The auditory steady state response in individuals with neurological insult of the central auditory nervous system

The auditory steady state response (ASSR) has recently gained attention with respect to estimates of hearing sensitivity and configuration of hearing loss. The present investigation compared behavioral thresholds to estimated ASSR thresholds in subjects with confirmed CANS lesions to determine if this population can be accurately evaluated with ASSR techniques. Comparisons were made between the experimental group and a normal control group matched for age and hearing sensitivity. ASSR thresholds were obtained for the carrier frequencies of 500 and 2000 Hz with a 46 Hz modulation rate and compared to behavioral thresholds. Within and between group comparisons were made. The control group demonstrated strong correlation between their behavioral and estimated ASSR thresholds which significantly contrasted the neurological group. Additionally, individuals with neurological impairment of the CANS exhibited elevated thresholds that were on average 24 dB greater at 2000 Hz than their behavioral thresholds. These results suggest that individuals with neurological insult may appear as hearing impaired or having greater hearing loss than is actually present. As a result, the ASSR may demonstrate the potential to assist in the detection of CANS dysfunction.