Richard J. Noel
Feeding includes food acquisition, ingestion, digestion, and absorption. This activity relieves hunger and provides multisensory stimulation, resulting in a pleasant, rewarding experience for both the child and the caretaker. Successful feeding experiences create positive reciprocal interactions that reinforce the bonding relationship between child and caretaker. Feeding disorders prevent the infant from ingesting adequate nutrients for continued health, growth, and development.
Feeding and swallowing are complex processes that can be divided functionally into 4 phases, as shown in Figures 31-1 and 31-2. The preoral phase is initiated when the child senses and communicates hunger. The oral phase is a food-processing step wherein the ingested material is formed into a bolus that can safely pass through the pharynx; the remainder of the swallowing process is involuntary and reflexive. The pharyngeal phase is quite rapid. It is initiated by bolus contact with the tonsillar pillars and pharyngeal wall with subsequent elevation of the larynx, vocal cord closure, and relaxation of the upper esophageal sphincter. A peristaltic wave of contraction of the pharynx propels the bolus into the esophagus.
FIGURE 31-1. Model of the normal phases of feeding in infants and children. Complex interactions between phases often obscure diagnosis of the primary cause of a feeding disorder.
FIGURE 31-2. A: The infant oropharynx. The larynx is elevated with the epiglottis touching the soft palate, creating a functional separation between the air passages (white arrow) and the food passages (black/gray arrow) in the pharynx. Food courses around the epiglottis, into the pharyngeal recess, and then to the esophagus. B: The toddler (2–3 years old) oropharynx. C: The adult oropharynx: (1) oral preparatory phase, (2) oral phase, (3) pharyngeal phase, (4) esophageal phase. Note that the infant oral cavity is much smaller than the child or adult oral cavity, providing little space for manipulation of the food bolus. The larynx is elevated so that the epiglottis almost touches the soft palate, and the larynx is at the level of the first to third cervical vertebrae. The tongue is entirely within the oral cavity, with no oral region of the pharynx. In the toddler, the larynx descends to the fifth cervical vertebra, and by adulthood it descends to the sixth to seventh cervical vertebra.
During passage of the bolus through the pharynx, excellent coordination between breathing and swallowing is essential to prevent aspiration. In the esophageal phase, the bolus is transported into the stomach. Finally, the bolus is broken down and absorbed during the digestive phase. Developmental and maturational changes in the phases of swallowing occurring from infancy to childhood can have a significant impact on a child’s ability to feed successfully.
Symptoms of feeding and swallowing disorders in children have many manifestations and clinical presentations, anywhere from food refusal, failure to gain weight, and oral aversion to recurrent pneumonia, chronic lung disease, and recurrent emesis. Swallowing and feeding disorders in infants and children are complex and can have multiple etiologies; these are listed in Table 31.1. Organic and nonorganic etiologies occur alone or in combination, making the diagnosis and treatment challenging and complicated. Feeding and swallowing can be interrupted in any phase. Successful management of the child with feeding problems begins with the identification and treatment of any correctable underlying physical cause of the feeding disorder. Identifying and addressing both parent and patient nonorganic behavioral factors occurring concurrently with a physical cause will enhance management. Only after all reasonable physical etiologies have been ruled out should a feeding or swallowing disorder be attributed to a nonorganic cause.
Centers for hunger and satiety in the hypothalamus receive afferent signals from a variety of sources. Sensory inputs that affect feeding behavior are well developed even in infants. Appetite also is affected by emotional state: Infants who are not nurtured reduce their food intake and fail to thrive. Reductions in appetite are frequent in infants and children with chronic debilitating disease; however, very specific food aversions may be observed in otherwise healthy people. If ingestion of a specific food is temporally associated with a painful or uncomfortable experience, a child may refuse to ingest that food again. This type of specific aversion is observed in patients with metabolic disease, gastroesophageal reflux, or allergies who experience nausea or discomfort after ingesting offending nutrients (eg, as seen with ingestion of sucrose in patients having hereditary fructose intolerance). More generalized feeding aversions can occur if an infant has negative experiences such as aspiration or choking during feeding. Infants who have required prolonged airway intubation or tube feeding often learn that efforts by a caretaker to approach their mouth or face likely result in discomfort, and “oral defensiveness” can persist long after the patient is extubated.
