Evaluation of regional cerebral blood flow in chronic subdural hematoma.

To clarify the mechanism responsible for neurological impairment associated with chronic subdural hematoma (CSDH), we performed quantitative measurements of cerebral blood flow (CBF) with xenon-enhanced computed tomographic scans in eight patients with unilateral CSDH. Vascular reserve capacity was also evaluated with acetazolamide challenge. CBF was depressed in all regions examined except the corona radiata. There was no statistical difference in hemispheric and regional CBF between the lesion and non-lesion sides. A significant increase in CBF values ranging from 32% to 69% was observed after acetazolamide administration in the whole brain. Postoperatively CBF remained depressed in all regions we analyzed except for the frontal and temporal lobes, despite the fact that all patients had improved clinical symptoms. Amplitude of N20 and central conduction time (N13-20) in SSEP showed no significant change in CSDH patients compared to normal control. So we conclude that preoperative neurological signs in CSDH are related to a reduction of CBF in the whole brain. However, other mechanisms must be involved to explain preoperative focal signs and good postoperative recovery.