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Query: UMLS:C0030193 (pain)
 261,466 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recently it has been shown that placement of 4 loose chromic gut sutures around the rat sciatic nerve produces hyperalgesia. A possible mechanism underlying this hyperalgesia is a preferential loss of large myelinated fibers. A difficulty, however, is that neuropathic symptoms are not static and the time course of the axon loss has not been determined. To remedy this deficit, the present study relates axonal changes to the behavior of the animal at various times after induction of the neuropathy. The findings are that a loss of all axon types, with a preferential loss of large myelinated axons, is associated with the development of heat hyperalgesia. As the axon loss progresses, however, the hyperalgesia lessens. In addition, at 28 days post surgery there are essentially no large myelinated axons in the distal segment, but the signs of hyperalgesia have almost resolved. These findings indicate that the onset of the hyperalgesia is accompanied by a preferential loss of large fibers and by a lesser but still substantial loss of small myelinated and unmyelinated axons. The subsequent course of the hyperalgesia, however, is not in any obvious way related to the proportions of large myelinated fibers in the affected nerve.
Pain 1993 Feb
PMID:Is large myelinated fiber loss associated with hyperalgesia in a model of experimental peripheral neuropathy in the rat? 823 55

Bowel preparation methods for total colonoscopy in children generally involve whole gut irrigation with electrolyte lavage solutions, which in most children will require hospitalisation for nasogastric tube administration. The aim of the study was to determine the efficacy of oral bisacodyl combined with a single phosphate enema as a bowel preparation regimen in children. In an open prospective trial, 30 children (aged 18 months-15 years) were given oral bisacodyl on each morning of the two days before colonoscopy. The children were maintained on a normal diet. A phosphate enema was administered on the morning of the procedure. The adequacy of bowel preparation was graded as grade I if no faecal material was encountered, grade II if small amounts of faecal material were present in scattered locations, and grade III if there was poor preparation with faecal material precluding satisfactory visualisation of the bowel mucosa. Eight children (26.6%) had minor abdominal cramps when taking bisacodyl, but all had a previous history of similar pain. Five children (16.6%), all under 5 years of age, cried during the administration of phosphate enema. Bowel preparation was considered excellent (grade I) in 26 (86.6%) and good (grade II) in four (13.3%). In all patients adequate visualisation of the bowel mucosa was obtained. Oral bisacodyl combined with a single phosphate enema provides an ideal method of preparing the bowel for total colonoscopy. This preparation allows colonoscopy to be carried out as a day case procedure in children while maintaining them on a normal diet.
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PMID:Preparing the bowel for colonoscopy. 855 68

This article reviews the basic anatomy and physiology of visceral afferent function and its application to a clearer understanding of visceral pain and symptoms in patients with functional gastrointestinal disorders. Recent investigations have focused on the potential role of visceral tone, different afferent (A delta and C) fibers, dorsal column neurons, and supraspinal modulation in the elicitation of visceral perception of noxious and nonnoxious stimuli arising in the gut. Greater understanding of these pathomechansims and their pharmacologic manipulation offers an opportunity for future therapeutic strategies for these disorders.
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PMID:Gastrointestinal sensation. Mechanisms and relation to functional gastrointestinal disorders. 868 76

The chronic constriction injury (CCI) is an animal model of an experimental peripheral neuropathy. In this model, a mononeuropathy is produced by loosely ligating the left sciatic nerve of the rat with chromic gut suture (Bennett and Xie 1988). Maves et al. (1993) have proposed that chemical constituents of chromic gut suture influence the behavioral changes of rats with the CCI. Considering their results, we became interested in evaluating whether the type of suture material used to produce the CCI also affected spinal levels of calcitonin-gene-related peptide immunoreactivity (CGRP-ir) and substance P immunoreactivity (SP-ir), peptides that are associated with small primary afferent neurons. Using methods of radioimmunoassay (RIA), we measured levels of CGRP-ir and SP-ir in the dorsal quadrants of approximately the lumbar 4-5 (L4-L5) spinal segments of rats with a CCI induced using polyglactin (Vicryl), plain gut, or chromic gut suture. We observed bilateral decreases in CGRP-ir and SP-ir 60 days after a CCI induced with chromic gut suture, but no changes in peptide levels after a CCI induced with either polyglactin or plain gut suture. These results suggest two possibilities: (1) chromic gut suture, when used to produce the CCI, has more than just a constrictive effect on the sciatic nerve, and/or (2) different suture materials produce changes in CGRP-ir and SP-ir with a differential time-course. Our experiments are unable to distinguish between these two possibilities.
Pain 1996 Mar
PMID:Chromic gut suture reduces calcitonin-gene-related peptide and substance P levels in the spinal cord following chronic constriction injury in the rat. 878 15