FOOD SEEKING AND INGESTION
Preverbal infants and developmentally delayed children communicate hunger by providing behavioral cues to their provider; in turn, the caretaker must correctly interpret these cues. If the caretaker misses the cue and offers food when the child is not interested in eating, the resultant struggle can easily exacerbate the situation. In toddlers, food seeking consists of communicating hunger. Efforts to independently use a spoon and cup and, ultimately, to obtain food from the refrigerator themselves progress through development. In adults, food seeking is a complicated process that includes most aspects of our daily lives. The mechanical process of ingestion requires the appropriate muscular coordination and sensation to bring food to the mouth. This is a learned process that evolves through normal development. Neuromuscular disorders, blindness, and fatigue resulting from illness all can interfere with food ingestion.
Table 31-1. Partial List of Medical Etiologies of Feeding Disorders in Children by Category
Infants with subtle feeding disorders are less resilient in responding to difficult environments and emotional deprivation than are normal infants. Many children who have been diagnosed with failure to thrive have subtle neuromuscular or oromotor disorders. Successful management in this setting requires teaching caretakers how to adjust feeding techniques appropriately. Continued unsuccessful efforts to feed the child can disrupt the caretaker-child relationship even in well-adjusted families.
The oral phase consists of bolus formation and movement of a food substance posteriorly toward the pharynx. Oral phase development begins at 15 weeks of gestation with mouthing and suckling movements. By 32 weeks, a disordered pattern of suckling bursts and pauses emerges. By 34 to 36 weeks, the fetus displays a stable pattern of rhythmic suckling and swallowing. After birth, swallowing is triggered when a certain volume of fluid occupies the oral cavity. Excellent tongue motion and coordination are needed for this phase of swallowing.
During postnatal development, anatomic changes occur in the oral cavity with concurrent development and maturation of motor skills required for safe feeding (see Figure 31-2). In infancy, the oral phase of swallowing consists of the subcortically regulated process of suckling, characterized by primitive extension-retraction motion of the tongue. The small size of the mandible and oral cavity relative to the tongue and the presence of buccal fat pads facilitate suckling and provide an ideal geometry for generating suction on a nipple but leave little room or ability for manipulation of a solid bolus. Food delivery is accomplished by sealing the lips around the breast or nipple and then sealing the posterior aspect of the oral cavity with the tongue against the palate. Depressing the oral surface of the tongue creates suction pressure for bolus delivery. Suction pressures greater than 100 mm Hg are generated in the oral cavity of healthy newborns, with the amount of pressure varying to adjust the flow rate to approximately 0.2 mL per suck. Too rapid a flow results in overflow of milk into the pharynx before the initiation of an organized swallow, with the potential for aspiration.
Between 3 and 6 months of age, the anatomy of oral cavity and pharynx begins to change, and infants start to suppress the suckle pattern and develop voluntary suck patterns. The anatomical changes include resorption of the buccal fat pads and the inferior and forward drop of the jaw, thus increasing the intraoral space. Tongue movements mature from extension-retraction motion of suckling to up-and-down movements of sucking, facilitating bolus manipulation and thereby allowing for a more coordinated transport of food and liquid into the oral cavity. This maturation in skills allows infants to begin eating textured food from a spoon by 4 months of age. Masticatory skills begin to develop by 6 to 8 months and continue to develop as the alveolar ridges mature and deciduous teeth erupt. At 12 months, suckling patterns are minimized, and children generally transition to cup drinking and no longer use the suck pattern. By 18 to 24 months, rotary chewing skills and increased lateral activity of the tongue contribute to more effective handling, crushing, and grinding of food.
