Associations of internal carotid artery stenosis and collateral circulation with cerebral edema after ischemic stroke

Cerebral edema is a life-threatening complication of ischemic stroke. In patients with stroke in anterior circulation, the development of cerebral edema is influenced by the stenosis of ipsilateral internal carotid artery (ICA), as well as the stenosis of contralateral ICA and status of collateral circulation. With this hypothesis, we aimed to investigate the morphological features of bilateral ICAs, the circle of Willis, and leptomeningeal collaterals for their associations with cerebral edema after acute ischemic stroke.

In this retrospective cohort study, we included patients with ischemic stroke in anterior circulation, who had head and neck computed tomography (CT) angiography within 24 hours of stroke onset. Brain CT/magnetic resonance imaging (MRI) was performed for each patient within 24 hours and between 24 hours and 7 days after stroke onset, respectively. Cerebral edema was defined as midline shift (MLS) and the maximal distance (in millimeter) of brain structure shifted from the midline was measured within 24 hours (24h-MLS) and within 7 days (7d-MLS).

We enrolled 408 patients (median age 71.0 years, male 60.7%), of whom 80 patients (19.6%) developed MLS within 24 hours and 142 patients (34.8%) developed MLS within 7 days. In multivariable logistic regression, severe stenosis to occlusion of ipsilateral cervical ICA was associated with an increased risk of the presence of 24h-MLS [adjusted odds ratio (OR) 2.922, 95% confidence interval (CI): 1.126-7.583, P=0.028] and severe stenosis to occlusion of contralateral cervical ICA was associated with an increased risk of the presence of 7d-MLS (adjusted OR 5.896, 95% CI: 1.723-20.173, P=0.005). Compared to none or minor stenosis, severe stenosis to occlusion in ipsilateral cervical ICA was associated with higher degree of 24h-MLS (P<0.001), and moderate stenosis (P=0.039) and severe stenosis to occlusion (P=0.014) in contralateral cervical ICA were associated with higher degree of 7d-MLS, respectively. The incompleteness of circle of Willis was not associated with the presence of MLS (P>0.05). Poor leptomeningeal collaterals were associated with the presence of 24h-MLS (P<0.001) and 7d-MLS (P<0.001), but the associations were not significant in multivariable regression after adjusting for the effect of clinical and imaging factors.

In patients with acute ischemic stroke in anterior circulation, severe stenosis to occlusion of ipsilateral cervical ICA was associated with the presence of MLS within 24 hours of stroke onset, and severe stenosis to occlusion of contralateral cervical ICA was associated with the presence of MLS within 7 days.