“This large retrospective study reveals that while pre-hospital stroke scales are quite useful in identifying large-vessel occlusions, the scales are imperfect and not currently adequate in identifying all large-vessel occlusions,” Dr. Jadhav concluded. “One take-home message is the importance of early large-vessel study in all patients presenting with transient ischemic attack or stroke, as the stroke scale alone may not be indicative of whether there is a large-vessel occlusion.”

In the absence of more advanced tools, a pre-hospital stroke scale is “a great start” in helping triage patients, particularly those with high NIHSS who are not eligible for tissue plasminogen activator, he added. “Ultimately, the pre-hospital stroke scale will be aided by further technologies, such as serum biomarkers, transcranial ultrasound imaging, and mobile imaging, and so the accuracy of pre-hospital assessment will improve with time.”

Dr. Nathan Manning, from Columbia University Medical Center, New York, and Florey Institute of Neuroscience, Melbourne, Australia, told Reuters Health by email, “Unfortunately, these results were not at all surprising. Clinical examination is excellent at identifying patients with acute stroke. However, the complexity of cerebral functional anatomy and the idiosyncrasies of cerebrovascular anatomy make identifying patients with large-vessel occlusions extremely challenging. In particular, the clinical exam may be remarkably variable depending on the relative strength of collateral blood supply between individuals.”

“Physician attitudes and hospital systems must be aligned to rapidly identify patients with acute ischemic stroke secondary to large-vessel occlusion,” he said. “The only reliable and practical way to achieve this is by noninvasive vascular imaging.”

“Endovascular thrombectomy using stent-retriever technology is now the standard of care for these patients, with a number needed to treat to reduce permanent disability in one patient of only 2.6,” Dr. Manning said. “This makes it one of the most successful interventions in medicine. We must all work together to rapidly identify as many patients as we can to benefit from this remarkable treatment.”

Dr. Turc did not respond to a request for comments.