Unique compensatory oculomotor behavior in people living with multiple sclerosis

Area of Science:

• Neuroscience
• Ophthalmology
• Neurology

Background:

• Multiple sclerosis (MS) affects millions globally, often causing central vestibular lesions.
• Vestibular-ocular control data in people living with MS (PLW-MS) is limited, despite frequent vestibular dysfunction.
• Understanding compensatory saccade (CS) behavior is crucial for assessing neurological impact in PLW-MS.

Purpose of the Study:

• To characterize compensatory saccade (CS) behavior in people living with MS (PLW-MS).
• To investigate the relationship between MS severity and vestibular-ocular control.
• To identify unique gaze stabilization strategies employed by PLW-MS.

Main Methods:

• Analysis of video head impulse test data from four groups: mild MS, moderate MS, unilateral vestibular deafferentation, and healthy controls.
• Comparison of vestibulo-ocular reflex (VOR) gain, CS frequency, latency, and peak velocity across groups.
• Assessment of gaze position error (GPE) and its correlation with MS-related disability.

Main Results:

• People living with moderate MS showed significantly lower VOR gain compared to mild MS, healthy controls, and those with unilateral vestibular deafferentation.
• Compensatory saccade characteristics, including frequency, latency, and peak velocity, differed between MS severity groups and sides of affliction.
• MS-related disability correlated with reduced VOR gain and increased gaze position error.
• Micro-saccades and position-correcting saccades were identified as unique compensatory strategies in PLW-MS.

Conclusions:

• Compensatory oculomotor behavior in PLW-MS is contingent upon the degree of residual VOR gain.
• Vestibular-ocular control deficits are more pronounced in moderate MS.
• The findings highlight the complex adaptations in gaze stabilization for PLW-MS.