Hypoperfusion without Ischemia Surrounding Acute Intracerebral Hemorrhage

A zone of hypoperfusion surrounding acute intracerebral hemorrhage (ICH) has been interpreted as regional ischemia. To determine if ischemia is present in the periclot area, the authors measured cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), and oxygen extraction fraction (OEF) with positron emission tomography (PET) in 19 patients 5 to 22 hours after hemorrhage onset. Periclot CBF, CMRO2, and OEF were determined in a 1-cm-wide area around the clot. In the 16 patients without midline shift, periclot data were compared with mirror contralateral regions. All PET images were masked to exclude noncerebral structures, and all PET measurements were corrected for partial volume effect due to clot and ventricles. Both periclot CBF and CMRO2 were significantly reduced compared with contralateral values (CBF: 20.9 ± 7.6 vs. 37.0 ± 13.9 mL 100 g−1 min−1, P = 0.0004; CMRO2: 1.4 ± 0.5 vs. 2.9 ± 0.9 mL 100 g−1 min−1, P = 0.00001). Periclot OEF was less than both hemispheric OEF (0.42 ± 0.15 vs. 0.47 ± 0.13, P = 0.05; n = 19) and contralateral regional OEF (0.44 ± 0.16 vs. 0.51 ± 0.13, P = 0.05; n = 16). In conclusion, CMRO2 was reduced to a greater degree than CBF in the periclot region in acute ICH, resulting in reduced OEF rather than the increased OEF that occurs in ischemia. Thus, the authors found no evidence for ischemia in the periclot zone of hypoperfusion in acute ICH patients studied 5 to 22 hours after hemorrhage onset.