Normal cerebral arteriography in patients with spontaneous subarachnoid hemorrhage.

Previous studies have reported that 18 to 27% of patients with spontaneous subarachnoid hemorrhage have normal cerebral arteriograms. Our series of 220 patients from three hospitals demonstrated normal arteriograms in only 16 (7%). Recent improvements in neuroradiologic techniques, such as femoral catheterization, magnification angiography, oblique and basal projections, and subtraction most probably contribute to the improved yield. Nonvisualization of a cerebral aneurysm probably represents the most common explanation for a normal cerebral arteriogram.