Association between hearing sensitivity and dopamine transporter availability in Parkinson's disease

Area of Science:

• Neurology
• Audiology
• Nuclear Medicine

Background:

• Previous studies indicated hearing impairment and lateralization in Parkinson's disease (PD) patients.
• Hearing dysfunction in PD was noted to be worse on the side with more severe motor symptoms.

Purpose of the Study:

• To investigate the association between basal ganglia dopamine transporter availability and hearing function in PD patients.
• To examine the lateralization of hearing and dopamine transporter dysfunction relative to motor symptoms.
• To differentiate between left-sided and right-sided predominant motor symptoms in PD patients.

Main Methods:

• Utilized pure tone audiometry and distortion product otoacoustic emissions for audiological testing.
• Assessed dopamine transporter availability using ¹²³I-FP-CIT striatal uptake scans.
• Included 39 right-handed PD patients, categorizing them by predominant motor symptom side.

Main Results:

• A significant association was found in the left-side predominant PD group between otoacoustic emission levels and contralateral dopamine transporter availability.
• In the left-side predominant group, hearing threshold was associated with the difference in dopamine transporter availability between ipsilateral and contralateral sides.
• Hearing impairment lateralization correlated with motor symptom asymmetry exclusively in left-side predominant PD patients.

Conclusions:

• The association between hearing function and dopamine transporter availability supports the role of dopamine depletion in PD-related hearing decline.
• Findings highlight significant differences between PD patients with left-sided versus right-sided predominant motor symptoms.
• Peripheral hearing function evaluation and its lateralization may serve as crucial biomarkers for PD subtyping.