Cortical origin of mini-asterixis in hepatic encephalopathy

The authors investigated 12 patients with cirrhosis who had hepatic encephalopathy (HE): six with continuous mini-asterixis and six with subclinical HE without asterixis. They studied the coupling between hand-muscle electromyography (EMG) recordings and brain activity recorded by magnetoencephalography. On forearm elevation, patients with tremor developed excessive coupling between activity in the motor cortex (M1) and contralateral hand-muscle EMG recordings at the frequency of mini-asterixis, which was not found in controls. The corticomuscular coupling demonstrates the involvement of M1 in asterixis and may reflect a pathologically slowed and synchronized motor cortical drive.