Electro-oculographic and electroencephalographic correlative study of optokinetic responses in brain lesions

Electro-oculograms of induced optokinetic responses (OKR) and EEG were recorded in 61 patients with either left or right hemisphere lesions. Of the 61 patients 55 showed focal EEG disturbances as follows: occipito-temporal (7 cases), parieto-temporal (10 cases), occipito-parieto-temporal (26 cases), temporal (9 cases) and frontal (3 cases). Symmetric OKR (21 cases) were recorded when no EEG changes were observed or when these were localized to left or right temporal and frontal electrodes and exceptionally when unilateral occipital and parietal regions were also involved. In 40 cases with unilateral hemispheric lesion a contralateral abnormal OKR was observed. Low frequency OKR with or without amplitude changes, especially of fast (saccadic) component, was mainly observed in parietal localization. In severely disturbed OKR, i.e. random jerks, the abnormal brain waves were mainly localized to the occipito-parieto-temporal region. In all cases in which no response was obtained the affected area was the occipito-parieto-temporal. These findings are discussed with reference to the regulating systems of slow (smooth) and fast (saccadic) eye movements triggered by visual stimuli.