1160. Non-traumatic Angiographically Negative SAH and Characterization of Associated Risk Factors: a Single Center Study

Authors: Saeed Sam Sadrameli, MD, MS; Meng Huang, MD; Rajan Gadhia, MD; Todd Trask, MD; Gavin Britz, MD (Houston, TX)

Introduction: Non-traumatic angiographically negative subarachnoid hemorrhage (ANSAH) represents about 15% of all SAH. Etiological theories suggest rupture of anomalous venous tributaries or small basilar perforating arteries. Valsalva maneuvers are associated with ictus an average of36% of the time.Recently, an association with antiplatelet use and ANSAH has also been reported.We aim toevaluate and report our institution’s clinical demographics and outcomes of ANSAH patients and any other associated factors. Methods: We retrospectively reviewed the Houston MethodistNeurological Institute Stroke database from 2016-2018 with CPT forcerebral angiography and ICD9/10 codes for SAH. Twenty-seven cases without positive angiographic structural lesions were identified for review.All available clinicaldata were reviewed including age, sex, SAH etiology, SAH location, Hunt Hess Score, Fisher Score, anti-platelet/anticoagulant medication, need for EVD acutely and or VPS chronically, other pathology found on angiogram, incidence of vasospasm, and long term follow up modified rankin outcome score. Results: Thirteen males and 14 females were reviewed. The average age on presentation was 59. There was no correlation between the etiology of SAH (spontaneous vs post coital) and HH/F scores or 90-day mRS. 11.1% of patients developed late onset hydrocephalus and required a VPS. Patients who were not on anti-platelet/anticoagulation medications had more favorable 90-day mRS outcomes (p = 0.044). Six patients required placement of EVD and all were males. Conclusions: Non-traumatic angiographically negative SAH presents with a benign clinical picture with a Hunt Hess score of 3 or below, despite often having significant basal cisternal SAH volume and high Fisher grade. There seems to be a correlation between presence of anti-platelet/anticoagulation on admission and worse long term clinical outcome. Our study also indicates male dominance when analyzing need for EVD (p = 0.006).