title: Abnormal brain processing in hepatic encephalopathy: evidence of cerebral reorganization?
abstract: OBJECTIVE
  Hepatic encephalopathy (HE) is a severe and frequent complication of liver cirrhosis characterized by abnormal cerebral function. Little is known about the underlying neural mechanisms in HE and human data are sparse. Electrophysiological methods such as evoked brain potentials after somatic stimuli can be combined with inverse modeling of the underlying brain activity. Thereby, information on neuronal dynamics and brain activity can be studied in vivo. The aim of this study was to investigate the sensory brain processing in patients with HE.
  
  
  METHODS
  Twelve patients with minimal or overt HE and 26 healthy volunteers were included in the study. Cerebral sensory processing was investigated as (i) an auditory reaction time task; (ii) visual and somatosensory evoked brain potentials, and (iii) reconstruction of the underlying brain activity.
  
  
  RESULTS
  Somatosensory evoked potentials were reproducible (all P>0.05), whereas flash evoked potentials were not reproducible (all P<0.05). Compared with healthy volunteers, the patient group had a prolonged reaction time index (P=0.03) along with increasing prolongation of latencies of median nerve evoked potentials (P<0.03). Reconstruction of the underlying brain sources showed a lateral shift in source localization of the P45 (P<0.001) and N60 components (P=0.02). A correlation between the psychometric hepatic encephalopathy score and the dipole shift corresponding to the N60 (P=0.003) component was seen.
  
  
  CONCLUSIONS
  HE patients have evidence of prolonged intracerebral nerve conduction, along with lateralization of brain activity following median nerve stimulation. This possibly represents cortical reorganization and may be important in our understanding of this condition.
authors.affiliation: Mech-Sense, Department of Gastroenterology and Hepatology, Aalborg Hospital, Aarhus University Hospital, Denmark.
authors.forename: Rolf Ankerlund
authors.initials: RA
authors.lastname: Blauenfeldt
authors.forename: Søren Schou
authors.initials: SS
authors.lastname: Olesen
authors.forename: Jesper Bach
authors.initials: JB
authors.lastname: Hansen
authors.forename: Carina
authors.initials: C
authors.lastname: Graversen
authors.forename: Asbjørn Mohr
authors.initials: AM
authors.lastname: Drewes
mesh_terms: D000161:Acoustic Stimulation; D000368:Aged; D001307:Auditory Perception; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D058256:Brain Waves; D016022:Case-Control Studies; D003718:Denmark; D004558:Electric Stimulation; D004569:Electroencephalography; D005073:Evoked Potentials, Somatosensory; D005074:Evoked Potentials, Visual; D005260:Female; D007839:Functional Laterality; D006501:Hepatic Encephalopathy / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008475:Median Nerve / Q000503:physiopathology; D008875:Middle Aged; D009431:Neural Conduction; D009483:Neuropsychological Tests; D010775:Photic Stimulation; D011594:Psychometrics; D011930:Reaction Time; D013997:Time Factors