The natural history of subarachnoid haemorrhage with negative angiography: a prospective study and 3-year follow-up.

One hundred and forty-eight patients with negative cerebral angiography after subarachnoid haemorrhage are reported. Good grade, normotension and normal CT are associated with a favourable outcome. In 89 patients with negative four-vessel angiography the overall annual risks of rebleeding and fatal rebleeding were 1.5% and 0.4% respectively. In 52 patients undergoing appropriate limited angiography corresponding risks were 2.5% and 1.9%. No fatal rebleeds occurred after 6 months. Initial CT scanning in 104 patients was abnormal in 34. Of these, 14 had SAH alone, in whom no episodes of rebleeding occurred, although SAH on CT was associated with an increased chance of a poor outcome. Twenty had other abnormalities, three of whom rebled, two (both with ICH on CT) being fatal. The annual risks of rebleeding and fatal rebleeding in patients with these CT abnormalities were 5.0% and 3.33% respectively. Fifty-two patients were hypertensive, of whom six rebled, four fatally. Two of the 89 normotensive patients rebled, neither fatally.