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O El-Sibai

Publications and source records attributed to O El-Sibai.

35 records · Page 2Linked to original sources

The anocavernosal erectile dysfunction syndrome. II Anal fissure and erectile dysfunction.

A previous study has demonstrated that the bulbocavernosus muscle (BCM) is a part of the external anal sphincter (EAS) [Shafik, Arch Androl, 1999]. It aids erection by compressing the penile bulb and the dorsal penile vein, and acts as a 'suction-ejection' pump in the ejaculatory process. Being a part of the EAS, the BCM is assumed to be involved in the different EAS pathologies. A recent study showed that erectile (ED) and ejaculatory dysfunction in 16 men with fecal incontinence (FI) after an anal fistula operation was cured after sphincteroplasty [Shafik, in press]. This article investigates the erectile and ejaculatory status in patients with anal fissure. The study comprised 32 men with acute anal fissure (mean age 36.7 +/- 8.2 s.d. years), 21 with chronic anal fissure (mean age 38.8 +/- 10.3 s.d. years), and 10 healthy volunteers (mean age 35.2 +/- 7.3 s.d. years). Erectile dysfunction occurred in all men with an acute fissure and in 16 of the chronic fissure patients; erection had been normal before fissure occurrence. The volunteers had normal erection. The anal pain radiated to the penis and was exaggerated on erection and penile thrusting. Erectile dysfunction investigations showed normal results. The electromyographic (EMG) activity of the external and internal (IAS) anal sphincters and the BCM as well as anal, penile bulb and cavernosal pressures were recorded. The acute fissures were treated conservatively and chronic ones by internal anal sphincterotomy. The patients were followed for mean periods of 17.3 +/- 3.6 s.d. months. The bulbocavernosus reflex as well as EMG activity of EAS and BCM were normal, while the resting EMG activity of the IAS was increased. The anal pressure in the acute and chronic anal fissure was increased (P < 0.01, P < 0.05, respectively), while the bulbar and cavernosal pressures showed no significant changes. Fissure treatment effected cure of the fissure and the ED in 30/32 of the acute and in 19/21 of the chronic cases. Erectile dysfunction persisted in the four patients in whom the fissures did not heal. In conclusion, a relationship is suggested to exist between anal fissure and ED. The ED occurred in the presence of anal fissure and was normalized with fissure cure. The BCM and anal pain seem to play a role in the etiology of ED associated with anal fissure.

Adult↗

Vaginismus: results of treatment with botulin toxin.

In view of the long-term therapy necessary to cure vaginismus and specially persistent cases, we considered using botulin toxin (BT) injections for the treatment of such cases. Eight women (mean age 26.6 +/- 1.2 years) with vaginismus were treated with BT. Another five women with vaginismus, matching the eight patients in age, acted as controls. The patients in the study group were injected with BT (25 IU diluted in 1 ml saline) into each of the two bulbospongiosus muscles. Control patients were injected with saline. Mean follow-up was 10.2 +/- 3.3 months. All the patients injected with BT improved. The couples could achieve satisfactory intromission. No patient was in need of re-injection and there was no recurrence during the follow-up period. Control subjects did not improve with the saline injection into the bulbospongiosus muscle. In conclusion, BT injection effected cure in all of the vaginismus patients with no complications or recurrence. The technique is simple, easy, cost-effective, not time-consuming and can be achieved on an outpatient basis.

Journal Article↗

Effect of sigmoid colon distension on the rectosigmoid junction. Description of the rectosigmoid junction tightening reflex and its clinical implications.

