Published in 2003, it has been included as a tool in only a few case series 13 but will be used in a number of prospective trials currently being planned or underway.Ī thrombolysis in brain ischemia (TIBI) score has been derived for a transcranial sonography description of intracranial flow at the occlusion site 14 on the basis of flow-velocity signal intensity. 11 Subsequent to PROACT II, Higashida et al 12 made an attempt to standardize reporting of flow restoration and described a thrombolysis in cerebral infarction (TICI) score. 10 In the EKOS MicroLysUS feasibility trial of sonography-catheter–assisted thrombolysis, a TIMI flow score was ascribed by operators (ie, no core laboratory) to the recanalization of each occluded vessel and to each successive occluded vessel, without specific description of distal perfusion. The Prolyse in Acute Cerebral Thromboembolism (PROACT II) protocol called for application of the TIMI perfusion method of assessment, but then the final core laboratory analysis reported patency of the middle cerebral artery (MCA) M1 and M2 branches. Various authors have reported TIMI recanalization or TIMI perfusion scores, without fully describing the features of each grade and ignoring the issues of AOL recanalization versus distal perfusion. 9 It was applied to intracranial thrombolysis, though the TIMI score does not specifically describe both the recanalization effect and the distal perfusion effect simultaneously. The Thrombolysis in Myocardial Infarction (TIMI) score described distal flow perfusion and revascularization before and following therapy and became a standard for reporting cardiac reperfusion procedure efficacy. Others have followed Mori et al and Zeumer et al in their descriptions, with variations on the themes. Zeumer et al 8 described complete, partial, or no recanalization but did not clarify the magnitude of perfusion achieved, with no specific reference to flow in distal branches. Mori et al 7 first described a system that assessed both recanalization and perfusion following intravenous administration of recombinant tissue plasminogen activator (rtPA). Varying degrees of reperfusion occur via collateral sources and may be very effective in certain patients. 5, 6 Recanalization does not equal reperfusion, though total reperfusion does not occur without some recanalization. Incomplete recanalization may lead to reocclusion, with clinical deterioration. Variable distal patency and perfusion may be due to pre-existing emboli or emboli released by the recanalization procedure itself. Conversely, recanalization may be incomplete, sometimes with complete distal patency and perfusion, though at a reduced flow rate difficult to quantitate angiographically. Complete proximal recanalization with limited distal perfusion may be associated with a greater central hemorrhage risk into areas supplied by injured penetrating arteries subjected to altered pulse pressures. Complete recanalization of the primary occlusion may have variable distal patency and perfusion/reperfusion. Arteriographic demonstration of flow restoration or revascularization, in reality, has 2 components: recanalization of the original or primary arterial occlusive lesion (AOL) and reperfusion past the occlusion and into the distal arterial bed and terminal branches with tissue staining.
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