Objective Recent data have shown increasing numbers of non-aneurysmal subarachnoid hemorrhage (NASAH). However, data are limited and often only small series have been published. Our objective was to analyze the rate of cerebral vasospasm (CVS), delayed cerebral infarction (DCI), and their influence on the clinical outcome, especially in patients with diffuse Fisher 3 bleeding pattern NASAH (Fi3).

Methods Between 1999 and 2014, 225 patients had NASAH. CVS, DCI, and outcome (according to the modified Rankin Scale at 6 months) were analyzed retrospectively. Patients were stratified according to the bleeding type. After univariate analysis a multivariate analysis was performed and NASAH Fi3 was also compared with aneurysmal SAH Fi3.

Results Patient characteristics and the outcome of perimesencephalic (PM) and non-PM (NPM) SAH were similar. Excluding Fi3, PM and NPM without Fi3 had similar patient characteristics, clinical course, and outcome. In particular, the Fi3 subgroup had a significantly increased risk of CVS, DCI, unfavorable outcome, hydrocephalus, and death. Early hydrocephalus was associated with Fi3 and intraventricular hemorrhage. The multivariate regression model showed the variables elderly patients, Fi3, and early hydrocephalus as independent and significant predictors for an unfavorable outcome. A further comparison of NASAH Fi3 with aneurysmal SAH Fi3 showed similar characteristics, CVS rate, and mortality.

Conclusions Patients with NASAH without a Fi3 bleeding pattern had a similar excellent outcome to patients with PM-SAH. Patients with Fi3 had a high risk for early hydrocephalus, CVS, DCI, and an unfavorable outcome, similar to patients with aneurysmal SAH. After multivariate analysis, early hydrocephalus, elderly patients, and Fi3 were identified as negative prognostic factors. Therefore, patients with Fi3 are at risk and need careful clinical observation.