We trained 24 trauma system-based emergency communication center (ECC) paramedics in the EMSA and compared the sensitivity, specificity, AUC, and 95% CI of ECC-guided prehospital EMSA for right versus left hemispheric ICA or M1 occlusions.

We enrolled 569 patients from September 2016 through February 2018 - 236 had a discharge diagnosis of stroke and 173 had a diagnosis of AIS. We excluded patients with bilateral (n=21) and brainstem (n=21) AIS. There were 64 patients with left hemispheric AIS including 19 with LVO. There were 67 patients with right hemispheric AIS including 22 with LVO. A score of ≥ 4 points yielded a sensitivity of 84.2 (95% CI = 60.4-96.6) and specificity of 66.7 (51.1-80.0) for left hemispheric LVO compared to a sensitivity of 68.2 (45.1-86.1) and specificity of 73.9 (58.9-85.7) for right hemispheric LVO. For predicting a left hemispheric LVO, the AUC was 0.77 (0.65-0.90) compared to 0.66 (0.50-0.82) for the right-sided LVO. Assigning 2 points for abnormal gaze yielded an AUC of 0.78 (0.66-0.91) versus 0.67 (0.52-0.83) for left and right hemispheric LVO, respectively.

The EMSA, like the NIHSS upon which it is based, is more sensitive to left compared to right hemispheric LVO. There is no comparable data on the right versus left hemisphere performance of other prehospital scales. There is a need to develop sensitive tests of right hemisphere dysfunction that are suitable for use in the field.