Irritable Bowel Syndrome

Materials for practical classes for 4-years student

Background

Irritable bowel syndrome (IBS) is defined as chronic or recurrent abdominal pain, altered bowel habits, and bloating, with the absence of structural or biochemical abnormalities to explain these symptoms. IBS is part of a broader group of disorders known as functional gastrointestinal disorders. It is the most common gastrointestinal diagnosis among gastroenterology practices in the United States and is one of the top 10 reasons for visits to primary care physicians. IBS is recognized in children, and many patients trace the onset of their symptoms to childhood. Children who have a history of recurrent abdominal pain are at increased risk of IBS during adolescence and young adulthood.

Pathophysiology

IBS has no identifiable cause, and laboratory testing is unrevealing. Over the last 5 decades, the understanding of IBS has evolved from a disorder of motor activities in the upper and lower gastrointestinal tracts to a more integrated understanding of visceral hypersensitivity and brain-gut interaction.

Gastrointestinal motility abnormalities

Studies evaluating the motor response of the colon to meals, pain, and stress suggest a difference between control subjects and patients with IBS. Pretreatment with anticholinergic medication in IBS was demonstrated to reduce meal-stimulated pain and diarrhea. The finding of an abnormal, 3-cycle-per-minute, slow-wave activity in the colon of patients with IBS was not confirmed by other studies and was noted in some individuals without IBS.

Abnormal small-bowel motility has also been reported by some investigators. Intestinal transit has been demonstrated to be delayed in patients with constipation-predominant IBS. In contrast, the transit was accelerated in patients with diarrhea-predominant IBS. Clustered contractions in the duodenum and jejunum and prolonged propagated contractions in the ileum were noted more frequently in patients with IBS. Small-bowel motility studies have demonstrated more abnormal findings in patients with IBS in conscious states than during sleep, suggesting that the condition may result in part from CNS input.

Nongastrointestinal smooth-muscle abnormalities

Bladder dysfunction was identified in 50% of patients with IBS and in only 13% of control subjects. One study found patients with IBS to have a higher incidence of orthostatic hypotension. A clinical study demonstrated a greater reduction of forced expiratory volumes in 1 second (FEV1) induced by methacholine in patients with IBS than in control subjects.

Visceral hypersensitivity

Most patients with functional disorders appear to have inappropriate perception of physiologic events and altered reflex responses in different gut regions. Patients with IBS undergoing balloon distension studies of the colorectum demonstrated awareness of distension and pain at pressures and volumes that were significantly lower than in control subjects. The development of chronic hyperalgesia within the gastrointestinal tract can be explained by the development of hyperexcitability of neurons in the dorsal horn in response to peripheral tissue irritation or to descending influences from the brain stem. Multiple factors are proposed to alter neuroreceptors and afferent spinal neuron functions. These factors include genetic, inflammatory, local nerve mechanical irritation, motility, and psychological factors.

Brain-gut interaction

The brain-gut axis is a bidirectional pathway that links higher cortical centers with visceral afferent sensation and intestinal motor function. Regulation of these connections occurs via numerous neurotransmitters found in the brain and gut, including cholecystokinin, vasoactive intestinal peptide, substance P, 5-hydroxytryptamine (5-HT), and many others. These transmitters act at different sites in the brain and gut and lead to varied effects on gastrointestinal motility, pain control, emotional behavior, and immunity. The 5-HT receptors are implicated in the mechanisms controlling gastrointestinal functions.

Dysregulation of the brain-gut system is becoming an acceptable theory to explain the functional gastrointestinal disorders. Furthermore, several studies have hypothesized that specific 5-HT receptor antagonists may be beneficial in IBS. Recently, a number of newer noninvasive imaging techniques (eg, positron emission tomography, functional MRI) have been applied to assess brain-gut interactions in healthy patients and in those with IBS.

Psychosocial factors in irritable bowel syndrome

Numerous studies have found an increased prevalence of abnormal psychiatric disorders, including anxiety, major depression, personality disorders, and hysteria, in adult patients with IBS, especially patients referred to medical facilities. These psychological disturbances are not believed to cause or induce the symptoms of IBS, but they are thought to influence the patient's perception of the symptoms and affect the clinical outcome. Stressful events are known to affect gastrointestinal functions and may lead to exacerbation of symptoms in patients with IBS. In addition, antidepressant or antipsychotic therapy is helpful in some patients with IBS. A recent meta-analysis has confirmed the relative efficacy of antidepressant medications in irritable bowel syndrome, particularly in predominantly diarrheic patients experiencing severe pain. Recent studies have reported an increased frequency of prior sexual or physical abuse in patients with IBS and other functional gastrointestinal disorders.

Dietary factors

Some studies have proposed that carbohydrate intolerance may produce significant symptoms in patients with IBS. Ingestion of lactose, sorbitol, or fructose is associated with increased gastrointestinal symptoms. Likewise, a food allergy may play a minor role in triggering or exacerbating symptoms in some patients with IBS.

