Signs and symptoms
• Coughing, choking, gagging with or after feeds
• Wheezing, noisy or wet breathing
• Blue spells, apneas, bradycardias
• Feeding refusal, arching during feeds
• Voice changes
• Tearing and red eyes
• Nasal congestion
• Recurrent pneumonia
Mimickers of swallowing disorders
• Gastroesophageal reflux
• Esophageal stasis from dysmotility (esophageal atresia, achalasia)
Weir et al. performed a retrospective study in which they compared 11 clinical markers of dysphagia with results of videofluoroscopic swallow studies in 150 children. The authors found that wet voice, wet breathing, and cough were reliable clinical markers for and significantly associated with aspiration of thin liquids but there were no good markers for aspiration of purees or for other types of swallowing dysfunction such as laryngeal penetration suggesting that any patient with persistent symptoms should undergo a clinical feeding evaluation or videofluoroscopic study because history alone is not adequate [10].
In most children, the laryngeal cough reflex serves as a protective mechanism by which mechanoreceptors and chemoreceptors in the hypopharynx trigger a cough when irritated by aspirated material [12]. It is as a result of these signaling pathways that patients, parents, and providers are able to discern some of the symptoms of overt aspiration. Some groups have found that signs and symptoms vary by age, perhaps as a result of differential airway responses to aspiration, such that infants tend to exhibit apnea, vocal cord constriction, rapid swallowing, and bradycardia as a result of laryngeal chemoreflexes while older children tend to have cough [3, 10, 13]. This is thought to be due to development of higher level central neural processing in adults as opposed to changes in the chemoreceptors in the larynx [13]. Newman et al. showed that children also exhibit a different pattern for clearing laryngeal penetration. In contrast to adults, who must cough to clear the material, children with laryngeal penetration were able to clear the area with additional swallows [14].
While chemoreceptors and mechanoreceptors may exist in the pediatric airway, a significant proportion of aspiration in children is silent. It has been suggested that silent aspiration results from dysregulation of the laryngeal cough reflex in addition to weakness or incoordination of the pharyngeal musculature and inability to produce a cough [15]. Studies by Weir et al. have revealed that silent aspiration is quite common in children with feeding difficulties and especially those with neurologic disorders and developmental delay. In their prospective cohort, Weir found that in the 34 % of patients with dysphagia in their study had silent aspiration [12]. In another cohort, silent aspiration was observed in as many as 94 % of patients [16]. These rates of silent aspiration in children are much higher than rates in adults [12]. This high rate of silent aspiration lowers the value of the clinical feeding evaluation and thus empowers the clinician to order a swallowing study based on clinical suspicion rather than symptoms during feeding alone.
Because the majority of aspiration is silent, these children are often misdiagnosed as having gastroesophageal reflux disease as the symptoms are identical [17–19] and include with gagging, choking, coughing, and blue spells in infants and children [20]. Making the correct diagnosis is critical to avoid unnecessary therapies because, although thickening of feeds might be effective in the treatment of reflux, acid blockade is not sufficient treatment for oropharyngeal aspiration.
Causes of Oropharyngeal Dysphagia
The differential for swallowing disorders and aspiration includes developmental issues, neurologic conditions, and anatomic abnormalities . Rommel et al. differentiated swallowing disorders into the categories of medical, oral, and behavioral and emphasized the importance of considering the contribution of each of these elements in diagnosing and managing swallow dysfunction [21]. Regardless of the underlying trigger for swallowing disorders, secondary behavioral feeding disorders are common; Burklow et al. identified factors related to dysphagia in 103 children and found that in 80 % of cases there was a behavioral component to the complex feeding problem [22]. Therefore, multifactorial approaches to feeding disorders are needed. The following discussion will focus on the three main categories of swallowing dysfunction: developmental abnormalities, neurologic abnormalities, and anatomic abnormalities (Table 20.2).
Table 20.2
Differential diagnosis of aspiration
Developmental |
• Prematurity |
• Neonatal swallowing dysfunction |
Neurologic |
• Chiari malformation |
• Cerebral palsy |
• Other neuromuscular disorders |
Anatomic |
• Laryngeal cleft |
• Vocal cord paralysis |
• Tracheoesophageal fistula |
Other |
• Upper esophageal sphincter dysfunction, enlarged tonsils, tongue-tie, submucosal cleft palate, esophagitis |
Developmental Disorders
Swallowing development starts at 10–14 weeks of gestation. Sucking behavior develops initially between 18 and 24 weeks of gestation and in premature infants continues to develop up to 36 weeks postmenstrual age. In most cases by 34 weeks premature infants are capable of coordinated oral feeding but even typically developing full term infants have improvement in coordination of feeding over time [23]. As premature infants develop many continue to have issues with oropharyngeal dysphagia, however with up to 70 % of very low birth weight infants showing swallowing abnormalities and up to 30 % are not sufficiently protecting their airway to prevent aspiration [23, 24].
