Cerebral ocular motor signs.

Abstract

Eye movement disturbances resulting from cerebral lesions are reviewed and the specific roles of the different ocular motor areas are summarized. Three cortical areas may trigger saccades: the frontal eye field (FEF), the supplementary eye field (SEF) and the parietal eye field (PEF). The FEF could be involved mainly in intentional visual exploration (intentional saccades), the PEF mainly in reflexive visual exploration (reflexive saccades) and the SEF in the preparation of motor programs (sequences of saccades). Only bilateral lesions affecting these areas result in visible saccade disturbances (at bedside examination), as manifested in Balint's syndrome after parietal lesions, and ocular motor apraxia after fronto-parietal lesions. Other cortical areas prepare saccades: the posterior parietal cortex (near the PEF) controls visuomotor integration; the prefrontal cortex (i.e. area 46 of Brodmann) is involved in inhibition of unwanted reflexive saccades, prediction (predictive saccades) and spatial memory. Smooth pursuit is controlled by the FEF and the medial superior temporal area, located in the posterior part of the cerebral hemisphere. Eye movement disorders resulting from basal ganglia lesions are also reviewed. Lastly, the contribution of eye movement recordings in early diagnosis of some cerebral degenerative diseases (such as progressive supranuclear palsy or corticobasal degeneration) is emphasized.