• Symptomatic intracranial hemorrhage (safety)
  
• Functional outcome (efficacy)
  

• Asymptomatic intracranial hemorrhage 24-48 hours after t-PA infusion
  
• Early clinical recovery by 10 or more NIHSS points or dramatic recovery (total NIHSS 3 or less)at 24-48 hours after t-PA infusion
  
• Mean mRS score at 90 days after t-PA infusion
  
• Death occurring during study period
  
• Recanalization at 24-48 hours after t-PA infusion
  

Thrombolysis with intravenous(iv) tissue plasminogen activator (t-PA) is the only effective and approved therapy for acute ischemic stroke. The most frequent cause of ischemic stroke is thrombosis of the middle cerebral artery (MCA). Preliminary in vitro, animal and human studies suggest that ultrasound accelerates thrombolysis induced by t-PA, and recanalization of acute MCA occlusion due to thrombolysis is an independent predictor of good clinical outcome. Thus, insonation of an occluded MCA through the temporal bone in stroke patients who are treated with iv t-PA might enhance recanalization and improve clinical outcome. The present prospective, randomized, controlled multicenter pilot study will investigate the safety and efficacy of continuous 1-hour insonation of the occluded MCA with 2 MHz transcranial color duplex sonography in patients with ischemic stroke treated with iv t-PA within 3 hours after symptom onset. It is planned to randomize 400 patients in 6 Swiss centers during an enrolment period of 33 months with an individual follow up of 3 months. The study endpoints include safety and efficacy assessments. The primary safety endpoint is to determine the rate of symptomatic intracranial hemorrhage (ICH) in both treatment groups. The primary efficacy endpoint is to determine whether a good functional outcome (modified Rankin scale, mRs, score of 0-2) differs between both treatment groups. Secondary endpoints include (1) asymptomatic ICH occuring during or within the first 24-48 hours after t-PA infusion, (2) early clinical recovery by 10 or more National Institute of Health Stroke Scale (NIHSS) points or dramatic recovery (total NIHSS score of 3 or less) at 24-48 hours after t-PA infusion, (3) mean mRS score at 90 days after t-PA infusion, (4) death occuring during the study period, and (5) recanalization at 24-48 hours after t-PA infusion.