Background: The Los Angeles Motor Scale (LAMS) is a rapid pre-hospital scale used to predict stroke severity which has also been shown to accurately predict large vessel occlusions (LVOs). However, to date there is no study exploring whether LAMS correlates with the computed tomography perfusion (CTP) parameters in LVOs. Methods: Patients with LVO between September 2019 and October 2021 were retrospectively reviewed and included if the CTP data and admission neurologic exams were available. The LAMS was documented based on emergency personnel exams or scored retrospectively using an admission neurologic exam. The CTP data was processed by RAPID (IschemaView, Menlo Park, CA, USA) with an ischemic core volume (relative cerebral blood flow [rCBF] < 30%), time-to-maximum (Tmax) volume (Tmax > 6 s delay), hypoperfusion index (HI), and cerebral blood volume (CBV) index. Spearman’s correlations were performed between the LAMS and CTP parameters. Results: A total of 85 patients were included, of which there were 9 intracranial internal carotid artery (ICA), 53 proximal M1 branch middle cerebral artery M1, and 23 proximal M2 branch occlusions. Overall, 26 patients had LAMS 0–3, and 59 had LAMS 4–5. In total, LAMS positively correlated with CBF < 30% (Correlation Coefficient (CC): 0.32, p < 0.01), Tmax > 6 s (CC:0.23, p < 0.04), HI (CC:0.27, p < 0.01), and negatively correlated with the CBV index (CC:−0.24, p < 0.05). The relationships between LAMS and CBF were < 30% and the HI was more pronounced in M1 occlusions (CC:0.42, p < 0.01; 0.34, p < 0.01 respectively) and proximal M2 occlusions (CC:0.53, p < 0.01; 0.48, p < 0.03 respectively). The LAMS also correlated with a Tmax > 6 s in M1 occlusions (CC:0.42, p < 0.01), and negatively correlated with the CBV index in M2 occlusions (CC:−0.69, p < 0.01). There were no significant correlations between the LAMS and intracranial ICA occlusions. Conclusions: The results of our preliminary study indicate that the LAMS is positively correlated with the estimated ischemic core, perfusion deficit, and HI, and negatively correlated with the CBV index in patients with anterior circulation LVO, with stronger relationships in the M1 and M2 occlusions. This is the first study showing that the LAMS may be correlated with the collateral status and estimated ischemic core in patients with LVO.

The Los Angeles Motor Scale (LAMS) is a rapid pre-hospital scale used to predict stroke severity. LAMS has also been shown to accurately predict large vessel occlusions (LVOs), however, to date there is no study exploring whether LAMS correlates with CT perfusion (CTP) parameters used to decide mechanical thrombectomy (MT) candidacy. The aim of this study is to elucidate the potential relationship between LAMS and these CTP parameters. We retrospectively reviewed patients with LVO between September 2019 and October 2021. Patients were included if they had available CTP data and neurologic exam on admission. LAMS was documented based on EMS exam or scored retrospectively based on admission neurologic exam. CTP data was processed by RAPID (IschemaView, Menlo Park, CA) with ischemic core volume (rCBF < 30%), Tmax volume (Tmax > 6 second delay), hypoperfusion index (HI), and CBV index. Spearman’s correlations were performed between LAMS and the aforementioned CTP parameters. Eighty-five patients were included, of which 11 had intracranial internal carotid artery (ICA) occlusions, 52 had M1 occlusions, and 22 had proximal M2 occlusions. Of all patients, 26 had LAMS of 0-3, and 59 had LAMS of 4-5. In all cases, LAMS was positively correlated with CBF <30% (Correlation Coefficient (CC): 0.32, p < 0.01), Tmax > 6 s (CC:0.23, p< 0.04), HI (CC:0.27, p < 0.01), and negatively correlated with CBV index (CC:-0.24, p < 0.05). These relationships between LAMS and CBF < 30% and HI were more pronounced in M1 occlusions (CC:0.42, p< 0.01; 0.34, p< 0.01 respectively) and proximal M2 occlusions (CC:0.53, p<0.01; 0.48, p< 0.03 respectively). LAMS also correlated with Tmax > 6 s in M1 occlusions (CC:0.42, p< 0.01), and negatively correlated with CBV index in M2 occlusions (CC:-0.69, p< 0.01). There was no significant correlation between LAMS and CTP parameters in intracranial ICA occlusions. Our results indicate that LAMS is positively correlated with estimated ischemic core, perfusion deficit, and HI, and negatively correlated with CBV index in patients with LVO. Vessel based analyses reveal stronger correlations with M1 and M2 occlusions. This is the first study showing that the LAMS may be correlated with estimated ischemic core and collateral status parameters in patients with LVO.