MM202 - Evaluating Equivalent Ear-Canal Volume in Children with Down Syndrome

Abstract:
Children with Down Syndrome tend to have higher rates of otologic/audiologic conditions arising from characteristic craniofacial differences as compared with typically developing children, resulting in higher rates of tympanostomy tube placements. Though evaluating equivalent ear canal volume via tympanometry is a critical factor in concluding tympanostomy tube patency, characteristic stenotic ear canals in children with Down Syndrome may warrant the use of population-specific normative values to determine tympanostomy tube patency. In this session, novel evidence of equivalent ear canal volume measurements in 269 children with Down Syndrome from ages 5-10 years will be compared with previously obtained normative ranges in typically developing children.

Summary:
Children who have Down Syndrome (DS) tend to have higher rates of otologic/audiologic conditions arising from characteristic craniofacial differences compared with typically developing (TD) children, including otitis media with effusion (OME; Kong et al., 2017; Nightengale et al., 2017). Children with DS undergo higher rates of tympanostomy tube placements than TD children, and require more repeat placements, to successfully manage chronic OME (Bernardi et al., 2017; Iino et al., 1999). Audiologic measurement of equivalent ear canal volume (V_eq) via tympanometry is used to corroborate otologic otoscopy in determining tube patency and procedure success (Higson et al., 2008)

However, no normative evidence regarding typical V_eq values for children with DS yet exists, despite medical observation of characteristic and persistent stenotic ear canals in children with DS that differ from TD children (Khanna et al., 2018). Evaluation of population-wide differences in V_eq size between children with DS and TD children would provide evidence to improve the accuracy of tympanometry interpretation for V_eq in children with DS.

To address this clinical knowledge gap, V_eq measurements from 269 children with DS were examined in a retrospective medical record review. Each participant was between 5 to 10 years of age at the time of data collection and had at least one audiology appointment at a major children’s hospital. For each child, a maximum of two measures of V_eq per year from birth were obtained, resulting in 1,888 ear-level measurements. Mean V_eq was significantly smaller at all ages when compared with TD children of the same age in previous research (Shanks et al, 1992), and 90% of observed data occurred less than or equal to 0.80 cm³. Consistent with prior medical and clinical observations, children with DS have significantly smaller V_eq values than TD children of the same age, with little variability. To achieve similar error rates as normative values currently used for TD children (Shanks et al., 1992), V_eq values greater than 0.8 cm³ would be indicated to confirm patent tympanostomy tubes or tympanic membrane perforations in children with DS. In this session, the current state of evaluating pediatric V_eq obtained via tympanometry will be compared with novel measurements obtained from a group of children with DS. Primary clinical implications of these findings support the use of a smaller normative range to indicate a closed ear canal volume in children with DS than for TD children.