PURPOSE: The sigmoid colon (SC) is the site of stool storage. The stools accumulate in the SC until, at a certain volume, the mechanoreceptors in the SC wall are stimulated, evoking the sigmoidorectal junction inhibitory reflex with a resulting SC contraction, rectosigmoid junction (RSJ) relaxation and passage of the stools to the rectum. However, the RSJ status during stool accumulation in the SC has been scarcely addressed in the literature. The current study investigated this point. METHODS: A balloon-ended tube was introduced into the SC of 21 healthy volunteers [mean age (+/- SD) 36.8 +/- 10.3 years; 15 men and 6 women]. The pressures in the SC and RSJ were measured by means of a perfused tube, at rest and during balloon inflation with carbon dioxide at two rates: slow (3 ml/min) and rapid (150 ml/min). The tests were repeated after individual anesthetization of the SC and RSJ. RESULTS: During slow SC distension up to 80 ml included, the RSJ pressure progressively increased while the SC exhibited no pressure response (p > 0.05). At a distending volume of 100 ml, the pressure in the SC rose (p < 0. 01) and declined in the RSJ (p < 0.05), and the balloon was dispelled to the rectum. Rapid SC distension up to 40 ml included, effected no SC pressure response (p > 0.05) while the RSJ showed progressive pressure elevation. At 60 ml distension, the SC recorded a pressure rise (p < 0.001) and the RSJ a pressure decrease (p < 0. 05); the balloon was dispelled to the rectum. The pressure in the RSJ did not respond to distension of the anesthetized SC. CONCLUSION: The study has shown that, during accumulation of stools in the SC, leakage to the rectum seems to be prevented by a reflex action which we call 'rectosigmoid junction tightening reflex'. This reflex probably acts to control both storage and emptying of the SC contents. Reflex dysfunction might lead to defecation disorders. We suggest that the RSJ tightening reflex be included as an investigative tool in the diagnosis of defecation disorders.

Adult↗

Effect of magnetic stimulation on the contractile activity of the rectum in humans.

Magnetic stimulation (MS) has been used to activate the neuromuscular tissue by inducing an electric field. Based on the results of a recent study on a canine model (Eur Surg Res 1998;30:268-72), which demonstrated that sacral MS effected a rectal and vesical pressure rise and a drop of rectal neck (anal canal) pressure, thereby achieving evacuation, the test was performed on 28 healthy volunteers (mean age, 36.6 years; 18 men and 10 women). The rectal, rectal neck, and vesical pressures were recorded during sacral MS with a magnetic coil while the rectum was empty and distended by a balloon. Electromyographic activity of the two rectus abdominis muscles was determined to exclude the possible interference of intra-abdominal pressure with the MS recordings. Stimulation parameters were set at 70 per cent intensity, 40-Hz frequency, and 1-to 2-second burst length. Sacral MS effected significant rectal and vesical pressure rise (P < 0.01 and P < 0.01, respectively) and drop of rectal neck pressure (P < 0.01). Intermittent stimulation induced balloon expulsion from the rectum. The two rectus abdominis muscles did not show change in electromyographic activity during MS, indicating that the rectal and vesical pressure rise was not due to increased intra-abdominal pressure. Sacral MS induced rectal evacuation with no adverse effects. The method is simple, easy, safe, and noninvasive and is suggested to be applied for the treatment of the inertic or neuropathic rectum. As the vesical pressure proved to be elevated too, MS might also be used for rectal and vesical evacuation in patients with spinal cord lesions.

Adolescent↗

Levator ani muscle activity in pregnancy and the postpartum period: a myoelectric study.

The levator ani (LA) is a muscle of evacuation and acts as well to support the pelvic viscera. An increase of the intra-abdominal pressure beyond the physiologic limits and visceral overload are speculated to interfere with LA functional activity. This consideration was a stimulus to study the effect of pregnancy on the LA muscle. The EMG activity of the LA muscle was recorded before and during pregnancy and after delivery in 36 women (mean age 27.2+/-3.1 years, 20 multigravida, 16 primigravida). A needle electrode was inserted into the muscle and LA activity was recorded at rest, and on squeezing and straining in both the erect and recumbent position. In the erect position, the resting and squeezing EMG activity during the first 8 weeks of pregnancy, showed no significant difference (p>0.05) from that before pregnancy, and after that, increased progressively and significantly until delivery. On straining, the EMG activity showed no significant difference from that before pregnancy in the first 8 weeks, and after that, decreased progressively and significantly till delivery. In the recumbent position, the LA EMG registered similar activity to that in the erect position but with significantly lower values (p<0.05). The reduction in the LA EMG activity was more evident in the multi-than in the primigravida. In the postpartum period, no LA EMG activity was recorded in the first month; the activity increased progressively after that time to reach the pre-pregnancy level in the forth postpartum month. In conclusion, pregnancy interferes with EMG and functional activity of the LA from the 8th week onwards due to the progressively increasing size and weight of the uterus. This effect was most marked in the last 12 weeks. Delivery seems to maximally inhibit the LA activity in the first postpartum month. Excessive LA traumatization may eventually lead to levator dysfunction syndrome.

