Willisian collateral and carotid stenosis during large vessel occlusion stroke: Observations from computed tomography angiography.

OBJECTIVE: The larger (≧1 mm) conducting and distributing arteries to the brain are sources of collateral during acute stroke, and include the cervical carotid, ophthalmic, and Circle of Willis (CoW) vessels. This study assessed their anatomy for relationships with stroke severity in large vessel occlusion (LVO), and with common grading scales of cerebral collateral. METHODS: One hundred consecutive endovascular thrombectomy (EVT) patients had imaging measurements made on 16 large (≧1 mm) candidate arteries visualized on axial source computed tomography angiography (CTA). Admission National Institutes of Health Stroke Scale score (NIHSS), Alberta Stroke Program Early CT Score (ASPECTS), and multiphasic CTA collateral scores were used as outcome measures. RESULTS: Ophthalmic arteries show a significant connection with stroke severity and collateral scores. A 1-mm increase in ophthalmic artery diameter leads to a lower NIHSS score of 4.8 points (p<0.008) in multivariable analysis, and 1.53-point increase in ASPECTS (p<0.001). The opposite applies to the contralateral ophthalmic: a 6.3-point higher NIHSS score and 2.6-point drop in ASPECTS. CONCLUSIONS: Native collateral and stroke severity scores are significantly affected by ophthalmic artery size.