Stroke Recognition: FAST and BE-FAST for Paramedics

Why Stroke Recognition Matters in Pre-Hospital Care

Stroke is a time-critical emergency. In the UK, approximately 100,000 people suffer a stroke each year, and every minute of delayed treatment results in the loss of around 1.9 million neurons. As a paramedic, you are often the first clinician to assess a patient presenting with neurological symptoms — making your ability to rapidly and accurately identify a stroke absolutely essential.

The pre-hospital recognition of stroke has evolved significantly over the past decade. While the original FAST acronym remains widely known by the public, student paramedics and registered clinicians working within JRCALC guidelines need a deeper understanding of validated screening tools, their limitations, and how to apply them in a dynamic clinical environment.

The FAST Acronym: A Foundation, Not a Ceiling

FAST was introduced as a public-facing awareness tool and has been used in UK emergency services for many years. It stands for:

• F — Facial drooping: Ask the patient to smile. Is one side of the face drooping or uneven?
• A — Arm weakness: Ask the patient to raise both arms. Does one arm drift downward or fail to elevate?
• S — Speech disturbance: Is the patient's speech slurred, confused, or absent? Can they repeat a simple sentence correctly?
• T — Time to call 999: For the public, this means calling emergency services. For you as a clinician, this means noting the exact time of symptom onset and treating transport as urgent.

FAST is a useful mnemonic and performs reasonably well for identifying anterior circulation strokes — those affecting the middle cerebral artery territory. However, research has consistently shown that it misses a significant proportion of posterior circulation strokes, which can present with more subtle or atypical features.

BE-FAST: Improving Sensitivity in Pre-Hospital Practice

BE-FAST was developed to address the limitations of FAST, particularly its poor sensitivity for posterior fossa and brainstem strokes. It adds two additional features at the beginning of the acronym:

• B — Balance: Has the patient experienced a sudden loss of balance, coordination problems, or an unexplained fall?
• E — Eyes: Is the patient reporting sudden visual disturbance, double vision (diplopia), or loss of vision in one or both eyes?
• F — Face: As above — facial asymmetry or droop.
• A — Arms: As above — unilateral arm weakness or drift.
• S — Speech: As above — dysarthria or aphasia.
• T — Time: Establish the last known well time and treat as an emergency.

Studies suggest BE-FAST can identify up to 95% of stroke presentations, compared to approximately 79% with FAST alone. The inclusion of balance and visual disturbance makes it a more comprehensive screening tool, particularly relevant in pre-hospital settings where patients may present with dizziness, ataxia, or falls that initially appear non-neurological in origin.

Posterior Circulation Strokes: The Ones You Cannot Afford to Miss

Posterior circulation strokes are notoriously difficult to identify and are more likely to be misdiagnosed — even in-hospital. As a paramedic, you should maintain a high index of suspicion when a patient presents with:

• Sudden severe vertigo or dizziness
• Diplopia or visual field deficits
• Ataxia, unsteady gait, or sudden collapse
• Dysphagia or dysphonia
• Unilateral limb weakness or sensory loss without facial involvement
• Sudden severe headache (consider haemorrhagic stroke or subarachnoid haemorrhage)

These presentations may not trigger a positive FAST screen, but should absolutely prompt you to consider stroke and escalate accordingly. Don't anchor on a negative FAST result — use your full clinical assessment.

JRCALC Guidance and Pre-Hospital Stroke Pathways

The Joint Royal Colleges Ambulance Liaison Committee (JRCALC) guidelines provide the clinical framework for paramedic stroke management in the UK. Key pre-hospital priorities include:

1. Accurate symptom onset time: This is critical for determining eligibility for thrombolysis (tPA) or mechanical thrombectomy. The treatment window for thrombolysis is generally up to 4.5 hours from onset, while thrombectomy may be considered up to 24 hours in selected patients.
2. Pre-alert the receiving hospital: A pre-hospital stroke pre-alert allows the stroke team to prepare, significantly reducing door-to-needle times. Use your ambulance service's local pre-alert protocol.
3. Blood glucose measurement: Hypoglycaemia is the most common stroke mimic. Always check BM — a blood glucose below 4 mmol/L in a symptomatic patient should be treated before a stroke diagnosis is assumed.
4. Avoid unnecessary on-scene delays: The principle of "scoop and go" is appropriate in suspected stroke. Keep on-scene time to a minimum and perform detailed assessment en route where possible.
5. Target appropriate receiving facility: Know your local stroke network. Patients within the thrombectomy window may need to bypass a closer hospital in favour of a Hyper Acute Stroke Unit (HASU).

Stroke Mimics: Keeping Your Differential Broad

Not every patient with focal neurological signs is having a stroke. Common stroke mimics include:

• Hypoglycaemia
• Todd's paresis (post-ictal weakness following a seizure)
• Complicated migraine (hemiplegic migraine)
• Functional neurological disorder
• Hypertensive encephalopathy
• Brain tumour with acute decompensation
• Septic encephalopathy

Your job in the pre-hospital environment is not necessarily to definitively diagnose a stroke — it is to identify patients who require urgent neurological assessment and rapid transport. When in doubt, treat as a stroke until proven otherwise.

Putting It All Together: A Practical Approach

When you arrive at a scene with a potential stroke patient, structure your approach as follows:

1. Conduct a rapid primary survey — airway, breathing, circulation, disability (AVPU, GCS, pupils, BM).
2. Apply BE-FAST as part of your neurological assessment, documenting each component clearly.
3. Establish the exact time of symptom onset or last known well time from the patient, family, or bystanders.
4. Check blood glucose and correct hypoglycaemia if present before progressing with a stroke pathway.
5. Pre-alert the hospital with patient age, symptom onset time, positive BE-FAST findings, and current observations.
6. Aim for an on-scene time of under 15 minutes in confirmed stroke presentations.

Documentation should be thorough and time-stamped. The information you record will directly influence the treatment decisions made by the stroke team on arrival.