Adult↗

Esophageal and gastric motile response to rectal distension with identification of a recto-esophagogastric reflex.

PURPOSE: To investigate the effect of rectal distension with a balloon simulating fecal mass, on the motile activity of the esophagus and stomach. METHOD: Nine healthy volunteers (7 men, 2 women, mean age 46.6 +/- 4.7 years) were studied. A manometric tube was introduced into the stomach and a balloon-tipped catheter into the rectum. The gastric and esophageal pressure response to rectal distension in increments of 10 ml up to 80 ml of water was recorded. The test was repeated after rectal anesthetization. RESULTS: There was no esophageal or gastric pressure response to rectal distension up to 70 ml. At 80 ml distension, the rectal pressure rose (p < 0.001) and the balloon was dispelled to the exterior. Meanwhile, the pressure in the esophagus, corpus of the stomach and pyloric antrum showed a significant drop (p < 0.05) and in the lower esophageal sphincter and pyloric sphincter a significant rise (p < 0.05). There was no esophageal or gastric response to distension of the anesthetized rectum. CONCLUSION: Lower esophageal and pyloric sphincter contraction and esophageal and gastric relaxation during rectal distension appear to delay gastric emptying. The response of the esophagus and stomach to rectal distension seems to be elicited by a reflex which we call "recto-esophagogastric reflex". It is suggested that rectal lesions or dysfunction might disturb the esophageal or gastric motility and vice versa. The reflex may therefore prove to be of significance in the diagnosis of such disorders.

Adult↗

Role of rectosigmoid junction in fecal continence: an experimental study.

To investigate the reason why, during a mass contraction, the stool moving from the colon to the sigmoid colon stops short of the rectosigmoid junction (RSJ) instead of passing directly to the rectum, and whether the sigmoid colon and RSJ share in the anorectal continent mechanism, 12 mongrel dogs were studied. Under anesthesia, the anorectum was excised, sigmoid colon and RSJ were mobilized and the caudal end was anastomosed to the perianal skin within the external anal sphincter. The pressures in the sigmoid colon, RSJ, rectum and rectal neck were measured before anorectal excision. After excision, the pressure was registered in the neorectum (sigmoid colon) and the RSJ. The external anal sphincter EMG was recorded and the balloon expulsion test performed before and after anorectal excision and after anesthetization of the neorectum. Balloon distension of the sigmoid colon to a mean volume of 46.6+/-7. 6 ml raised the pressure in the sigmoid colon (p<0.001) and decreased it in the RSJ (p<0.05) and the balloon was dispelled to the rectum; no change occurred in the external anal sphincter EMG activity. Neorectal balloon distension to a mean volume of 62.3 +/- 8.2 ml effected a pressure rise in the neorectum (p<0.001) and a momentary increase in the external anal sphincter EMG activity, followed by a decrease of the RSJ pressure (p<0.05); the balloon was dispelled to the exterior. Balloon distension of the anesthetized neorectum effected no significant changes in neorectum and RSJ pressures or external anal sphincter EMG activity. In conclusion, it is assumed that the stools arriving from the colon are halted at the RSJ by the existing high-pressure-zone and the presence of a potential sphincter at the RSJ. We suggest that fecal continence occurs at 2 levels: an involuntary one at the RSJ and a voluntary one at the rectal neck.

