To enhance pre-hospital LVO triage with Vision, Aphasia, Neglect (VAN) by including asymmetric, bilateral weakness.

The prehospital stroke severity assessment VAN identifies unilateral arm or hand weakness to predict large vessel occlusion (LVO). However, LVO may also present with bilateral upper extremity (BUE) weakness which can be symmetric or asymmetric. We utilized our local VAN database to determine if the presence of asymmetric BUE weakness improves accuracy for LVO detection.

Paramedics from two Emergency Medical Services (EMS) agencies documented a pre-hospital VAN assessment from June 2017 through Dec 2019 for all stroke alerts less than 6 hours from last known well. The prehospital VAN score, emergency department (ED) NIHSS upon arrival, advanced neuroimaging interpretation, and hospital discharge diagnosis were collected from three comprehensive stroke centers. The ED NIHSS was used to categorize BUE weakness into symmetric or asymmetric. Patients without ED NIHSS documented upper extremity weakness were excluded.

Using ED NIHSS, BUE weakness was noted in 20 VAN positive patients which included 10 asymmetric and 10 symmetric. Chi-square test with Yates correction demonstrated a significant association between BUE weakness type and LVO (χ²=5, p<0.05). LVO was identified in 8 of 10 asymmetric and 2 of 10 symmetric patients. The 2 symmetric patients with LVO had a right vertebral occlusion and a left middle cerebral M2 occlusion. The two asymmetric patients without LVO had acute lateral midbrain infarction and chronic basal ganglia infarction.

Of our VAN positive patients, asymmetric BUE weakness based on ED NIHSS is associated with a higher probability of LVO compared to symmetric. In its current form, VAN teaches unilateral arm or hand weakness; however, the addition of asymmetric BUE weakness may improve accuracy and further facilitate LVO triage. This addition may also improve performance of other pre-hospital stroke severity tools that rely on unilateral weakness.