Subarachnoid hemorrhage on computed tomography scanning and the development of cerebral vasospasm: the Fisher grade revisited

Abstract

Background The Fisher grade (FG) is widely used to predict cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH). We revisited the grading scale to determine its validity in the era of modern management. Methods We retrospectively reviewed the records of 134 patients with SAH. The amount and distribution of subarachnoid blood on admission computed tomography (CT) scan was quantified according to the FG and compared with development of symptomatic vasospasm. Results We reviewed 134 patients (median age, 54) who presented with aneurysmal SAH. Six (5%) were FG 1, 34 (25%) were FG 2, 25 (19%) were FG 3, and 69 (51%) were FG 4. Symptomatic vasospasm developed in no (0%) FG 1, 8 (24%) FG 2, 7 (28 %) FG 3, and 13 (19%) FG 4 patients (28 of 134 total patients; 21%). Development of symptomatic vasospasm was not associated with admission FG, Hunt and Hess grade, age, sex, or location of blood on presenting CT scan. Elevated transcranial Doppler blood flow velocity was associated with blood in the basal cisterns ( P = .0047), lateral ventricles ( P = .026), or blood in any ventricle ( P = .04). Postoperative angiograms were obtained in 57 patients; moderate to severe vasospasm was observed in 5 (15%) FG 2, 6 (24%) FG 3, and 14 (20%) FG 4 patients. Twenty patients (71%) with symptomatic vasospasm had moderate or severe angiographic vasospasm. Angiographic vasospasm was associated with intraventricular blood ( P = .054) but not with FG. Conclusions Symptomatic vasospasm occurred in 21% of cases. The FG correlated with symptomatic vasospasm in only half the patients. A new predictive CT grading scale for vasospasm may be necessary.