Anal Canal↗

Anal submucosal injection: a novel modality for the treatment of advanced rectal cancer.

AIMS: To investigate the efficacy of methotrexate (MTX) submucosal anal injection in the treatment of advanced rectal cancer. METHODS: Thirty-six patients (age 36-66 years; 21 men, 15 women; 20 patients with stage T3N1M0 and 16 with T4N1M1 rectal cancer) were injected with MTX in the anal submucosa. A comparative group of eight patients (age 38-62 years: five men, three women; four with T3N1M0 and four with T4N1M1 rectal cancer) was injected with MTX intravenously. The dose in both groups was 100 mg every 5 days for five consecutive doses and the course was repeated at 3-week intervals. MTX serum and tumour concentrations were estimated 30 and 60 min after MTX injection. The patients received MTX as outpatients. RESULTS: In the anal group, six of 20 patients with T3 tumour showed complete tumour regression and were alive 28-46 months after the start of the treatment. Partial response occurred in 25 patients: 14 of stage T3 and 11 of T4. The 14 T3 patients underwent combined excision operation and 9/14 were alive 26-68 months from the time of operation. Five of the 16 T4 patients showed tumour and metastatic progression. Mild toxicity occurred in six of 36 patients while the haematological reserve was unchanged in all the patients. All eight patients in the parenteral group showed progress of the malignant lesions under treatment and toxic manifestations were so severe that the treatment had to be interrupted. The MTX concentration in serum was significantly higher after parenteral than after anal injection, while in tumour tissue it was higher after anal administration. CONCLUSIONS: The results show that MTX submucosal anal injection is effective in treatment of T3 rectal cancer due to high MTX concentration in the tumour. Toxicity was mild owing to low level of serum MTX. The anal route of administration is safe, well tolerated and can be used on an outpatient basis.

Adult↗

Botulin toxin in the treatment of nonrelaxing puborectalis syndrome.

PURPOSE: To evaluate the results of botulin toxin injection in the external anal sphincter for the treatment of nonrelaxing puborectalis syndrome. METHOD: 15 patients (13 women, 2 men; aged 36-48 years) were treated with botulinum A toxin injection, using a dose of 25 IU diluted in 1 ml normal saline injected into the top loop of the external anal sphincter at the 3 and 9 o'clock positions. The mean follow-up period was 14.6 +/- 3.3 (SD) months. RESULTS: Two patients did not respond to the treatment while improvement occurred in 13. Straining at defecation disappeared and stool frequency was normalized. Improvement was maintained for a mean of 4. 8 +/- 1.4 SD months, after which time reinjection needed to be done. No adverse side effects were encountered. CONCLUSIONS: Botulin toxin injection is a simple, easy and safe method for the treatment of nonrelaxing puborectalis syndrome. It is to be considered after biofeedback has failed.

Adult↗

Response of the internal reproductive organs to clitoral stimulation: the clitorouterine reflex.

We investigated hypothesis that uterine erection, elevation and enlargement during sexual response are reflex and result from penis buffeting the glans clitoris (GC). In 23 healthy women, two recording electrodes were applied to the uterine mucosa and one to cervix uteri (CU). GC was stimulated electrically and mechanically by pencil electrode. The uterine and CU pressures were measured. Tests were repeated after anesthetization of the uterus or GC. Uterine electrodes recorded slow waves, followed by random bursts of action potentials (APs). No waves registered from CU. Electrical or mechanical GC stimulation eliminated uterine electric waves, but anesthetized GC did not, nor did GC stimulation while the uterus anesthetized. Uterine pressure declined on electrical or mechanical stimulation. Results suggest presence of reproducible reflex relationship between GC and the uterus, we call 'clitorouterine reflex'. GC buffeting seems to evoke reflex and initiate uterine responses. Reflex may prove of diagnostic significance in sexual disorders.

Adult↗

Mechanism of ejection during ejaculation: identification of a urethrocavernosus reflex.

