No cochlear dead regions detected in non-pulsatile tinnitus patients: an assessment with the threshold equalizing noise (sound pressure level) test.

One of the hypotheses on the etiology of non-pulsatile tinnitus in normal or hearing impaired patients is the existence of sharp edged cochlear dead regions (DR) flanking normal functioning hair cells. The lack of inhibition of DR on the neighboring neurons may lead to hyperactivity. Currently the Threshold Equalizing Noise test (TEN test) is the reference test to clinically assess cochlear DR. To identify cochlear DR in patients with non-pulsatile tinnitus with and without hearing loss using the TEN (sound pressure level)-test. Data were obtained from adult patients with non-pulsatile tinnitus visiting the Tinnitus Clinic of the University Hospital Antwerp. The TEN (SPL)-test was performed to assess the presence of cochlear DR for test frequencies ranging from 0.5 to 8 kHz. A total of 55 ears of 33 subjects (15 male; 18 female) with non-pulsatile tinnitus were included in the study. Subjects were divided into subgroups based on the audiometric configuration of hearing loss: Flat configuration (N = 23), high-frequency gently sloping (N = 10) and high-frequency steeply sloping (N = 22). In forty-eight ears there was no evidence of cochlear DR. In seven ears the results were inconclusive. This occurred in patients with high-frequency steeply sloping audiogram configurations. The present study does not support the TEN (SPL) test as a reliable tool for the detection of cochlear DR in a tinnitus population.