Prospection of chronic vasospasm by CT findings.

Haematoma of the basal cistern was classified into five grades. A little or moderate haematoma (1+ or 2+) disappeared from the basal cistern in 3 or 4 days, however much or severe haematoma (3+ or 4+) remained over a week. Vasospasm occurred in a high number of the cases in which the haematoma was recognized in the basal cistern later than 4 days after SAH not only in operative case but also in conservative case. However vasospasm occurred rarely in cases with early operation within 24 hours after onset except for cases with severe packed haematoma (4+) in the basal cistern.