Wake-up stroke: clinical and neuroimaging characteristics

Abstract

Background: Approximately 25% of ischemic stroke patients awaken with neurological deficits. In these patients, in whom the time from symptom onset is uncertain, brain imaging is a potential strategy to characterize the ischemia duration and the presence of salvageable brain tissue.

Methods: We prospectively evaluated consecutive patients with acute ischemic stroke. CT angiography and CT perfusion (CTP) were performed in patients within 24 h of symptom onset. The patients were classified into 'known onset', 'indefinite onset but not on awakening' and 'wake-up stroke' groups.

Results: Of 676 patients evaluated, 420 had known-onset strokes, 131 wake-up strokes and 125 strokes with an indefinite time of symptom onset. Ischemic lesion volumes were higher in patients with indefinite-onset strokes (p = 0.04). The frequencies of CTP mismatch and of large-vessel intracranial occlusions were similar among the groups (p = 0.9 and p = 0.2, respectively).

Conclusion: The considerable prevalence of CTP mismatch and of intracranial artery occlusions in our patients with wake-up strokes suggests that arterial and perfusion imaging might be particularly important in this population. Revised indications for thrombolysis by using imaging-based protocols might offer these patients the prospect of receiving acute stroke treatment even without a clear time of symptom onset.

Fig. 1

Frequency of patients with CBF/CBV mismatch, intracranial occlusions amenable to neurointerventional approaches on CTA, and an mRS score of 0–2 at discharge in each group. ∗ p < 0.025 when compared to the reference category (known-onset strokes) after Bonferroni correction. Error bars: 95% CI.

Fig. 2

CTA-SI ischemic volumes in the 3 stroke groups. 50% of the values are within the box, 25% are higher and 25% lower than the values within the box. Horizontal line inside the box: median. Upper boundary of whisker: highest observed value that is not an outlier. Lower boundary of whisker: lowest observed value that is not an outlier. Circles: outliers.