Proximal arterial occlusion in acute ischemic stroke with low NIHSS scores should not be considered as mild stroke

Abstract

Background: Untreated acute mild stroke patients have substantial 90-day disability rates and worse outcomes than those who are treated with thrombolysis. There is little information regarding which patients with acute mild stroke will benefit from thrombolysis. We sought to investigate factors that are associated with early neurological deterioration (END) and poor prognosis in patients with acute mild stroke.

Methods: This was a retrospective study of consecutively registered patients with acute mild stroke (NIHSS ≤3) at our tertiary stroke center between October 2008 and December 2011. END was defined as an increase in NIHSS ≥2 points between hospital days 0 and 5. Modified Rankin Scale (mRS) scores of 0-1 at 90 days post-stroke were defined as favorable outcomes.

Results: A total of 378 (mean age, 65.9±13.0 years) patients were included in this study. END occurred in 55 patients (14.6%). IV-thrombolysis was performed in only 9 patients. Symptomatic arterial occlusion on the initial MRA was independently associated with END (OR, 2.206; 95% CI, 1.219-3.994; p = 0.009) by multivariate logistic regression. Of the 119 patients with symptomatic arterial occlusion, ICA occlusion was independently associated with END (OR, 8.606; 95% CI, 2.312-32.043; p = 0.001).

Conclusions: This study demonstrates that symptomatic arterial occlusion may be an important predictor of END in patients with acute mild stroke. It may therefore be important to consider that acute ischemic stroke with symptomatic arterial occlusion and low NIHSS scores may not represent mild stroke in acute periods.

Figure 1. The distribution of various types of END and mRS scores of 0–1 and 0–2 at 90 days in terms of baseline NIHSS scores (^* p for trends <0.05).

Figure 2. The distribution of occlusion sites according to END type.

MCA and ICA occlusions contributed most frequently to severe END. (Abbreviation: MCAO, middle cerebral artery occlusion; ICAO, internal carotid artery occlusion; VBAO, vertebrobasilar artery occlusion; otherAO, other arterial occlusion; no RAO, no relevant arterial occlusion).