Blood-brain barrier changes after experimental subarachnoid haemorrhage.

Cerebral vascular permeability and blood-brain barrier in the acute stage of subarachnoid haemorrhage were studied in experiments on cats. The bleeding was induced by a special method, imitating the natural course os subarachnoid haemorrhage. Fluorescence of the Evans blue injected intravitally was used as an indicator. It was found that one hour after the subarachnoid haemorrhage there are discrete diffuse spots of translucency related to the individual vessels, appearing bilaterally in the cerebral cortex and to a lesser extent in the white substance. Four hours after the bleeding, the extravasations and tissue staining become more widespread and confluent. There are more areas with disturbed blood-brain barrier, and they are better differentiated from the normal tissue. They are distributed bilaterally throughout the brain with predominance on the side of the bleeding vessel. The possible mechanisms of the blood-brain barrier disturbance afer subarachnoid haemorrhage are discussed.