Figure 2.

Pre- and post-test probability of large vessel occlusion (LVO) when using the Los Angeles Motor Scale (LAMS) with its typical cut-off of LAMS ≥4. Of course, the National Institutes of Health Stroke Scale (NIHSS) is not typically determined in the pre-hospital setting, but we show it here as a quantification of the manifest stroke severity observed by the pre-hospital team. We also show what the post-test probabilities would be with hypothetical pre-hospital technologies that achieve a slightly better positive likelihood ratio (+LR) of 3.00 (vs. 2.17 for LAMS) and a much better +LR of 19.00, including at the mildest end of the severity spectrum, to which current scales are likely insensitive. Such technologies would be especially valuable if ongoing trials of endovascular therapy (EVT) in low-NIHSS populations are positive.