gms | German Medical Science

Objective: Recent data showed increasing numbers of cases of spontaneous nonaneurysmal subarachnoid hemorrhage (NASAH), which constitutes a heterogeneous group of patients, both perimesencephalic (PM-SAH) and non-perimesencephalic (NPM-SAH). The differences in clinical course and outcome between PM-SAH and NPM-SAH are evident and have to be taken into consideration at the time of admission. Although the clinical profile of patients with PM-SAH is well documented, there are scarce data available for patients with nonaneurysmal NPM-SAH. We therefore conducted a systematic review evaluating the clinical characteristics of patients with NPM-SAH and comparing those with PM-SAH.

Method: To identify relevant studies, we systematically searched PubMed without language restriction from 1995 through November 2015, evaluated the quality of selected studies and abstracted the data. We included peer-reviewed studies comparing the differences in clinical course at admission, during hospital stay and clinical outcome between patients with PM-SAH and NPM-SAH.

Results: Of the total of 143 titles, 24 studies were included in the systematic review. Data from 2137 patients with NASAH were extracted, containing two groups of perimesencephalic (n=964; 45%) and non-perimesencephalic (n=1173; 55%) SAH. According to the blood pattern patients with NPM-SAH were divided into Fisher 3 and non-Fisher 3 groups. A total of 210 (34,4%) NPM-SAH patients from 12 studies, included in our analysis, had a Fisher 3 blood pattern associated with a significant unfavorable outcome. The studied settings were patient characteristics at admission, including Hunt & Hess or WFNS classification (20/24 studies [83,3%]), clinical complications such as rehemorrhage, cerebral vasospasm, delayed ischemic deficit, hydrocephalus and ventriculoperitoneal shunt placement (21/24 [87,5%]), clinical outcome using modified ranking scale (mRS) or Glascow outcome scale (GOS) (17/24 [70,8%]), and antithrombotic treatment as a risk factor for NASAH (4/24 [16,7%]).

Conclusions: Contrary to PM-SAH, which is rarely associated with complications and long-term neurological dysfunction and disability, NPM-SAH, especially associated with Fisher 3 blood pattern, often demonstrates a worse condition at admission, and a less favorable clinical outcome, probably due to higher incidence of complications such as subsequent bleeding, hydrocephalus, and vasospasm.