Saccadic palsy after cardiac surgery: characteristics and pathogenesis

Area of Science:

• Neuroscience
• Ophthalmology
• Neurology

Background:

• Cardiac surgery, particularly aortic valve replacement, can lead to neurological complications.
• Saccadic palsy, a disorder of rapid eye movements, is a potential, often overlooked, consequence.

Purpose of the Study:

• To characterize the syndrome of saccadic palsy post-cardiac surgery.
• To interpret these findings within the neurobiological framework of eye movement control.

Main Methods:

• Magnetic search coil technique used to measure eye, eyelid, and head movements.
• Study included 10 patients with selective saccadic palsy after cardiac surgery.

Main Results:

• Patients exhibited slowed and hypometric saccades, primarily vertical, or in both planes. One patient lost all saccades.
• Other eye movements like smooth pursuit and vestibulo-ocular reflex were generally preserved.
• Visual disability resulted from the inability to voluntarily shift gaze; blinks and head thrusts offered minor improvements.

Conclusions:

• Selective saccade loss suggests dysfunction in the brainstem saccade-generating circuitry.
• A current model of brainstem circuits can explain the observed hypometria and slowing.
• This syndrome and its associated visual disability are often missed without systematic bedside saccade testing.