Abstract
It is generally accepted that some patients with cerebral ischemia have abnormal CBF dynamics, EEG findings or neurological findings not only in the ischemic regions but also in other regions of the ipsilateral and the contralateral hemisphere.
In nine patients with one-sided occlusion of the internal carotid artery, authers have observed abnormal findings of somatosensory evoked potentials (SEP) on the non-affected hemisphere in the resting state and/or in the induced hypertension.
The abnormal findings of SEPs were classified into three groups. In the group I, SEPs of the non-affected hemisphere were abnormal even in the resting state and not changed by the induced hypertension. In the group II, SEPs of the non-affected side were worsened under the induced hypertension. In the group III, SEPs of the non-affected side were activated by the induced hypertension.
In the group I and III, it is considered that ischemic regions and/or dysautoregulatory areas were completed by the interhemispheric steal or the transneural depression even in the non-affected hemisphere.
But, in the group III, reversible ischemic dysfunctions of the non-affected hemisphere were improved by the increase of the blood flow in the dysautoregulatory areas under the induced hypertension. In the group II, it is considered that, under the induced-hypertension, the interhemispheric steal from the non-affected hemisphere was occured by the increase of the blood flow on the dysautoregulatory areas of the ischemic regions.
In conclusion, it is necessary to improve the hemodynamics of the ischemic regions by the bypass surgery and except the disappearance of these abnormal phenomenon.
