Audiologic testing in children with Down Syndrome: Are current guidelines optimal?

Abstract

Introduction

Down Syndrome (DS) is a Tier 1 risk factor for hearing loss. Guidelines exist to ensure close monitoring of children with DS for hearing loss. It is important to consider the timing of testing in order to obtain meaningful audiologic data in this high-risk population. The purpose of this study is to present hearing outcomes for children with DS during the first 8 years of life and to assess these outcomes in the context of current screening guidelines.

Methods

Retrospective review of audiometric outcomes was conducted for children with DS age 8 or younger who presented to a multidisciplinary DS clinic between January 2014 to June 2017. Age at the time of testing, as well as test success rate and hearing loss type and severity were noted.

Results

131 patients were included in the study, 52% of which were male. 36% of the patients failed their newborn hearing screening and only 9% of those subjects had normal hearing on subsequent testing. Most hearing loss identified was mild and conductive in nature. Inconclusive results were most likely to be obtained at 6–10 months of age.

Conclusion

Hearing loss is common among children with DS. To optimize the quality of testing and avoid the need for sedation in followup testing, routine follow-up hearing screening should be performed either before 6 months of age or after 10 months of age.

Introduction

Down Syndrome (DS) is the most common chromosomal disorder and the leading cause of intellectual disability in the United States [1]. 1 in every 700 babies are born with DS resulting in a US incidence of about 6000 babies each year [2]. DS is characterized by developmental delay, characteristic facial features, and hypotonia. Other medical disorders, such as congenital heart defects, leukemia, obstructive sleep apnea, gastrointestinal issues, vision problems and hearing loss, are present in a smaller subset of patients with DS [3].

The incidence of hearing loss in children with DS is much higher compared to the general population, and DS is considered a Tier 1 risk factor for hearing loss [4]. According to the CDC, up to 75% of DS children are affected by hearing loss [2]. Hearing loss is well known to impact speech and language development in children, and can be especially detrimental to children with DS who are already at risk for speech and language delay. Children with DS are more likely to have narrow ear canals, Eustachian tube dysfunction, and chronic otitis media, thereby increasing their risk of conductive hearing loss [5].

To identify congenital hearing loss, all states have implemented a newborn hearing screening program and approximately 95% of infants are screened before hospital discharge [6]. In 2001, the American Academy of Pediatrics (AAP) recommended that all children with DS be screened for hearing loss at birth or by 3 months of age. The AAP also suggested that these infants be tested every 2 months for the first 6 months of life, then again at 9 and 12 months of age using either subjective or objective testing methods [7]. These recommendations were updated in 2011, removing the recommendation for testing every 2 months until age 6 months and instead recommending that children with DS who pass their newborn hearing screening have an audiology evaluation at 6 months of age [8].

Given the challenging nature of performing hearing testing in young infants and children, it is important to consider the time of testing, especially for this vulnerable population. There are two primary methods utilized to screen newborns for hearing loss. Auditory brainstem response (ABR) testing can detect sensorineural hearing loss using electrodes placed on the scalp while the patient is asleep or sedated [9]. To avoid exposing infants to sedation, most guidelines recommend that patients undergo ABR testing before 6 months of age, as it is typically easier for young babies to tolerate the test under natural sleep conditions [10]. Another method to evaluate hearing loss is evoked otoacoustic emissions (OAE) which can detect hearing loss caused by abnormalities of the inner or middle ear. However, unlike an ABR, OAE cannot detect certain neural abnormalities that can cause hearing loss [11]. Once children are 9 months or older, behavioral testing, such as visual reinforcement audiometry (VRA) and conditioned play audiometry (CPA), becomes feasible as a method to obtain audiometric data [11].

Because children with DS are at an increased risk for hearing loss, they should be monitored closely in order to identify any hearing loss as early as possible to optimize speech and language outcomes. It is important to consider the time of testing in order to obtain meaningful results while also reducing patient exposure to sedation or anesthesia. The purpose of this study is to present our experience with hearing testing in children with DS that underwent routine testing at a multidisciplinary DS clinic and to assess whether the existing AAP guidelines for hearing testing are optimal for successful testing and diagnosis of hearing loss in this population.