Inhibitory saccadic dysfunction is associated with cerebellar injury in multiple sclerosis

Area of Science:

• Neuroscience
• Neurology
• Ophthalmology

Background:

• Cognitive dysfunction is prevalent in multiple sclerosis (MS).
• Antisaccade (AS) eye movement tasks are sensitive measures of executive functions like response inhibition.
• Previous studies identified AS deficits in MS, but underlying neuropathology was unclear.

Purpose of the Study:

• To investigate the neuropathological correlates of AS task deficits in MS patients.
• To determine if AS errors are associated with clinical, radiological, or regional brain damage.

Main Methods:

• 24 relapsing-remitting MS patients performed an AS paradigm.
• Analyses included rank correlation and multiple regression.
• Correlations were assessed against clinical disability, T2 lesion load, brain parenchymal fraction, neuropsychological tests, and regional brain matter integrity (using diffusion tensor imaging and volumetric analysis).

Main Results:

• AS error rates did not correlate with clinical disability, T2 lesion load, or brain parenchymal fraction.
• AS errors significantly correlated with poorer performance on the Paced Auditory Serial Addition Task and Symbol Digit Modalities Test.
• Reduced fractional anisotropy in the cerebellum and increased mean diffusivity in the cerebellar vermis were associated with AS errors.
• Gray matter atrophy in the right cerebellar VI subregion also correlated with AS errors.

Conclusions:

• The AS paradigm is a valuable tool for detecting cognitive dysfunction in MS.
• Structural and microstructural cerebellar damage contributes to AS deficits in MS patients.