Specific oral skills such as sucking or chewing solids are learned only at certain ages. Infants who do not orally feed during these critical periods of development have a difficult time mastering these skills later; these patients may learn how to spoon and cup feed without ever learning to suck effectively. Development of the oral phase requires normal anatomy, intact sensory feedback, and normal muscle strength and coordination. Anatomic defects include cleft lip with or without cleft palate, micrognathia, and macroglossia. A weak suck may be congenital or acquired. Other causes of oral-phase dysfunction include xerostomia and temporomandibular joint pathology.
The pharyngeal phase of swallowing is involuntary and is triggered by bolus contact with the tonsillar pillars and pharyngeal wall. During pharyngeal swallowing, the upper pharynx and soft palate close to seal the nasal cavity as the bolus enters the pharynx. The bolus is propelled to the esophagus by contraction of the pharyngeal muscles. Proprioceptive feedback adjusts this activity as needed to compensate for different types of boluses. During pharyngeal contraction, the larynx elevates, the vocal cords close, and respiration ceases to protect the lower airway from aspiration. The upper esophageal sphincter relaxes, and peristaltic contractions of the pharynx push the bolus past the displaced, closed larynx into the upper esophagus. Because the pharynx is the common chamber for the respiration and digestive pathways, important developmental changes occur to allow for safe swallowing. In the infant, the larynx sits high in the neck at the level of vertebrae C1-3, allowing the velum, tongue, and epiglottis to approximate and thereby functionally separate the respiratory and digestive tracts. This allows the infant to safely breathe and feed. Even though this unique functional separation exists in infants, vigorous sucking and swallowing during feeding can cause significant reductions of minute ventilation and mild hypoxia even in healthy babies. Babies with compromised cardiac or respiratory function may have serious difficulties with hypoxia during feeding.
By age 2 to 3 years, the larynx descends, decreasing the separation of the swallowing and digestive tracts. Intact oral motor skills and laryngeal function are essential for coordinating the oral and pharyngeal phases of swallowing to prevent complications of aspiration. Early overflow of the bolus into the pharynx before respiration ceases may allow food to enter the trachea during inspiration. Lack of relaxation of the upper esophageal sphincter causes pooling in the piriform sinuses with resultant food overflow into the airway when the larynx descends at the end of the swallow sequence and inspiration begins. Because there is less separation of the swallowing and digestive tracts at this developmental stage, subtle anatomic or neuromuscular disorders that are not problematic in an infant can cause recurrent aspiration in a toddler.
Laryngopharyngeal sensory deficits from neurologic disorders or decreased laryngeal sensitivity from chronic extraesophageal gastroesophageal reflux predispose to problems with coordinating swallowing and increase aspiration risk. Congenital abnormalities, including laryngeal clefts and laryngomalacia, can result in dysphagia and aspiration. Myopathies, central nervous system abnormalities, tumor masses, foreign bodies, esophageal peristaltic disorders, and inflammation can disrupt the pharyngeal phase of swallowing. As noted previously, infants or children with tachypnea or cardiac compromise often have difficulty coordinating swallowing and breathing, thereby making feeding more difficult.
ESOPHAGEAL AND GASTROINTESTINAL PHASES
Abnormal peristalsis, esophageal inflammation from gastroesophageal reflux, eosinophilic esophagitis, infection, allergy, and mechanical obstruction may all cause dysphagia. Odynophagia or postprandial pain or discomfort from any gastrointestinal disorder may result in the development of feeding aversions.
