CT patterns and long-term outcome in patients with an aneurysmal type of subarachnoid hemorrhage and repeatedly negative angiograms.

The fate of patients with subarachnoid haemorrhage, an aneurysmal pattern of haemorrhage on CT and two or more negative angiographies is unknown. We studied the long-term outcome of patients with three negative angiograms (n = 15) and compared the pattern of hemorrhage of these patients with that of patients with perimesencephalic hemorrhage (n = 73). We reviewed the CT scans of all patients and we followed up the patients with three negative angiograms. The mean period of follow up was 65 months; the number of patient years was 81. In five of the 15 patients with an aneurysmal pattern of hemorrhage the CT scan showed a hemorrhage resembling an anterior circulation aneurysm; in the other 10 patients the center of hemorrhage was behind the chiasm but extended too far in anterior or lateral cisterns to meet the criteria of a true perimesencephalic hemorrhage ('extended perimesencephalic pattern'). During follow up no episodes of proven aneurysmal rupture had occurred. Three patients subsequently had serious vascular events; one patient (with an extended perimesencephalic pattern) died suddenly; two patients with a pattern of hemorrhage suggestive of an anterior circulation aneurysm were left disabled, one from two episodes of cerebral ischemia and another from a spontaneous intracerbral hemorrhage. In contrast to patients with perimesencephalic hemorrhage who have an uneventful clinical course and an excellent outcome, patients with three negative angiograms and an aneurysmal pattern of hemorrhage are still at some risk of vascular complications and poor outcome. Subdivisions according to the center of hemorrhage once the anterior cisterns are involved is not helpful in identifying patients with good or poor outcome.