To date, the time window of intravenous thrombolysis is limited within 4.5 hours of stroke onset. Although EXTEND study has proved that intravenous thrombolysis can be extended from 4.5 to 9 hours, but the eligible patients must be selected by CTP. Thus, it is of clinical importance how to extend the time window of intravenous thrombolysis, which can benifit more patients. The current trial aims to investigate the effect of intravenous thrombolysis with TNK from 4.5 to 6 hours in ischemic stroke with help of Butyphthalide, which was found to be neuroprotective.

Inclusion Criteria:

• age: 18-80;
• ischemic stroke confirmed by brain CT or MRI
• the time from onset to treatment: 4.5-6 hours
• NIHSS≥4
• prestroke mRS≤1
• signed informed consent

Exclusion Criteria:

• prestroke mRS≥2
• planned endovascular treatment
• planned intravenous thrombolysis based on WAKE-UP or EXTEND study criterion
• any contraindiction of intravenous thrombolysis
• other unsuitable conditions judged by investigator