The prognostic value of EEG in ischaemic cerebral insults

In a prospective study the authors analysed the EEG and clinical parameters in 79 patients with an acute ischaemic cerebral insult in the territory of the internal corotid or the middle cerebral artery. The findings within 48 h after the onset of the vascular accident, on the 10th and the 22nd days were evaluated. The data show that the initial focal and background changes correlate significantly with the severity of the initial clinical findings provided the EEG is registered within the first days (in this investigation within the first 48 h) of the illness. The time of registration of the EEG is of major importance in determining correlations between the neurological deficits and the EEG changes. Although a significant correlation exists between the initial focal changes and the state of consciousness and severity of motor impairment of the first day, the focal EEG changes have no prognostic value regarding the outcome of the ischaemic insult. The background changes in the initial EEG give reliable information about the return of function and the clinical courese of an ischaemic insult in its acute stage, i.e., death, worsening, no change from onset or improvement. Diffuse slowing of the EEG corresponds to the impairment of consciousness, which is a manifestation of the degree and extent of brain damage caused by the ischaemia.