Blood-brain barrier permeability derangements in posterior circulation ischemic stroke: frequency and relation to hemorrhagic transformation

Abstract

Background: Early disruption of the blood-brain barrier (BBB) due to severe ischemia can be detected by MRI T2* permeability imaging. In middle cerebral artery (MCA) infarction, pretreatment T2* permeability derangements have been found in 22% of patients and are powerful predictors of hemorrhagic transformation after revascularization therapy. The frequency, clinical correlates, and relation to hemorrhagic transformation of permeability derangements in posterior circulation have not been previously explored, and may differ as ischemia volume and collateral status are different between vertebrobasilar and MCA infarcts.

Methods: We analyzed clinical and pretreatment MRI data on consecutive patients undergoing recanalization therapy for acute vertebrobasilar ischemia at a medical center November 2001 through September 2009. Pretreatment MRI permeability images were derived from perfusion source imaging acquisitions. Permeability abnormality was detected as persisting increased signal intensity at later time points in perfusion MRI acquisition, indicating local accumulation of contrast caused by BBB leakage.

Results: Among the 14 patients meeting study entry criteria, mean age was 71.1 years and median pretreatment NIHSS was 20.5. Permeability imaging abnormality was present in 1 of the 14 patients (7%). Among 14 patients, post-treatment parenchymal hematoma occurred in one and more minor degrees of hemorrhagic transformation in four. The one patient with pretreatment permeability abnormality was the patient to develop post-treatment parenchymal hematoma (Fisher's exact test, P=0.07).

Conclusion: Pretreatment permeability abnormality, an indicator of BBB derangements, is an infrequent finding in acute posterior circulation ischemic stroke and may be associated with an increased risk of parenchymal hematoma development undergoing recanalization therapy.

Figure 1

Pretreatment magnetic resonance imaging and post-treatment computed tomographic (CT) findings in a patient (patient 14) with parenchymal hematoma. Diffusion sequence shows right pontine infarct (arrowhead) (A); perfusion sequence demonstrates delayed mean transient time in right pons (arrowhead) (B); and permeability image shows abnormality hypointensity in right pons (arrowhead) (C). The area of hypodensity on this permeability-image indicates tissue with breakdown of the blood-brain barrier and consequent contrast-staining of the parenchyma on late T2* images following bolus administration. Post-treatment CT show pontine hematoma and subarachnoid hemorrhage (arrowhead) (D).