[Unilateral asterixis and focal brain lesions. 12 cases]

Asterixis is a involuntary movement with spontaneous interruptions and intermittent muscle tone. It occurs during posture maintenance. It is usually bilateral and, in this case, is observed in metabolic encephalopathy. Unilateral asterixis is more uncommon. We report 12 cases which occurred in patients with focal brain lesions. In all cases asterixis involved the upper limb and the lower limb in only 2 cases. Asterixis was transient, discrete and always associated with other neurological signs. The causal lesions (7 infracts, 2 haematomas, 2 abscesses, 1 meningioma) were unique in 7 cases and multiple in 5. Asterixis was always contralateral to the unilateral lesions. Lesions mainly involved the thalamus (7 cases) and other structures (lenticular nucleus, frontal lobe, internal capsule, precentral regions and cerebellum). The frequency of thalamic involvement suggested dysfunction of the thalamo-cortical loop.