PP1009 - Comparison of Auditory Brainstem Response Latencies Recorded from Three Different Clinical Systems

Abstract:
The auditory brainstem response (ABR) test is used for threshold estimation and neurodiagnostic purposes. ABR peak V latency measurements are essential for neurodiagnostic purposes but may not be for threshold estimation purposes. The peak V ABR latencies recorded from different systems should be similar. However, this has not been verified. In this study, we analyzed ABRs recorded for different stimuli from three different FDA-approved systems (Interacoustics EP25, Intelligent Hearing System, and Vivosonic Integrity V500). Fifteen normal-hearing adults participated in this study. There were significant differences in ABR peak latencies between systems. Findings suggest that instrument-specific normative data should be used.

Summary:
Rationale
The auditory brainstem response (ABR) test is used to estimate hearing thresholds and for neurodiagnostic purposes. The ABR can be recorded by presenting short-duration stimuli, such as broadband Click and Chirp, or frequency-specific stimuli [tone bursts (TB), or narrowband chirps (NBC)]. In frequency-specific ABRs, the latency of the peak V is not usually examined. However, with click-evoked ABRs recorded for neurodiagnostic purposes, the peak V latency is examined. If the peak V latency is not within normal limits, then it is considered clinically abnormal. There are a variety of FDA-approved ABR recording systems available, each using different technology to record ABRs. ABR latencies should be similar between systems for different test stimuli. Similarities in ABR latencies between systems is crucial for neurodiagnostic purposes to avoid misdiagnosis. Some authors recommend using published normative data for absolute latencies. The FDA-approved ABR systems differ in technology which might affect the latencies of ABR peaks. We are not aware of any studies that have compared ABR latencies between FDA-approved ABR systems. Hence, in this research, we examined whether there are any significant differences in ABR latencies for different stimuli between the three FDA-approved ABR systems.

Design
ABRs were recorded from 15 normal-hearing adults (22.44-37.85 years, mean = 25.91 years) using the Interacoustics EP25 (uses Bayesian weighting technique), Intelligent Hearing System (IHS) (uses conventional averaging technique), and Vivosonic Integrity V500 (SOAP-Kalman weighted average technique) systems. ABRs were obtained for traditional stimuli [click, TBs (0.5, 1, 2, and 4 kHz)] and chirp stimuli [broadband chirp and NBCs (0.5, 1, 2, and 4 kHz)]. Stimuli were presented at 80 dB nHL (39.1/sec) and the ABRs were then averaged over a 25 ms window, amplified, and filtered (30-3000 Hz). ABRs were recorded from one ear only. Only the peak V latencies were analyzed.

Brief Summary of Clinical Takeaways:
There were significant differences in peak V latencies between systems. For the click stimulus, the IHS system’s peak V latencies were significantly prolonged (p < 0.05) when compared to the other two systems. For 1 and 2 kHz TB stimuli, the IHS system’s peak V latencies were significantly prolonged (p < 0.05) when compared to the EP25 system and Vivosonic Integrity V500 system, respectively. For broadband chirp and 0.5 kHz NBC, the IHS system’s peak V latencies were significantly prolonged (p < 0.05) when compared to the other two systems.

Conclusions
The findings of our study suggest that latencies do vary significantly between ABR systems and clinicians should be aware of these differences. The findings of the current study suggest that instrument-specific normative data is required. The use of a common set of published normative data could increase the incidence of misdiagnosis. We recommend that audiologists use normative data that are instrument and protocol-specific.