The investigators have developed a simple prehospital stroke scale (FPSS), containing 5 dichotomized items to recognize both large and small artery thrombi of the brain. FPSS is implemented to both emergency medical services and later, to emergency response centers. The efficacy of the scale and possible improvement of both the patient flow and treatment results will be evaluated.

Finnish Prehospital Stroke Scale, FPSS, was developed for prehospital setting for prediction of large vessel occlusions (LVOs) and stroke in common. It contains four stroke signs used universally in emergency medical services (EMSs) and emergency response centers (ERCs): 1) facial weakness, 2) extremity weakness, 3) speech disturbance, 4) visual disturbance. Additionally, it contains only one item 5) conjugated gaze deviation, while all the items are presented in dichotomized form. In an earlier, retrospective cohort of 856 code stroke patients, the sensitivity of FPSS for LVOs was highest for thrombi of areas with the documented cost effectiveness of endovascular treatment: internal carotid artery (ICA) and M1 segment of middle cerebral artery (72 % and 82 %). The overall specificity of FPSS for the LVOs was 91 %. For its simplicity it is easy to implement in EMS and ERC as a single score predicting both thrombolysis and thrombectomy candidates.

In the present study accuracy of FPSS will be studied prospectively. FPSS is launched 5/18 in EMS in an area with a population of more than a million, containing districts of five central hospitals capable for thrombolysis and one university hospital capable for endovascular treatment. During 2019-20 FPSS will be launched in two ERCs triaging stroke patients in the study area.

The hypotheses that are tested are:

1. FPSS is accurate to detect ICA and M1 thrombi in EMS setting
2. The use of FPSS shortens door-in-door-out (DIDO) delay patients arriving to central hospitals and redirected to university hospital for thrombectomy.
3. The use of FPSS aids to triage LVO-patients straight to a center capable for thrombectomy
4. FPSS is accurate in the detection of ICA and M1 thrombi in ERC setting
5. The effect of fluent triage of LVO is seen in overall shortened recanalization delay and better outcomes as lower modified Rankin Scores (mRS) in 3 months control compared recanalization delays and 3 month mRS during the pre-implementation period.

Inclusion Criteria:

• Acute ischaemic stroke
• Prehospital susipicion of large vessel occlusion

Exclusion Criteria:

- Stroke mimic

All patients with acute stroke in a population of 1 million