Comparison of cerebral blood flow and injury following intracerebral and subdural hematoma in the rat

Subdural hematomas (SDH) can induce ischemia and neuronal damage in the und erlying cortex. However, the extent to which intracerebral hematomas (ICH) produce reductions in cerebral blood flow (CBF) sufficient to cause ischemi c damage is uncertain. Intracranial hemorrhage was induced by the injection of 100 or 200 mu l of blood into the subdural space (SDH) or into the caud ate nucleus (ICH) of the rat. CBF was measured using [C-14]-iodoantipyrine autoradiography at 4 h. Brain damage was measured using 2,3,5-triphenyl tet razolium chloride (TTC) staining at 24 h and brain edema was measured using the wet/dry weight method. Brain ion contents were measured at 24 h using a flame photometer and chloridometer. In the CBF studies, the volume of tis sue perfused below the ischemic threshold (< 20 ml/100 g/min) for SDH was 1 22 +/- 35 mm(3) (sham: 3.3 +/- 1.7 mm(3)). Following ICH, there was a small volume of tissue perfused below the ischemic threshold 50 +/- 11 mm(3) (sh am: 3.3 +/- 2.5 mm(3)) but this volume corresponded closely to the volume o f clot (71 +/- 5 mm(3)). The extent of brain damage, measured by TTC staini ng, in the cerebral cortex correlated with the increasing volume of the sub dural blood clot (sham: 9 +/- 3 mm(3); 200 mu l: 81 +/- 19 mm(3); P < 0,01) . Conversely, minimal brain damage was detected following ICH, The injectio n of blood into the subdural space or into the brain parenchyma induced blo od volume-dependent increases in brain water content at 24 h. Increases in brain water content after SDH, were confined to the cerebral cortex (sham: 0.1 +/- 0.1 g/g dry weight; 200 mu l: 0.8 +/- 0.3 g/g dry weight; P < 0,001 ). In contrast, increases in brain water content after ICH were predominant ly in the subcortical region (sham: 0.1 +/- 0.1 g/g dry weight; 200 mu l: 0 .4 +/- 0.2 g/g dry weight; P < 0.01). The present investigations demonstrat e differences in CBF, brain injury and edema formation following SDH and IC H indicating that these conditions may require different therapeutic interv entions. (C) 1999 Elsevier Science B.V. All rights reserved.