Other Functional Gastrointestinal Disorders in Infants and Young Children

Functional gastrointestinal disorders (FGIDs) are conditions defined by clusters of symptoms related to a disorder in function at the level of the GI tract and/or in the central processing of information originating from the GI tract. Although FGIDs are common in adults and children, they are often considered by the lay public and by many medical providers to be rare in infants and toddlers. Indeed, conditions that would readily be accepted as benign in older children, such as constipation or regurgitation, often prompt extensive workup by concerned physicians and anxious parents. Among the most common FGIDs in the first few months of life are infant regurgitation and infantile colic, 2 conditions that are usually time limited and resolve or improve by 6 to 8 months of age. Despite their favorable prognosis, such disorders often are extensively investigated and treated with multiple dietary changes and use of medications of uncertain benefit. Other FGIDs, which occur in the first 24 months of life, include infantile dyschezia, rumination syndrome, functional diarrhea, cyclic vomiting syndrome, and functional constipation. The prevalence of these conditions seems to be similar in different countries characterized by diverse socioeconomic factors, health care structure, and dietary habits. This article represents an overview of some of the main FGIDs in infancy (Table 1). Infant colic is extensively discussed in this supplement; cyclic vomiting syndrome and functional constipation are more common in older children and do not have any peculiar characteristic when presenting earlier in life and are not addressed.

Table 1: FGIDs of infants and toddlers

The common factor in all of the FGIDs of infancy, much like in other FGIDs in older children, is the lack of a biological marker. Thus, as in the field of psychiatry, another discipline with rare demonstrable abnormal findings on diagnostic laboratory or radiologic testing, pediatricians and subspecialists rely on clusters of symptoms to make a positive diagnosis. The Rome symptoms-based criteria for FGID were published to facilitate diagnosis of such disorders and avoid extensive, usually fruitless, testing. Initially developed for adult conditions only, the Rome criteria have been adapted to children and have become widely used in pediatrics. One of the Rome III committees specifically addressed FGIDs in the infant and toddler periods ⁽¹⁾. Such criteria, initially based mostly on expert opinion, have undergone several iterations in an attempt to become more evidence based.

INFANT REGURGITATION

Infant regurgitation often is considered responsible for multiple GI and extraintestinal symptoms. The evidence disputes some of these beliefs, and it has been suggested that there has been an overtreatment of what should actually be considered a normal physiologic event ⁽²⁾. In young infants, daily regurgitation is within the range of expected behaviors, and the great majority of regurgitating infants are thriving and do not develop any disease. Infant regurgitation seems to peak at 4 to 6 months and decreases in frequency during the second semester of life ⁽³⁾. At 1 year of age, <10% of infants still exhibit daily regurgitation. Despite the high prevalence of this symptom and the overall well-being of affected infants, almost 25% of the parents are concerned enough to seek medical advice because they are worried about the severity of the regurgitation ⁽⁴⁾. Exclusively breast-fed infants seem to regurgitate less than partially breast-fed babies ⁽⁵⁾. The forcefulness of regurgitation or its outflow through the mouth or nares carries little diagnostic relevance. Alarm signs that should trigger an evaluation for gastroesophageal reflux (GER) disease include failure to thrive, food refusal, swallowing difficulties, hematemesis, apnea, and recurrent pneumonia. Bilious emesis and delayed neurodevelopmental progress necessitate prompt referral for more in-depth testing. Regurgitation persisting past the first year of life justifies the use of imaging studies to exclude an anatomical abnormality, such as a malrotation or a gastric outlet obstruction. In 2009, the North American and the European Societies for Pediatric Gastroenterology, Hepatology, and Nutrition jointly published practice guidelines that discuss evidence for when to evaluate and treat an infant with regurgitation and suspected GER ⁽⁶⁾. The guidelines expressly stated that GER “is not a common cause of unexplained crying, irritability, or distressed behavior in otherwise healthy infants.” Treatment directed at gastric acid suppression exerts little effect on infantile regurgitation and may be associated with adverse effects ⁽⁷⁾. Thickening the formulas with cereals or using “antiregurgitant” formulas decrease overregurgitation ^(8,9).

