“…Among these variables, some have been proposed, like the patient's age and gender [22,23,33,35,36,47,48], the neurological status at presentation (Hunt & Hess and WFNS scales) [12, 20-22, 25, 27, 47, 48], the amount of cisternal blood on the first CT scan (Fisher and BNI scales) [12, 16, 21-23, 25, 35, 47], the presence of acute hydrocephalus on the first CT scan and the need for external ventricular drain (EVD) [1, 12, 21-23, 25, 27, 33, 36, 43, 47, 48], the duration of EVD treatment [25,48], aneurysms location and size [9,22,25,33,36,47], the type of treatment for aneurysm exclusion (endovascular or surgical) [9,25,35,36,50], the onset and duration of posttreatment complications (i.e., fever and/or infections) [25,27,36,47,50], the duration of blood clearance detected on serial CT scans [29], and altered values of blood or cerebrospinal fluid (CSF) markers [27,31,46]. Some meta-analyses [11,45,47,50] have synthesized this information, and scores for risk stratification have been proposed to be used in the clinical practice [5,12,13,21,27], whose validity, however, has not yet been confir...…”