OBJECTIVE METHODS OF UNILATERAL DEAFNESS SIMULATION UNDER PARTICULAR CONSIDERATION OF DPOAE FINDINGS IN A CASE-STUDY

The simulation of unilateral deafness is Very rare. Objective findings are of special interest if it happens. A patient with alleged deafnes s on the left-hand side due to commotio cerebri was treated in our hos pital. Pure tone audiometry showed deafness on the left-hand side and normal hearing on the right-hand side. However, stapedius reflexes wer e found ipsilaterally left as well as contralaterally right, at 0.5 to 2 kHz with a stimulation of approxamately 90 dB SPL. Transiently evok ed otoacoustic emissions (TEOAE) and distortion-product otoacoustic em issions (DPOAE) were measured. The TEOAE had the same reproducibility but a very low response on both sides, such that inner ear function co uld not be evaluated. In comparison,the DP gram showed clear DP amplit udes over the whole frequency range on both sides. Nonphysiological DP s could be excluded by assessing the DP growth rate at three different frequencies. By means of brainstem electric response audiometry (BERA ), with which the IV/V complex was detectable up to stimulation with 2 0 dB SPL clicks,and the Stenger test, a neural or central hearing loss could be excluded. Normal hearing on the left-hand side was thus conf irmed. In cases of simulated deafness it is possible to prove a normal inner ear function by DPOAE. DPOAE therefore complements the list of potential audiological simulation tests.