A clinical sign indicating a lapse of posture and is usually manifest by a bilateral flapping tremor at the wrist, metacarpophalangeal, and hip joints.
Comment:
The examiner can test for asterixis by asking the patient to extend the arms, spread the fingers, dorsiflex the wrist and observe for the abnormal "flapping" tremor at the wrist. Asterixis represents the failure to actively maintain a position and is caused by the abnormal function of diencephalic motor centers that regulate the tone of the agonist and antagonist muscles involved in maintaining posture.