The correlation between CBF dynamics and drug-induced EEG or somatosensory evoked potentials (SEP) has been analysed in TIA, RIND, minor or major completed stroke and rapid progressing stroke of acute cerebral ischemia.
In 4 patients with TIA, RIND and minor stroke, the CBF values were randing from 30 to 40ml/100g/min. with no apparent dysautoregulatory areas.
However, when significant decrease of mean systemic arterial blood pressure (MSABP) were brought by administration of Regitine®, reduction of rCBF in the territory of MCA occurred and EEGs or SEPs were worsened. It is considered that the results mean the focal low perfusion phenamena in such cases.
The bypass surgery was performed in 28 cases with major completed stroke. In them, the CBF values were 25-32 ml/100g/min. with apparent dysautoregulation and disturbance of CO2-reactivity. In cases with improvement obtained by the bypass, EEGs or SEPs (especially, SEP) were activated by induced-hypertension. This pattern was classified to the“CBF-dependence”.
In 8 patients, who were rapidly worsened during a short time after onset in acute stage, the emergency STA-MCA bypasses were carried out within 3 days of onset. The patients with changes of EEG or SEP depending on CBF were remarkably improved by the bypass.
In cases with activation of EEGs or SEPs by glycerol administration, the bypass surgery was not effective but, the external decompression was beneficial for improvement of consciousness. We call this pattern as the“intracranial pressure (ICP)-dependence”.
Accordingly, it is concluded that patients who have the patterns of the CBF-dependence in the functional EEG or SEP test would be suitable candidates for the bypass surgery in any cerebral ischemia.