INFANT RUMINATION

Infant rumination has been defined as a disorder that must include all of the following aspects: repetitive contractions of the abdominal muscles, diaphragm, and tongue; regurgitation of gastric content into the mouth, which is either expectorated or rechewed and reswallowed; onset between 3 and 8 months; does not respond to treatment of GER or formula changes; is not associated with signs of distress; and does not occur during sleep or when the infant is interacting with individuals in the environment ⁽¹⁾. It is unclear how common this condition is, but it has received little attention in the past 2 decades in the medical literature. It is probably most common in infants with severe neurodevelopmental delay. The most comprehensive review of the topic is attributed to Fleisher, who in 1994 discussed the difference among “innocent vomiting” (an entity which is probably akin to infant regurgitation), “nervous vomiting,” and infant rumination syndrome ⁽¹⁰⁾. Nervous vomiting was thought to accompany other symptoms of impaired maternal–infant reciprocity and often associated with failure to thrive. Fleisher described infant rumination as an acquired skill used by an emotionally deprived infant for the purpose of self-stimulation and needs satisfaction. According to Fleisher and in line with initial reports in the medical literature ^(11,12), this condition was often lethal, unless improved mothering and increased environmental stimulation was provided. It is likely that the condition described as infant rumination syndrome in the Rome criteria includes both Fleisher's nervous vomiting and rumination syndrome. Behavioral therapy with use of aversive techniques and positive reinforcement has been shown to be an effective treatment for rumination syndrome ^(12,13). Once the nutritional deficiencies are corrected and the ruminant behavior has improved, it usually does not recur ⁽¹⁴⁾.

INFANT DYSCHEZIA

Infant dyschezia is a condition that despite being extremely common had received little or no attention in the medical literature until the Rome Committee attempted to define it based on characteristic symptoms ⁽¹⁾. It also is known as “grunting baby syndrome,” based on the behavior of the infant, who seems to struggle to have a bowel movement. Parents describe otherwise healthy infants with dyschezia as straining for several minutes, often crying, and turning red or purple in the face with effort. The symptoms persist until there is passage of soft or liquid stool. Often well-meaning parents try to alleviate the child's perceived pain by stimulating the anus with a suppository or a thermometer, an act that usually leads to stooling and resolution of the distressed behavior. This “success” then leads the parents to replicate the intervention every time the grunt reoccurs. Failure to coordinate increased intraabdominal pressure with relaxation of the pelvic floor is thought to be the underlying pathophysiological mechanism in infant dyschezia. The simultaneous contractions of abdominal and gluteal muscles are not conducive to successful passage of stools and some infants struggle in acquiring the necessary behavioral skills needed for a pleasant defecation. Unlike infant colic, the distress occurs only during the act of defecation. The symptoms begin in the first months of life and resolve spontaneously after a few weeks, once the infant has mastered more effective defecation dynamics. The clinician must provide effective reassurance to the parents that there is no disease and no testing or treatment is necessary. Reassurance includes listening to the parents’ worries, performing a thorough physical examination (including anal inspection), providing a plausible explanation for the symptom, and expressing an expectation for spontaneous recovery. Repeated anal stimulation is discouraged so as not to delay the infant's learning the correct defecation process.

FUNCTIONAL DIARRHEA

Functional diarrhea (commonly also known as toddlers’ diarrhea or chronic nonspecific diarrhea) is defined by the daily painless passage of ≥3 large, unformed stools for ≥4 weeks with onset between 6 and 36 months of age ⁽¹⁾. The stooling occurs during waking hours and there is no failure to thrive if the diet has adequate calories ⁽¹⁵⁾. Parents often become concerned that their child may have malabsorption when they find in the stools mucous or easily identifiable pieces of undigested food (usually vegetable matter) eaten just a few hours earlier. Although the frequency of the defecations may increase and the stools may become looser, the child does not seem to be in pain, and the condition resolves spontaneously by school age. A dietary history often uncovers overfeeding, excessive carbohydrate ingestion (especially fruit juice and sorbitol), and low fat intake. In the absence of failure to thrive, malabsorption is unlikely. Pathophysiology has been thought to involve abnormalities in the control of postprandial motility, increased activities of (Na⁺-K⁺)-adenosine triphosphatase and percentage of activation and basal activity of adenylate cyclase, and bile salt malabsorption ^(16–18). Behavioral problems relating to sleep, crying and irritability, activity, and discipline also were found to be significantly more frequent or severe in a group of children with chronic nonspecific diarrhea ⁽¹⁹⁾. Therapeutic interventions for functional diarrhea should focus on increasing dietary fiber and fat intake and avoid excessively restrictive diets that may cause calorie deprivation.