Model of minor stroke with mild peri-infarct ischemic injury

Background: Transient ischemic attack, minor stroke and stroke recurrence need improved treatment but lack animal models for research. Tile aim was to modify photothrombosis methods thereby producing both a minor stroke (with adjacent mild damage) or a minor recurrent stroke. New method: A minor stroke, as detected using magnetic resonance imaging and histology, was produced using a low intensity beam of white light with a bright centre, a low dose of Rose Bengal and a short 5 min illumination of thinned skull. A recurrent minor stroke was produced by repeating the procedure two days later except the cortical mask was positioned 1.5 mm posteriorly. Results: The minor photothrombosis procedure produced a small superficial infarct surrounded by a region of scattered necrosis detected histologically. Marked hyperintensities in diffusion weighted and T-2 images identified the infarct. Peri-infarct regions with modest T-2 increases corresponded to regions of scattered cell death. A recurrent minor photothrombosis produced additional damage in regions with overlapping mild injury. Comparison with existing methods: Previous photothrombosis methods usually produce large cortical infarcts with little penumbra. The current method produces small infarcts with diffuse mild peri-infarct ischemic injury that can be diagnosed using T-2 imaging. Conclusions: The modified photothrombotic procedure will produce a minor stroke consisting of a small infarct in a region with marked diffusion and T-2 hyperintensities and a peri-infarct region of selective necrosis with modest T-2 changes. Minor recurrent stroke is readily produced but imaging is key for assessing size and location of each insult. (C) 2016 The Authors. Published by Elsevier B.V.