The comparison of the average thresholds of auditory steady-state response in adult subjective idiopathic tinnitus and normal subjects

Tinnitus is a common symptom among lots of people but little is known about its origins. This study was aimed at comparing the Auditory Steady-State Response (ASSR) thresholds in normal cases and patients with subjective idiopathic tinnitus (SIT) in order to diagnose its real origins.

This case-control study was conducted on 19 patients with tinnitus and 24 normal cases aged 18-40 yr.The patients underwent broad medical tests to roll out any background reason for their tinnitus. ASSR thresholds were estimated in both groups at 20 and 40 amplitude modulation. The patients were selected from tinnitus patients in Research Center in Hazrat Rasoul Hospital, Tehran, Iran.

The mean ASSR thresholds at 40HZ modulation were worse in tinnitus patients compared to normal ones (p<0.05) but no significant statistical differences was detected at 20HZ. These results were found in both situations in which we averaged both ears thresholds and when we estimated the thresholds of the ears separately.

It seems that the origin of the responses of the modulation of 40Hz, primary auditory cortex, midbrain regions and subcortical areas, in these patients is involved or the origin of their tinnitus is related to some kind of problems in these areas, although more investigation is needed about 20Hz.