Gastrointestinal infection and irritable bowel syndrome

Some investigations found a correlation between the development of IBS and a prior severe gastrointestinal infection, especially in patients with higher scores for anxiety. Symptoms compatible with IBS will affect 10-15% of patients after acute infectious gastroenteritis. Recent studies have demonstrated low-grade lymphocytic infiltration in the intestinal mucosa, increased permeability, and increases in inflammatory components including enterochromaffin and mast cells.

Some studies have shown that small intestinal bacterial overgrowth is common in subjects with IBS. A double-blind placebo-controlled study by Pimentel et al (2003) showed that normalization of lactulose breath testing with neomycin correlated with symptom improvement in patients with IBS.

Frequency

United States

Symptoms consistent with IBS are present in 10-20% of adolescents and adults. Less than one third of patients seek medical advice. In the pediatric population, IBS symptoms are reported in 14% of high school students and 6% of middle school students. One third of patients with IBS trace their symptoms to childhood.

International

Prevalence in developing countries is probably lower than in Western countries, but this may be explained by a combination of reduced availability of medical care and different cultural approaches to illness.

Mortality/Morbidity

IBS is not a life-threatening condition, but it can have a serious impact on a patient's daily activities and quality of life. Greater impairments in quality of life are reported in patients with IBS who sought medical care compared to those who did not consult their physicians for IBS symptoms. It is a major cause of absenteeism at the workplace and at school. Abdominal pain in patients with IBS is responsible for significant school absences in 4-5% of middle and high school students.

Race

IBS is not well characterized outside Western countries. According to reported studies, the disease prevalence is lower in Hispanic and Asian populations than in Caucasian populations, and whites are more likely to have IBS than blacks.

Sex

Women are 2-3 times more likely than men to have IBS.

In pediatric patients, both sexes are affected equally.

Age

IBS is a disorder of young people. One half of patients experience symptom onset when younger than 35 years, and 40% of patients are aged 35-50 years when symptoms begin.

IBS is recognized in children. Symptoms consistent with IBS are reported in 16% of students aged 11-17 years.

IBS is not described in preschool-aged and younger children because the diagnosis depends on the child's ability to report detailed symptoms.

Clinical

History

IBS has a broad range of symptoms; the most common are abdominal pain and altered bowel movements. Although symptoms may vary among patients, a pattern usually develops for each patient. The presence of characteristic symptoms in an otherwise healthy individual is sufficient to make a diagnosis of IBS in most individuals.

The characteristics of abdominal pain vary between patients and even within an individual patient.

The pain can be dull, achy, colicky, or sharp.

Pain can occur anywhere in the abdomen but is commonly located in the hypogastric or periumbilical regions.

The pain has no specific pattern but may be aggravated by stress and food and partially relieved after defecation.

Altered bowel habits include constipation, diarrhea, or alternating constipation with diarrhea.

Stools usually are of small volume and pasty. Constipation is associated with small, hard, pelletlike stools. Diarrhea characteristically occurs during waking hours and often is precipitated by meals.

Mucus can be a component of the stool in as many as 50% of patients with IBS.

In some patients, defecation is associated with a sense of incomplete evacuation that can lead to repeated trips to the bathroom and prolonged straining.

Symptoms of abdominal distension (ie, bloating, increased belching, flatulence) frequently are reported by patients with IBS. They are less common in children than adults.

Other gastrointestinal symptoms (ie, heartburn, dyspepsia, nausea, vomiting) are reported in 25-50% of adult patients with IBS. Dyspeptic symptoms are present in as many as 30% of pediatric patients with IBS.

Extraintestinal symptoms are also reported. Patients with IBS frequently report dysmenorrhea, urinary frequency, incomplete bladder emptying, back pain, and headache. These complaints are common in adults but rare in children.

Patients may relate a history of inciting events.

Exacerbation of IBS symptoms is sometimes reported to follow stressful experiences, ingestion of specific foods, or consumption of alcohol or caffeine.

Menses may exacerbate IBS symptoms in women.

In children, symptom precipitants include school-related problems, overeating, or eating problems.

The following clinical features should alert the physician to the possibility of a disorder other than IBS:

Frequent awakening by symptoms

Steady progressive course

Fever

Weight loss

Arthritis

Rectal bleeding

Persistent vomiting

The diagnosis of IBS requires the identification of the symptoms characteristic of IBS and the exclusion of other medical conditions with similar clinical presentations. Symptom-based criteria have been established for the diagnosis of IBS, which includes the Manning or, more recently, the Rome criteria. The pediatric working team adopted the Rome II criteria in the adult population because these criteria seemed to apply equally well to children. Rome II criteria apply to children old enough to provide an accurate pain history of at least 12 weeks, which need not to be consecutive, in the preceding 12 months. The history can include the following:

The abdominal discomfort or pain has 2 out of 3 features, ie, (1) relief with defecation, (2) onset associated with a change in frequency of stool, and (3) onset associated with a change in the form of stool.

