• Exclude hypoglycaemia and other 'stroke mimics' — see Differential diagnosis.
• Make a working diagnosis of stroke if the FAST (Face, Arm, Speech, Test) test is positive:
• Facial weakness:
• Ask the person to smile or show their teeth.
• The FAST test is failed if there is new facial asymmetry (e.g. the mouth or eye droops).
• Arm weakness:
• Raise the person's arms to 90° if they are sitting or 45° if they are lying. Ask the person to maintain the position when you let go.
• The FAST test is failed if, when you let go, one arm falls or drifts down.
• Speech problems:
• Involve the person in conversation and determine whether the speech is slurred or the person has difficulty finding the name for commonplace objects (e.g. cup, table, chair, keys, pen). If they have difficulty seeing, place the objects in their hands. If they have a companion, check whether this is a new problem.
• The FAST test is failed if there is a new unexplained speech problem.
• If the test is failed, then call 999.
• Consider making a working diagnosis of stroke if the person has sudden onset of:
• Visual field defect.
• Disorder of perception.
• Disorder of balance.
• Coordination disorder.
• Unilateral weakness confined to the leg.

• If the person is seen within 24 hours of onset of neurological symptoms and still has symptoms and signs, it is not possible to distinguish clinically between a transient ischaemic attack and a stroke. Therefore, make a working diagnosis of stroke.
• The FAST test is intended to be used as a rapid screening test by the general public, ambulance workers, and medical practitioners. It does not detect people with less common presentations of acute stroke or transient ischaemic attack, such as a defect of the visual field, disorder of perception, disorder of balance, coordination disorder, or unilateral weakness confined to the leg.

These recommendations are in line with guidelines issued by the National Institute for Health and Clinical Excellence (NICE) and the Royal College of Physicians Intercollegiate Stroke Working Party (RCP ICSWP) [Intercollegiate Stroke Working Party, 2008; National Collaborating Centre for Chronic Conditions, 2008], and with the National Stroke Strategy [DH, 2007]:

Excluding hypoglycaemia:

• Excluding hypoglycaemia is recommended in all people presenting with symptoms suggestive of acute stroke. The typical response to hypoglycaemia is confusion, drowsiness, diminished level of consciousness, or coma. However, hypoglycaemia can produce a stroke-like picture with hemiplegia and aphasia; affected people are typically drowsy, but can be alert [Huff, 2002].
• This recommendation is based on expert opinion [Intercollegiate Stroke Working Party, 2008; National Collaborating Centre for Chronic Conditions, 2008].

Use of the FAST test:

• Because people with acute stroke or transient ischaemic attack (TIA) benefit from rapid appropriate management in hospital, several tools have been developed to help ambulance paramedics and other healthcare professionals in the community make an accurate and rapid diagnosis [Harbison et al, 2003; Nor et al, 2004; Stroke Association, 2008].
• Observational studies in the UK and elsewhere found that the diagnosis by ambulance paramedics using FAST (or similar tools) agreed well with the diagnosis made by stroke physicians. However:
• They provide no evidence on the clinical benefits of using FAST.
• They provide no information on what proportion of people in the community are given false-negative diagnoses, or on the clinical outcomes of these people.
• Because some acute strokes and TIAs will not be identified by FAST (or similar tools), CKS recommends that people be considered to have an acute stroke when they have any unexplained symptoms of acute stroke or TIA that the FAST test will not identify.