Directional Preponderance of Caloric Nystagmus in Patients with Organic Brain Diseases: An Electroencephalographic Study

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Abstract
In 68 patients with cerebral disorders a study was carried out on the relation between the site of the eeg abnormality and the presence of directional preponderance of caloric nystagmus. A directional preponderance was found in 29 cases, and the eeg showed a focal abnormality in 25 of these cases. Focal abnormal waves were recorded from either the frontal, temporal or parieto-occipital regions, and lesions in these regions were in some cases subsequently verified at operation. In 8 cases with normal caloric responses, focal abnormal waves were recorded from either the frontal or the temporal region. In the present investigation a directional preponderance was found both with lesions of the temporal lobe and with lesions of the frontal and parieto-occipital regions. This is quite in accord with the observations made in animal experiments by Wycis and Spiegel. It is concluded that directional preponderance in cases with cerebral lesions has no unequivocal localizing value, as was previously claimed, and that the absence of directional preponderance does not exclude a lesion of either the frontal or temporal region. It is pointed out that the presence of both directional preponderance to one side and a focal eeg abnormality on the same side indicates a cortical lesion in cases in which other signs of cortical damage are absent.

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