No structural or metabolic abnormalities exist to explain the symptoms.

Physical

Physical examination findings generally are unremarkable. The patient may appear tense and anxious with sweaty palms. Abdominal tenderness may be present. Tender and palpable sigmoid is found in some patients.

Findings against the diagnosis of IBS include the following:

Abdominal rigidity

Rebound tenderness

Lymphadenopathy

Hepatosplenomegaly

Positive fecal bleeding test result

Causes

IBS has no identifiable cause (see Pathophysiology).

Laboratory Studies

No specific laboratory markers exist for IBS. Patients who have characteristic symptoms and meet the Rome criteria for IBS (see History) do not require a thorough diagnostic evaluation. A more aggressive approach is recommended for individuals with atypical symptoms, those with a rapidly progressive course, or when the index of suspicion for an organic disease is high.

In classic cases, a limited screen for organic disease is reassuring and should consist of the following:

Complete blood count

Erythrocyte sedimentation rate

Stool studies for ova and parasites

Stool cultures and stool Clostridium difficile toxin assay, if clinically indicated

A breath hydrogen test or a trial of dietary lactose restriction to exclude lactose intolerance

The following laboratory tests are indicated in special instances:

Lead level assessment

Celiac serologic tests

Serum immune markers for inflammatory bowel disease

Thyroid function tests

Tests for Helicobacter pylori (ie, serum antibody titers, urea breath test)

Imaging Studies

Plain abdominal radiography is recommended for patients with pain-predominant symptoms. Perform plain abdominal radiography during a pain episode to exclude intermittent obstruction.

Upper gastrointestinal study with small-bowel follow through is a useful study if Crohn disease or celiac sprue is suggested.

Barium enema can be useful for patients in whom Hirschsprung disease or congenital structural anomalies of the colon are suspected. Barium enema is also indicated in older patients (>50 y) because of the increased likelihood of colonic neoplasms.

Gastric scintigraphy is indicated for selected patients to evaluate for gastroparesis.

Abdominal ultrasonography is suggested for patients in whom biliary disease is suspected. It has high sensitivity and specificity for gallstones. It can also detect gallbladder wall thickening.

Other Tests

Gastrointestinal manometry can assist in evaluating patients in whom gastroparesis or intestinal pseudoobstruction is suspected.

Anorectal manometry is useful to screen patients in whom Hirschsprung disease is suspected.

Procedures

Sigmoidoscopy or complete colonoscopy is useful to evaluate for inflammatory conditions such as ulcerative colitis and microscopic colitis.

Upper endoscopy with small-intestinal biopsies is recommended in patients in whom peptic ulcer disease, Helicobacter pylori infection, Crohn disease, celiac disease, or other malabsorption conditions are suspected.

Treatment

Medical Care

IBS is a chronic illness and has no cure. Treatment may be challenging and even frustrating to the physician, the patient, and the patient's family. The most important component of treatment is to establish an effective and therapeutic relationship with the patient and his or her family. Educate the child and parents that IBS is a chronic illness that cannot be cured. At the same time, reassure them that it is not a life-threatening condition and it does not lead to physical impairment. Tell the patient and the family that the symptoms are real and respond to their worries and concerns. Reassurance is more effective if offered after a careful history and physical examination and a conservative diagnostic evaluation.

Most patients have mild symptoms and maintain normal daily activities and regular school attendance. Address the possible dietary and psychosocial triggering factors. Counseling, dietary modifications, and lifestyle changes usually are effective and sufficient for treatment.

A smaller proportion of patients have moderate-to-severe symptoms with some disruption of their activities and school performance. This group of patients may benefit from pharmacotherapy and behavioral treatment. Referral to a psychologist may be required.

Consultations

Consider further evaluation and a referral to a pediatric gastroenterologist if findings from the patient's history, physical examination, or screening laboratory tests are suggestive of organic disease.

Diet

Dietary modification

Some patients with IBS report exacerbation of their symptoms after ingestion of certain foods. Elimination of certain foods, such as sorbitol, fructose, and gas-forming legumes, achieves relief in some patients with IBS, especially those with excess gas. Attempt lactose restriction in patients with documented lactose malabsorption.

Foods associated with increased flatulence include onions, beans, celery, carrots, prunes, bananas, raisins, brussel sprouts, wheat germ, and bagels.

Fiber supplements

A high-fiber diet or supplement is useful in patients with constipation-predominant IBS. Several studies have demonstrated that fiber enhances water-retentive properties of stool, increases stool weight, and accelerates colonic transit.

In general, dietary fibers are less soluble and more effective as bulking agents, whereas synthetic fibers are more soluble and increase water retention.

The recommended daily intake of fiber (in grams) for children is estimated by adding 5 to their age in years.

