colonic myotomy, and the balloon moved up to the cut. In the SI, waves were recorded both proximally and distally to the ileal myotomy, and the balloon moved across the cut. The fact that the colonic electric waves displayed the same variables from the 3 electrodes and that they were not recorded distally to the colonic myotomy, would suggest the presence of a "single" colonic pacemaker, probably situated in the cecum. This is in contrast to the hypothesis of the "multiplicity" of the small intestinal pacemakers, which is based on the fact that the electric activity diminished as the waves propagated aborally and on the existence of slow waves distal to the ileal myotomy. The concept of "single" and "multiple" pacemakers explaining the difference in the motility of small from that of large gut needs further studies.
Animals↗
Effect of pelvic floor muscle contraction on vesical and rectal function with identification of puborectalis-rectovesical inhibitory reflex and levator-rectovesical excitatory reflex.
The effects of pelvic floor muscle contraction on rectal and vesical function were studied in 19 healthy volunteers with the aim of shedding light on some of the hitherto vague aspects of the mechanisms involved in micturition and defecation and their disorders. Rectal and vesical pressures were recorded during puborectalis (PR) and levator ani (LA) muscle stimulation with the rectum or urinary bladder empty and full. Muscle stimulation was effected by needle EMG electrode. The pressure responses to stimulation of the PR and LA muscles were also recorded with these muscles and the rectum and urinary bladder individually anesthetized in 12 of the 19 subjects. The test was repeated using saline instead of xylocaine. PR and LA muscle stimulation produced no pressure response in the empty rectum or bladder. Upon rectal balloon distension with a mean of 156.6+/-34.2 ml of carbon dioxide the mean rectal pressure was 64.6+/-18.7 cm H2O, the subject felt the urge to evacuate and the balloon was expelled to the exterior. On PR muscle stimulation at rectal distension with the above volume, the subject did not feel the urge to evacuate, the rectal pressure was 8.2+/-1.6 cm H2O and the balloon was not expelled. Upon LA stimulation at the same volume, the urge persisted, the rectal pressure was higher and the balloon was expelled. Vesical filling with a mean of 378.2+/-23.6 ml of saline initiated the urge to urinate and elevated the vesical pressure. PR muscle stimulation at this volume aborted the urge and pressure elevation, while LA stimulation caused more elevation of the vesical pressure and spontaneous micturition. Bladder filling with a mean of 423.6+/-38.2 ml produced high vesical pressure and spontaneous urination, both of which were prevented by PR muscle stimulation but not by LA muscle stimulation. Stimulation of the PR and LA muscles during individual anesthetization of the rectum, bladder or PR and LA muscles resulted in no significant rectal or vesical pressure changes. Repetition of the test using saline instead of xylocaine resulted in rectal and vesical pressure responses similar to those without the use of saline. In conclusion, the decline in rectal and vesical responses upon PR muscle contraction indicates a reflex relationship which we term 'puborectalis rectovesical inhibitory reflex'. This reflex is suggested to abort the urge to defecate or urinate. In contrast, LA muscle contraction produced rectal and vesical pressure elevation which is suggested to be mediated through the 'levator rectovesical excitatory reflex'. 'This reflex is probably evoked to promote rectal and vesical evacuation.
Adolescent↗
Identification of 'vagino-anorectal reflex'.
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Adult↗
Effect of levator ani muscle contraction on urethrovesical and anorectal pressures and role of the muscle in urination and defecation.
