Head-down tilt 15° increases cerebral perfusion before recanalization in acute ischemic stroke. A pre-clinical MRI study.

We investigated the therapeutic effect of head-down tilt at -15° (HDT15) on cerebral collateral flow and early infarct growth in a rat model of large vessel occlusion stroke, using multi-modal MRI. Endovascular occlusion of the proximal middle cerebral artery was induced for 90 min in Wistar rats (n = 28), followed by reperfusion. Rats were randomly assigned to HDT15 or flat position for 60 min, starting 30 min after occlusion. Multi-modal brain MRI, including perfusion, angiographic and structural sequences were acquired before treatment, after 60 min of treatment and 24 h after reperfusion. The primary outcome was change in cerebral perfusion after the 60-min treatment, assessed by time-to-peak (rTTP), adjusted for baseline collateral score. The secondary outcome was infarct growth in the first 24 h. The perfusion shift analysis, comparing post- versus pre-treatment changes in time-to-peak 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). Early infarct growth at 24 h was +15.4 % in the HDT15 group (224 versus 192 mm3; 95 % CI -26.9 to 85.9; p = 0.2272) and + 31.4 % in the flat group (343 versus 250 mm3; 95 % CI 2.4 to 165.1; p = 0.0447). In conclusion, MRI-based analysis indicated that HDT15 acutely increased cerebral perfusion in large vessel occlusion and exerted a tissue-saving effect before recanalization in experimental ischemic stroke.