asterixis
Pronunciation: as-ter-IK-sis
Brief, irregular lapses of sustained muscle contraction, classically seen as a flapping tremor when arms are extended.
Full Definition
Asterixis, also known as flapping tremor or negative myoclonus, is a neurological sign characterized by brief interruptions of sustained muscle contraction. It is most commonly elicited by asking patients to extend their arms and dorsiflex their wrists, revealing irregular, brief lapses in posture that create a flapping motion. While classically associated with hepatic encephalopathy, asterixis can occur in various metabolic encephalopathies, including uremic, hypercapnic, and drug-induced states. The phenomenon results from dysfunction in neural circuits responsible for maintaining sustained muscle activity, particularly involving thalamic and brainstem structures.
Usage
Usage note: Describe the method of elicitation and specify bilateral versus unilateral presentation.
In Context
- "Bilateral asterixis was present when the patient extended both arms, suggesting metabolic encephalopathy." — Emergency medicine evaluation
- "The absence of asterixis argued against hepatic encephalopathy as the cause of altered mental status." — Gastroenterology consultation