Early CT findings in unknown-onset and wake-up strokes

Approximately one quarter of the acute ischemic stroke patients notice the event at awakening. Such patients with stroke at awakening are usually excluded from thrombolysis, since the time of stroke onset cannot be definitely identified. We compared the hyperacute CT findings of awakening stroke patients with those of stroke patients with known onset to assess whether the time of stroke onset is shortly before awakening.

Subjects were cardioembolic stroke patients who were consecutively admitted to our department within 3 h after the recognition of stroke during the period between January 2000 and March 2003. The patients were classified into three groups: group A with stroke of known onset, group B with stroke at awakening, and group C with stroke of unknown onset due to lack of a witness. The clinical and CT findings in each group were compared.

A total of 81 patients fulfilled the study criteria. There were 46 patients in group A, 17 patients in group B, and 18 patients in group C. There was no significant difference in CT findings between groups A and B. In group C, however, definite hypodense areas were more commonly found than in group A (56 vs. 0%; p<0.001) or in group B (56 vs. 11%; p=0.012).

Based on our CT findings, stroke at awakening seems to be developing shortly before in a large subset of patients, making them potential candidates for acute stroke therapies.