If someone near you suddenly became dizzy and had trouble speaking, would you call 911? Would you know those are two signs of major stroke?

A new survey of U.S. adults finds just 44% know the five main symptoms of stroke. 38% would call 911 if they thought someone was having a stroke. Because timely treatment is crucial to a stroke patient's survival and recovery, experts say knowing the signs of a stroke could save someone's life.

Along with sudden dizziness or loss of coordination, and sudden confusion or trouble speaking, other signs : sudden trouble with vision, numbness or weakness in the face, arms or legs and sudden severe headache.