Video : Testing for "Pronator Drift" in "Stroke". The patient is asked to hold both arms fully extended at shoulder level in front of them, with the palms upwards, and hold the position. If they are unable to maintain the position the result is positive. Closing the eyes accentuates the effect, because the brain is deprived of visual information about the position of the body and must rely on proprioception. If a forearm pronates with downward motion, then the person is said to have pronator dri