EVALUATION OF THE CHILD WITH A FEEDING DISORDER
Symptoms of feeding disorders include refusal to eat or drink, failure to gain weight, aversions to specific food types or textures, recurrent pneumonias, and chronic lung disease. Because of the complex nature and multiple etiologies of pediatric feeding and swallowing disorders, evaluation is best achieved by an interdisciplinary team approach that includes a variety of professionals with expertise in pediatric feeding disorders.1 These may include speech and language pathologists, occupational therapists, dietitians, behavioral psychologists, nurse clinicians, dentists, and pediatric subspecialists in gastroenterology, otolaryngology, pulmonology, radiology, and neurology or rehabilitative medicine. This approach facilitates integration of expertise from different disciplines to determine how organic and nonorganic factors interact in contributing to the child’s swallowing disorder and overall health. The goal of a comprehensive evaluation should first be to assess the safety of oral feeding, establish the risk of aspiration, and identify anatomic, physiologic, behavioral, and psychosocial issues that may limit feeding. A careful developmental, medical, feeding, and dietary history and physical examination provide clues to the diagnosis and direct subsequent evaluation.
The evaluation begins with a focused feeding history including current diet, textures, and route of administration, modifications, and feeding position. A specific query into the medical comorbidities that affect swallowing is made. A history of recurrent pneumonia may indicate chronic aspiration, and a history of stridor in relation to feeding may indicate a glottic or subglottic pathology contributing to the feeding disorder. Specific inquiry about any previous operations involving the aerodigestive tract is important because these factors influence the assessment.
Nutritional and psychological assessments should be undertaken early in the evaluative process. It is important to assess if caloric intake meets the metabolic needs of the child, as many patients with swallowing disorders have concurrent illness that may increase metabolic needs. Psychological assessments help to identify behavioral and parental factors that may be contributing to a feeding disorder.
A clinical oromotor assessment evaluates nonnutritive and nutritive oral motor skills. This assessment includes an evaluation of neuromuscular tone, posture, and position during feeding; patient motivation; oral structure and function; and efficiency of oral intake. The oral cavity is carefully examined for anatomic abnormalities, including enlarged tonsils that may interfere with feeding. Poor lip closure may indicate a cranial nerve V or VII abnormality, and a loss of gag reflux may indicate cranial nerve IX or X insult. The nutrition assessment involves the observation of feeding involving the patient and his or her primary feeders. The observation team notes both positive and negative interactions among the child, food, and feeder to identify primary or secondary behavioral problems, which guides future structuring of treatment interventions. The oromotor assessment evaluates for obvious problems with sucking and bolus manipulation. Difficulty with oral secretions, abnormal pace of feeding, food escaping from the mouth, abnormal airway sounds, and poor coordination of suck and/or swallow with laryngeal elevation and breathing, gagging, coughing, or emesis suggests an underlying neurologic or structural problem. Attention to articulation and voice quality also may provide useful information because the structures used for the oropharyngeal phases of feeding also are important for speech production. Velopharyngeal insufficiency from a structural or neurologic abnormality can present with hypernasal speech. Velopharyngeal insufficiency results in failure to adequately close the velopharynx or nasopharynx, predisposing to nasal regurgitation of food and poor pharyngeal propulsion force during swallowing.
At the end of the investigation, the evaluator should have a better assessment of optimal posture for feeding efficiency and safety and optimal food consistencies and textures. This assessment will help direct further studies to complete the feeding evaluation.
Anatomic disorders and other physiological disorders may manifest as a behavioral disorder and must be excluded before interventions are initiated. Identifying such factors is facilitated by other diagnostic tests.
It often is difficult to diagnose a feeding disorder or the safety of continued oral feeding using clinical observations alone. Aspiration may occur without coughing or gagging during the clinical exam (silent aspiration). Oral, pharyngeal, laryngeal, and esophageal anatomy and function should be assessed. Three approaches are used: imaging studies, direct visualization, and occasional pharyngeal/esophageal manometry. Each modality provides complementary information.
Radiographic studies may reveal anatomic or structural abnormalities such as strictures, fistulas, or masses. Current evaluative radiographic studies of swallowing function are fluoroscopic imaging in the form of videofluoroscopic swallowing study and ultrasonography. Accessory radiographic studies are indicated in some patients with feeding and swallowing disorders, and indications are based on the clinical history and physical examination findings.
