Abstract
Objectives
Understand the utility of intraoperative ABR testing after myringotomy and tube placement.
Methods
We performed a retrospective chart review of 27 patients (mean age 23 months) who underwent intraoperative ABR (ioABR) after myringotomy and tube placement at Primary Childrens Medical Center from 2004 to 2007. Paired t-tests were perfomed to analyze the difference in threshold levels from the ioABR to follow up behavioral audiometry at 1kHz and 4kHz frequencies, accounting for the presence or absence of fluid at the time of surgery.
Results
15 patients (29 ears) showed a mean improvement of 10 dB at the 1 kHz frequency (p=0.007), and 16 patients (31 ears) improved by 5 dB at 4kHz (p=0.83). An improvement of at least 15 dB was seen in 45% of patients (13/29 ears) at 1 kHz and in 26% (8/31 ears) at 4 kHz; 5 patients improved by as much as 35–50 dB. Of the patients whose thresholds improved by at least 15 dB, 77% at 1 kHz and 83% at 4 kHz showed evidence of fluid at the time of the ioABR
Conclusions
Patients who undergo ioABR testing show a significant improvement of dB level on follow-up behavioral audiometry. Many patients whose hearing threshold improved by at least 15 dB had fluid at the time of myringotomy. Therefore, the presence of middle ear pathology may lead to an overestimation of ioABR thresholds. Consequently, ioABR results should be interpreted with caution in isolation, and subsequent audiometric testing should always be performed to validate prior results.
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