Medication

Pharmacotherapy is recommended for patients with moderate-to-severe symptoms that cause disruptions in activity. Treatment is symptomatic and is directed at the most predominant symptom (eg, dietary fiber supplementation and stool softeners for constipation, antidiarrheals for diarrhea, smooth muscle relaxants for pain). A better understanding of the pathophysiology of IBS and the role of neurotransmitters and receptors involved in the gastrointestinal sensory and motor functions have provided opportunities for the development of newer therapeutic agents. The role of serotonin in the pathophysiology of IBS has drawn much attention, and agonists and antagonists at 5-hydroxytryptamine (5-HT) receptors have been approved for the treatment of subgroups of patients with IBS.

Antispasmodic and anticholinergic agents

These are the most frequently used medications (ie, hyoscyamine, dicyclomine) in the United States for the treatment of pain episodes in patients with IBS. Results from adult studies on the efficacy of these medications have provided conflicting data. The meta-analysis of the use of smooth muscle relaxants (eg, cimetropium, otilonium bromide, pinaverium, mebeverine, trimebutine) by Poynard et al showed efficacy over placebo in IBS. These drugs have calcium channel?blocking properties or antimuscarinic activities. No pediatric data exist with which to evaluate their efficacy or adverse effects.

Hyoscyamine (Levsin, Levbid)

Blocks action of acetylcholine at parasympathetic sites in smooth muscle, secretory glands, and CNS, which in turn has antispasmodic effects.

Adult

Levsin: 0.125-0.25 mg (1-2 tab) PO/SL q4h prn; not to exceed 12 tab per d

Levbid: 0.375-0.75 mg PO bid

Pediatric

<2 years: 0.125-mg/mL gtt; repeat q4h PO prn

The following is an approximate dosage guide:

2.3 kg (5 lb): 3 gtt; not to exceed 18 gtt per d

3.4 kg (7.5 lb): 4 gtt; not to exceed 24 gtt per d

5 kg (11 lb): 5 gtt; not to exceed 30 gtt per d

7 kg (15 lb): 6 gtt; not to exceed 36 gtt per d

10 kg (22 lb): 8 gtt; not to exceed 48 gtt per d

15 kg (33 lb): 11 gtt; not to exceed 66 gtt per d

2-12 years: Use 1.25-5 mL of elixir (0.03125-0.125 mg) PO q4h prn; not to exceed 30 mL/d

The following is an approximate dosage guide:

10 kg (22 lb): 1.25 mL

20 kg (44 lb): 2.5 mL

40 kg (88 lb): 3.75 mL

50 kg (110 lb): 5 mL

>12 years: Administer as in adults

Dicyclomine (Bentyl)

Treats GI motility disturbances. Blocks action of acetylcholine at parasympathetic sites in secretory glands, smooth muscle, and CNS.

Reports show that administration of dicyclomine syrup in infants has been followed by serious respiratory symptoms, seizures, syncope, pulse rate fluctuations, and coma. Death has been reported.

20-40 mg PO qid; discontinue if not effective within 2 wk or if 80 mg qd is associated with adverse effects

Pediatric

<6 months: Contraindicated

>6 months to 2 years: 5-10 mg PO tid/qid 15 min ac; not to exceed 40 mg/d

>2 years to 12 years: 10 mg PO tid

>12 years: Administer as in adults

Antidiarrheal agents

These agents are used to treat diarrhea adjunctly with rehydration therapy to correct fluid and electrolyte depletion. They are usually helpful when diarrhea is the predominant symptom. Studies of the opiate agent loperamide show that it improves stool consistency, decreases stool frequency, and reduces abdominal pain. Cholestyramine acts by binding bile acids and can be helpful in some patients with IBS. Alosetron and tegaserod are 5-HT4 receptor partial agonists that bind with high affinity at human 5-HT4 receptors. The activation of 5-HT4 receptors in the gastrointestinal tract stimulates the peristaltic reflex and intestinal secretion and inhibits visceral sensitivity. In vivo studies showed that tegaserod enhanced basal motor activity and normalized impaired motility throughout the gastrointestinal tract. In addition, studies demonstrated that tegaserod moderated visceral sensitivity during colorectal distension in animals.

Tegaserod was temporarily withdrawn from the US market in March 2007; however, as of July 27, 2007, restricted use of tegaserod is now permitted via a treatment IND protocol. The treatment IND allows tegaserod treatment of irritable bowel syndrome (IBS) with constipation or chronic idiopathic constipation (CIC) in women younger than 55 years who meet specific guidelines. Its use is further restricted to those in critical need who have no known or preexisting heart disease.