Videofluoroscopic swallowing study should be considered in all infants and children with a feeding or swallowing disorder.2 A speech pathologist or occupational therapist in conjunction with a radiologist performs this examination. The advantage of this evaluation is that it provides a dynamic assessment of all phases of swallowing simultaneously, thereby providing an assessment of velopharyngeal closure, pharyngeal contraction, laryngeal penetration or aspiration, and esophageal propagation. Additionally, this evaluation can reveal any obstructive or congenital pathology that can interfere with swallowing. When performed completely (which is often problematic), the study also includes an assessment of food transit through the esophagus and can provide valuable information about potential esophageal causes of dysphagia. This is not a substitute for a formal esophagram. Food substances given during this examination typically mirror what was determined as adequate during the oromotor clinical examination. Infants are fed barium through a nipple or given a thin barium-coated puree. Children older than 12 months are assessed using 3 textures: a liquid, a puree, and a solid. Studying the patient in the usual and then the optimal feeding positions may provide therapeutic information. The therapeutic effect of modification of bolus size and consistency, nipple, or feeding utensils can be explored. The primary limitations of videofluoroscopic swallowing study in children is that repeated exposure to radiation limits its use for extensive teaching of compensatory maneuvers and repeat assessments of swallowing over time to evaluate progress. Additionally, infants and children with oral aversion and feeding disorders may not ingest an adequate volume of barium to provide a meaningful study. There are other evaluative tests that can be used to overcome these limitations.
Ultrasonography can capture tongue, hyoid, and palate activity and bolus transport across the tongue to the hypopharynx, thereby providing a useful evaluation of the oral phase of swallowing. It can also demonstrate the coordination of laryngeal elevation during swallowing. This test is limited in its ability to determine dysfunction of the pharyngeal phases of swallowing and lacks sensitivity for detecting aspiration. An additional limitation of this technique is its lack of standardization and varied interpretations.
Accessory imaging studies are useful in specific clinical scenarios. Any infant or child with recurrent pneumonia requires a carefully performed esophagram specifically to rule out an H-type tracheoesophageal fistula, even if aspiration is identified during a swallowing study. If any clinical findings suggest cranial nerve IX or X involvement, the child should have a brain MRI study to identify potential brainstem, skull base, or spinal problems that can interfere with swallowing, such as Chiari malformations with tonsillar herniation, hydromyelia with myelomeningocele, and cervicomedullary junction compression by a craniovertebral junction malformation with the impingement by the tip of the odontoid process. MRI evaluation of the chest is useful in patients suspected of having a vascular ring or sling cause for stridor or dysphagia and can be diagnostic, eliminating the need for endos-copy in some cases.
Flexible endoscopic evaluation of swallowing utilizes a flexible fiberoptic laryngoscope that is passed through the nose to visualize the larynx and pharynx.3 With simultaneous endoscopic visualization of feeding, this evaluation allows for assessment of velopharyngeal closure and its impact on swallowing, pharyngeal contractility and proficiency, secretion management, laryngeal penetration, and aspiration. This test is particularly valuable for assessing the risk of aspiration in patients who are unable or unwilling to feed. Green food coloring is placed into the oral cavity to mix with the patient’s own secretions. Visualization of the path of secretions and how the child handles them by spontaneous or voluntary swallows can help determine aspiration risk. Swallowing safety by modifications in food consistencies and volumes and compensatory postural changes can be assessed by flexible endoscopic evaluation of swallowing without exposing the patient to radiation. Although anatomic abnormalities can be assessed with flexible endoscopy, a laryngeal cleft is difficult to identify except during rigid laryngoscopy. If it is suspected, flexible laryngoscopy alone is inadequate.
Manometry requires transnasal passage of a catheter that is fitted with multiple pressure ports. It is used for evaluating pharyngeal and esophageal peristalsis as well as upper and lower esophageal sphincter function. These tests are very difficult to perform in infants and children and therefore should be performed in centers with specific expertise in pediatric manometry.
TREATMENT OF FEEDING DISORDERS
The careful evaluation of children with feeding disorders allows recognition and treatment of correctable lesions. Unfortunately, many children with feeding disorders have noncorrectable physical abnormalities that make oral feeding either dangerous or impossible. Some patients will need behavioral therapy to overcome secondary learned food refusal.
