Objective frequency-specific hearing thresholds definition for medicolegal purposes in case of occupational NIHL: ASSR outperforms CERA

Abstract

Audiological use of the 40 Hz-ASSR (auditory steady state responses) could be valuable for objectively estimating the frequency-specific threshold in adults undergoing an expertise examination for medicolegal and/or compensation purposes. The present prospective study was set up to clarify the relationship between the thresholds obtained by cortical evoked response audiometry (CERA) and by 40 Hz-ASSR, in the same ears, within a large homogeneous sample of 164 subjects (328 ears) with NIHL and well documented exposure to noise. All these subjects claimed financial compensation for occupational NIHL, and there was a suspicion of exaggeration of the reported NIHLs. ASSR thresholds show a good correlation with the CERA thresholds. However, a systematic shift is noticed, ASSR thresholds being on average (1–2 – 3 kHz) 4.38 dB lower (i.e. showing less hearing loss) than CERA thresholds. Moreover, the binaural multiple ASSR technique allows a considerable time gain when compared to the CERA.

The comparison of auditory behavioral and evoked potential responses (steady state and cortical) in subjects with occupational noise-induced hearing loss

“…As to the two objective approaches, the results of the present study are in line with our previous findings in less reliable subjects showing comparable NIHL. In the latter, CERA thresholds exceeded ASSR thresholds on average by 2.35 dB at 1 kHz, by 5.31 dB and by 6.81 dB at 3 kHz ( DeJonckere et al., 2021 ).…”

“…Forty-four subjects claiming for benefit at the Federal Agency for Occupational Risks (FEDRIS, Brussels) and acceptable for inclusion in our analysis were considered in the present study, that ran over a period of 22 months. As in our previous study ( DeJonckere et al., 2021 ), their occupational history was scrutinized by the Engineering Dept. of FEDRIS before medical examination, so as to only include cases with an exposure to noise ≥ one year to ≥85 dB A (Time Weighted Average, i.e.…”

“…The Belgian scale allowing financial benefit for NIHL considers an average of air conduction thresholds on 1, 2 and 3 kHz at the best ear, weighted by the corresponding thresholds at the worse ear (5/6 better ear – 1/6 worse ear) in the cases of asymmetry. The essential test for inclusion in our previous study ( DeJonckere et al., 2021 ) was a suspicion of excessive reported NIHL, based on a worsening (≥5 dB HL on average at the best ear) of the threshold values obtained in PTA during the evaluation at FEDRIS, compared to those of the audiogram supplied by the claimant in his/her application document. The rationale of this approach has been explained in our previous article ( DeJonckere et al., 2021 ).The main inclusion criterion in the present study was the opposite of that of our previous study, i.e .…”

“…The essential test for inclusion in our previous study ( DeJonckere et al., 2021 ) was a suspicion of excessive reported NIHL, based on a worsening (≥5 dB HL on average at the best ear) of the threshold values obtained in PTA during the evaluation at FEDRIS, compared to those of the audiogram supplied by the claimant in his/her application document. The rationale of this approach has been explained in our previous article ( DeJonckere et al., 2021 ).The main inclusion criterion in the present study was the opposite of that of our previous study, i.e . the strict absence of any PTA threshold measured at FEDRIS that is higher (worse) than the corresponding one in the audiogram of the PTA supplied by the claimant with his/her application.…”

“…NIHL: noise induced hearing loss) are likely to be covered by an insurance system providing financial compensation the prospect of a potential benefit may encourage some insured workers to either deliberately worsen their actual hearing loss or to raise - to some extent unconsciously – their behavioral response criteria ( DeJonckere et al., 1992 , 2000 , DeJonckere and Lebacq, 2005 , 2009 , 2011 ). In a previous study ( DeJonckere et al., 2021 ), we demonstrated that the 40 Hz binaural multiple ASSR (Auditory Steady State Response) technique is adequate for medico-legal evaluation of hearing thresholds in adults who are claiming financial compensation for work related NIHL, as soon as the traditional methods of behavioral audiometry lack reliability. As a matter of fact, the electrophysiological ASSR approach of the hearing level is totally noninvasive, well-tolerated and frequency specific.…”