Prognostic value of cerebral blood flow autoregulation in the long-term prognosis of ischemic cerebrovascular disease

The correlation between long-term prognosis, cerebral blood flow (CBF) and CBF autoregulation was studied in 34 patients with cerebral infarction (mean age, 64 years). CBF was measured by the nitrous oxide method 1–6 months (mean 87 days) after disease onset. CBF autoregulation was evaluated quantitatively from the Dysautoregulation Index (DI) (ΔCBF/Δeffective MABP). Reductions in effective MABP were induced with a tilt table. No significant correlation was noted among CBF, DI and activities of daily living at the time of measurement. The patients' physical condition was reevaluated by questionnaire 2 years or more (mean 32 months) later. Better functional state at follow-up was related to higher CBF and lower DI values although the differences were not significant. The relationships among CBF, DI and changes in physical condition during the period were evaluated. The mean CBF values in patients with a better prognosis exceeded those of poor prognosis patients. The CBF values in the group who became independent significantly exceeded those in the group that deteriorated (P < 0.05). The CBF values in the latter showed small but significant decreases during head-up tilting (P < 0.05). The DI in this group was significantly higher than in the groups with a less severe outcome (P < 0.01, P < 0.05, respectively).In conclusion, determinations of CBF autoregulation, together with flow values, in the chronic state may have some value in predicting the long-term prognosis in cerebral infarction.