Determinants of Central Sympathetic Activation in Spontaneous Primary Subarachnoid Hemorrhage

Background Subarachnoid hemorrhage (SAH) has been associated with pronounced acute sympathetic activation. The purpose of this investigation is to identify demographic, clinical, radiological, and anatomical features of SAH that relate to sympathetic activation. Methods Observational study of consecutive Grades 3–5 SAH patients requiring ventriculostomy and undergoing endovascular aneurysmal obliteration. All patients underwent cerebrospinal fluid (CSF) sampling within 48 h of SAH onset, and samples were assayed for various catecholamine compounds and metabolites. Univariate analyses were performed to identify variables associated with catecholamine levels, and to correlate linearity among catecholamine compounds and metabolites. Variables demonstrating a possible association and variables of interest were entered into linear regression models to determine predictors of catecholamine elevations. Results Of the 102 patients, mean age was 58 years and 74% were female; 42% were Hunt–Hess (H/H) grade 4/5, 61% had a computed tomography (CT) score of 3/4, 57% had anterior cerebral or communicating artery (ACA/ACom) aneursysms, and 23% had aneurysms in the posterior circulation. In the univariate analysis, age, gender, H/H grade, CT score, and aneurysm location demonstrated various associations with catecholamine levels, and substantial positive correlations existed between the various catecholamine compounds and metabolites. Linear regression analyses revealed H/H grade to be an independent predictor of elevated CSF epinephrine (EPI), 3,4-dihydroxyphenylalanine (DOPA) and 3,4-dihydroxyphenyl acetic acid (DOPAC) levels, and of the norepinephrine/3,4-dihydroxyphenylglycol (NE/DHPG) ratio ( p < 0.05 for all analyses). Female gender independently predicted increased dopamine (DA) and DOPAC levels ( p < 0.05 for two analyses), as well as possibly DOPA levels ( p < 0.1). Age, CT score and aneurysm location demonstrated only inconsistent associations and trends. Conclusions Central sympathetic activation relates to clinical severity and female gender. No definitive associations were found for age, hemorrhage amount, or aneurysm location.