This is an investigator initiated and conducted, multicentre, ambulance-delivered, prospective, randomised, open-label, blinded outcome (PROBE) study. EAST aims to evaluate the effects of pre-hospital levetiracetam and different head positions initiated in ambulance settings on the functional outcome of participants assessed at 90 days.

EAST is a multicenter, ambulance-delivered, prospective, randomized controlled, open label blinded outcome assessment (PROBE) study to be conducted through a regional-cluster hospital network of investigators. A total of 2323 patients with suspected acute stroke will be recruited from approximately 50 hospitals in China. Potentially eligible patients will be recruited into the study by either of two mechanisms: (1) waver of consent to the intervention, and consent to follow-up obtained in hospital; or (ii) consent to the intervention through a brief written consent which is combined with a usual care consent form delivered in hospital for follow-up (if a waver of consent is not approved by the ethics committee). All patients will enter Part A and Part B at the same time, randomised allocation of intervention will be done in a 1:1 ratio in each part, using a central, automated, mobile phone Wechat mini program-based electronic randomization software according to minimization method stratified by ambulance systems, age (≥65 vs <65) and FAST(>2 vs =2). The intervention of Part A is to commence IV levetiracetam(LEV) 500mg as a single bolus in the ambulance and then to continue as LEV 500mg Bid orally after hospital admission for 14 days(at least 7 days if discharged or death early), compared to avoid prophylactic use of antiseizure drugs. Part B is to lie flat or sit up in the ambulance as soon as possible until hospital arrival. Ambulance staff will be well trained across the whole study to master mobile randomisation and simple key data collection. All information in ambulance, including basic demographics, randomised allocation, BP measurement and treatment details, will be collected through mobile phone based electronic database system connected with investigator clinicians in hospitals. Other relevant documents such as consent paper, BP chart will be handed over to hospital investigators. Endpoint assessment will be blinded to treatment allocation.

Inclusion Criteria:

• Adults (age ≥18 years);
• Acute condition that is presumed due to acute stroke, defined on the FAST (Face, Arm, Speech, Time) screen (score ≥2 with an arm deficit);
• Time ≤2 hours from last seen well;
• Able to provide brief consent (if a waver of consent not approved by ethics committee).

Exclusion Criteria:

• coma (no response to painful stimulation);
• severe co-morbid disease (e.g. cancer, chronic airflow disease, severe dementia, severe heart failure, pre-existing disability [needing help with everyday activities]);
• history of epilepsy or seizure at onset;
• recent head injury;
• hypoglycaemia (glucose <2.8mmol/L);
• clear indications or contraindications (allergies) for levetiracetam;
• lactating women;
• clear indications for a particular head position or situations where either head position cannot be maintained (such as severe vomiting and inability to lie down, severe obesity with fatigue and difficulty sitting up, etc.).