Distal Hyperintense Vessels Alleviate Insula Infarction In Proximal Middle Cerebral Artery Occlusion

Purpose: Insula involvement in acute cerebral ischemia more likely causes penumbral loss and poor clinical outcome than infarct-sparing insula. Our objective was to prove the hypothesis that abundant collateral circulation represented by distal hyperintense vessels (HV) on MRI alleviates insula infarction and facilitates prognosis. Material and Methods: One hundred and fourteen stroke cases with M1 totally occlusion on MR angiography were documented consecutively from 2012 to 2014. The degree of HV was graded as absent, subtle or prominent. Clinical data were recorded retrospectively by reviewing the medical records. The infarct volume on diffusion-weighted image, along with National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS), was used to evaluate the clinical severity and prognosis. Results: The degree of HV was more abundant in insula-uninvolved stroke compared with stroke involving insula infarction (p= 0.026). Insula-involved stroke patients were older (p= 0.039) with a higher percentage of atrial fibrillation history (p= 0.042). Univariate analysis revealed that insula infarction, age, infarct volume and NIHSS predicted unfavorable prognosis of stroke, whereas HV had a favorable effect. The protective effect of HV was confirmed by multivariate analysis. Conclusion: HV is a protective barrier between insula infarction and severity of clinical symptoms among stroke patients.