J Clin Neurol.  2013 Apr;9(2):97-102. 10.3988/jcn.2013.9.2.97.

Hemispheric Differences in Ischemic Stroke: Is Left-Hemisphere Stroke More Common?

  • 1Department of Neurology, University of Florida, Gainesville, FL, USA. vhedna@mail.ufl.edu
  • 2Department of Emergency Medicine, University of Florida, Gainesville, FL, USA.
  • 3Department of Neurosciences, University of Florida, Gainesville, FL, USA.
  • 4Department of Neurosurgery, University of Florida, Gainesville, FL, USA.


Understanding the mechanisms underlying stroke can aid the development of therapies and improve the final outcome. The purposes of this study were to establish whether there are characteristic mechanistic differences in the frequency, severity, functional outcome, and mortality between left- and right-hemisphere ischemic stroke and, given the velocity differences in the carotid circulation and direct branching of the left common carotid artery from the aorta, whether large-vessel ischemia (including cardioembolism) is more common in the territory of the left middle cerebral artery.
Trial cohorts were combined into a data set of 476 samples. Using Trial of Org 10172 in Acute Stroke Treatment criteria, ischemic strokes in a total 317 patients were included in the analysis. Hemorrhagic stroke, stroke of undetermined etiology, cryptogenic stroke, and bilateral ischemic strokes were excluded. Laterality and vascular distribution were correlated with outcomes using a logistic regression model. The etiologies of the large-vessel strokes were atherosclerosis and cardioembolism.
The overall event frequency, mortality, National Institutes of Health Stroke Scale (NIHSS) score, Glasgow Coma Scale score, and rate of mechanical thrombectomy interventions differed significantly between the hemispheres. Left-hemispheric strokes (54%) were more common than right-hemispheric strokes (46%; p=0.0073), and had higher admission NIHSS scores (p=0.011), increased mortality (p=0.0339), and higher endovascular intervention rates (p< or =0.0001). ischemic strokes were more frequent in the distribution of the left middle cerebral artery (122 vs. 97; p=0.0003) due to the higher incidence of large-vessel ischemic stroke in this area (p=0.0011).
Left-hemispheric ischemic strokes appear to be more frequent and often have a worse outcome than their right-hemispheric counterparts. The incidence of large-vessel ischemic strokes is higher in the left middle cerebral artery distribution, contributing to these hemispheric differences. The hemispheric differences exhibit a nonsignificant trend when strokes in the middle cerebral artery distribution are excluded from the analysis.


motor grade; collaterals; ischemic stroke; endovascular intervention; outcome after stroke; mortality after stroke; acute stroke; endovascular treatment; mechanical thrombectomy

MeSH Terms

Carotid Artery, Common
Chondroitin Sulfates
Cohort Studies
Dermatan Sulfate
Glasgow Coma Scale
Heparitin Sulfate
Logistic Models
Middle Cerebral Artery
National Institutes of Health (U.S.)
Chondroitin Sulfates
Dermatan Sulfate
Heparitin Sulfate
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