Baseline NIH Stroke Scale Score predicting outcome in anterior and posterior circulation strokes

Abstract

OBJECTIVE: The NIH Stroke Scale (NIHSS) may not appropriately assess the spectrum of posterior circulation (PC)-related neurologic deficits. We determined the cutoff baseline NIHSS score that predicts independent daily life activity during the chronic stage in anterior circulation (AC) vs PC ischemic strokes. METHODS: A total of 310 consecutive patients hospitalized within 3 days after the onset of an ischemic stroke were prospectively enrolled in the study. Patients on thrombolytic therapy were excluded. In all patients, infarcts and vascular lesions were identified primarily using magnetic resonance techniques. A favorable outcome was defined as a modified Rankin Scale score of < or =2 at 3 months poststroke. RESULTS: In 101 patients with PC stroke, the total baseline NIHSS score was lower (p < 0.001), and the subscores of ataxia (p < 0.001) and visual fields (p = 0.043) were higher than in 209 patients with AC stroke. Multivariate-adjusted OR for the favorable outcome in patients with PC vs AC stroke was 2.339 (95% CI 1.331-4.109, p = 0.003). A low baseline NIHSS score was independently predictive of a favorable outcome in both patients with PC (OR 1.547, 95% CI 1.232-1.941) and AC (1.279, 1.188-1.376) stroke. The optimal cutoff scores of the baseline NIHSS for the favorable outcome were < or =5 for patients with PC stroke (sensitivity, 84%; specificity, 81%) and < or =8 for patients with AC stroke (sensitivity, 80%; specificity, 82%). CONCLUSIONS: The cutoff score of the baseline NIH Stroke Scale (NIHSS) for a favorable chronic outcome was relatively low in patients with PC stroke compared to patients with AC stroke. The NIHSS appears to have limitations with respect to its use when comparing the neurologic severity of PC and AC stroke.