Flapping tremor is, when the hand is outstretched, and wrist is bent upward, the Pt is unable to actively maintain the position, but instead, tremors with jerky movement, resembling a bird flapping its wings.

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Abnormal function of the diencephalic/forebrain motor centers of the brain, which regulates the muscles involved in maintaining position. It can be a sign of hepatic encephalopathy, where the liver is unable to metabolize ammonia to urea, which thus damages brain cells.