The ejaculatory mechanism involves 2 reflexes: the "glans-vasal," which seems to bring the semen to the posterior urethra (emission phase of ejaculation), and the "urethromuscular" which ejects it to the exterior (ejection phase). This study investigated the mechanism of bulbocavernosus muscle (BCM) contraction, once the seminal fluid reaches the bulbous urethra. The study included 14 healthy male volunteers (mean age 37 +/- 10.2 SD years). To test the response of the BCM to urethral distension, a 10F balloon-tipped catheter was introduced into the prostatic urethra and filled with saline in increments of 0.25 mL: a needle electrode recorded the response. The balloon was then withdrawn to lie in the membranous. bulbous, and pendulous urethra and the test was repeated at each site. The latency of the muscle response was calculated. The BCM response to each of the anesthetized bulbous urethra and anesthetized BCM was recorded. Distension of the prostatic, membraneous, or pendulous urethra effected no BCM EMG response. Bulbous urethral distension with 0.25 mL of saline also produced no muscle response, whereas distension with 0.5 mL and up to 1.5 mL caused increased EMG activity of the BCM. The muscle response augmented with the increase of the distending volume. The mean latency was 10 +/- 1.3 ms and showed no significant change (p > .05) with the different distending volumes. Neither the anesthetized bulbous urethra nor the anesthetized BCM responded to bulbous urethral distension. The BCM contraction upon distension of the bulbous urethra is probably reflex and mediated through the urethrocavernosus reflex. Small-volume distension did not effect BCM contraction. The latter presumably propels the semen from the posterior to the pendulous urethra. It is suggested that the urethrocavernosus reflex be included in current andrologic investigations for patients with ejaculatory disorders.

Adult↗

Electrocavernosogram in erectile dysfunction: a diagnostic tool.

Corpora cavernosa (CC) evoke electric waves that appear to be of diagnostic significance in evaluation of erectile dysfunction (ED). We investigated the hypothesis that electrocavernosography (ECG) exhibits different patterns in the various types of ED: neurogenic, vasculogenic, and psychogenic. Electrocavernosography was performed in the flaccid phase in 16 neurogenic, 28 vasculogenic (15 arteriogenic, 13 venogenic), and 24 psychogenic patients with ED, and in 15 healthy volunteers (controls). Two needle electrodes were introduced into the CC and the EMG activity was recorded in each of the 2 CCs of the same subject. Two 20 minute recording sessions were performed for each subject. The controls recorded slow waves (SWs) with regular rhythm and identical frequency, amplitude and conduction velocity from the 2 electrodes of the same subject. Random action potentials (APs) were superimposed on or followed the SWs. The ECG in the neurogenic ED recorded no waves in 14/16 patients and occasional irregular waves in 2. The SWs of the arteriogenic ED had irregular rhythm and variable and low parameters compared to those of the controls. The ECG of the patients with venogenic ED was similar to that of the controls, while the ECG of the psychogenic ED exhibited SWs with irregular rhythm and higher parameters than the controls. The study has revealed various ECG patterns in ED: "silent" in neurogenic. "bradyarrhythmic" in arteriogenic, "normal" in venogenic, and "overactive" in psychogenic ED. We suggest that electrocavernosography has the potential to function as an investigative tool in diagnosing the type of ED provided further studies are performed to verify the described findings.

Action Potentials↗

Interstitial cells of Cajal in erectile dysfunction.

The corpora cavernosa (CC) evokes electric activity. Slow waves (SWs) appear to originate from interstitial cells of Cajal (ICCs), which seem to control the activity of the smooth muscle cells (SMC). The ICCs were demonstrated to exist in the CC. We investigated the hypothesis that the ICC distribution differs with each of the various ED types. The study comprised 62 men with ED: 16 neurogenic (NGED), 15 arteriogenic (AGED), 11 venogenic (VGED) and 22 psychogenic (PGED). 15 volunteers with normal erections acted as controls. The patients underwent a complete diagnostic evaluation. A biopsy of 3 x 3 mm from the CC was subjected to C-kit immunohistochemistry examination. Specificity control of the antisera consisted of incubation of the tissue with normal rabbit serum substituted for the primary antiserum. C-kit positive stellate-appearing cells resembling those of ICC were detected in the controls. The branches were either laterally located (multipolar) or lying at each pole (bipolar). They were distinguishable from the SMC, which were C-kit negative. ICC were detected in all specimens from patients with NGED and VGED, absent in 13/15 with AGED and scanty in PGED. ICC distribution was different in the various types of ED. It is suggested that this distribution interferes with SW discharge and the control of SMC activity with a resulting ED.

