Normative Data for Cortical Evoked Response Audiometry of a Heterogeneous Indian Population and Its Comparison with Behavioral Audiometry.

ABSTRACT

OBJECTIVE: The objective of the study is to establish normative values of cortical evoked response audiometry (CERA) in a heterogeneous Indian population and correlate CERA threshold with pure tone audiometric (PTA) threshold values. MATERIALS AND METHODS: A prospective study was carried out on 31 volunteers (n = 62) who had no otological or neurological complaints. Two study groups were formed; Group 1 with individuals from 20 to 40 years (mean age of 29.1 years) and Group 2 with individuals from 41 to 60 years (mean age of 46.2 years). The latencies and amplitudes of the waves of P1, N1, and P2 at threshold and 70 dBnHL were measured. RESULTS: Twenty-nine participants (94% of the ears) had CERA threshold within 20 dB of true behavioral threshold with only 6% having a difference of >20 dB with their PTA thresholds. There was a significant difference (P < 0.05) at 70 dB in amplitudes for waves P1, N1, and P2 at 2 kHz and additionally at 1 kHz for N1 between the two groups. CONCLUSION: Normative values for CERA in a heterogeneous Indian population at 70 dB nHL using tone burst stimulus was found to have an average latency of 46.5, 90.1, and 155.5 ms for P1, N1, and P2, respectively. The average amplitude of P1 at 70 dB nHL was 4.3 µV, N1, was 6.5 µV and P2 was 3.2 µV. Hearing threshold obtained with CERA gave a good indication of the actual behavioral hearing threshold of the normal controls, and the age of an individual had a significant effect on the values obtained during CERA testing with N1 being significantly larger at 1 kHz and 2 kHz in older adults when compared to young adults.