OBJECTIVES: To investigate the effect of levator ani muscle (LAM) (the main muscle in the pelvic floor) contraction on the anorectal and urethrovesical pressures and elucidate its role in the mechanisms of defecation and urination. METHODS: In 18 healthy volunteers (10 men and 8 women; mean age 38.6 +/- 10.2 years), the LAM was stimulated to contract by a concentric needle electrode, and the anal, rectal, urethral, and vesical pressure responses were recorded. The test was repeated once after LAM anesthetization with Xylocaine injection and again after saline instead of Xylocaine injection into the LAM. RESULTS: On LAM stimulation, the anal and urethral pressures had a significant decline (both P <0.05), and the rectal and vesical pressures exhibited no significant changes (both P >0.05). The anal, rectal, urethral, and vesical pressures did not show significant changes on stimulation of the anesthetized LAM; after saline injection, the pressure response was similar to that before injection (P >0.05). These results were reproducible. CONCLUSIONS: LAM contraction lowers the anal and urethral pressures and appears to assist in the evacuation process. We therefore propose that the LAM is a muscle of evacuation and that LAM dysfunction could lead to defecation and urination disorders.
Adolescent↗
Transmission of rectal electric waves: is it through circular or longitudinal smooth muscle layers or both?
The rectum possesses electric activity in the form of pacesetter (PPs) and action potentials (APs). In recent studies we suggested that the waves are not initiated by the extrarectal autonomic innervation but might be triggered by a 'rectosigmoid pacemaker' and are transmitted in the rectal wall through the rectal musculature and not the enteric nerve plexus. To investigate whether the rectal waves are transmitted through the circular or longitudinal muscle layer, the rectum of 18 mongrel dogs was exposed under anesthesia through an abdominal incision. Three electrodes were applied to the rectal wall (longitudinal muscle layer) and another 3 electrodes to the circular muscle; the latter was exposed by splitting apart the fibers of the longitudinal muscle. Rectal electric activity and pressure were recorded from the 6 electrodes before and after performing individual myotomy of the rectal longitudinal (9 dogs), circular (9 dogs), and then the whole muscle layers (18 dogs). The myotomy was performed proximal to and between the electrodes. Pacesetter (PPs) and action potentials (APs) were recorded from the 3 electrodes on the longitudinal muscle but no waves were registered from those on the circular muscle. After longitudinal muscle myotomy was performed between electrodes 1 and 2, PPs and APs were recorded from electrode 1 but not 2 and 3 and when performed proximally to electrode 1, no waves were registered. The rectal pressure increased concomitantly with occurrence of APs. Circular muscle myotomy effected no change in the rectal electric activity recorded from the 3 electrodes applied to the longitudinal muscle. In total muscle myotomy, the electric waves were recorded from the electrodes proximal but not distal to the myotomy. We propose that the motile activity of the rectal longitudinal muscle is initiated by the electric activity which appears to be triggered by the rectosigmoid pacemaker, while that of the circular muscle fibers is believed to be initiated by the stretch reflex induced by rectal distension. This concept is evidenced not only by the current findings but also by the histologic structure of the rectal musculature being of the unitary type of smooth muscles.
Action Potentials↗
Study of the mechanism of rectal motility: the 'mass squeeze contraction'.
The motor physiology of the rectum has remained largely obscure, especially concerning the mechanism of rectal motility. In the current communication we tested the possibility of characterizing the mechanism of rectal motility during filling and evacuation through the study of the rectal electric activity in 16 healthy volunteers (mean age 43.6 +/- 10.8 years; 11 men). Two monopolar silver-silver chloride electrodes were introduced per annum and fixed to the rectal mucosa by suction. The rectum was distended in 10 ml increments of water by means of a balloon-ended catheter inserted into the rectum. The rectal pressure was measured by one catheter placed above and a second one below the rectal balloon, and the 2 catheters were connected to 2 strain gauge pressure transducers. Regular triphasic slow waves or pacesetter potentials (PPs) were recorded from the 2 electrodes at rest. PPs were superimposed or followed randomly by action potentials (APs). APs but not PPs were coupled with elevated rectal pressure. Rectal distension with 10 ml of water caused no significant changes of the rectal pressure or EMG activity. Distension with a mean volume of 27.3 +/- 4.7 ml effected a significant increase (p < 0.05) of the rectal electromechanical activity proximally to the balloon and a decrease distally (p < 0.05) to it. With progressive increase of the rectal distension, the electromechanical activity continued to increase proximally and to decrease distally to the balloon, until, at a mean distending volume of 76.3 +/- 3.7 ml, the balloon was dispelled to the exterior. In conclusion, the identification of the modality of rectal motility during defecation was feasible by recording the rectal electromechanical activity. The rectal contraction is suggested to occur in a 'mass squeeze manner' which squeezes the rectal contents aborally into the anal canal. The recognition of the rectal motor modality appears to be important for the understanding of rectal motility disorders. However, further studies are required to confirm these findings.
