Otolaryngologist Perspective

The most important diagnostic tool for identifying LPR is the clinical history. This can be difficult considering that infants and toddlers cannot verbalize their symptoms. Parents and pediatricians must be astute in their recognition of the aforementioned symptoms that can present differently in infants and children to help determine when it is appropriate to refer to an otolaryngologist for further evaluation and management. Based on the most recent clinical practice guidelines, physicians should also be looking for warning signs that might suggest a pathology aside from GERD as a part of the history. These include weight loss, lethargy, persistent emesis, seizures, chronic diarrhea, or rectal bleeding [2, 17, 18]. These symptoms should prompt further testing to rule out other serious disease processes including gastrointestinal, neurologic, metabolic, toxic, and cardiac disorders.

Fiber-optic laryngoscopic examination can be helpful for both infants and children as an initial diagnostic evaluation since it is brief and minimally invasive. Though cooperation may be a limiting factor, it provides a brief dynamic view of the larynx that can help identify findings consistent with reflux changes or other pathologies such as laryngomalacia or vocal fold nodules [14]. Findings can be subtle, but those most associated with reflux include posterior glottic edema, lingual tonsillar hypertrophy, arytenoid edema, vocal fold edema or nodules, and hypopharyngeal cobblestoning (Figs. 23.1, 23.2, and 23.3) [3, 19]. In adults, the Reflux Finding Score (RFS) can be used to interpret laryngeal findings suggestive of GERD [20, 21]. This was attempted to be extrapolated to children (the Reflux Finding Score for Infants or RFS-I) in a prospective cohort study out of Boston Children’s Hospital which determined that laryngeal appearance using the RFS did not correlate with results of multichannel pH probe monitoring, suggesting that such scoring systems have a low positive predictive value for detecting reflux in pediatric populations [22]. In response to this study, Ida et al. postulated that these results raise the issue of the “reactive larynx” and non-reflux-related laryngeal inflammation as a barrier to airway surgery [23]. Another group assessed the reliability of the RFS-I in flexible versus rigid laryngoscopy noting no difference between the two diagnostic procedures as well as concern regarding limited reliability of the grading system (only moderate in both cases) [24]. Posterior cricoid biopsy has been shown to have a weak association with reflux symptoms and pH probe findings, but more specific randomized treatment-driven studies are needed to further explore this notion [25]. Two studies attempted to correlate laryngeal findings on direct laryngoscopy with bronchoscopy in an attempt to establish a more consistent grading system. These studies were either retrospective [5] or prospective unrandomized [26]. In both studies, posterior laryngeal edema had the strongest correlation with reflux. Other findings were not consistent enough to establish a definitive relationship [5, 26].

Barium esophagrams, which were used in the past, have been found to have a relatively low sensitivity and specificity for evaluating LPR/GER, with the added disadvantage of radiation exposure [27]. No true gold standard currently exists for the diagnosis of LPR in children. In most cases, four to five events of pharyngeal reflux can be considered normal in infant populations, while one or more episodes in older children and adults are considered abnormal [28]. A common study in pediatric and adult patients to diagnose GERD is 24-h pH probe monitoring, which can involve either a single distal probe or dual probes in the distal and proximal esophagus. In adults, the use of 24-h dual-probe pH monitoring has been helpful in demonstrating pharyngeal reflux at acidic pH (defined as pH <4.0) in the diagnosis of LPR. In children, however, this is difficult to assess because of the common presence of non-acidic reflux into the proximal esophagus and pharynx. Rabinowitz et al. found that distal pH probe monitoring alone gives a high rate of false negatives in pediatric patients with extraesophageal symptoms of GER, suggesting that non-acidic reflux plays an important role in generating these symptoms [29]. Another study reviewed 68 pediatric patients with GER that underwent distal probe pH monitoring and anti-reflux therapy. In patients with extraesophageal symptoms, they found that distal pH studies were not predictive of positive response to anti-reflux therapy and thus should be avoided in this subset of patients [30]. Thus, single distal pH probe monitoring is not considered an adequate study for the diagnosis of LPR.

Dual-probe pH testing involves placing a measuring probe just above the lower esophageal sphincter as well as just below or just above the upper esophageal sphincter in the pharynx. Refluxate at pH <4 is recorded. However, in infants and children, many of these reflux events will occur in physiologic pH range [5–7] and thus not be detected by pH probes alone [31]. Using a pharyngeal probe, Little et al. did show that 76 out of 168 pediatric patients (aged 1 day to 16 years) had pharyngeal reflux as measured by the pharyngeal probe in spite of many having normal levels of esophageal acid exposure as measured by the esophageal probe. They estimated that in the absence of a pharyngeal probe, 46% of participants would have been underdiagnosed [32]. Other studies have found that dual-probe pH testing was not easily reproducible in children as compared to adults and is therefore not a reliable diagnostic tool on its own [33, 34].

