Horizontal eye movements and vestibular-visual interactions in progressive supranuclear palsy

Abstract

Ocular motor abnormalities can be a good clue in the differential diagnosis of parkinsonism. All types of eye movements, including saccade, pursuit, optokinetic nystagmus (OKN) and vestibulo-ocular reflexes (VOR) are affected to some extent in parkinsonism. To diagnose progressive supranuclear palsy (PSP), the most important finding is slowing of vertical saccades, especially downgaze. However, other eye movements mentioned above may become affected in PSP. The objective of the study was to investigate quantitatively horizontal eye movements, VOR and VOR suppression in PSP. Method : We studied 6 patients with PSP (4 males and 2 females, aged 58-77 years) and age-matched 8 healthy controls. Eye movements were recorded using a Nystagliner (TOENNIES, German). Subjects sat n a Nystagliner chair without head movement during all the experimental paradigms. We measured velocity and latency of saccades (20-degree gaze angle), gain of smooth pursuit (0.1 Hz and 0.2Hz, sinusoidal motion of the laser spot), OKN (25 deg/s), gain of VOR (25 deg/s, 50 deg/s at various frequencies) and VOR suppression (25 deg/s, 50 deg/s at various frequencies).