Relation among aneurysm size, amount of subarachnoid blood, and clinical outcome.

OBJECT: The authors of recent reports have suggested that smaller aneurysms are associated with more extensive subarachnoid hemorrhage (SAH), which could potentially presage poor outcome in patients harboring these lesions. The authors reviewed their clinical experience to determine if this theory has a basis in truth.

METHODS: The authors undertook a retrospective review of a consecutive series of patients with aneurysmal SAH. Computed tomography scans and angiograms were studied to establish SAH scores and aneurysm size.

RESULTS: One hundred thirty-three patients were treated during a 2-year period (January 2003-December 2004). There were 101 female and 32 male patients whose mean age was 56.7 years. The location distribution of aneurysms that bled was as follows: anterior communicating artery (56 cases), posterior communicating artery (34 cases), middle cerebral artery (21 cases), posterior circulation (16 cases), and paraclinoid region (six cases). The mean aneurysm size was 6.2 mm (range 2-26 mm). The mean SAH score was 18.3 (not normally distributed, p < 0.01, D'Agostino-Pearson test). One hundred three patients underwent surgical exploration and placement of an aneurysm clip, 21 underwent deployment of a coil, and two underwent both therapies; seven patients died prior to intervention. No correlation was found between aneurysm size and SAH score (r(s) = -0.023, p = 0.8) or between small aneurysm size and poor Glasgow Outcome Scale score (p = 0.13). In fact, the trend was the opposite. The SAH score did, however, correspond strongly with the admission Hunt and Hess grade (p < 0.0001), indicating the strong correlation between grade and volume of intracranial blood. Outcome was best explained in the multivariate analysis by the following factors: admission Hunt and Hess grade, age, and clinical vasospasm (p < 0.0001) with the proportion of cases correctly classified as 79.7%.

CONCLUSIONS: Evaluation of the results in the present clinical series suggests that there is no relation between aneurysm size and volume of subarachnoid blood. The volume of cisternal blood correlates with Hunt and Hess grade but is not an independent determinant of outcome. Outcome is related to the following triad of well-established clinical factors: Hunt and Hess grade, age, and clinical vasospasm.