Easily applied ear canal electrodes improve the diagnostic potential of auditory brainstem response

The diagnostic potential of easily applied ear canal electrodes was studied in patients with asymmetric auditory brainstem response (ABR). The study included 50 consecutive patients with unilateral auditory signs or symptoms who at conventional ABR testing manifested not only a delayed wave V in relation to the non-symptomatic ear, but also absence of wave I in the symptomatic ear. The patients were examined with ear canal electrodes at the same session as the conventional ABR testing. As application of the ear canal electrode is easy, painless and safe, the auditory assistant could use the ear canal electrode and obtain the recordings unaided and without having first to consult a physician. Estimated extra time for the canal electrode procedure was 15 min and no adverse effects were noted. With the use of an ear canal electrode a significant wave I could be identified in 72% (36.50) of cases. Thus, ability to observe the most peripheral component (wave I) of the ABR was facilitated by using an easily applied ear canal electrode. Hence, in these patients the diagnostic potential of ABR for acoustic tumors was increased owing to the availability of a direct measure of tumor effect on the auditory nerve, i.e., the neural transmission time.