Time from symptom onset is crucial for the effectiveness of intravenous thrombolysis in acute ischemic stroke patients. Many patients receive tissue Plasminogen Activator (tPA) with considerable delay. The investigators developed an ambulance equipped with a CT-scanner, point-of-care laboratory, teleradiological support and an emergency trained neurologist on board. In the Pre-Hospital Acute Neurological Therapy and Optimization of Medical care in Stroke patients (PHANTOM-S)-study the investigators aim at a reduction of the current alarm-to-needle time by pre-hospital use of tissue Plasminogen Activator in an ambulance.