The relationship between the 4 diagnostic age groups and clinical manifestations (A), number of infarcted zones (B), distribution of corticosubcortical infarcted zones (C), ICA staging (D), PCA staging (E), and number of transdural collaterals (F). Asterisks indicate significant differences. Double asterisks indicate a significant difference and a positive relationship to diagnostic age among the 3 oldest diagnostic age groups.