Wake-Up Stroke versus Stroke with Known Onset Time: Clinical and Multimodality CT Imaging Characteristics

Abstract

Background: Current guidelines for the treatment of acute ischemic stroke are mainly based on the time between symptom onset and initiation of treatment. This time is unknown in patients with wake-up stroke (WUS). We investigated clinical and multimodality CT imaging characteristics on admission in patients with WUS and in patients with a stroke with a known onset time.

Methods: All patients were selected from a large prospective cohort study (Dutch acute stroke study). WUS patients last seen well > 4.5 and ≤4.5 h were separately compared to patients with a known onset time ≤4.5 h. In addition, WUS patients with a proximal occlusion of the anterior circulation last seen well > 6 and ≤6 h were separately compared to patients with a known onset time ≤6 h and a proximal occlusion. National Institute of Health Stroke Score, age, gender, history of atrial fibrillation, non-contrast CT (NCCT) Alberta Stroke Program Early CT Score (ASPECTS), CT-perfusion abnormalities, proximal occlusions, and collateral filling on CT angiography were compared between groups using the Mann-Whitney U test and Fisher's exact test.

Results: WUS occurred in 149/1,393 (10.7%) patients. Admission clinical and imaging characteristics of WUS patients last seen well > 4.5 h (n = 81) were not different from WUS patients last seen well ≤4.5 h (n = 68). Although WUS patients last seen well > 4.5 h had a significantly lower NCCT ASPECTS than patients with a known time of stroke symptom onset of ≤4.5 h (n = 1,026), 85.2% had an NCCT ASPECTS > 7 and 75% had a combination of favorable ASPECTS > 7 and good collateral filling. There were no statistically significant differences between the admission clinical and imaging characteristics of WUS patients with proximal occlusions last seen well > 6 h (n = 23), last seen well ≤6 h (n = 40), and patients with a known time to stroke symptom onset ≤6 h (n = 399). Of all WUS patients with proximal occlusions last seen well > 6 h, only 4.3% had severe ischemia (ASPECTS < 5), 13 (56.5%) had ASPECTS > 7 and good collateral filling.

Conclusions: There are only minor differences between clinical and imaging characteristics of WUS patients and patients who arrive in the hospital within the time criteria for intravenous or endovascular treatment. Therefore, CT imaging may help to identify WUS patients who would benefit from treatment and rule out those patients with severe ischemia and poor collaterals.

Keywords: Acute ischemic stroke; Acute stroke imaging; Computed tomography; Wake-up stroke.

Fig. 1

Spread of pc-ASPECTS: (a) patients with symptom onset within 4.5 h before imaging and > 4.5 h WUS patients; (b) patients with symptom onset within 6 h before imaging and a proximal anterior circulation occlusion and > 6 h WUS patients with a proximal anterior circulation occlusion. ASPECTS, Alberta Stroke Program Early CT Score; WUS, wake-up stroke.

Fig. 2

Fifty-one-year-old male patient WUS patient last seen well 7.5 h before imaging. a The NCCT showed some hypodensity in the left temporal lobe (red oval) with ASPECTS 9. b The CTA showed collateral filling of > 50% of the MCA flow territory (red oval) and an occlusion in the distal M1 segment (not shown). The CTP showed (c) a large area with an increased Tmax (red oval), and (d) a smaller area with decreased CBF (red oval). The CTP summary map (e) shows the area of Tmax > 6 s (green) and the area of > 30% relative CBF decrease (red). The patient was not treated with IV-rtPA but showed good recovery with a 90-day mRS of 2. WUS, wake-up stroke; NCCT, non-contrast CT; ASPECTS, Alberta Stroke Program Early CT Score; CTA, CT angiography; MCA, middle cerebral artery; CTP, CT-perfusion; IV-rtPA, intravenous tissue plasminogen activator; mRS, modified Rankin Scale.

Fig. 3

Eighty-six-year-old female patient imaged within 4.5 h after symptom onset. a The NCCT showed a large hypodense area (red oval) in the right hemisphere with ASPECTS 1. b The CTA showed poor collateral filling (red oval) and a proximal occlusion in the distal ICA and M1 segment (different slice). The CTP showed (c) a large area with an increased Tmax (red oval), and (d) a large area with decreased CBF (red oval). The CTP summary map (e) shows the area of Tmax > 6 s (green) and the area of > 30% relative CBF decrease (red). The patient was treated with IV-rtPA and died within 90 days. NCCT, non-contrast CT; ASPECTS, Alberta Stroke Program Early CT Score; CTA, CT angiography; ICA, intracranial carotid artery; CTP, CT-perfusion; IV-rtPA, intravenous tissue plasminogen activator.