Angiogram-Negative Subarachnoid Hemorrhage: Relationship Between Bleeding Pattern and Clinical Outcome

Angiogram-negative subarachnoid hemorrhage (anSAH) accounts for 15% of spontaneous SAH. Recent studies suggest the outcome and diagnostic yield in anSAH differ based on initial bleeding pattern. We present a single-center experience in managing patients with SAH and negative initial digital-subtracted angiogram (DSA).

Records of all patients with anSAH were reviewed. Bleeding pattern was determined from computed tomography (CT) and was categorized as perimesencephalic (PMN), diffuse, cortical, or xanthochromia (blood not detectable by CT). Diagnostic yield, in-hospital complications, and outcome parameters were analyzed.

Of 352 patients admitted with spontaneous SAH from 2003 to 2008, 68 (19.3%) had negative initial DSA. Mean age was 59.5 ± 14, and 33 were female. By CT, 27 (39.7%) patients exhibited PMN SAH, 33 (48.5%) diffuse SAH, 6 (8.8%) cortical SAH, and 2 (2.9%) xanthochromia only. Sixty-one patients had good Hunt and Hess (H/H) grades (I–III) and seven had poor grades (IV–V). Additional diagnostic studies included repeat angiogram (54), brain and C-spine magnetic resonance imaging (20), and repeat CTA (15). A structural bleeding cause was determined in six (8.8%) patients, 4 of which had diffuse SAH and 2 cortical SAH. Among these, two aneurysms (2.9%) were detected and surgically clipped, and both had diffuse SAH. Twenty-nine patients (42.6%) experienced medical complications, with infection (18), cardiovascular problems (12), and vasospasm (10) being the most frequent events. Additional surgeries included 13 ventriculoperitoneal shunts, 4 tracheostomies, and 9 gastric tube placements. Favorable outcome (mRS = 0–2) was recorded in 49 (72.1%) patients and unfavorable (3–6) in 19 (17.49%), with 1 (1.2%) in-hospital death. Multivariable logistic regression revealed older age and diffuse bleeding pattern were significant predictors of unfavorable outcome.

The overall incidence of true aneurysms in patients with angiogram-negative SAH is low (2.9%). Initial bleeding pattern strongly correlates with diagnostic yield and clinical outcome. Diffuse bleeding pattern is associated with significantly higher diagnostic yield, more in-hospital complications, and worse clinical outcome. Patients with initial imaging characteristics other than diffuse pattern SAH developed few disease related complications, with the majority of in-hospital adverse events treatment related.