Treating Wake-Up Stroke Patients

Abstract

In 20-25 % of stroke patients, stroke occurs during sleep. Due to the missing information on time of symptom onset, these patients with ''wake-up stroke'' are excluded from treatment with intravenous thrombolysis based on licensing criteria. Within the past years, however, new approaches to guide treatment in wake-up stroke patients have been suggested and are currently being tested in clinical trials. This article gives an overview of imaging and clinical characteristics of wake-up stroke patients and recent approaches to guide treatment in these patients. Penumbral imaging using multiparametric MRI including diffusion-weighted imaging (DWI) and perfusion imaging or multiparametric CT including CT perfusion is hypothesized to identify stroke patients with tissue at risk independent from time of symptom onset who might benefit from reperfusion treatment. This approach is currently being tested in the EXTEND trial, which also allows for randomization of wake-up stroke patients. A different approach is the use of multiparametric MRI to estimate lesion age in patients with unknown time of symptom onset based on the characteristic course of signal changes and MR parameter changes. The mismatch between a visible lesion on DWI and normal FLAIR (DWI-FLAIR mismatch) identifies patients that are likely to be within a time window of 4.5 h of symptom onset and thus likely to benefit from intravenous thrombolysis. This concept is used to enroll patients in the European randomized controlled WAKE-UP trial of MRIbased thrombolysis in patients with unknown time of symptom onset. The results of these clinical trials are expected to change clinical practice and to improve the treatment of wake-up stroke patients in the near future.