Introduction: The pathogenesis of delayed cerebral ischemia (DCI) after subarachnoid hemorrhage (SAH) is unclear. We assessed whether DCI relates to focal or global cerebral perfusion on admission and on follow-up imaging.
Materials and methods: Twenty-seven SAH patients underwent computed tomography (CT) perfusion (CTP) on admission and at clinical deterioration or 1 week after admission in clinically stable patients. We compared global and focal (least perfused territory) perfusion in patients with DCI (n = 12), clinically stable patients (n = 7), and patients with non-DCI-related deterioration (n = 8).
Results: Global cerebral blood flow (CBF) increased on follow-up: 29% (95% confidence interval (CI) 15% to 43%) in patients with DCI, 12% (95%CI -1% to 25%) in stable patients, and 20% (95%CI 4% to 36%) in patients with non-DCI-related deterioration. Focal CBF decreased in patients with DCI, (-23%; 95%CI -58% to 12%) but increased in patients with non-DCI-related deterioration (23%; 95%CI -26% to 55%) and stable patients (7%; 95%CI -30% to 45%).On follow-up, global CBF was lower in patients with DCI (70.0 ml per 100 g/min) than in clinically stable patients (81.6; difference 11.6; 95%CI 0.8 to 22.5 ml per 100 g/min) but comparable to patients with non-DCI-related deterioration (67.6; difference -2.4; 95%CI -11.9 to 7.2 ml per 100 g/min). Focal CBF was lower in patients with DCI (30.7) than in clinically stable patients (53.6; difference 22.9; 95%CI 5.1 to 40.6 ml per 100 g/min) and patients with non-DCI-related deterioration (46.6; difference 15.9; 95%CI -2.6 to 28.4 ml per 100 g/min)
Conclusion: Our results suggest that DCI is more likely a focal than a global process.