Why do patients with PSP fall? Evidence for abnormal otolith responses

Area of Science:

• Neuroscience
• Ophthalmology
• Vestibular System

Background:

• Progressive supranuclear palsy (PSP) is characterized by frequent falls early in disease progression.
• Vestibulospinal reflexes are implicated, yet the angular vestibulo-ocular reflex remains intact late in PSP.

Purpose of the Study:

• To investigate the hypothesis that otolithic-mediated reflexes are abnormal in patients with PSP.

Main Methods:

• Otolith-ocular reflexes (translational vestibulo-ocular reflex, tVOR) were assessed during combined rotation-translation in PSP patients and controls.
• Otolith-spinal reflexes (vestibular-evoked myogenic potentials, VEMPs) were measured using auditory clicks in PSP patients and controls.

Main Results:

• PSP patients exhibited significantly reduced tVOR responses during near viewing (12% of controls, p=0.001).
• A notable reduction in VEMP amplitude was observed in PSP patients compared to controls (p=0.001).

Conclusions:

• Abnormal otolithic reflexes may contribute significantly to the frequent falls observed in progressive supranuclear palsy.
• These findings warrant further investigation into the role of otolithic dysfunction in PSP-related falls.