Cerebral vasospasm after aneurysmal subarachnoid hemorrhage (SAH) is associated with the volume and location of subarachnoid blood clots. Factors that influence the volume of SAH have seldom been studied.METHODS
Two independent sets of data were analyzed. Data from 3028 patients with SAH enrolled in four clinical trials of the drug tirilazad were analyzed in addition to data from 74 patients with SAH who underwent digital volumetric analysis of admission computed tomographic scans to determine the subarachnoid clot volume. In the smaller sample of 74 patients, aneurysm width, length, neck size, aspect ratio, and volume were measured on diagnostic cerebral angiograms. Statistical inference bearing on the question of what factors are associated with clot volume was derived by univariate methods, including analysis of variance, χ2 and t tests, and polytomous logistic regression.RESULTS
Of 22 clinical parameters examined by univariate analysis of the tirilazad dataset, age, World Federation of Neurological Surgeons (WFNS) clinical grade, time from SAH to admission, history of hypertension or diabetes mellitus, aneurysm location, and admission diastolic and systolic blood pressure were correlated with the subarachnoid clot volume (P < 0.05). Polytomous logistic regression found that only age, WFNS grade, time to admission, admission systolic blood pressure, and history of hypertension were higher in patients with larger subarachnoid clots (P < 0.05). Analysis of 74 patients with quantitative subarachnoid clot volumes also found that age and WFNS grade were higher in patients with larger subarachnoid clots (P < 0.05). No aneurysm location or measurement of aneurysm size showed a statistically significant relationship to clot volume in either dataset.CONCLUSION
SAH volume is correlated with clinical characteristics, including age, history of hypertension, admission systolic blood pressure, and WFNS grade. Anatomic aneurysm characteristics such as size and location do not reliably predict clot volume.