Diagnostic confusion resolved by being upbeat.

The classical stroke presentation - captured by the public health campaign mnemonic FAST (face, arm, speech, time) - does not apply in a large number of stroke cases; yet establishing a prompt diagnosis is imperative for optimal management. Here, we describe a patient with acute bulbar weakness, numbness in all extremities and an apparently normal magnetic resonance imaging (MRI) of the brain upon admission for whom even the fundamental question of whether this reflected a central or peripheral nervous system process was unclear. The critical localizing sign was upbeat nystagmus that denotes a brainstem cause. MRI of the brain in the second week confirmed a diagnosis of medial medullary infarction.