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some cases, older children were referred to our institution after
behavioral testing and/or ABR testing had already been per-
formed. If any behavioral data had been obtained before ABR
testing regardless of testing method, the ABR was considered
confirmatory (cABR). Often, cABR was performed just before
CI surgery to also rule out ANSD. Patients ultimately receiving
bilateral CIs were noted, but analysis included only time course
up to the date of the first CI.
RESULTS
A total of 1142 pediatric patients underwent ABR testing
in the 5-year period and 105 (9.2%) met the above criteria for
inclusion in the study. A summary of hearing loss etiologies and
significant comorbidities can be found in Table 2.
Of the 105 children identified in the review, 11 (10.5%) were
lost to follow-up at the time of data collection and/or did not have
reliable behavioral audiometry results. Ninety-four (
n
= 94) chil-
dren with NRABRs had adequate data to report with appropriate
follow-up. Of the 94 patients, 80 (85.1%) failed the NBHS in at
least one ear, 8 (8.5%) passed, and 6 (6.4%) did not have newborn
screening data because of birth outside of the United States or
adoption history. As a tertiary care medical center, many children
were referred after some degree of workup or diagnosis else-
where before initial evaluation at our institution. The mean age at
presentation to our institution was 16.9 months (SD 25.3, range
1–137). The mean age at the time of ABR testing for all included
patients was 19.3 months (SD 26.9, range 1–140). The mean age
at dABR was 5.40 months (SD 6.2, range 1–36) as compared to
35.79 months (SD 28.4, range 4–131) for cABR.
Although all 94 patients had an NR response on ABR test-
ing at the maximum stimulus level for the frequency tested,
the actual corresponding thresholds documented on behavioral
testing showed a wide range of results. Figure 1 compiles the
corresponding behavioral thresholds for all tested ears (175
total ears), although not all frequencies were able to be tested
on both ears for all subjects. Behavioral responses at 250 Hz
demonstrated a particularly broad range varying from 40 dB
HL to no measurable responses. The range at higher frequen-
cies showed somewhat less variability. Of the four children with
thresholds 65 dB HL or better at 250 and 500 Hz, one had pro-
gressive hearing loss and the remainder failed to make progress
with amplification. All had a history of prematurity with three
requiring mechanical ventilation in the neonatal intensive care
unit. The majority of patients (>50%) with a NR ABR had no
demonstrable evidence of residual hearing on behavioral testing
at any of the frequencies tested.
The various clinical outcomes are graphically depicted in
Figure 2. Of the 94 children, 91 (96.8%) ultimately received at
least one CI and 49 (52.1%) received bilateral CIs. Importantly,
no child (0%) demonstrated auditory thresholds on behavioral
testing or sufficient progress in speech and language develop-
ment with amplification to contraindicate implantation. Of the
3 (3.2%) children who did not receive a CI, this result was sec-
ondary to significant and pervasive comorbidities.
For the 91 patients who ultimately went on to receive a
CI, the progression through the CI evaluation process varied
greatly. Two distinct patterns of progression emerged from
this group based on the purpose of the initial ABR. ABRs
were considered as dABR if the study was performed before
any behavioral testing. If the ABR was performed with the
purpose of verifying prior behavioral testing data, then it was
considered as cABR. Table 3 summarizes the range, average,
and SD of ages at ABR testing, behavioral testing, and CI
surgery, as well as the amount of time elapsed between each
of the above measures. The overall mean age at time of ABR
TABLE 2. Etiology of hearing loss and comorbidities in patients
with a “no response” auditory brainstem response
Etiology
N
(%)
Unknown
57 (54.3)
Connexin 26
9 (8.6)
Cytomegalovirus infection
11 (10.5)
Waardenburg syndrome
7 (6.7)
CHARGE syndrome
5 (4.8)
Meningitis
3 (2.9)
Other congenital syndrome
5 (4.8)
Inner ear malformations
29 (27.6)
Cochleo-vestibular dysplasia
18 (17.1)
Enlarged vestibular aqueduct
3 (2.9)
Cochlear nerve deficiency or hypoplasia
8 (7.6)
Medical co-morbidities
Prematurity
20 (19.0)
Hyperbilirubinemia
11 (10.5)
Neonatal intensive care unit stay
17 (16.1)
Seizure disorder
9 (8.6)
Developmental delay
23 (21.9)
Cerebral palsy
7 (6.7)
Family history of hearing loss
17 (16.1)
Fig. 1. Residual hearing as confirmed by behavioral audiometry for patients
with no response on auditory brainstem response.
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