Beretta, S.; Carone, D.; Cho, T.-H.; Vigano, M.; Diamanti, S.; Mariani, J.; Pedrazzini, F. A.; Bianchi, E.; Pini, C.; Bolbos, R.; Wiart, M.; Ferrarese, C.; Chauveau, F.

We investigated the therapeutic effect of head down positioning at -15{degrees} (head down tilt; HDT15) on cerebral collateral flow and infarct growth in a rat model of large vessel occlusion (LVO) stroke, using multimodal MRI. Twenty-eight Wistar rats were randomly assigned to HDT15 or flat position for 60 minutes, starting 30 minutes after occlusion of the middle cerebral artery, followed by reperfusion. The perfusion shift analysis, comparing post- versus pre-treatment voxel-level changes in time-to-peak perfusion maps, showed a significant increase in cerebral perfusion in the HDT15 group (common odds ratio 1.50; 95% CI 1.41-1.60; p < 0.0001), but not in the flat group (common odds ratio 0.97; 95% CI 0.92-1.03; p = 0.3503). Infarct growth at 24 hours was + 31.4% in the flat group (343 versus 250 mm3; 95% CI 2.4 to 165.1; p = 0.0447) and + 15.4% in the HDT15 group (224 versus 192 mm3; 95% CI -26.9 to 85.9; p = 0.2272). Our findings indicate that HDT15 acutely increases cerebral perfusion in LVO acute ischemic stroke and provides a tissue-saving effect before recanalization. Further research is needed to develop HDT15 as an emergency therapy to acutely increase collateral flow in ischemic stroke prior to recanalization therapy.