Assessing adenoid hypertrophy in children: X‐ray or nasal endoscopy?

Assessing Adenoid Hypertrophy in Children: X-ray or Nasal Endoscopy? Upper airway obstruction is a common complaint in children presenting to otolaryngology clinics. In such children, adenoid hypertrophy is often suspected. There are numerous ways to determine adenoid size, including palpation, mirror examination, endoscopic examination, lateral neck roentgenogram (X-ray), magnetic resonance imaging (MRI), and acoustic rhinometry. Pediatric patient cooperation limits the utilization of palpation and mirror examination, while acoustic rhinometry and MRI are not practical in the clinical setting. Thus, flexible fiberoptic nasal endoscopy (FNE) and lateral neck X-ray are the two most common diagnostic tools used to assess for adenoid hypertrophy. Cost-effective, age-specific guidelines on how best to evaluate adenoid size are lacking. The aim of this review is to determine whether X-ray or endoscopy is superior in assessing adenoid hypertrophy in pediatric patients presenting with upper airway obstruction. Different measurements have been proposed for assessing adenoid size on lateral neck X-ray, including: 1) the adenoid-nasopharynx ratio (A/N ratio), 2) the adenoid thickness (distance along a perpendicular line from the basiocciput to the adenoid convexity), and 3) the linear distance between the antrum and adenoid tissue.1 The A/N ratio, the most commonly used measurement, is defined as the ratio of the measurement of the adenoid thickness and the nasopharyngeal aperture (the distance between the basiocciput and the posterior edge of the hard palate).1 There have been numerous articles that have focused on the utility of the A/N ratio in diagnosing adenoid hypertrophy. A recent systematic review1 reported conflicting data on the accuracy of the A/N ratio. Of the five studies identified in the analysis that focused on the A/N ratio, three studies found no relation between the A/N ratio and adenoid size, and two studies demonstrated a significant correlation. Thus, the authors concluded that the utility of lateral neck X-ray to detect adenoid hypertrophy could not be clearly substantiated. While lateral neck X-rays have the advantage of being noninvasive and quickly accessible in the clinical setting, these films are static in nature and are a two-dimensional representation of a three-dimensional space. Other limitations include radiation exposure and the impact of patient respiration and phonation on the interpretability of the results. For example, mouth breathing, crying, or swallowing during the examination may cause soft palate elevation and thus reduce the size of the nasopharyngeal cavity. To optimize image quality, lateral neck X-rays should be performed at the end of inspiration with the neck in slight extension. FNE examination of the adenoid is safe and reliable in the pediatric population.2-5 The main advantage of FNE is its dynamic nature. Wang et al.3 conducted a prospective study of 180 children presenting with nasal obstruction and suspected adenoid hypertrophy. All children underwent FNE, tympanogram, and a survey regarding their obstructive symptoms. During FNE, the adenoid size was objectively quantified by measuring the distance from the vomer to the adenoid. Ninety-three percent of participants less than 1 year of age and greater than 6 years of age were able to tolerate the FNE with topical anesthesia. Thirty-three percent of children between 1 and 3 years of age could tolerate FNE without premedication. The authors concluded that adenoid size as determined by FNE was significantly (P < 0.0001) correlated with both nasal obstructive symptomatology and tympanogram type. In this study, children with a large adenoid on FNE had a higher incidence of both nasal obstruction complaints and type B tympanograms when compared to children with small or moderate-size adenoids. Several publications have compared lateral neck X-ray and FNE for the evaluation of adenoid hypertrophy in children.2-5 Thirty-nine children with suspected adenoid hypertrophy were evaluated by both FNE and lateral neck X-ray in a study by Mlynarek et al.4 Caregivers of the patients also completed a standardized questionnaire on upper airway obstructive symptoms. There was a significant (P = 0.039) correlation between the total symptom score and the percentage of airway occlusion as assessed by FNE. Lateral neck X-ray measurements such as adenoid thickness and A/N ratio did not correlate with obstructive symptom scores. Conversely, Caylakli2 et al. published a blinded, prospective study demonstrating that the A/N ratio significantly correlated with FNE findings in 85 children with probable adenoid hypertrophy. FNE findings in this study were standardized by calculating the obstruction ratio of adenoid tissue to choanal opening. Finally, Lertsburapa et al.5 retrospectively reviewed the FNE and lateral neck X-ray findings of children who underwent adenoidectomy. Both FNE findings and the A/N ratio on lateral neck X-ray significantly correlated with adenoid size on intraoperative nasopharyngeal mirror exam. However, the radiologists' subjective report of adenoid size as either mild, moderate, or severe on lateral neck X-ray did not correlate. The authors also noted that children that had a lateral neck X-ray to assess for adenoid hypertrophy were younger than those who underwent FNE. The costs of FNE and X-ray were comparable in this study. Flexible nasal endoscopy is well tolerated in most children and has the advantage of allowing for direct visualization of the adenoid. Adenoid hypertrophy diagnosed on flexible nasal endoscopy correlates with airway obstruction symptomatology. While A/N ratio on lateral neck X-ray frequently correlates with adenoid size, lateral neck films can be impacted by patient positioning and involve radiation exposure. Furthermore, the cost of flexible nasal endoscopy and lateral neck X-ray are comparable. Thus, in children presenting with upper airway obstruction and suspected adenoid hypertrophy, flexible nasal endoscopy is the best initial choice for evaluation of adenoid size. Clinicians may consider lateral neck X-ray in those children who need an objective assessment of their adenoid size and are unable to cooperate with flexible nasal endoscopy. Future research is necessary to determine whether initial adenoid size noted on FNE or lateral neck X-ray correlates with improvement in airway obstruction symptoms following surgical removal of the adenoid. MFN Feres et al.1 is a systematic review of mostly level 3 and 4 studies. F. Caylakli et al.2 is a blinded, prospective level 3 study. Wang D. et al,3 A. Mlynarek et al.,4 and K. Lertsburapa et al.5 are level 4 studies.