How Do I Examine for a Supranuclear Gaze Palsy?

Abstract

Classically, a supranuclear gaze palsy (SNGP) is a conjugate gaze limitation that can be overcome (i.e., corrected) by the vestibulo-ocular reflex (VOR). It involves vertical eye movement most commonly. In practice, SNGP can be encountered as a limitation in excursion of self-generated conjugate saccades (fast eye movements) that can be improved or overcome with verbal command, visual targets, or VOR. Thus, mild SNGPs may be overcome with verbal commands (e.g., "look down") or visual targets (e.g., "look down at my hand"), whereas moderate SNGPs may be overcome by smooth pursuit mechanisms and following a visual target (e.g., "look at my pen as it moves") and severe SNGPs can only be overcome with the VOR (i.e., fixating straight ahead while the head is passively rotated). So, it is best to assess for an SNGP in a hierarchical fashion; initially assessing saccades to command, then saccades to visual targets, then smooth pursuit of a target, and finally with the VOR.