When a neonate has swallowing dysfunction by videofluoroscopic swallow study, with normal upper airway and with no major associated neurological, anatomic, or craniofacial abnormalities at the time of presentation, they are given the diagnosis of neonatal swallowing dysfunction though the dysfunction can persist through the first 2 years of life. Infants born premature or with low birth weight (below the tenth percentile) are at increased risk for swallowing problems and a gestational age of 34 weeks is considered critical for the development of appropriate swallow function [21]. Deglutition is commonly considered one of the most complex reflex neural activities for all humans and for infants in particular it is one of the most intricate acts they must perform safely in order to survive and grow [23].
The exact etiology of neonatal swallowing dysfunction is poorly understood but these conditions are most likely multifactorial and due to delayed development of the reflexes and neuromuscular coordination needed for safe swallowing. Contributors to swallowing dysfunction in premature infants include prolonged respiratory cessation (up to 4 s compared to 1 s in adults) and inward as opposed to protective outward airflow in the pharynx around the period of swallowing [3]. There are some studies in mice that suggest that developmental swallowing disorders might be due to altered hindbrain patterning during prenatal development [25].
Fortunately, the prognosis is good for patients with developmental swallowing dysfunction. Most infants show improvement in swallow study results within 3-4 months from their first study and will have resolution of their swallowing dysfunction within 1 year of starting feeding therapy [26, 27]. From studies of diagnostic testing, the rate of abnormal swallow tests in children decreases significantly with time such that an abnormal assessment of swallow function beyond the age of 2 years warrants further evaluation.
The therapeutic consequence of this encouraging natural history are great; the goal in patients with neonatal swallowing dysfunction to determine the safest method of feeding (NG, thickened oral feeds) to buy time, avoid placing a permanent feeding tube (gastrostomy), and await resolution of the swallowing dysfunction. In a single study comparing outcomes of children with swallowing dysfunction who received gastrostomy tube feeding compared to patients given thickened feeds, those who continued with oral feeds had improved outcomes compared to patients that received gastrostomy tube feeds [28]. This study, combined with the natural history of improved swallow function over time, supports a noninvasive approach to these patients.
Neurologic Disorders
The central and peripheral nervous systems are both essential for coordinated, effective, and safe swallow function in all age groups. Swallow dysfunction can result from issues with the muscles, nerves, and receptors of the pharynx in addition to problems in the spinal cord, brainstem, and other regions of the brain. Peripheral neuromuscular disorders typically cause a combination of low muscle tone in addition to poor coordination of the stages of swallowing and decreased ability to clear the airway [3]. Central nervous system insults include conditions such as cerebral palsy, Arnold-Chiari malformations, and cerebral vascular accidents [2].
In children with persistent aspiration beyond the age of 2 years who show no improvement in swallowing function merit further evaluation which often included magnetic resonance imaging of the brain to evaluate for a Chiari malformation. Up to 20 % of patients with Chiari malformations have been found to have aspiration and in these patients the dysphagia is often progressive as a result of compression of the brainstem and cranial nerves by low-lying cerebellar tonsils [29]. Type 1 Chiari malformation is more likely in these cases that are diagnosed as a result of dysphagia since type 2 malformations usually have other associated malformations such as spinal dysraphism that typically lead to earlier diagnosis [29, 30]. In a small pediatric case series of patients with Chiari malformations, there was significant UES dysfunction which resulted in dysphagia and aspiration risk which completely resolved after surgical repair [31]. Fortunately, the prognosis is good for these patients after surgical repair.
Cerebral palsy is also associated with a high proportion of children having dysphagia. This condition is becoming a more common neurologic cause of swallow dysfunction as the survival rate of extreme premature infants has increased. It is also important to note that although cerebral palsy is a static central neurologic condition, swallow function in these patients can worsen over time and must be monitored closely [3]. Risk factors for worsening dysfunction may include infections, hypothyroidism, seizure disorders, and medication effects, among others.
