Prediction of large vessel occlusion for ischaemic stroke by the Van scale

Abstract

ABSTRACT Background: Rapid and accurate detection of stroke by paramedics or emergency clinicians at the time of first contact is crucial for timely initiation of appropriate treatment. Several stroke recognition scales have been developed to support the initial triage Identification of emergent large vessel occlusion (ELVO) stroke has become increasingly important with the recent publications of favorable acute stroke thrombectomy trials. Multiple screening tools exist but the length of the examination and the false positive rate range from good to adequate. A screening tool was designed and tested in the emergency department using nurse responders without a scoring system. Methods: Suspected stroke patients admitted by ambulance paramedics directly to an acute stroke unit through a rapid ambulance protocol were examined by a neurologist or admitting stroke physician. The vision, aphasia, and neglect (VAN) screening tool was designed to quickly assess functional neurovascular anatomy, which was used as an LVO screen for all stroke patients. Results: There were 162 consecutive code stroke activations during the pilot study. 60 (37%) of the patients were VAN positive and 128 (79%) had a National Institutes of Health Stroke Scale (NIHSS) score of ≥ 6. NIHSS > 6 was more sensitive (100% vs 93% for VAN) but VAN was more specific (90% vs 74% for NIHSS ≥ 6). Similarly, VAN had 83% positive predictive value while NIHSS ≥ 6 had only a 42% positive predictive value. No patient that was NIHSS < 6 had an LVO (100% negative predictive value), there were 4 patients with VAN negative who had LVO (97% negative predictive value). However, VAN had 91% specificity versus 32% for NIHSS. Conclusions: VAN assessment performed well in identifying patients with LVO. Keywords: Stroke, VAN, NIHSS, Large vessel occlusion.