Decisions regarding whether to allow oral feeding depend on balancing the potential risks of aspiration and chronic lung disease with the emotional rewards and convenience of oral feeding. Empiric evidence regarding even the potential benefit of water restriction in children with aspiration is not available.4 Deciding to continue oral feeding in children with aspiration requires ongoing medical supervision because of the potential of damage to developing alveolar units during the first 18 months of life.5 These decisions must be reviewed periodically because of changes in anatomic, physiological, and cognitive skill with the child’s development. For example, an infant who was a “safe” feeder may develop aspiration problems when the larynx descends, and feeding will become unsafe. In contrast, a child with an anatomic abnormality of the larynx may be unsafe to feed orally as an infant, but as his or her cognitive function improves, the child may be able to learn compensatory strategies that allow a “safe” swallow. In some patients, the time required to feed orally consumes the patient’s and caretaker’s lives, leaving little time for other nurturing activities. Sometimes supplying a portion of the patient’s nutrition by tube may be beneficial. Families may need counseling to help them realize that, for their child, alternative approaches to providing nutrition may be better for the child’s overall well-being than persisting in efforts to feed only by mouth. The timing for aggressive behavioral intervention or the initiation of attempts at oral feeding must be decided in the context of the child’s overall development and well-being.
Behavioral therapy is often required to overcome learned aversive responses to feeding. Preschool children often respond to a combination of social praise and making the availability of preferred foods contingent on eating nonpreferred foods. Patients with more severe problems may require combination treatment, which may include contingency management, “shaping” (ie, rewarding successive approximations of targeted behaviors), positive reinforcement (ie, rewarding the child for completing a desired behavior), and ignoring (ie, inattention when the child engages in inappropriate behavior). The slow advancement of goals eventually leads to full oral feeding, but success may require inpatient management.
In addition to nutritional problems, children with real or perceived feeding disorders are at risk for developing long-term psychosocial problems. Therefore, in cases of nonorganic failure to thrive, intervention should include providing access to food and parental training in compensatory approaches to feeding. In many cases, caretakers suffer tremendous emotional distress, feelings of inadequacy, and guilt that also need to be acknowledged and addressed. Family support services, respite care, and financial assistance programs should be integrated with the child’s overall medical and social needs.
A variety of therapeutic compensatory maneuvers may be useful to prevent aspiration or improve the efficiency of feeding. By combining the clinical history, physical examination, and imaging studies, the therapist can determine the best bolus volume and texture, pace of administration, and nipples or utensils for oral feeding. Changes in body and head position also may protect the airway or allow easier passage of material through the oropharynx. For example, tilting the head forward widens the vallecular space, thereby diverting food away from the laryngeal inlet. Nipple shape, pliability, perforation size, and geometry determine the rate of milk flow. More rapid milk delivery increases the frequency of swallowing and therefore decreases the time that is available for breathing between swallows. However, decreasing the flow rate increases the work of sucking, thereby increasing the total time required for feeding.
Feeding an infant with an open cleft palate is particularly challenging. In this setting, mealtimes usually are most successful when a paced feeding is delivered into the infant’s oral cavity and the infant is allowed to initiate swallows. Working together with a consistent feeder, the infant can learn how to coordinate swallows with the rate of formula delivery to allow oral feeding to succeed. In selected cases, prosthodontic appliances can be effective, particularly when there are anatomic abnormalities. For example, a palatal prosthesis that mechanically stimulates the pharynx during swallowing has been effective in the treatment of infants with delayed initiation of the pharyngeal phase of swallowing.
If full oral feeding cannot be achieved, then providing some oral feedings, or at least water, may be feasible. This experience will facilitate the later introduction of oral feeds and usually is rewarding for both the parents and patient. Continuing oral stimulation is important to prevent the development of aversion to oral touch, thus allowing good dental care.