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Pelvic Floor: Coloproctology

Resting Anal Pressure Following Hemorrhoidectomy and Lateral Sphincterotomy.
Alper D, Ram E, Stein GY, Dreznik Z
Dis Colon Rectum 2005 Sep 22;.

PURPOSE: The role of high anal pressure in the pathophysiology of hemorrhoids and anal fissures is debated. We compared resting anal pressures following left lateral sphincterotomy and hemorrhoidectomy in a prospective manometric study with emphasis on the recovery of the internal anal sphincter activity. METHODS: Included in the study were 38 patients with third-degree or fourth-degree symptomatic hemorrhoids who underwent hemorrhoidectomy, 50 patients with anal fissure who underwent sphincterotomy, and 12 healthy patients who served as controls. All patients with anal fissure or hemorrhoids underwent periodic manometric evaluation: 1 month before surgery and 1, 3, 6, and 12 months after surgery. The control group had three manometric evaluations 6 months apart. RESULTS: Baseline pressure measurement in the fissure group was significantly higher than in the hemorrhoid group, which was significantly higher than in the control group (138 +/- 28.4 mmHg vs. 108.4 +/- 23 mmHg vs. 73 +/- 5.9 mmHg, P < 0.0001). Twelve months after surgery, anal resting pressure remained significantly lower than the baseline measurements in both the fissure (110 +/- 18.2 vs. 138 +/- 28.4, P < 0.0001) and hemorrhoid groups (103.6 +/- 21.5 vs. 108 +/- 23, P < 0.0001), but both remained higher than the control group (103.6 +/- 21.5 mmHg vs. 73 +/- 5.9 mmHg, P < 0.0001). CONCLUSIONS: Resting pressure is elevated in hemorrhoid and anal fissure patients. After surgery the anal resting pressure is reduced but is still higher than in the control group. Further studies are required to investigate the protective effect of postsurgical reduction of anal resting pressure against recurrence.

Effect of Warming on the Rectal Motile Activity: Identification of Rectal Warming Reflex.
Shafik A, Shafik AA, El Sibai O, Shafik I
J Surg Res 2005 Sep 7;.

BACKGROUND: The identification in the rectal wall of warm receptors sensitive to warm temperature has not been found in the literature. Therefore, we investigated the hypothesis that rectal warming effects rectal dilation, which seems to indicate the existence of warm receptors. MATERIALS AND METHODS: The rectal wall tone was studied in 24 healthy volunteers (14 men, 10 women, mean age 36.7 +/- 10.4 years). It was assessed by a barostat system during rectal infusion with normal saline at 30 degrees C, 40 degrees C, 45 degrees C, and 50 degrees C. The test was repeated after rectal anesthetization with lidocaine. RESULTS: The rectal tone on rectal saline infusion at a temperature of 30 degrees C showed no response (P > 0.05), whereas at a temperature of 40 degrees C, 45 degrees C, and 50 degrees C, it exhibited a significant decrease (P < 0.05, < 0.01, < 0.001, respectively), which was proportional to the rising degree of temperature. Warm saline infusion into the anesthetized rectum resulted in no significant change in the rectal wall tone. CONCLUSIONS: Rectal infusion with warm saline produced rectal dilation that increased with temperature elevation. This effect is suggested to be mediated through a reflex called "rectal warming reflex: and advances the possibility of the existence of warm receptors in the rectal wall; however, further studies are needed to confirm the issue.

Selective block of external anal sphincter activation during electrical stimulation of the sacral anterior roots in a canine model.
Bhadra N, Mortimer JT
Neurogastroenterol Motil 2005 Oct;17(5):721-6.