Action Potentials↗
Experimental use of the obturator internus muscle as a functioning pelvic floor muscle in dogs.
OBJECTIVE: To investigate the possibility of using the obturator internus muscle instead of the levator ani as a pelvic floor muscle. DESIGN: Experimental study. SETTING: Teaching hospital, Egypt. ANIMALS: 7 male and 3 female mongrel dogs. INTERVENTIONS: Through a para-anal incision both muscles were exposed; the levator ani was excised and the lower border of the obturator internus was mobilised and sutured to the anorectal junction, the vesical neck, and the vaginal fornix. MAIN OUTCOME MEASURES: Rectal and anal pressures and electromyographic (EMG) activity recorded before and during transposition, and 1, 3, and 6 months later. Histological examination of biopsy specimens taken from the levator ani before, and from the obturator internus before, and 3, 6, and 12 months after, transposition. RESULTS: Stimulation of the levator ani caused anal pressure to decline significantly (p < 0.05). Stimulation of the obturator internus did not change anal pressure before transposition but caused a decline after it. There was EMG activity in the levator ani at rest, but not in the obturator internus before transposition though it was evident by 6 months afterwards. Levator ani consisted of skeletal muscle fibres with smooth muscle fibres in places, whereas the obturator internus consisted of skeletal fibres alone. Six months after operation examination of the obturator internus showed the presence of some smooth muscle fibres. CONCLUSION: These results suggest that the obturator internus might be suitable both anatomically and physiologically to replace the levator ani. However, before it can be suggested as a treatment for levator dysfunction syndrome further experimental studies are necessary.
Anal Canal↗
Effect of vaginal distention on vesicourethral function with identification of the vagino-vesicourethral reflex.
PURPOSE: To our knowledge the physiological mechanisms involved in sexual intercourse have not been completely explored. We hypothesized that vaginal distention induced by penile thrusting may affect the function of the bladder and urethra. To verify this supposition we assessed the effect of vaginal distention on vesical and urethral pressure. No relevant reports in the literature were identified. MATERIALS AND METHODS: The response of vesical and urethral pressure to vaginal distention was recorded in 26 healthy women volunteers with a mean age plus or minus standard deviation of 36.7 +/- 9.8 years. A condom was introduced into the vagina and inflated with carbon dioxide in increments of 10 ml. up to 80 ml. Vesical and urethral pressure was measured by a 2-channel microtip catheter connected to a transducer. The vesicourethral pressure response to vaginal distention was also tested after individual anesthetization of the bladder, urethra and vagina. RESULTS: No vesicourethral pressure response was recorded with 10 and 20 ml. of vaginal distention. At 30 and up to 80 ml. of distention bladder pressure decreased and urethral pressure increased (p <0.05). There was no significant difference when the volume of vaginal distention was increased. Mean duration of the pressure response was 4.2 +/- 0.6 seconds. Pressure returned to normal after a latency period of 5.2 +/- 1.1 seconds, although the vagina was continuously distended. Vaginal distention during anesthetization of the bladder, urethra or vagina did not evoke a pressure response. CONCLUSIONS: The vesicourethral response to the inserted condom, which by inflation adopts the shape of the erect penis, seems to simulate the response of the vagina when it is distended by the erect penis during coitus. The constant vesicourethral pressure response to vaginal distention postulates a reflex relation, which we call the vagino-vesicourethral reflex. This reflex is apparently evoked during coitus, leading to momentary vesical dilatation and increased urethral sphincter activity, which most likely acts to prevent urinary leakage during coitus. Reflex disorders may explain urinary leakage during coitus in some neuropathic conditions.
