Background: Considering the recent advances in endovascular thrombectomy and advances in neurocritical care of patients with intracranial hemorrhage (ICH), there is an urgent need to develop tools for paramedics to identify patients likely to benefit from direct routing to comprehensive stroke centers (CSC). We report prospective validation of the Los Angeles Motor Scale (LAMS) performed by paramedics in the field, and compare its performance with other proposed prehospital LVO-identification scales.
Methods: We analyzed all subjects enrolled in the NIH Field Administration of Stroke Therapy -Magnesium (FAST-MAG) trial transported directly to an academic center with a policy of performing immediate CTA or MRA imaging for all likely strokes. Prehospital LAMS was performed by paramedics prior to field enrollment. Hospital arrival (HA) LAMS and NIHSS were performed by trained study nurses after ED arrival. RACE, PASS, and 3i SS scales were calculated from NIHSS items. LVO in a proximal cerebral artery (ICA, MCA M1 & M2, Vertebral, Basilar and PCA P1 & 2) was determined by 3 vascular neurologists with expertise in neuroimaging. An LVO or ICH were considered as CSC appropriate patients.
Results: Among 94 patients, age was 68 (±13) and 49% were female. Final diagnoses were acute cerebral ischemia in 71 (76%), intracranial hemorrhage in 18 (19%), mimic in 5 (5%). Overall, 48 patients (68%) had LVO, including MCA (30), ICA (14), basilar (1), vertebral (1) and PCA (2), and 66 (70%) were CSC-appropriate (LVO or ICH). In prediction of LVO, prehospital LAMS had the highest sensitivity (71%) and moderate specificity (54%). 3i-SS had the highest specificity (83%) but lowest sensitivity (40%). In prediction of CSC-appropriate patients, prehospital LAMS had the highest sensitivity (69%) and 3i-SS had the highest specificity (93%) but lowest sensitivity (37%). When comparing receiver operating curves, PM LAMS had AUC of 0.761, HA RACE 0.752, HA 3i SS 0.732, and HA PASS 0.712.
Conclusions: Prehospital LAMS score of 4 or higher identified CSC-appropriate patients with good sensitivity and moderate specificity, and performed similar to or better than other proposed scales. LAMS is easy to administer and reproducible, and widely used currently by paramedics nationwide.