Anatomic Abnormalities
Pathologic conditions at any of the sites along the aerodigestive tract can negatively affect swallow function and lead to oropharyngeal dysphagia. Anatomic abnormalities that can cause aspiration include defects in the nasopharynx, oropharynx, larynx, esophagus, and trachea.
Obstruction in the nasopharynx typically impairs breathing, which in young infants can cause dyscoordination of the oral and pharyngeal swallow phases. Choanal atresia is the most severe form of nasal obstruction but a similar end result can also be seen with other conditions including allergic rhinitis, adenoid hypertrophy, or congenital masses of the nasopharynx [2]. These lesions can lead to aspiration, slow eating, and aversion to textures. While it is beyond the scope of this chapter, palatal abnormalities (cleft palate, submucosal cleft palate, asymmetrical palate movement) can lead to nasal reflux, aspiration, and food avoidance. Exam of the palate is critical in children with chronic nasal congestion, ineffective suck, recurrent sinus disease, and nasal voice quality.
From a laryngeal perspective, the biggest diagnosis to rule out in patients with persistent or severe aspiration is a laryngeal cleft. Laryngeal clefts were once felt to be a rare congenital malformations but more recent studies suggest this is a more common cause of aspiration than originally thought [32]. This anomaly occurs in 1 in 10–20,000 live births and is thought to result from the failure of fusion of the tracheoesophageal septum. The diagnosis of laryngeal cleft can only be made by direct laryngoscopy under anesthesia. Laryngoscopy can determine the extent of the defect, ranging from type 1, which is a supraglottic interarytenoid defect in which the cleft lies above the level of the posterior cricoid cartilage, to type 4, in which the cleft extends as far down as the thoracic trachea. The management of these anomalies ranges from conservative medical management for type 1 if the patient is minimally symptomatic to surgical approaches that are now performed endoscopically [33]. It is important to know, however, that even when these laryngeal clefts are repaired, 23 % of patients continue to have aspiration, even after repair, suggesting that the swallowing dysfunction, even with patients with anatomic abnormalities, is multifactorial [34].
Vocal cord paralysis is another anatomic etiology of aspiration. This condition places patients at risk for aspiration by means of both decreased sensation and a limitation of the typical airway protective mechanisms. It can be diagnosed with a bedside flexible scope in an awake patient. Tabaee et al. showed that in a bedside flexible endoscopic exam of 81 patients with unilateral vocal cord paralysis, 23 % had frank aspiration, 25 % had penetration, and 56 % had pooling [35]. Risk factors for vocal cord paralysis include cardiothoracic surgery, prolonged intubation, and neurologic conditions, among others. Reports have shown that up to 20 % of patients suffer from vocal cord paralysis after esophageal atresia repairs [36]. After cardiothoracic surgery, up to 10 % of patients have abnormal swallowing and of these patients, only 35 % of patients recover vocal cord function without surgery [37]. The natural history of this disorder involves significant morbidity and the median time to resolution of vocal cord paralysis is varied, ranging from 2.3 months for neurologic causes to 5.9 months for idiopathic with a wide range for all causes from 0.4 to 38.7 months [38]. Again, understanding the natural history is critical; if vocal cord function is expected to improve, then the goal of management is to avoid a permanent feeding tube and either feed with thickened feeds or an NG tube.
Other Conditions
There are a number of other conditions that can also cause swallowing dysfunction. These include enlarged tonsils, tongue-tie, macroglossia, and sub-mucosal cleft palate in addition to other congenital anatomic abnormalities such as tracheoesophageal fistula and oropharyngeal facial anomaly syndromes such as CHARGE syndrome and Pierre-Robin sequence . Any disorders of motility or esophageal inflammation can cause dysphagia, impact swallowing, and cause dysfunctional eating including food restriction, pocketing of food, and gagging, among others, but other chapters will address this concern. Many of these will be discussed in other chapters.
Upper esophageal dysfunction is another condition that can place infants at risk for aspiration. This dysfunction can range from a complete lack of relaxation to dyscoordination of pharyngeal contraction and UES relaxation. Studies in neonates with hypoxic-ischemic encephalopathy had higher rates of abnormal pharyngeal-upper esophageal sphincter dyscoordination and increases UES basal tone [39]. Premature infants and those under 34 weeks in particular often suffer from low and therefore poor pharyngeal pressures at the laryngeal inlet combined with incomplete coordination of upper esophageal sphincter relaxation. This combination of defects makes appropriate swallowing difficult and more likely to result in laryngeal pooling and choking episodes [40]. In infants with acute life-threatening events, there are also subtle UES abnormalities compared to healthy infants; there is a faster post-deglutitive rise in UES pressures which may impact the effectiveness of bolus clearance from the pharynx though studies with impedance and manometry (to assess bolus movement) are needed to prove if this is clinically significant [41]. There are conflicting results about the impact of gastroesophageal reflux on the upper sphincter; some studies show no effect while others show a lower resting upper esophageal sphincter pressure, which might allow for easier passage of full column refluxate into the larynx and the airway [42, 43].
