evidence: Physicians and scientists who reviewed the information generally agreed that tongue crookedness, or "tongue deviation" in clinical terms, could be useful for detecting a stroke, but cautioned that it should not be used on its own and is best considered together with FAST, especially since the ability to detect a stroke accurately using tongue deviation has not been determined yet. For example, not all cases of stroke display the sign, and a person may also display the sign without actually having a stroke. [...] Tongue deviation might happen after a stroke, but it is not a common sign and if you see it, it is likely to be present along with other, more obvious signs of stroke: such as weakness of the arm or leg on one side, a drooping face on one side, slurred or unintelligible speech. These are part of the FAST (Face, Arm, Speech, Time – get to hospital quickly) message. You would never see tongue deviation as a symptom on its own. [...] There are numerous symptoms and signs of stroke, including tongue deviation, which can be caused by weakness on one side of the tongue or reflect weakness on one side of the face (the "F" in the BE-FAST mnemonic). I am not aware of any specific research on detection rates if tongue deviation is added to BE-FAST as part of a public education effort.