Risk factors for ischemic lesions following aneurysmal subarachnoid hemorrhage

The aim of this study was to test whether enoxaparin treatment (40 mg subcutaneously once daily) reduces the risk of cerebral infarction after subarachnoid hemorrhage (SAH) and to investigate predictive risk factors for permanent ischemic lesions visible on follow-up computerized tomography (CT) scans obtained 3 months after SAH.

After undergoing surgery for a ruptured aneurysm, 170 patients were randomized in a prospective, double-blind, placebo-controlled trial to test the effect of enoxaparin on the occurrence of ischemic lesions, which were demonstrated on follow-up CT scans available for 156 patients. The presence of lesions correlated highly with an impaired outcome, as assessed using both the Glasgow Outcome and modified Rankin Scales (p < 0.01). Lesions occurred in 101 (65%) of the 156 patients. In half of the patients (51 patients) no lesion was visible on the CT scan obtained on the 1st postoperative day in 51 patients. On univariate analysis, the presence of lesions at 3 months post-SAH was not associated with enoxaparin treatment but did correlate with several clinical, radiological, and prehemorrhage variables. Significant independent risk factors for lesions consisted of an impaired initial clinical condition (odds ratio [OR] 2.63, 95% confidence interval [CI] 1.03-6.73), amount of subarachnoid blood (OR 6.51, 95% CI 2.27-18.65), nocturnal occurrence of SAH (that is, between 12:01 a.m. and 8:00 a.m.; OR 4.32, 95% CI 1.28-14.52), fixed symptoms of delayed ischemia (OR 5.21, 95% CI 1.02-26.49), duration of temporary artery occlusion during surgery (OR 1.66 per minute, 95% CI 1.20-2.31), and body mass index (OR 1.13/kg/m2, 95% CI 1.01-1.28).

The presence of ischemic lesions can be predicted by the severity of bleeding, delayed cerebral ischemia, excess weight, duration of temporary artery occlusion, and occurrence of nocturnal aneurysm rupture.