The treatment for UES dysfunction includes Botulinum toxin injection to the UES or dilation. While there are only isolated case reports in pediatrics, a review of the adult literature supports benefit to both. For example, in adults with aspiration, injection of Botox into the UES of patients with dyscoordination resulted in transition to full oral feeding in 70 % of patients who were initially tube fed [44]. In another adult study, 65 % of patients had improvement in dysphagia symptoms though there can be transient worsening in the immediate postoperative period [45]. In a small blinded radiologic study, there was significant improvement in bolus movement and the presence of residue in 6/8 patients who received cricopharyngeal Botox [46]. Interesting, even one injection may have long-lasting benefit on the function of the UES [47]. Again, while there are no pediatric studies, balloon dilation of patients with UES dysfunction has beneficial results with up to 80 % of patients resuming oral feeding after dilation [48]. As with any therapy, the risks need to be weighed against the benefit and the risks can include with Botox and/or dilation, perforation, paralysis of the vocal cords, and worsening of aspiration and gastroesophageal reflux due to a loss of the UES protective barrier.
Finally, aspiration can be caused by abnormalities in the suck-swallow-breathe cycle that is a result of a primary respiratory problem or secondary to other medical issues such as underlying cardiac disease. This is seen in children with laryngomalacia as a result of respiratory distress leading to poor swallow coordination [2]. Likewise, studies have suggested that infants with bronchiolitis can also have transient swallow dysfunction, which resolves over time as they overcome the infection and resultant pulmonary inflammation [49]. Finally, in patients with acute changes in respiratory status such as after supraglottoplasty, there can be a worsening of aspiration and swallowing function though this degree varies depending on the institution [50–53]. These situations suggest that there are a variety of conditions that when overlaid on normal swallowing can cause clinically significant dysfunction, which likely needs to be addressed until the insult resolves.
Management o f Swallowing Dysfunction
There are a number of considerations for the management of swallowing disorders in pediatrics. Swallowing dysfunction and aspiration therapies are guided by the diagnostic test, the severity of dysfunction, the complications from this dysfunction, and the expected natural history of the underlying cause for this dysfunction. Aspiration treatment options include thickening of feeds, feeding therapy, gastrostomy and gastrojejunostomy tubes, fundoplication, and pharmacologic approaches. Anatomic abnormalities that lead to aspiration can often be addressed surgically with the help of general and otolaryngology surgeons. The management of patients with normal upper airway anatomy can be more challenging, however, and we typically recommend feeding and swallowing therapy for these children [27].
Oropharyngeal dysphagia with aspiration can be treated with thickening of feeds without the need for gastric tubes in the majority of cases and this continued oral feeding with thickened liquids has superior outcomes than feeding with enteral tubes [28]. Most pediatric patients will be able to tolerate some degree of thickening and the videofluoroscopic study can guide which textures are safe to eat and which improve the quality of swallowing. Thickening has been shown to improve swallow function by slowing down the velocity at which the bolus travels through the oral and pharyngeal phases of swallowing, increase the duration of pharyngeal contractions and prolong and increase opening of the upper esophageal sphincter [54]. Rofes et al. showed that increasing bolus viscosity using a commercial xanthan gum thickener improved the safety of swallowing by decreasing aspiration and penetration events on swallow studies [55]. This thickening continues until the swallowing dysfunction resolves as the infants mature or until the child’s clinical situation improves [26]. It is also important to note that several studies have failed to show any evidence of dehydration from thickening feeds, so the worry that children will dehydrate on honey thick or even purees is not substantiated [56]. Another important aside is that thickening will also treat gastroesophageal reflux disease and decrease spit-ups and therefore weaning of thickening may result in worsening reflux which may appear as if aspiration is worsening again [57].
Related posts:
Integration of Biomedical and Psychosocial Issues in Pediatric Functional Gastrointestinal and Motility Disorders
Gastric Function After Fundoplication
Cyclic Vomiting Syndrome: Comorbidities and Treatment
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Introduction to Gut Motility and Sensitivity
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