Drug-induced asterixis in Parkinson disease.

Asterixis was observed in five parkinsonian patients who were taking levodopa. A prospective study revealed that 4 of 55 consecutive patients had asterixis. Liver and metabolic functions were normal in all patients. Asterixis always occurred as part of a toxic confusional state superimposed on a parkinsonian state associated with some dementia. Insomnia, hallucinosis, and myoclonus were also prominent in the affected patients. Because of this association with other signs of chronic drug toxicity and its reversal with drug withdrawal, the asterixis seemed to be drug-related.