Cerebral Blood Flow in Patients with Hypertensive Intracerebral Hemorrhage

With Regard to Differences in the Mechanism of Flow Reduction between Putaminal and Thalamic Hemorrhages

Abstract

Cerebral blood flow (CBF) is usually decreased in patients with hypertensive intracrebral hemorrhage.
A total of 81 regional CBF measurements were performed using an Anger-type dynamic gamma camera with the Xe-133 intracarotid injection technique in 23 patients with thalamic hemorrhage, 18 with small putaminal hemorrhage, and 5 with large putaminal hemorrhage.
The results were as follows: Bilateral CBF in thalamic hemorrhages was markedly reduced from 1 week to 2 or 3 weeks after onset; it then showed a tendency to increase from 4 weeks to 3 months. In putaminal hemorrhages, however, CBF in the affected hemisphere did not tend to increase despite increased CBF in the contralateral hemisphere. CBF of the affected hemisphere was plotted against the hematoma volume, and the biphasic curve showed an initial steep and subsequent gentle slope in both putaminal and thalamic hemorrhages. The degree of CBF reduction in the affected hemisphere was more evident in thalamic than in putaminal hemorrhages. However, the flow reduction in the contralateral hemisphere was more obvious in thalamic than in putaminal hemorrhages. Factors such as mean arterial blood pressure, partial pressure of arterial carbon dioxide, cerebrospinal fluid pressure, hematocrit and the degree of involvement of the internal capsule, as shown on CT scan were not directly related to CBF reduction.
In conclusion, it is unlikely that the mass effect of the hematoma plays an important role in the discrepancy between CBF reduction in putaminal and thalamic hemorrhages. Rather, the discrepancy may result from the impairment of respective anatomical sites in the thalamic and putaminal regions. It is also suggested that ipsilateral as well as contralateral CBF reduction is probably caused by the decreased cortical metabolic demand. This may be based on the disruption of the transneural fiber pathways, which connect both the thalamus and putamen to the cerebral cortex.