Adult↗

Role of the enteric nervous plexus in rectal motile activity: an experimental study.

The gut innervation is formed by an intrinsic and an extrinsic component. The former is responsible for the intestinal contractions that occur in the total absence of extrinsic innervation. We hypothesize that the intrinsic plexuses do not produce local contraction, but mediate reflex actions of the gut musculature. This hypothesis was investigated in the rectum of the experimental animal. In 16 anesthetized mongrel dogs, the rectum was exposed, and 3 monopolar silver-silver chloride electrodes were sutured serially to the rectal wall and connected to a rectilinear pen recorder. The rectal electric activity was recorded at rest and on rectal inflation while the anal pressure was synchronously registered. The tests were repeated after separate drug administration using phentolamine, propranolol (adrenoceptor blocking agents), atropine (cholinergic blocking agent), drotaverine (direct smooth muscle relaxant), and nitroglycerine. (NO donor, inhibitory noncholinergic, nonadrenergic mediator). Slow waves or pacesetter potentials (PPs) and action potentials (APs) were recorded from the three electrodes. Rectal balloon distension caused an increase of frequency, amplitude, and conduction velocity of these waves, as well as a decrease of anal pressure. Repetition of the test after administration of phentolamine, propranotol, and atropine effected no change in rectal electromyelographic (EMG) activity or anal pressure, while drotaverine and nitroglycerine administration aborted both the electric activity and the anal pressure response. We conclude that the rectal electric activity, presumably responsible for rectal motility, was not aborted by enteric nervous plexus block but by direct muscle relaxant. This suggests that the enteric plexus has no direct action on the rectal motile activity but mediates the rectal reflex actions. This concept might explain some of the hitherto unknown mechanisms of rectal dyssynergia syndromes.

Action Potentials↗

Effect of rectal distension on rectal electromechanical activity.

The rectum possesses electric activity in the form of pacesetter potentials (PPs) and action potentials (APs). The latter are associated with rectal pressure elevation and share in the rectal motile activity. A recent study has shown that electric waves are transmitted by the longitudinal but not the circular rectal muscle fibers. Rectal motile activity under normal physiologic conditions was suggested to be induced by the electric waves, that effect longitudinal muscle contraction, as well as by circular muscle stretch resulting from rectal distension. The current study investigated the effect of rectal overdistension on the rectal electromechanical activity aiming at assessing the effect of stool accumulation in the rectum on rectal motile activity. Under general anesthesia, the abdomen of 16 mongrel dogs was opened, the rectum exposed, and 3 electrodes were sutured to the rectal serosa. The rectal pressure was measured by a 10-F catheter connected to a pressure transducer. Rectal distension was achieved by a balloon inflated with carbon dioxide (CO2). Simultaneous recording of the electric activity and rectal pressure was performed during rectal inflation in increments of 10 mL CO2. There was significant increase of rectal pressure as well as of frequency, amplitude, and conduction velocity of PPs and APs on rectal distension. The more the rectal balloon was distended, the more was the increase in rectal pressure and waves variables; the increase was maximal just before balloon expulsion at 40 mL distension. Upon rectal overdistension (50 and 60 mL), no PPs or APs were recorded and the rectal pressure was 0; no balloon expulsion occurred. Rectal overdistension (pathologic distension) appears to abort the electromechanical activity of the rectum and lead to failure of the rectum to expel the balloon. This effect is suggested to be due to overstretch of rectal musculature with a resulting loss of the rectal electric waves and noncontraction of the muscle fibers. These findings appear to explain the cause of rectal atony, which occurs in rectal inertia and leads to constipation.

