Experimental intracerebral haematoma: the role of blood constituents in early ischaemia.

In patients with intracerebral haematoma, ischaemic damage and final outcome are often more serious than the size of the lesion would suggest. The aetiology of the ischaemia in relation to space-occupying effects or specific factors present in blood is unclear. In a rat model of an intracerebral space-occupying lesion, the pathophysiological effects of a haematoma were compared with those of an equal volume of inert fluid (mock cerebrospinal fluid [CSF] or silicone oil). Cerebral blood flow was measured at 1 min by 14C iodoantipyrine autoradiography, and ischaemic cell damage was assessed by light microscopy at 4 h. In all animals, cerebral blood flow was reduced immediately adjacent to the lesion. In the group with a haematoma, blood flow was reduced (p less than 0.001) over a greater radius and also in the ipsilateral frontal and parietal cortex. Ischaemic damage was seen in animals lesioned with blood or oil of blood viscosity, but not in animals with CSF lesions. These data suggest that both tissue pressure and vasoactive substances are components of the immediate reduction in blood flow following intracranial haemorrhage. Tissue pressure may be the more important factor in later ischaemic neuronal damage.