Tremor of the wrist when the wrist is extended (dorsiflexion) due to metabolic encephalopathy is described as which term?

• A. Tremor
• B. Asterixis
• C. Dystonia
• D. Myoclonus

Answer: (B)

Asterixis is the flapping tremor seen in metabolic encephalopathy. When the wrist is extended and held in dorsiflexion, the hands exhibit brief, irregular lapses of posture that cause a rhythmic “flap.” This is a negative myoclonus—a temporary loss of tone rather than a rhythmic tremor. It’s classically associated with hepatic encephalopathy and other metabolic disturbances. In contrast, a simple tremor is rhythmic and continuous, dystonia involves sustained abnormal postures from muscle contractions, and myoclonus refers to sudden, brief jerks rather than the intermittent postural flapping seen here.