One of the physiological changes accompanying neuropathic pain from nerve injury is the spontaneous firing of primary afferent fibers. At least some of this activity is thought to arise from the dorsal root ganglion. We have investigated whether this activity is resident in the cell bodies of dorsal root ganglion neurons and if it is retained in vitro. Dorsal root ganglion neurons from rats with a chronic constriction injury (CCI) from 4 loose ligatures of chromic gut sutures around the sciatic nerve were used. Isolated neurons were studied using the whole cell patch technique in current clamp mode within 6 hours of preparation. Neurons from rats with CCI showed a significantly increased incidence of spontaneous action potential activity (18/88 vs. 1/36 neurons). Firing activity consisted of both random spikes and long trains of regular, rapid spikes, with random activity being the exclusive mode in most cells. Spontaneous resting potential fluctuations (up to 10 m V peak-to-peak) occurred in both control and CCI neurons, and triggered the spontaneous, random action potentials in neurons from CCI rats. Spontaneously firing neurons exhibited more negative action potential threshold (-34.8 mV) when compared to quiescent neurons from ganglia either after CCI (-18.7 mV) or controls (-20.5 mV). These findings show that spontaneous action potential activity after CCI is a property residing in the cell bodies of dorsal root ganglion neurons and is amenable to more detailed analysis using such an in vitro system, allowing better understanding of the cellular changes underlying neuropathic pain from nerve injury.
Pain
PMID:Spontaneous action potential activity in isolated dorsal root ganglion neurons from rats with a painful neuropathy. 882 12

Chronic symptoms of abdominal pain and discomfort are reported by patients with inflammatory bowel disease (IBD) and functional disorders of the gut, such as Irritable Bowel Syndrome (IBS). It has recently been suggested that transient inflammatory mucosal events may result in long-lasting sensitization of visceral afferent pathways. To determine the effect of recurring intestinal tissue irritation on lumbosacral afferent pathways, and to identify a plausible mechanism that could account for the overlap in symptomatology between IBD and IBS, we compared rectal afferent mechanisms in patients with Crohn's disease (inflammation limited to the ileum) with those observed in patients with diarrhea-predominant IBS. Continuous volume ramp and phasic pressure step distension of a rectal balloon were performed in 9 healthy male control subjects, 12 male patients with isolated ileal Crohn's disease and 9 male patients with diarrhea-predominant IBS using an electronic visceral stimulation device. The response of rectal afferents to distension was evaluated by measuring thresholds for the perception of physiological (stool) and aversive (discomfort) sensations, viscerosomatic referral patterns, skin conductance responses, receptive relaxation, and rectoanal reflex responses. In response to slow ramp distension, thresholds for aversive sensations were significantly higher in Crohn's disease patients, but similar between the two other groups. In response to rapid phasic distension, IBS patients reported discomfort at lower distension pressures, while all other thresholds were similar between groups. Skin conductance responses to aversive distension were greatly reduced in Crohn's disease patients while IBS patients had greater responses when compared to normals. Changes in viscerosomatic referral patterns and receptive relaxation rate were similar in Crohn's disease and IBS patients. These findings demonstrate that chronic ileal inflammation is associated with increased thresholds for discomfort and greatly diminished systemic autonomic reflex responses. In contrast, IBS patients show lowered thresholds for discomfort associated with increased autonomic responses. The findings in Crohn's patients may result from descending bulbospinal inhibition of sacral dorsal horn neurons in response to chronic intestinal tissue irritation.
Pain 1996 Aug
PMID:Rectal afferent function in patients with inflammatory and functional intestinal disorders. 888 Aug 36

The pathophysiology of functional gastro-intestinal disorders remains unclear. A relatively new approach to these disorders has been the study of visceral sensory perception. A decreased pain threshold to intraluminal balloon distension has been demonstrated in patients with irritable bowel syndrome, functional dyspepsia, and non-cardiac chest pain. This altered visceral sensitivity does not appear to extend to somatic sensation; patients have generally had normal sensory thresholds to various stimuli applied to the skin. It is uncertain whether altered gut sensation represents a primary event in the pathogenesis of disease or simply a disease marker. In this review, we examine the evidence of altered visceral sensation and discuss the implications for patient management and drug therapy.
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PMID:Visceral perception in functional gastro-intestinal disorders: disease marker or epiphenomenon? 890 13

Intrinsic neurons containing serotonin (5-HT) are involved in the regulation of gastrointestinal motor function and are also thought to be important in the modulation of visceral sensory function. We have evaluated the effect of a specific 5-HT3 antagonist (ondansetron, O) on visceral sensation and rectal compliance in a randomized, double-blind, cross-over, placebo (P) controlled study of O 16 mg 3 times/day, in healthy volunteers and patients with irritable bowel syndrome (IBS). Symptoms were also evaluated in the latter group. A 2-week run-in period was followed by two 2-week treatment arms of P and O, separated by a 2-week wash-out period. Twelve healthy subjects and 9 patients with IBS were recruited. Assessment was by daily symptom and bowel function diary, and physiological tests of anal manometry, rectal sensory testing to distension and electrical stimulation, and rectal compliance. Ten healthy subjects completed the entire study, and 6 IBS patients completed the diary card evaluation, including 5 who also completed the physiological evaluation. O caused significantly (p < 0.01) firmer stools when considering both subject groups together. In the healthy subjects no physiological parameters were altered by O. In IBS patients the rectal sensory threshold to electrical stimulation tended to increase with O (20 vs. 28 mA, P vs. O, median, p = 0.06) while the urge (80 vs. 60 ml, p = 0.05) and maximum tolerated volumes (130 vs. 90, p = 0.03) to distension tended to decrease with O. Patients with IBS experienced significantly fewer daily episodes of pain while on O (2 vs. 1, p = 0.03). Serotonin-3 antagonism (O) causes firmer bowel actions in all subjects, and may affect gut sensitivity and pain in patients with IBS.
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PMID:Modification of visceral sensitivity and pain in irritable bowel syndrome by 5-HT3 antagonism (ondansetron). 891 11

