Validation of multi-channel auditory steady-state response in adults with sensorineural hearing loss

For various medico-legal and financial reasons, some patients may clinically demonstrate an exaggerated hearing loss that varies in degree, nature and laterality. The purpose of this study was to evaluate whether multi-channel auditory steady-state response measurement can be used as an objective test of auditory thresholds in adults with sensorineural hearing loss.

This was a prospective, comparative, experimental research design study conducted in an academic medical centre. From January to June 2007, 142 subjects (284 ears) with varying degrees of sensorineural hearing loss were included. Four commonly used frequencies (500, 1000, 2000 and 4000 Hz) were evaluated. Both pure tone thresholds and multi-channel auditory steady-state response thresholds were obtained for each ear in all subjects. The correlation of auditory steady-state response thresholds and pure tone thresholds was assessed. The time taken for multi-channel auditory steady-state response testing was also recorded.

Results for multi-channel auditory steady-state response thresholds and pure tone thresholds were compared for each test frequency. A difference of less than 15 dB was found in 71 per cent of patients, while a difference of less than 20 dB was found in 83 per cent. Correlation between auditory steady-state response thresholds and pure tone thresholds, expressed as the correlation coefficient (r), was 0.89, 0.95, 0.96 and 0.97 at 500, 1000, 2000 and 4000 Hz, respectively. The strength of the relationship between auditory steady-state response thresholds and pure tone thresholds increased with increasing frequency and increasing degree of hearing loss. The recorded auditory steady-state response thresholds were used to calculate regression lines predicting pure tone threshold results. The mean estimated pure tone thresholds calculated from these regression lines were all within 10 dB of the actual recorded pure tone thresholds. The average multi-channel auditory steady-state response test duration was 42 minutes per patient.

Measurement of multi-channel auditory steady-state response could be a powerful, convenient electro-physiological examination with which to objectively certify clinical hearing impairment in adults.