Clinical implication and prognosis of normal baseline cerebral blood flow with impaired vascular reserve in patients with major cerebral artery occlusive disease

Objective To investigate the prognosis of patients with cerebrovascular steno-occlusive disease who have preserved baseline cerebral blood flow (CBF) and reduced cerebral vasoreactivity (CVR), they were followed up after scans of positron emission tomography (PET). Methods Fifty-seven patients with symptomatic unilateral major cerebral arterial occlusion or severe stenosis underwent O-15 gas and water PET scans to measure cerebral blood volume, metabolic rate of oxygen, oxygen extraction fraction (OEF), and CBF at the baseline and after acetazolamide administration. Thirty of them (mean age 60 +/- 10 years) had normal ipsilateral CBF, and were followed prospectively at least 30 months from the last ischemic event. They were medically treated for cerebral circulation and underlying diseases during follow-up periods. The primary endpoint was determined as stroke recurrence during the follow-up. Results Thirty patients were divided into two groups of reduced CVR (N = 16, 63 +/- 8 years) and normal CVR (N = 14, 56 +/- 10 years) on the basis of CVR values from healthy volunteers. None of them showed significant laterality in baseline CBF and OEF between the hemispheres although patients with reduced CVR showed a tendency of ipsilateral increases in OEF and CBV. Patients were followed up for 50.5 +/- 19.0 and 48.1 +/- 12.4 months in the reduced and normal CVR groups, respectively. Although one patient with reduced CVR died of heart disease, there was no incidence of ischemic events during follow-up periods for either group. Conclusion In the present prospective study, patients with sufficient baseline CBF showed good prognosis and no difference in recurrent stroke risks even though they had poor CVR in the affected hemisphere, indicating that these patients can be treated by medication for cerebral circulation and baseline diseases if they have high risk factors for neurosurgical treatment.