Objective: The evaluation of patients with subarachnoid hemorrhage (SAH) with negative initial catheter-based angiography is a diagnostic challenge. Better diagnostic strategies based on hemorrhage patterns are needed.
Methods: We retrospectively investigated the yield of focused history taking, magnetic resonance imaging of the brain and cervical spine, follow-up vascular imaging, laboratory investigations, and craniotomy for vessel exploration in 100 patients with SAH and negative initial catheter-based angiography.
Results: The most common distribution of hemorrhage was in a "classic" aneurysmal pattern filling the basal cisterns or posterior fossa (44 patients). A cause was determined in 13 patients (13%), the most common of which was aneurysm (7 patients). Repeat angiography was the most useful diagnostic modality, detecting seven lesions. The yield of the second angiogram was best in patients with a classic hemorrhage pattern (10%) and worse in patients with a negative computed tomographic scan and positive lumbar puncture (0%). The most common reason that a lesion was not detected on initial angiography was aneurysmal thrombosis (five patients). Magnetic resonance imaging of the brain and cervical spine detected one cervical ependymoma. Factors that may contribute to SAH, such as antiplatelet agent use and drug use, were found in 13 patients (13%). Adjunctive laboratory studies alerted practitioners to modifiable risk factors.
Conclusion: These data suggest useful modifications to current diagnostic paradigms for patients with angiographically negative spontaneous SAH.