Motor cortex excitability in severe liver failure: effects of Molecular Adsorbent Recycling System

One patient, suffering from severe hepatic failure, who had not responded to the state of art therapy, was treated with the Molecular Adsorbent Recycling System (MARS). Recently the MARS has been introduced by Stange et al. as a new extracorporeal blood purification method. This system uses a double-sided albumin impregnated high-flux polysulphone filter and a closed-loop dialysate circuit, containing human serum albumin. The dialysate is continuously regenerated on-line by the perfusion over charcoal and adsorbent resin. The recent introduction of techniques, able to stimulate transcranially cerebral cortex, makes it possible to investigate non-invasively central motor circuits in man. We studied one patient (28 years old, female) with severe hepatic failure and a control population matched for age. After a preliminary standard central motor conduction study, we evaluated motor cortex excitability by measuring threshold for EMG responses recorded from right FDI. Comparison of results obtained before and after MARS makes it possible to study the effects of severe hepatic failure on intrinsic excitability properties of the motor cortex. Central motor conduction time was within normal limits in the patient. Patient threshold for responses was significantly higher than normal before MARS and dramatically decreased after the treatment. The decrease in resting motor threshold was concomitant to the improvement of her neurologic status and the decrease in total and conjugated bilirubin and bile acid observed after the procedure. Transcranial magnetic stimulation activates the pyramidal tract neurones transinaptically via excitatory interneurones. This is a first report that excitatory interneurones are reversibly involved during severe hepatic failure.

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