Earlier this year, tegaserod marketing was suspended because of a meta-analysis of safety data pooled from 29 clinical trials that involved more than 18,000 patients. The results showed an excess number of serious cardiovascular adverse events, including angina, myocardial infarction, and stroke, in those taking tegaserod compared with placebo. In each study, patients were assigned at random to either tegaserod or placebo. Tegaserod was taken by 11,614 patients, and placebo was taken by 7,031 patients. The average age of patients in these studies was 43 years, and most patients (ie, 88%) were women. Serious and life-threatening cardiovascular adverse effects occurred in 13 patients (0.1%) treated with tegaserod; among these, 4 patients had a heart attack (1 died), 6 had unstable angina, and 3 had a stroke. Among the patients taking placebo, only 1 (0.01%) had symptoms suggesting the beginning of a stroke that went away without complication.

For more information, see the FDA MedWatch Product Safety Alert.

Loperamide (Imodium)

Synthetic opioid; does not have central nervous action in therapeutic doses. Acts by slowing intestinal motility and enhancing water and electrolyte absorption. Reduces diarrhea and pain in patients with diarrhea-predominant IBS.

Adult

2-12 mg/d PO divided bid/tid; necessary doses differ greatly between individuals

Pediatric

<2 years: Not recommended

>2 years: 0.08-0.24 mg/kg/d PO divided bid/tid; not to exceed 2 mg/dose

Cholestyramine (Prevalite, Questran)

Binds endogenous bile acids and can improve diarrhea in patients with unexplained diarrhea or idiopathic bile acid malabsorption.

Adult

3-4 g PO bid/qid mixed with fluid or food

Pediatric

240 mg/kg/d PO divided tid ac as slurry in water, juice, or milk

Antidepressant drugs

A number of studies have shown that TCAs (ie, imipramine, amitriptyline) can be useful in the treatment of IBS in some patients. In addition to their antidepressant effects, TCAs have neuromodulatory and analgesic properties, which can be achieved at lower doses than those required for treatment of depression. Because of their inhibitory effect on gut motor function, TCAs may benefit patients with IBS with predominant diarrhea or pain. TCAs particularly benefit patients with IBS who have well-defined depression or panic attacks.

Amitriptyline (Elavil)

Inhibits reuptake of serotonin and/or norepinephrine at presynaptic neuronal membrane, which increases concentration in CNS.

Adult

10-50 mg/d PO qhs; administered at lower doses than required for depression

Pediatric

0.2-0.4 mg/kg/d PO qhs

Laxatives and stool softeners

Can be useful in patients with constipation-predominant IBS. Osmotic laxatives (eg, magnesium hydroxide, lactulose, sorbitol) or stool lubricants (eg, mineral oil) are usually required for long-term therapy for children with moderate-to-severe constipation. Long-term studies have shown that these medications are safe and equally effective. Stimulant laxatives may be necessary intermittently and for short periods, but avoid prolonged use.

Mineral oil (Milkinol)

An emollient laxative that does not appear to have any pharmacologic action on the GI tract. Acts by lubrication. When taken for 2-3 d, penetrates and softens stool and may interfere with absorption of water. Generally is well tolerated and without major adverse effects. Onset of action is approximately 6-8 h. Indigestible; limited absorption.

Prognosis

IBS is a chronic disorder that cannot be cured and usually persists in a waxing and waning fashion. Many children and adolescents who are diagnosed with IBS continue to experience symptoms into adulthood, and many adult patients with IBS trace their symptoms to childhood. The intensity of pain for a particular patient may vary with time, but the nature of symptoms usually remains unchanged.

The quality of life for many patients with IBS can be enhanced with ongoing education, reassurance, psychosocial support, and appropriate pharmacotherapy when indicated.

Constipation

Constipation is a commonly used term, but its definition is somewhat ambiguous. It could refer to conditions such as: a) the stools are hard, b) the stool is difficult or painful to pass, 3) no stools for a period of time, 4) a bloated feeling, 5) painful cramps associated with a segment of stool that is not moving well, 6) a chronic condition in which a patient's stooling frequency is less than average. All of these definitions are used in medical and/or everyday communication, but it is preferable to use specific terms to describe the symptoms of the patient. The specific findings and their clinical significance will be described in this chapter.

Enterocolitis is the extreme sequel of fecal retention, and is almost unique to Hirschsprung's disease, itself a uniquely pediatric version of the broader definition of chronic constipation: "a delay or difficulty in defecation, present for two or more weeks, sufficient to cause significant distress to the patient" adopted by the guidelines of the North American Society for Pediatric Gastroenterology and Nutrition (NASPGN) (1). The subject is best broken into two broad categories: infants and children.

Infantile constipation: Per the guidelines, this does not include neonatal delays in defecation since the structural anomalies (imperforate anus, cloacal exstrophy, and other perineal anomalies, as well as intestinal atresia, stricture or web, volvulus, duplication, or perforation) and genetic diseases (e.g., meconium ileus of cystic fibrosis) often present in the first few days. Newborns should pass their first meconium stool within 24 hours. Those who don't have a higher risk of GI conditions associated with constipation. However, this criterion should not be relied on in isolation since pathologic conditions will not necessarily present this way. The algorithm proposed by the NASPGN constipation subcommittee emphasizes early suspicion of serious disease, by rapidly sorting out newborns with delayed passage of meconium for rectal biopsy and directing infants with "fever, vomiting, bloody diarrhea, failure to thrive, anal stenosis, tight empty rectum, impaction and distention" (1) to immediate further evaluation, including subspecialty consultation as needed.

