Unclear-onset stroke: Daytime-unwitnessed stroke vs. wake-up stroke

Background and purpose: The onset of wake-up stroke and daytime-unwitnessed stroke is unclear. Though the clinical importance is similar by both being excluded from reperfusion therapy, the characteristics of daytime-unwitnessed stroke are less known than that of wake-up stroke. Here, we compared the characteristics between daytime-unwitnessed stroke and wake-up stroke. Methods: Unclear-onset (i.e., last-known normal timefirst-found abnormal time) stroke patients admitted within 24h of recognition of stroke between February 2011 and October 2013 were reviewed. Demographics and clinical and imaging variables were compared between patients with daytime-unwitnessed stroke and those with wake-up stroke. Results: Among the 762 ischemic stroke patients, 276 (36.2%) had unclear-onset stroke (104 daytime-unwitnessed stroke and 172 wake-up stroke). Compared to wake-up stroke, daytime-unwitnessed stroke patients had a higher prevalence of cardioembolic stroke and more frequently presented altered mental status (p<0.001) and/or aphasia (p<0.001) with more severe neurological deficit (p<0.001). However, the time from symptom recognition to hospital arrival was shorter (p<0.001), and diffusion-weighted image-fluid-attenuated inversion recovery image mismatch (p=0.02) and perfusion-diffusion mismatch (p=0.001) were also more frequently observed in daytime-unwitnessed stroke. Finally, the proportion of patients eligible for thrombolysis (p<0.001) was higher in daytime-unwitnessed stroke patients. Conclusions: Clinical and imaging characteristics of daytime-unwitnessed stroke significantly differ from those of wake-up stroke. Daytime-unwitnessed stroke patients are more likely to receive reperfusion therapy, as they arrive at the hospital earlier after symptom recognition, compared to wake-up stroke patients.