Background: It remains unclear why chronic subdural hematoma (CSH) can cause hemiparesis, although the contribution of impaired cerebral blood flow and metabolism has been suggested.
Methods: We studied six hemiparetic patients (five men, one woman; mean age 60.5 +/- 7.5 years) with unilateral CSH using positron emission tomography. The 15O2 steady state technique was used to measure regional cerebral blood flow (rCBF), regional oxygen extraction fraction (rOEF), and regional cerebral metabolic rate of oxygen (rCMRO2), followed by the 1-minute inhalation of C15O to measure regional cerebral blood volume (rCBV).
Results: On the hematoma side, rCBF and rCMRO2 were significantly reduced in the caudate nucleus and the cingulate gyrus. We observed a tendency toward reduced levels of rCBF and rCMRO2 in the lentiform nucleus. rCBV was not elevated. rOEF was significantly elevated in the lentiform nucleus, the cingulate gyrus, the frontal gray matters under the hematoma and the semioval center. On the nonhematoma side, rCBF and rCMRO2 were normal except for the significant reduction in the cingulate gyrus. rCBV was elevated in the lentiform nucleus, the middle temporal gyrus and the inferior frontal gyrus. rOEF was elevated significantly in the cingulate gyrus, the precentral gyrus and the semioval center.
Conclusions: Our hemiparetic patients with CSH were observed to have a circulatory disturbance of blood; it was manifested by an elevation of rOEF, specifically in the hemisphere adjacent to the hematoma. This circulatory disturbance was highly pronounced and resulted in a consistent reduction in rCBF and rCMRO2 in the anterior central cerebral area such as the caudate nucleus, the lentiform nucleus and the cingulate gyrus.