Action Potentials↗

Percutaneous peripheral neuromodulation in the treatment of fecal incontinence.

BACKGROUND/AIMS: To assess the results of peripheral neuromodulation for the treatment of fecal incontinence (FI) resulting from uninhibited rectal contraction (URC) or uninhibited anal sphincter relaxation (UASR). METHODS: The work comprised 32 patients (age 38.2 +/- 6.7 years; 22 women) with FI in whom conventional therapy had failed before enrollment in the study. Twenty-six had URC and 6 UASR. Peripheral neurostimulation was effected by posterior tibial nerve stimulation using a Stoller Afferent Nerve Stimulator (UroSurge, Coralville, lowa, USA). The needle was introduced into the skin cephalad to the medial malleolus. Stimulation (parameters: 0.5-10 mA, 200 micros, 20 Hz) was performed every other day for 4 weeks. Functional assessment was done by a questionnaire (incontinence score: 0-20) and physiologic studies. RESULTS: Group 1: 17 patients (13 URC, 4 UASR) had FI improvement, recording a mean score of 1.7 of 20. Group 2: 10 patients (8 URC, 2 UASR) had fair improvement (score 8.6). Group 3: 5 patients had poor results (score 14.8). Rectometric recording showed improvement in groups 1 and 2. Recurrence of symptoms occurred in 8 patients; 6 improved after retreatment. CONCLUSIONS: A percutaneous access to the S(3) spinal region was achieved through the posterior tibial nerve. Improvement of FI was achieved in 78.2%. The technique is simple, easy, without complications and cost-effective. It can be done as an outpatient procedure or by the patient at home. The results need to be reproduced on a large number of patients.

Adult↗

Electromotor activity of the cecum and ascending colon: the concept of 'individual pacemakers'.

BACKGROUND/AIMS: The cecum is described as differing anatomically from the ascending colon (AC); yet their similarity or difference in terms of motile activity has not been studied sufficiently. The cecum is separated from the AC by the cecocolonic junction (CCJ) which contains a cecocolonic sphincter. We assumed that the motile activity of the AC is different from that of the cecum and hypothesized that both the AC and the cecum might have different pacemakers which initiate the motile activity. This hypothesis was investigated in the current study. METHODS: The study was performed in 10 subjects (mean age 41.6 +/- 12.8 SD years; 7 women) during the repair of huge abdominal incisional hernias. The electric activity was recorded from 2 monopolar electrodes applied each to the cecum, CCJ and AC. The CCJ was then anesthetized by xylocaine and the electric waves of the cecum, CCJ and AC were registered after 10 and 90 min. The test was repeated using normal saline instead of xylocaine. RESULTS: Electric waves were recorded from the cecum, CCJ and AC in the form of monophasic pacesetter (PPs) and action potentials (APs). The PPs occurred regularly and the APs randomly. The frequency, amplitude and conduction velocity of the waves recorded from the CCJ and AC had higher readings than those from the cecum (p < 0.05). The CCJ and AC showed similar frequency and conduction velocity (p > 0.05). Ten minutes after CCJ anesthetization, electric waves were recorded from the cecum but not from the CCJ or AC; however, electric activity returned after 90 min. Saline injection did not affect the electric activity of the cecum, CCJ and AC. CONCLUSION: The electric wave parameters of the cecum differed from those of the CCJ and AC, suggesting that the motile activity of the CCJ and AC is not a continuation of the motile activity of the cecum and that it might be evoked by 2 different pacemakers. The similarity in frequency and conduction velocity of electric waves of the CCJ and AC, however, most likely denotes that the AC waves are a continuation of those of the CCJ, and that both are evoked by the same pacemaker probably located in the CCJ. The higher amplitude of cecal waves might be due to the thicker cecal musculature compared to that of the AC.

Adult↗