2015 HSC Section 1 Book of Articles

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Reprinted by permission of Ear Hear. 2015; 36(1):8-13.

Is “No Response” on Diagnostic Auditory Brainstem Response Testing an Indication for Cochlear Implantation in Children? Anna X. Hang, 1 Patricia A. Roush, 2 Holly F. B. Teagle, 2 Carlton Zdanski, 1 Harold C. Pillsbury, 1 Oliver F. Adunka, 1 and Craig A. Buchman 1

Objectives: To compare the results of a “no response” (NR) result on auditory brainstem response (ABR) testing with those of behavioral pure-tone audiometry and ultimate clinical tracking to cochlear implan- tation (CI). Design: Retrospective review of pediatric patients who underwent mul- tifrequency ABR testing in a 5 year span. Total of 1143 pediatric patients underwent ABR testing during the study period and 105 (9.2%) were identified with bilateral NR based on absent responses to both click and tone burst stimuli. For the children with NR, various clinical parameters were evaluated as these children progressed through the CI evaluation process. Children were grouped based on whether they underwent ABRs for diagnostic or for confirmatory purposes. Results: Of the 105 children who met inclusion criteria, 94 had suffi- cient follow-up to be included in this analysis. Ninety-one (96.8%) of 94 children with bilateral NR ABRs were ultimately recommended for and received a CI. Three (3.2%) children were not recommended for implantation based on the presence of multiple comorbidities rather than auditory factors. None of the children (0%) had enough usable residual hearing to preclude CI. For those who had diagnostic ABRs, the average time at ABR testing was 5.4 months (SD 6.2, range 1–36) and the aver- age time from ABR to CI was 10.78 months (SD 5.0, range 3–38). Conclusions: CI should tentatively be recommended for children with a bilateral NR result with multifrequency ABR, assuming confirmatory results with behavioral audiometric testing. Amplification trials, counsel- ing, and auditory-based intervention therapy should commence but not delay surgical intervention, as it does not appear to change the even- tual clinical course. Children not appropriate for this “fast-tracking” to implantation might include those with significant comorbidities, audi- tory neuropathy spectrum disorder, and unreliable or poorly correlated results on behavioral audiometric testing. Key words: Auditory brainstem response, Cochlear implant, Cochlear implant candidacy, Hearing loss. (Ear & Hearing 2015;36;8–13) INTRODUCTION Auditory brainstem response (ABR) testing is widely accepted for identification and diagnosis of hearing loss in the pediatric population. For patients who are unable to participate in behavioral audiometry because of age or medical comorbidi- ties, frequency-specific tone burst ABR is useful for estimat- ing the pure-tone audiogram so that early intervention can be implemented. There is extensive literature supporting a strong correlation between estimated ABR and behavioral pure-tone 1 Department of Otolaryngology-Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA; and 2 Division of Audiology, University of North Carolina Hospitals, Chapel Hill, North Carolina, USA.

thresholds (Stapells 2000). However, correlation does not nec- essarily imply that the test is predictive . In fact, there remains a great deal of variation regarding the accuracy of ABR as a predictor of actual behavioral thresholds. Factors that contribute to this variation include stimulus characteristics and recording parameters as well as developmental age and degree of hearing loss (Sininger 2006). In one study, the inherent degree of uncer- tainty in estimating pure-tone thresholds from ABR thresholds with a 95% confidence levels was ±15dB HL (Stapells 2000). So the range of pure-tone thresholds estimated from ABR thresh- olds can be quite large with individuals in the upper limits of the range possibly amenable to amplification (Marttila & Karikoski 2006). Furthermore, ABR estimates are generally less accurate in the lower frequencies and in those with severe to profound hearing loss (Gorga et al. 2006). ABR tends to overestimate the degree of hearing loss in individuals with severe to profound impairments (Marttila & Karikoski 2006; Sininger 2006). Thus, even in the setting of a “no response” (NR) result on ABR test- ing, definitive conclusions about usable residual hearing cannot be made. In the current management paradigm, children with congeni- tal hearing loss and a NR result onABR testing are initially fitted with hearing aids based on threshold estimates predicted by the ABR with the use of a prescriptive formula for estimating gain and output. Reliable behavioral audiometric testing is then used to confirm pure-tone thresholds more precisely between 6 and 8 months of age and hearing aid adjustments are made as needed. For those children who do not make appropriate progress in communication skills development, despite good compliance with well-fit amplification and auditory-based intervention, a cochlear implant (CI) is recommended. When uncomplicated, this process should result in cochlear implantation by the end of the first year of life. This paradigm is consistent with the goals and recommendations of the Joint Committee on Infant Hearing (Reference Note 1). Unfortunately, a variety of factors can and often do cause considerable delays in access to a CI (Table 1). From an auditory perspective, even in the setting of a bilateral NR result on ABR testing, behavioral audiometric testing often reveals that the degree of residual hearing might support meaningful progress with proper fit and use of amplification. In these cases, the hear- ing aid trial may be extended with the hope of greater progress in lieu of exposing the child to unnecessary surgery and poten- tial compromise of residual hearing. Moreover, for families that are noncompliant with the early stages of the hearing aid trial, a period of prolonged counseling and observation is often rec- ommended to improve acceptance of the commitment needed for success. In some cases, other medical diagnoses, including

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