This is a multi-centre, prospective cohort study. The aim of this study is to investigate causes, risk factors, clinical course, management and outcomes of severe ischaemic stroke in a real-world setting in tertiary hospitals in China. Patients with acute ischaemic stroke from nine tertiary hospitals in western China will be recruited. Participants will be visited within 24 hours after admission, on day 3, day 7 and at discharge, to collect their clinical data, blood biomarkers, and brain imaging. A structured telephone interview will be conducted for each participant at 3 months and 1 year after stroke onset, respectively, to collect their functional outcomes. In-hospital outcomes include haemorrhagic transformation, brain oedema and death, 3-month and 1-year outcomes include survival status (death or survival) and functional outcome (scores of modified Rankin scale, mRS).

Nine tertiary hospitals in Western China are participating in the study. In each participating hospital, stroke patients admitted to the Department of Neurology will be screened by their responsible doctors for eligibility. For patients who are potentially eligible, the doctor will introduce this study in detail with written information to the patient or their legal proxies. After participants (or their proxies) sign the consent form, investigators will collect their baseline data within 24 hours after admission (visit 1). Subsequent visits will be conducted on day 3 of admission or if the patient experiences neurological deterioration between visit 1 and day 3 (visit 2), on day 7 of admission or if neurological deterioration occurs between visit 2 and day 7 (visit 3), and on the day before discharge or on day 30 of admission, whichever is earlier (visit 4). At visit 1 investigators will record demographics, medical history, characteristics of current stroke, and results of the blood tests, brain imaging and other examinations, if applicable. At visit 4, investigators will record interventions and rehabilitation used during hospitalisation. At day 90 and 1 year of stroke onset, a trained investigator (neurologist) blind to all medical information will contact the participant to deliver a structured telephone interview and collect their functional outcomes.

Objectives of this study are: a) to explore causes of clinical worsening in acute ischaemic stroke, and for each type of clinical worsening to dynamically evaluate its clinical course and explore its risk factors; b) to explore the application of conventional stroke therapies in patients with severe ischaemic stroke in China; c) to investigate factors precipitating and predisposing malignant brain oedema following acute ischaemic stroke; and d) to better select patients with malignant brain oedema for individualised treatment strategies.

Inclusion Criteria:

• Aged 18 years or over
• Symptoms and signs of clinically definite acute stroke
• Time of stroke onset is known and within 30 days of admission
• CT or MRI brain scanning has reliably excluded both intracranial haemorrhage and structural brain lesions which can mimic stroke (e.g. brain tumour)

Exclusion Criteria:

• Likely to be unavailable for follow-up, e.g. no fixed home address
• Refuse to give consent to participate

Patients with acute ischaemic stroke admitted to the Department of Neurology of nine participating hospitals will be included if they meet all inclusion criteria and do not have any exclusion criteria.