Multiple intraluminal electrical impedance technique (IMP or MII) is a more recent diagnostic tool that is being used in conjunction with pH probe monitoring for the diagnosis of GER. The principle behind this testing is to measure opposition to the flow of current between electrodes along an esophageal probe. This allows movement of refluxate and/or food boluses at multiple heights along the esophagus irrespective of pH [35]. Several studies have shown the superiority of this method as compared to dual pH monitoring alone [36–39]. In a small German study of 50 infants with presumed GER, IMP identified 1866 episodes of retrograde reflux, while pH probe only identified 282 (15%) of these to be acidic with pH <4.0 [36]. The same group looked specifically at respiratory episodes associated with reflux such as apnea, aspiration, and abnormal chest wall movement in the setting of combined IMP and pH monitoring. In 22 patients, 364 episodes of reflux were recorded with IMP, and only 12% of these were found be acidic. Of these 364 episodes, 312 (86%) were associated with breathing abnormalities, 128 of which were associated with an oxygen desaturation of >10%. They also found that longer episodes of reflux greater than 30 s were more likely to be associated with apnea [37]. Both studies demonstrate the importance of impedance monitoring in the evaluation of reflux, particularly in infants when a higher percentage of refluxate will be non-acidic. In older children, combined pH-MII monitoring was shown to be significantly better at detecting cough in the setting of reflux as compared to patient and parental reporting [40].

Despite the clear advantages of pH-MII as compared to pH monitoring alone, there are still widely recognized limitations of impedance monitoring, particularly in light of the fact that there is no control group from which to establish a threshold of what constitutes a “normal” amount of non-acidic reflux. With this in mind, pH-MII testing is an option to consider when trying to correlate troublesome symptoms of acidic and non-acidic reflux in infants and children [2] and prior to airway reconstructive surgery.

In adults, brief trials of anti-reflux medications have been successfully used as a diagnostic tool, with the thought that if symptoms improve with treatment, it is likely that reflux is playing a role. In infants and children, however, this has not been as well studied. The use of proton-pump inhibitors (PPI) for the treatment of asthma and cough has been looked at with no good correlation found. One study explored symptoms of asthma noting that during a trial of a PPI at 4–8 weeks, there were no noted benefits from use of the medication [41]. In infants, a similar study looked at lansoprazole treatment noting no significant difference in extraesophageal symptoms after a 2-week trial [42]. Findings from these studies and concerns about side effects of PPI use have reduced the frequency of diagnostic PPI trials in children.

Workup

Clinical histories can differ among reporters due to varying perceptions of the child’s skills and abilities [43], and inconsistencies should be further explored. For example, food refusal may be interpreted as laziness or lack of hunger when, in fact, the child is saying “no” because of the discomfort which might be related to silent aspiration, gastroesophageal reflux, or esophagitis/gastritis [44]. Parents should be asked open-ended questions to describe feeding behaviors.

A speech pathologist’s intake includes pregnancy and birth history, general development, and medical background (including prior testing, respiratory issues, and hospitalizations). The feeding history includes a “typical” day in the child’s life. Often the 24-h period prior to the appointment is a good example of the child’s feeding habits and is easy for the parent to recall. Details surrounding positioning, volume, texture, utensils, and intervals between meals are also collected. If the child is tube-fed, the feeding history also includes looking at feeding volume and any behavioral responses to changes. The timing of onset and duration of feeding problems can help identify signs and symptoms of gastroesophageal reflux. Questions should include asking about possible pain/discomfort during feeding; crying, gagging, or coughing/choking while eating; refusal to eat/chew/swallow; lack of hunger awareness; and bottle feeding only while falling asleep. If there is recurrent vomiting, the timing and frequency of the emesis and whether or not it is forceful/projectile are important to ask. In addition, questions about bowel movements and/or constipation are helpful. A general history of vocal quality is important for consideration of both vocal fold impairment and irritation. This should include listening to the child’s voice, assessing for hoarseness/raspiness, and asking the parent(s) if they are at their baseline in terms of vocal quality.

Clinical swallowing evaluation, videofluoroscopic swallowing study (VFSS), and flexible endoscopic evaluation of swallowing (FEES) can all be useful in evaluating swallowing function in infants and children with reflux. These evaluations are described in detail in previous chapters.