Anorectal disorders are commonly encountered in the practice of emergency medicine. Most can be diagnosed and treated in the emergency department setting. Almost all anorectal disorders once diagnosed and treated in the emergency department need appropriate follow-up to ensure adequacy of treatment, for further possible diagnostic procedures (e.g., endoscopy, biopsy), or for definitive treatment. Hemorrhoids are the most prevalent anorectal disorder and are the most common cause of hematochezia. Treatment is dependent on the degree of hemorrhoid prolapse and symptoms. Most cases can be treated by conservative medical treatment (e.g., dietary changes, sitz baths) or nonsurgical procedures (e.g., rubber band liagation, infrared coagulation). Surgical excision of symptomatic thrombosed external hemorrhoids is indicated if within 48 to 72 hours of pain onset. Anal fissures are one of the most common causes of anorectal pain. They are most frequently idiopathic, and most are located in the posterior midline of the anal canal. Most anal fissures are adequately treated by a medical approach using sitz baths, stool softeners, and analgesics. If the anal fissure becomes chronic and is not responsive to medical therapy, a lateral sphincterotomy of the internal anal sphincter is the surgical procedure of choice. Pharmacologic treatment (botulinum toxin or nitroglycerin ointment) to decrease internal anal sphincter tone has shown promise in the treatment of anal fissure. Anorectal abscesses are categorized into four types: perianal, ischiorectal, intersphincteric, and supralevator. Most are idiopathic and contain mixed aerobic-anaerobic pathogens. Fistula formation varies from 25% to 50% and is much more common with gut-derived organisms (e.g., E. coli, B. fragilis). Definitive treatment for an anorectal abscess is timely surgical incision and drainage to prevent more serious complications (e.g., serious infection, extension of the abscess). Anal carcinomas are infrequent, the majority of them being squamous cell or epidermoid carcinomas. The emergency physician must maintain a high index of suspicion and obtain a biopsy of suspicious lesions in order not to miss the diagnosis of a cancer. The most common presenting complaint of anal tumors is rectal bleeding. Combination chemotherapy and radiotherapy have shown promising results in the treatment of anal canal tumors. Bacterial, viral, and protozoal infections can be transmitted to the anorectum via anoreceptive intercourse. Such infections must be considered when a patient presents with rectal pain or discharge, tenesmus, or rectal or perineal ulcers. Proctosigmoidoscopy and rectal cultures may be necessary to determine the cause. Potential rectal complications of HIV infection include infectious diarrhea, acyclovir-resistant strains of HSV2, Kaposi's sarcoma, lymphoma, and squamous cell carcinoma. Rectal injuries may result from penetrating or blunt trauma, iatrogenic injuries, or foreign bodies. Rectal injury should be suspected when a patient presents with low abdominal, pelvic, or perineal pain or blood per rectum after sustaining trauma or undergoing an endoscopic or surgical procedure. Tetanus prophylaxis, intravenous antibiotics, and surgical intervention are indicated in all but superficial rectal tears.
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PMID:Anorectal disorders. 892 68

The possibility that 5-hydroxytryptamine (5-HT) acts as a key sensitising agent in the aetiology of irritable bowel syndrome (IBS) is reviewed. The strategic locations of 5-HT and its receptors are described, the most dominant being the 5-HT3 and 5-HT4 type. 5-HT, acting mostly at 5-HT3 or 5-HT3-like receptors, enhances the sensitivity of visceral neurones projecting between the gut and the central nervous systems. 5-HT, acting at 5-HT4 receptors promotes the sensitivity of enteric neurones that react to luminal stimuli. 5-HT4 and 5-HT3 receptors also mediate, respectively, sensitising and physiological actions of 5-HT on gastro-intestinal motor and secretory functions. This distribution implies that some 5-HT3 receptor antagonists might reduce certain symptoms of IBS, such as pain, by reducing the reactivity of the visceral afferent neurones linking the gut with the brain and spinal cord. However, such antagonists are not likely to find widespread clinical acceptance because they can also affect normal lower bowel function and promote constipation. 5-HT4 receptor antagonists, by contrast, reduce 5-HT-induced enteric nerve hypersensitivity without notably affecting the function of the normal bowel. Accordingly, these agents may reduce the symptoms of IBS directly, by reducing the incidence of defecation and diarrhoea and indirectly, by reducing both 'rebound' constipation and the post-prandial discomfort and pain associated with gastrointestinal hyper-reactivity.
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PMID:5-Hydroxytryptamine and functional bowel disorders. 895 36


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