Static and dynamic otolith reflex function in people with Parkinson's disease.

Area of Science:

• Neuroscience
• Otolaryngology
• Neurology

Background:

• Parkinson's disease (PD) is a neurodegenerative disorder.
• Vestibular system dysfunction is increasingly recognized in PD.
• Otolith organs play a crucial role in balance and spatial orientation.

Purpose of the Study:

• To compare otolith organ function and reflex pathways in PD patients versus healthy controls (HC).
• To investigate the relationship between otolith function and a history of falls in PD.
• To assess both transient and sustained otolith functions.

Main Methods:

• Forty PD patients and 40 HC underwent vestibular assessments.
• Cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs) were measured using air-conducted clicks and bone-conducted taps.
• Static otolith function was evaluated using the Subjective Visual Vertical (SVV) test.

Main Results:

• PD patients showed significantly higher rates of absent cVEMP responses to both clicks and taps compared to HC.
• Absent tap cVEMPs in PD patients were associated with a history of falls.
• PD patients exhibited abnormal SVV responses and greater error compared to HC, with no correlation between SVV and VEMP results.

Conclusions:

• Parkinson's disease significantly affects cVEMP reflex pathways, indicating otolith dysfunction.
• Bone-conducted vibration is a more robust stimulus than air-conducted sound for assessing otolith reflexes in PD.
• Static (SVV) and dynamic (VEMP) otolith functions appear to be differentially impaired in PD.