Last reviewed May 6, 2026 by NPBoardSlay Medical Review Board

BE FAST

Stroke Recognition (Extended)

FAST misses posterior strokes — BE FAST catches them.

What this mnemonic does is fix the blind spot in the older FAST screen: posterior circulation strokes that present with vertigo, ataxia, or sudden visual loss instead of unilateral weakness. BE FAST adds Balance and Eyes — sudden imbalance, sudden double or lost vision — to the original Face, Arm, Speech, Time. The AANP exam will give you a vignette where a patient drops with vertigo and nystagmus and ask whether to reassure, refer to vestibular therapy, or activate stroke. BE FAST tells you to activate. Time-since-last-known-well still drives the thrombolytic and thrombectomy windows.

B
Balance
Sudden loss of balance or coordination.
E
Eyes
Sudden vision change in one or both eyes; diplopia.
F
Face
Asymmetric drooping on one side.
A
Arms
One-arm drift or weakness.
S
Speech
Slurred speech or word-finding difficulty.
T
Time
Note onset; call EMS immediately.

Clinical Context

Extends classic FAST to catch posterior-circulation (vertebrobasilar) strokes, which often present with balance and vision problems rather than limb weakness. BE FAST improves stroke detection sensitivity by roughly 20% compared to FAST alone.

Any positive → activate stroke protocol, clock "last known well," get the patient to non-contrast CT ± CTA. tPA window is 4.5 hours from onset; thrombectomy window is up to 24 hours for large vessel occlusion. AANP now tests BE FAST in addition to FAST — posterior strokes are a classic "trap" stem.