Flapping tremor is seen in all except: March 2005

Ans. B: Thyrotoxicosis BilateralAsterixis Metabolic encephalopathies, especially hepatic and renal, are the most common causes of bilateral asterixis. Those caused specifically by hepatic failure are known as "liver (or hepatic) flap". Other causes of asterixis include cardiac and respiratory disease, electrolyte abnormalities and drug intoxication. Electrolyte abnormalities known to cause asterixis include hypoglycaemia, hypokalaemia and hypomagnesaemia. Drug intoxications include barbiturate intoxication, alcoholism, phenytoin intoxication ("phenytoin flap") and primidone intoxication. Wilson's disease and focal brain lesions in the rostral midbrain tegmentum may also cause asterixis. Unilateral Asterixis These are most commonly due to focal brain lesions in the genu and anterior poion of the internal capsule or ventrolateral thalamus.