Systematic Audiological Assessment of Auditory Functioning in Patients With Parkinson's Disease

Abstract

Purpose Alterations in primary auditory functioning have been reported in patients with Parkinson's disease (PD). Despite the current findings, the pathophysiological mechanisms underlying these alterations remain unclear, and the effect of dopaminergic medication on auditory functioning in PD has been explored insufficiently. Therefore, this study aimed to systematically investigate primary auditory functioning in patients with PD by using both subjective and objective audiological measurements. Method In this case–control study, 25 patients with PD and 25 age-, gender-, and education-matched healthy controls underwent an audiological test battery consisting of tonal audiometry, short increment sensitivity index, otoacoustic emissions (OAEs), and speech audiometry. Patients with PD were tested in the on- and off-medication states. Results Increased OAE amplitudes were found when patients with PD were tested without dopaminergic medication. In addition, speech audiometry in silence and multitalker babble noise demonstrated higher phoneme scores for patients with PD in the off-medication condition. The results showed no differences in auditory functioning between patients with PD in the on-medication condition and healthy controls. No effect of disease stage or motor score was evident. Conclusions This study provides evidence for a top-down involvement in auditory processing in PD at both central and peripheral levels. Most important, the increase in OAE amplitude in the off-medication condition in PD is hypothesized to be linked to a dysfunction of the olivocochlear efferent system, which is known to have an inhibitory effect on outer hair cell functioning. Future studies may clarify whether OAEs may facilitate an early diagnosis of PD.

Future Perspectives on the Relevance of Auditory Markers in Prodromal Parkinson's Disease

“…More specifically, if pure-tone hearing thresholds are increased compared to HCs, as was the case for patients with PD in Vitale et al (26), abnormal speech recognition scores can be expected. Regarding speech audiometry in noise, no significant differences regarding speech recognition scores were reported between medicated patients with PD and HCs (17,22). Interestingly, a modulatory effect of dopaminergic medication state was found on both speech audiometry in silence and in noise (17).…”

“…Regarding speech audiometry in noise, no significant differences regarding speech recognition scores were reported between medicated patients with PD and HCs (17,22). Interestingly, a modulatory effect of dopaminergic medication state was found on both speech audiometry in silence and in noise (17). The same patients with PD performed slightly better when they were tested without medication compared to when they were tested with medication.…”

“…In contrast, De Keyser et al (17) found no significant differences regarding TEOAE response amplitudes between medicated patients with PD and age-matched HCs. Regarding DPOAEs, similar response amplitudes were found between medicated patients with PD compared to HCs (17,23). Nevertheless, a modulatory effect of dopaminergic medication on the OAE response amplitudes has been found.…”

“…Regarding TEOAEs, two studies reported lower response amplitudes in medicated patients with PD compared to HCs (18,23). In contrast, De Keyser et al (17) found no significant differences regarding TEOAE response amplitudes between medicated patients with PD and age-matched HCs. Regarding DPOAEs, similar response amplitudes were found between medicated patients with PD compared to HCs (17,23).…”

“…Hence, the presence of OAE decreases with increasing age, especially at higher frequencies. In patients with PD, the presence of TEOAE and DPOAE responses did not differ significantly from HCs (17,20). Additionally, for research purposes, the response amplitudes of OAEs can be used for group comparisons.…”