Adult↗
Rectal pacing: pacing parameters required for rectal evacuation of normal and constipated subjects.
BACKGROUND AND PURPOSE: Our previous studies have demonstrated that rectal electric waves start at the rectosigmoid junction (RSJ) and spread caudad along the rectum. A rectosigmoid pacemaker was postulated to exist at the RSJ. We also demonstrated that electric waves in rectal inertia are so scarce that a "silent" electrorectogram is recorded; the myoelectric activity in such cases was stimulated by an artificial pacemaker placed at the RSJ. For this article we investigated the pacing parameters necessary for rectal evacuation in rectal inertia patients. METHODS: The study comprised 24 patients with rectal inertia divided into two groups: study group (10 women, 6 men; mean age, 38.9 +/- 10.6 years) and control group (6 women, 2 men; mean age, 36.3 +/- 9.8 years). The main complaint was infrequent defecation and straining at stools. Eight healthy volunteers (6 women, 2 men; mean age, 37.2 +/- 9.4 years) with normal stool frequency were included in the study. Through a sigmoidoscope, an electrode was hooked to the RSJ (stimulating) and two electrodes were hooked to the rectal mucosa (recording). Rectal electric activity was recorded before (basal activity) and during electric stimulation of the RSJ electrode with an electrical stimulator delivering constant electric current of 5-mA amplitude and 200-ms pulse width. RESULTS: In the healthy volunteers, rectal pacing effected increases in frequency, amplitude, and velocity from a mean of 2.3 +/- 0.9 to 6.2 +/- 1.8 cycles/min (P < 0.01), 1.2 +/- 0.6 to 1.7 +/- 0.8 mV (P < 0.05), and 4.1 +/- 1. 2 to 6.3 +/- 1.7 cm/s (P < 0.05), respectively. No waves were recorded from rectal inertia patients at rest. Rectal pacing of the study group showed pacesetter potentials with a mean frequency of 2. 1 +/- 1.2 cycles/min, amplitude of 0.9 +/- 0.1 mV, and velocity of 3. 3 +/- 1.6 ms. The control group, in whom the pacemaker was not activated, showed no electric activity. CONCLUSIONS: Rectal pacing succeeded in producing myoelectric activity in patients with rectal inertia. It is therefore suggested that this method be applied for rectal evacuation in patients with inertia constipation.
Action Potentials↗
Rectal pacing in patients with constipation due to rectal inertia: technique and results.
In a previous study we determined the rectal pacing parameters needed for rectal evacuation in patients with rectal inertia. Here we investigated the effect of rectal pacing on rectal myoelectric activity, motility, and evacuation in ten patients with constipation due to rectal inertia. A pacemaker was implanted in a subcutaneous pocket above the inguinal area, with a lead threaded in the anal submucosa to be hooked at the rectosigmoid junction. The effect of rectal pacing on rectal electric activity was investigated by inserting two recording electrodes to the rectal mucosa. The patients were then trained for home pacing. No waves were recorded from the rectum at rest. On rectal pacing, slow waves or pacesetter potentials (mean frequency 2.3+/-1.1 cpm, amplitude 0.86+/-0.1 mV, velocity 3.4+/-1.6 ms) were registered after a latency period of 5.2+/-1.6 min. Rectal evacuation, on pacing, occurred in seven of the ten patients. The three who showed no significant response exhibited low wave parameters. Three of seven patients were able to evacuate spontaneously without pacing after having performed daily pacing for 5-6 months. The pacemaker was removed in six patients (three failures and three after spontaneous defecation). Thus rectal pacing succeeded in inducing rectal evacuation in 70% of the patients. The procedure failed in three patients. Three had spontaneous defecation after a few months of rectal pacing. No complications were encountered, and the method was tolerated and acceptable. Further studies on a large group of patients are required.
Action Potentials↗