Multi-Institutional Validation of the Interarytenoid Assessment Protocol for Pediatric Laryngeal Cleft

INTRODUCTION

Current assessment techniques for laryngeal clefts are highly variable, both across and within pediatric institutions. Previous reports have shown a discrepancy in the definitions of, and differentiation across, a normal larynx, deep interarytenoid notch (DIN), and Benjamin-Inglis type I laryngeal cleft (T1C). This discrepancy was highlighted in the 2017 consensus guidelines created by the International Pediatric Otolaryngology Group (IPOG) on the diagnosis and management of T1Cs1, where most IPOG members reported that they diagnose DINs based on visual inspection, while others defined a DIN as having a height less than 3 mm but remaining above the level of the true vocal folds. Within the guidelines, differentiating among normal anatomy, DIN, and T1C in addition to functional sequelae is important, given that it determines whether patients should be considered for surgical intervention.

To standardize descriptions of the interarytenoid mucosal height (IAMH), the Interarytenoid Assessment Protocol (IAAP) was developed. This protocol involves placing the patient in suspension with laryngeal distending forceps, palpating the interarytenoid musculature for subjective qualities, then swinging a right-angle microlaryngeal probe from the anterolateral interarytenoid mucosa toward the laryngeal anatomy to determine the point of initial mucosal contact, which is designated as the IAMH. The IAMH is then categorized as being at one of five levels in relation to the false vocal folds, ventricle, and true vocal folds. To date, a single institutional validation study has demonstrated substantial inter- and intra-rater reliability of the IAAP, but no multi-institutional validation studies have been conducted. The objective of this project was to perform a multi-institutional validation study to assess the reliability of the IAAP for evaluation of the IAMH.

METHODS

A retrospective review of 30 endoscopic videos of the IAAP from the Seattle Children’s Hospital Otolaryngology Database. Each of the IAAP procedures was performed by either an attending pediatric otolaryngologist or a resident/fellow supervised by an attending pediatric otolaryngologist at the same institution. Institutional review board (IRB) approval was obtained at the Seattle Children’s Hospital (IRB No. STUDY00000815).

Sample Selection

Figure 1: IAAP steps. (A) Step 1: Insert and suspend laryngoscope. This should be performed to optimize a Cormach-Lehane13 grade I exposure if possible. (B) Step 2: Insert laryngeal distending forceps. Infant distenders are best used for children up to approximately age five years; adult distenders may be used in older patients. The larynx should be distended to allow adequate visualization of the height of the interarytenoid mucosa, while not overdistending to avoid distorting the anatomy. Appropriate distension will position the vocal folds at an approximate 30-degree angle—most pediatric patients only require distension to the first “click” after touching the tissue. (C) Step 3: Palpate the interarytenoid region. Perform palpation using a nerve hook, right-angle microlaryngeal probe, or right-angle laryngeal measuring stick. Palpate and observe the bulk of the interarytenoid muscle anteroposterior and craniocaudal extent. Palpate the surface of the cricoid to observe for clefts or defects. (C) Step 3: Check for submucosal laryngeal clefts. These abnormalities, if found, should be described subjectively in documentation. (D) Step 4: Objective assessment of IAMH. With the right hand carefully braced on the patient’s face or the laryngoscope to prevent movement in or out, use the right angle microlaryngeal probe to swing anterolaterally from a resting place in contact with but not distorting the interarytenoid mucosa to an anterolateral point in line with the midpoint of the membranous TVFs to determine anatomical reference to the following laryngeal landmarks: (a) above FVFs, (b) at FVFs, (c) in ventricle, (d) at TVFs, and (e) below TVFs. (E, F) Setup for IAAP: patient placed in suspension, elastic band to secure laryngeal distending forceps, 0-degree telescope in left hand, microlaryngeal probe in right hand.