INFLUENCE OF THALAMIC LOCAL LESIONS ON TH E CHARACTER OF HUMAN BRAIN ELECTRICAL-ACTIVITY

The EEG recordings of 41 patients with thalamic arteriovenous malforma tions (AVM) were studied by means of multivariate statistical analysis . In 16 patients the AVM were located in pulvinar, in 17 patients in t he ventrolateral, in 4 patients in the medial, and in the remaining 4 patients in the anterior thalamic regions. Pathological EEG signs were visually classified and subjected to analysis of variance. The EEG si gns were separated caused by the lesion localization. It was shown tha t the lesions in the posterior thalamus resulted in the alpha-rhythm s uppression up to its total elimination. It was substituted for the bil ateral local pathological activity in the posterior areas of the hemis pheres. The diffuse beta-activity was observed. The ventrolateral and medial thalamic lesions led to the alpha-rhythm disorganization and it s exaltation. The local slow waves were revealed in the sensorimotor c ortical areas. The diffuse slow activity was observed as well as the s iugns of diencephalic irritation in the form of bilaterally synchronou s bursts of activity in the alpha-theta range.