Stroke scale expansions improve posterior circulation deficit detection

The National Institutes of Health Stroke Scale is the most widely used bedside scale for assessing neurological deficit severity in acute stroke and guiding early clinical decision-making. However, it has important limitations in posterior circulation stroke, particularly in cases involving the brainstem and cerebellum. Because posterior circulation ischemic stroke often presents with vertigo, nystagmus, truncal ataxia, bulbar dysfunction, and other cranial nerve-related symptoms, the conventional National Institutes of Health Stroke Scale may underestimate the initial severity of neurological impairment. This under-recognition can delay escalation of diagnostic evaluation and compromise prognostic stratification. This review specifically focuses on posterior circulation ischemic stroke because currently available posterior circulation-oriented derivatives of the National Institutes of Health Stroke Scale have been developed and clinically evaluated mainly in ischemic stroke cohorts. Recent studies suggest that the expanded National Institutes of Health Stroke Scale improves sensitivity to posterior circulation deficits missed by the conventional scale, whereas posterior circulation-specific tools such as the Posterior National Institutes of Health Stroke Scale and the Peoria Posterior Fossa Stroke Scale may further improve structured bedside assessment and prognostic stratification. Nevertheless, the evidence base remains limited by the small number of validation studies, lack of large multicenter external validation, and incomplete standardization of item definitions and scoring procedures. Future studies should focus on rigorous validation, standardization, and integration of these scales with imaging and clinical workflow to improve recognition and risk assessment in posterior circulation ischemic stroke.