Asterixis is best described as which of the following?

• A. Tremor of the wrist during flexion
• B. Myoclonus
• C. Asterixis
• D. Dystonia

Answer: (C)

Asterixis is a flapping tremor caused by brief lapses in muscle tone when a person tries to hold a posture, usually seen with the arms extended and the wrists dorsiflexed. This makes it a negative myoclonus rather than a true rhythmic tremor or clonus. It’s commonly associated with metabolic encephalopathy, such as hepatic failure, and appears as irregular, nonrhythmic hand flapping.

Why this description fits best: the sign is named after the fluttering movements that occur with sustained posture, not a simple wrist tremor during flexion. The other options describe different phenomena—regular tremor, true myoclonus (rapid, shock-like jerks), or dystonia (sustained abnormal postures)—which do not capture the distinctive flapping caused by brief loss of tone.