CORTICOSPINAL PATHWAYS AND INHIBITORY MECHANISMS IN HEPATIC-ENCEPHALOPATHY

Transcranial magnetic stimulation of the cerebral cortex was used to s tudy motor system function in 31 cirrhotics (29 post-necrotic and 2 cr yptogenic) with and without hepatic encephalopathy (HE). The results w ere compared with those of 14 healthy subjects matched for age. A sign ificant increase of central motor conduction time, a significant raisi ng of the motor evoked potential (MEP) threshold at rest and a signifi cant reduction of the MEP/muscle action potential (MAP) amplitude rati o were found only in patients with chronic stable (12 patients) and re current (9 patients) HE. Vice versa, a significant shortening of the c entral silent period was observed in all 31 cirrhotic patients. The pe ripheral silent period was normal in all instances. These results indi cate that the damage to the cortico-spinal pathways is related to the progression of cirrhosis to HE, and that cirrhotic patients present a dysfunction of the inhibitory motor mechanisms before HE is clinically manifest. (C) 1997 Elsevier Science Ireland Ltd.