Blood-brain barrier and ischaemic brain oedema.

According to classification of brain oedema into the cytotoxic and vasogenic types, the latter is closely related to the changes in permeability of the BBB. In cerebral ischaemia, although both types of oedema are involved, the important role of vasogenic oedema, associated with BBB changes, is increasingly recognized. This particularly applies to temporary arterial occlusions in which a biphasic character of two independent BBB openings has been described. The first opening, related mainly to haemodynamic factors, allows leakage of serum proteins into brain tissue and induces vasogenic oedema. The intensity of this oedema can be diminished by reducing the reactive hyperaemia, which promptly follows the release of arterial occlusion. According to recent investigations, infusion of aminophylline appears to be promising in this respect. The other circulatory disturbance, which can affect development of post-ischaemic oedema, is related to the post-ischaemic hypoperfusion which follows reactive hyperaemia. The repeated ischaemic insults during the period of hypoperfusion lead to a pronounced cumulative effect intensifying greatly ischaemic brain oedema and tissue injury.