RESUMO
<p><b>OBJECTIVE</b>There are a great number of modified models based on the four-vessel occlusion (4VO) model of Pulsinelli and Brierley which has been used worldwide for brain ischemia research. However, up to now the problems of collateral circulations of 4VO and the difficulty in arranging a surgery to occlude the basilar artery in other models are not satisfactorily solved yet. In this study, an improved 4-vessel occlusion (I4VO) rat model which is easy to handle and able to decrease the effect of collateral circulation is reported.</p><p><b>METHODS</b>The common carotid arteries and the beginning of the subclavical arteries of rats were occluded for different time by one-stage apertura thoracis superior approach. Neurological deficit scores defined by the modified Garcia scoring system and histopathological method were used to evaluate the effects of this model up to 7 days after reperfusion.</p><p><b>RESULTS</b>The neurological scores in the 15-min and 25-min groups decreased significantly at 24, 48 and 72 hours after reperfusion (P less than 0.05), and the histopathologic study showed that there were stable, symmetrical changes of lesions in bilateral hippocampus in all the ischemia samples from two ischemia groups compared with sham operated group (P less than 0.05).</p><p><b>CONCLUSION</b>This modified model is safe, easy, reliable, stable, mini-invasive as well as time-saving in making bilateral hemispheric ischemia, which can effectively decrease collateral circulations and meanwhile lead to stable lesions in hippocampus and cortex.</p>