The workup begins with a thorough history and physical examination. The above alarm indicators are searched for, as are signs of other structural anomalies. The rectal examination is key, with careful assessment of the anal location, anal neurologic function (the anal wink, which assesses both the sensory afferent and motor efferent pathways), anal structure (looking for distention of the internal anal sphincter), anal tone (looking for spasticity or patulousness), function of the muscles of the pelvic floor (which provide additional help with control of defecation), and rectal diameter and tone (looking for signs of chronic distention even if no stool is present on the day of exam). The anal location should be halfway between the posterior border of the scrotum or posterior fourchette and the tip of the coccyx. Anything outside of the middle third of this region should raise the suspicion for a "perforate imperforate anus" (a structure resembling an anus is visible externally, but it is not contiguous with the rectum). If benign constipation is found, treatment is stratified based on age and developmental state.

Exclusively breast fed infants are permitted a longer interval between stools if they show no signs of distress or distention and if they are not prone to becoming impacted.

In exclusively formula-fed infants, my favorite strategy is the substitution of a commercially available partially hydrolyzed formula, which may produce suitable loosening of the stools. Malt soup extract (a dehydrated powder derived from an effusion of malted barley used in the brewing industry) has been advocated by the committee, as have corn syrup, lactulose or sorbitol, while the use of mineral oil was cautioned against due to the risk of aspiration posed by the frequency of gastroesophageal reflux and swallowing incoordination in this age group.

Impaction is most commonly dislodged by glycerin (non-stimulant) suppositories for which the commercially pre-softened versions sold in soft plastic applicators (glycerin gel) have been my personal favorite, as they provide more immediate relief (the traditional refrigerated suppositories require a wait while they melt in situ). Stimulant enemas are to be avoided in young infants.

Older infants who are of an age where pureed foods would be appropriate should have the fiber content of their diet optimized (i.e., push fruits and vegetables and reduce the other starches). Another personal favorite in the older formula fed infant is the use of undiluted apple juice (not apple drink) for its sorbitol content, titrating the amount administered to the stool texture while making certain that formula intake remains adequate. Pear and prune juice can also be used as they are high in sorbitol, but the cost of the former and the TASTE of the latter are often limiting factors.

Unlike the child with Hirschsprung's disease in the first illustration, the retention of stool in the older child who does not have a structural or neurogenic anomaly will NOT cause secondary inflammation and enterocolitis, regardless of the duration of the problem. This lack of inflammation is an important differentiating factor that permits immediate identification of the older child with chronic constipation. The primary cause is voluntary fecal withholding, usually due to fear of pain on defecation, giving rise to the term "Psychogenic Constipation". The often accompanying overflow diarrhea or involuntary soiling arising from passage of looser chyme above and around the impaction is termed Encopresis in verbal analogy to enuresis. In simpler terms, the child has a football shaped mass of hard stool in the rectum which reduces the sphincter's ability to hold in liquified stool (chyme) coming from above, which results in soiling. The withholding behavior most often arises from a pattern of passage of large caliber stool as was the case with our illustration, but it can arise in response to a single traumatic event, such as a particularly large stool resulting in a traumatic fissure, a too-rapid transition from diarrhea with a raw perineum to fully formed stools, perianal cellulitis (more properly erysipelas, an intensely painful superficial infection of the anus and surrounding structures with Group A streptococcus identifiable by culture of the affected area), or least frequently but most insidious: overt trauma of physical or sexual abuse.

As in infantile constipation, the history and physical exam are key. The above historical markers are useful in establishing an understanding of the process by the patient and his or her caregivers. Dietary issues must also be explored, as well as the pattern of toileting (it is amazing how little time and opportunity school age children seem to have for sitting on the toilet, with some schools having policies of allowing only two minutes per bathroom break).

The issues on the physical examination of the older child are the same as those of the infant, particularly those regarding the rectal examination. Indicators of failure to thrive are more important beyond the first year, since celiac disease and cystic fibrosis occasionally present with constipation instead of diarrhea, and Crohn's disease can leave the rectum fully capable of extracting fluid from the reduced flow of chyme arising from the reduced appetite, if the inflammation is confined to the small bowel or proximal colon. Hypothyroidism is a particularly rare (but often cited) cause of constipation. A particular caution regarding Hirschsprung's disease bears noting as a significant fraction of the cases present beyond the second year of life in children who require stimulation to trigger defecation: repeated suppositories and enemas will often dilate the spastic segment making it impossible by digital examination alone to identify what should otherwise have been a microcolon. If suspicion is high (inability to spontaneously pass flatus or a strict requirement of stimulation to pass stool which when triggered tends to be foul, loose, and voluminous), an unprepped barium radiographic colon examination is indicated. This study should specifically look for a transition zone, to and fro peristalsis in the unobstructed segments, or uniform mixing of the contrast material throughout the colon (rather than concentration of the remaining barium in the rectum) on the 24 hour delayed film (hence the stipulation for barium rather than water soluble contrast which would tend to be absorbed by the next morning). If the radiographic study is equivocal, anorectal manometry may be of benefit. If either are indicative of Hirschsprung's disease, the diagnosis is confirmed by biopsy of the rectum deep enough to include the myenteric plexuses, as their absence indicates the disease.

