Accuracy of National Institutes of Health Stroke Scale Score in Predicting the Site of Arterial Occlusion in Acute Stroke: A Transcranial Doppler Study.

BACKGROUND: In acute stroke, it is crucial to assess for intracranial large-vessel occlusion and site of occlusion. The National Institutes of Health Stroke Scale score (NIHSSS) is the frequently used clinical tool to predict the site of arterial occlusion. In this study we aimed to determine the following: (1) if there is a correlation between the site of occlusion and the NIHSSS at presentation (bNIHSSS); and (2) if there is a bNIHSSS cutoff which can distinguish proximal occlusions (PO) from distal occlusions (DO).

METHODS: Up to 313 patients from CLOTBUST data bank with demonstrable intracranial arterial occlusion and having received intravenous recombinant tissue plasminogen activator (rt-PA) were included. Occlusions were classified as PO (terminal internal carotid artery, M1 segment of middle cerebral artery [M1 MCA], and basilar artery) or DO (M2 MCA, anterior cerebral artery, posterior cerebral artery, and vertebral artery).

RESULTS: By univariate analysis, bNIHSSS, thrombolysis in brain ischemia (TIBI) flow grade before rt-PA, degree of recanalization after rt-PA, and modified Rankin Scale score at 3 months were significantly different between various sites of occlusion. By univariate analysis, a higher bNIHSSS, lower TIBI flow grade, and lower ASPECTS (Alberta Stroke Program Early CT Score) differentiated PO from DO. Lower TIBI flow grade and higher bNIHSSS differentiated PO from DO by logistic regression analysis. No single NIHSSS cutoff with acceptable sensitivity and specificity could be derived to differentiate PO from DO.

CONCLUSIONS: Although NIHSSS are higher in PO, there is no satisfactory NIHSSS cutoff which differentiates PO from DO. A vascular imaging or transcranial doppler should be obtained to determine the site of arterial occlusion in acute stroke.