Nonocclusion and Spontaneous Recanalization Rates in Acute Ischemic Stroke: a Review of Cerebral Angiography Studies

Background: Spontaneous recanalization is an understudied phenomenon in stroke. It is often overestimated by nonocclusion rates. The heterogeneity of the causes and manifestations of stroke and of the studies assessing vascular patency has created difficulties in assigning accurate rates of its incidence.

Methods: Systematic review of published articles about cerebral angiography in stroke.

Results: Lack of anticipated occlusions (nonocclusion rates) was noted in 28% of patients in suspected vessels 6 hours after stroke onset, whereas documented occlusions were noted in 17% of patients who underwent spontaneous lysis at 6 to 8 hours. At 3 to 4 days, the nonocclusion rate was 50% of studied vessels.

Conclusions: In the first 6 to 8 hours from stroke onset, spontaneous recanalization occurs in approximately 17% of patients, whereas nonocclusion exists in about 28% of patients and up to 50% by 4 days after stroke.