If simple constipation without impaction or soiling is identified, therapy begins with education regarding the need for a more regular defecation pattern to prevent progression of the problem.

Dietary intervention is advocated, emphasizing fiber and fluid in accordance with proper nutritional guidelines. Here I find a concrete set of recommendations is most helpful in facilitating compliance, and I have abridged the USDA's food pyramid (2) to a set goal of 6 servings of fruit or vegetables daily with a like number of servings of fluid, which is even further simplifiable to 2 servings of fruit or veggies at each meal which is easily understood by preschool AND adolescent patients.

More importantly, the need for regular toileting in the already potty-trained is emphasized, and I ask that they sit on the commode twice daily after meals to take advantage of the gastrocolic reflex to promote more regular rectal emptying. As in our illustration above, there must be an immediately preceding meal for the process to be most effective, and I have found that eating two fruits before toileting to be helpful. Suppers eaten out should be followed by a trip to the restaurant toilet to avoid missing the increased post-prandial peristaltic activity. A five minute time limit is set for commode sitting to avoid any sense of a punitive nature to the requirement and in some cases I will advocate using a kitchen timer in a "beat the clock" game if appropriate for the patient's personality.

Encopresis on the other hand is an indicator of repeated impaction, and usually is accompanied by enough dilatation as to render the rectal musculature patulous. Here again, education is key, and to simplify the biophysics (the wall tension is proportional to the fourth power function of the bowel lumen diameter), a quick analogy to a balloon that has been repeatedly inflated to the point of flaccidity is readily within the experience of most 4 or 5 year olds. Likewise an analogy to repeatedly compacting the trash over a 3-4 day period rather than dumping it daily will usually trap a kindergartner into admitting such behavior is likely to lead to a heavier, harder and bigger trash bag (and stool). Most importantly, education and discussion is important which should center on the cycle of pain at defecation leading to withholding which results in larger, firmer stools which in turn leads to more pain at defecation, perpetuating the cycle. This helps create understanding in the patient and the parent as to the origin of the process and its ultimate eradication. A thorough discussion of the mechanics of impaction and overflow passage of the as-yet unformed stool around the obstruction helps explain why distention of the rectum and internal anal sphincter and distortion of the levator structures of the pelvic floor result in inadvertent passage of loose stool whenever voluntary control of the external anal sphincter is relaxed. A thorough understanding is important in defusing the animosity that often arises between the patient and caregivers (parents, school, babysitters, etc.) over misunderstanding of what causes and perpetuates the soiling.

Treatment in the impacted, encopretic patient starts with disimpaction. High dose mineral oil and polyethylene glycol bowel preparation solutions have demonstrated efficacy and magnesium citrate, lactulose, sorbitol, senna and bisacodyl having been used anecdotally (1). Though the NASPGN subcommittee found that the oral route can be effective, typically this route is messy and more time-consuming. I strongly prefer a series of hypertonic phosphate soda enemas that are administered at 12 hour intervals (3). Typically only 3 are required, but the importance of removal of all formed elements is emphasized to prevent worsening the overflow diarrhea in the face of the fecal softening to follow. Caution is advised in using too much or too many enemas as each leaches a substantial bolus of calcium. In the case of particularly large and firm impaction, pre-softening by application of a mineral oil enema an interval before the stimulant one can be helpful. Saline enemas were also advocated by the committee as safe and effective, but soap suds, tap water and magnesium enemas are discouraged due to toxicity (1).

The next step is fecal softening, the issues being two-fold: produce a stool loose enough to be eliminated by the patulous rectum, AND eliminating any association of pain with defecation. Again, while the committee found lactulose, sorbitol, magnesium hydroxide, magnesium citrate, and mineral oil to be effective (1), I strongly prefer mineral oil (3) starting at 2-3 ml/kg/day but specifically titrating the dose to achieve the desired stool texture which I specify as "pancake batter", which has enough form to be routinely retained by the internal anal sphincter yet which is loose enough to empty out of the rectum with little more force than that of gravity alone whenever the levator structures of the pelvic floor are lowered and the anal sphincters are opened. In most cases, a patient whose rectum is dilated enough to allow soiling will have trouble expelling stool even the texture of toothpaste, which is the softest that can routinely be expected from fiber and fluid alone. A looser stool is needed to start the process, and mineral oil provides the cheapest and least flatulent method of attaining that goal. While the committee also made provisions for short-term addition of laxatives to this regimen (1), I feel anyone whose rectum is patulous enough to require such additional assistance, should have subspecialist evaluation, as this is by far the exception rather than the rule.