Our aim was to electrically activate small diameter parasympathetic fibres in the sacral anterior roots, without activating the larger somatic fibres to the external anal sphincter (EAS). Electrodes were implanted on selected roots in five adult dogs. Pressures were recorded from the rectum and EAS. Quasitrapezoidal (Qzt) pulses for selective activation of smaller axons and narrow rectangular (Rct) pulses to activate all fibres were applied. Sphincter block was defined as [(P(max) - P(min))/P(max)] x 100%. Roots were also tested with 20 Hz trains. In three animals, evacuation of bowel contents was recorded with artificial fecal material. Stimulation with Qzt pulses showed decrease in sphincter recruitment with increasing pulse amplitudes, indicating propagation arrest in the large fibres. The average sphincter suppression was 94.1% in 16 roots implanted. With Qzt pulse trains, the average evoked sphincter pressure was significantly lower than Rct pulses. Evoked rectal pressures were not significantly different. The mean mass of expelled bowel contents of 51.1 g by Qzt trains was significantly higher than that of 14.8 g expelled by Rct trains. Our results demonstrate that this selective stimuli can activate small diameter fibres innervating the distal bowel and result in significant evacuation of rectal contents.

Classical conditioned response of rectosigmoid motility and regional cerebral activity in humans.
Kanazawa M, Endo M, Yamaguchi K, Hamaguchi T, Whitehead WE, Itoh M, Fukudo S
Neurogastroenterol Motil 2005 Oct;17(5):705-13.

The relationship between the central processes of classical conditioning and conditioned responses of the gastrointestinal function is incompletely understood in humans. We tested the hypothesis that the rectosigmoid motility becomes conditioned with anticipatory painful somatosensory stimulus and that characteristic brain areas become activated during anticipation. In nine right-handed healthy male subjects, a loud buzzer (CS, conditional stimulus) was paired with painful transcutaneus electrical nerve stimulation to the right hand (unconditional stimulus). Rectosigmoid muscle tone measured by the barostat as the intrabag volume, phasic contractions of the bowel measured as the number of phasic volume events (PVEs), and regional cerebral blood flow assessed by positron emission tomography (PET), were measured before and after conditioning. Following conditional trials, the bag volume after CS alone did not show significant changes between before and after the stimulus, but the number of PVEs after 2-minute interval of the CS alone was significantly greater than that before the stimulus (P < 0.05). The PET data showed the conditioning elicited significant cerebral activation of the prefrontal, anterior cingulate, parietal and insula cortices (P </= 0.001, uncorrected). Rectosigmoid motility can be conditioned with increase in phasic contractions in humans.

Lidocaine Anal Block Limits Autonomic Dysreflexia During Anorectal Procedures in Spinal Cord Injury: A Randomized, Double-Blind, Placebo-Controlled Trial.

Cosman BC, Vu TT
Dis Colon Rectum 2005 Jun 24;

PURPOSE: Autonomic dysreflexia is a common and potentially dangerous hypertensive response to stimulation below the level of injury that occurs in patients with spinal cord injury at T6 or above. Rectosigmoid distention and anal manipulation are among the stimuli that may precipitate autonomic dysreflexia. Instillation of topical local anesthetic into the rectum is the recommended prophylaxis against autonomic dysreflexia of anorectal origin. However, a previous randomized, double-blind, placebo-controlled trial showed that topical lidocaine in the rectum does not blunt the autonomic dysreflexia response to anorectal procedures. The purpose of this study was to determine whether lidocaine anal sphincter block would be effective in limiting anorectal procedure-associated autonomic dysreflexia. METHODS: We enrolled patients with chronic, complete spinal cord injury above T6, who were having anorectal procedures (flexible sigmoidoscopy and/or anoscopic hemorrhoid ligation). In a double-blind fashion, patients were randomized for intersphincteric anal block with 1 percent lidocaine or normal saline (placebo) before the procedure. Blood pressure was measured before, during, and after the block and procedure. RESULTS: Thirteen patients received lidocaine, and 13 received placebo. The groups were similar in age, level of injury, duration of spinal cord injury, type of procedure, and procedure duration. The mean maximal systolic blood pressure increase for the lidocaine group was 22 +/- 14 mmHg, significantly lower than the placebo group's 47 +/- 31 mmHg (P = 0.01). CONCLUSIONS: Lidocaine anal block significantly limits the autonomic dysreflexia response in susceptible patients undergoing anorectal procedures.