The third step is effective toileting: the already potty-trained patient should be seated on the commode with good foot support (to obviate any tendency to use the musculature of the buttocks and legs to assist in further withholding activity) on the commode twice daily after meals under the same guidelines and for the same reasons as outlined in the simple constipation as above. The sitting is made "non-negotiable" simply to ensure its application as it will become the most enduring and important part of the regimen as the weaning process progresses. Those who are not yet potty-trained are excused from formal sitting but are encouraged to crouch in diapers after meals in an analogous fashion.

Once a better than daily bowel habit is established and withholding is clearly extinguished, weaning off the mineral oil can begin. It is taken VERY slowly, in part to avoid recurrence of pain and resumption of withholding, but more to allow time for the patulous rectum to regain motor tone. I illustrate the importance of this to the patient and family by referring back to the balloon illustration, pointing out the difference between inanimate latex and living muscle, which can regain tone and function. I specifically warn that the process will take months to improve, and that prolonged use of mineral oil has been proven benign (4). This helps improve adherence to the long-term nature of the measures involved, and weaning typically occurs at monthly intervals, and then ONLY if the rectum is indeed shrinking in diameter (and improving in function) and if the withholding remains extinguished. Failure with either issue should result in either maintenance at the current step or return to the next higher one.

Adherence to the mechanical measures involved typically results in an immediate return to continence with the completion of disimpaction, as the nondistended internal anal sphincter is able to retain the loose stool. Continued adherence to the slow weaning typically results in return to long term function (and confidence) through the months of steady increase in stool texture. Permanent adherence to a daily defecation pattern results in long-term avoidance of reimpaction, and is the ultimate goal of the process. Each step along the way involves the physician acting as coach, cajoling and encouraging patients and caregivers, solving problems in techniques, and refereeing any residual conflicts. It must be kept in mind that control in this issue lies with the patient. There is nothing we can (or should) do that will force regular toileting, and there are times when I have to call a "time out" from the process to enable the patient to proceed on his or her merry way until THEY are ready to work on the problem. I often remind parents that the only thing one will die of with routine encopresis is embarrassment, remembering that children are often beaten to death by caregivers for soiling behavior. As can be seen above, the initial visit to address the issue of encopresis can be particularly time-consuming, not with regard to the history or physical examination, but because of the need to impart the understanding of the process of the disease that will encourage an apprehensive child to undertake the measures needed to clear it. The hour rapidly fills with illustrations and instruction, and does not readily fit into a routine sick-child office visit. Time must be set aside for proper handling of the process, and I know most consultations for encopresis arise from the inability to carve out such time in the primary care practice setting.

Biliary Dyskinesia (BD)

Biliary dyskinesia (BD) is a disorder of the sphincters? tonus and kinetics of the gall-bladder and the bile ducts. There are two basic forms of BD: hypotonic-hypokinetic and hypertonic-hyperkinetic. Usually BD is a concomitant disease: for example "Chronic cholecystitis. Biliary Dyskinesia of hypertonic-hyperkinetic type". BD as an independent diagnosis is used rarely.

Criteria of diagnosis

/. Clinical

In hypertonic forms of BD pain occurs 30-40 minutes after meal, it is localized in the right hypochondrium or round umbilicus, it is paroxysmal and cutting or shooting, and it lasts: for 5-15 minutes. On palpation there is painfulness in the right hypochondrium. Signs of Ortner, Merphy, Boas, frenicus-symptom are positive. There are common manifestations of vegetative dysfunction, neurotic symptoms.

In hypotonic dyskinesia pain occurs 1-1,5 hours after meal (especially fatty) or after physical exertion, it is localized in the right hypochondrium. It is dull or pressing, and it lasts 1-2 hours, sometimes accompanied by nausea. On palpation painfulness is revealed in the right hypochondrium. Bladder signs are distinctly positive. Enlargement and tenderness of the liver are common.

//. Instrumental

The most informative test for verification of diagnosis is USE with use of cholekynetics (egg yolk, sorbit) for functional investigations. Changing of size of gall bladder helps to evaluate its tonus and the rate of contraction and in an indirect way to conclude about the state of the sphincters.

The less informative one is fractional duodenal tubing. The signs of hypertonic-hyperkinetic type BD are prolongation of period of closed Oddi?s sphincter (more than 6 min), diminished volume and speeded up excretion of B and C bile portions (more than 1,5 ml/min). Shortening of period of closed Oddi?s sphincter (less than 2 min), increase of bladder portion of bile (more than 50 ml) and slowing down of its excretion (less than 1,1 ml/min) are the signs of hypotonic-hypokinetic disturbances.

Date: 2016-06-13; view: 6