title: Impaired brain activity in cirrhotic patients with minimal hepatic encephalopathy: Evaluation by near-infrared spectroscopy.
abstract: OBJECTIVE
  Near-infrared spectroscopy (NIRS) is a tool that could non-invasively measure the regional cerebral oxygenated hemoglobin (oxy-Hb) concentration with high time resolution. The aim of the present study is to reveal the time-dependent regional cerebral oxy-Hb concentration change coupled with brain activity during task performance in patients with minimal hepatic encephalopathy (MHE).
  
  
  METHODS
  Cerebral oxy-Hb concentration was measured by using NIRS in 29 cirrhotic patients without overt hepatic encephalopathy (HE). Of those, 16 patients who had abnormal electroencephalography findings were defined as having MHE. Responsive increase in oxy-Hb during a word-fluency task was compared between MHE and non-MHE patients.
  
  
  RESULTS
  There was no difference in the maximum value of oxy-Hb increase between patients with and without MHE (0.26 ± 0.12 vs 0.32 ± 0.22 mM·mm, P = 0.37). However, the pattern of the time course changes of oxy-Hb was different between the two groups. The MHE group was characterized by a gradual increase of oxy-Hb throughout the task compared to steep and repetitive increase in the non-MHE group. Increase in oxy-Hb concentration at 5 s after starting the task was significantly small in the MHE group compared to the non-MHE (0.03 ± 0.05 vs 0.11 ± 0.09 mM·mm, P = 0.006).
  
  
  CONCLUSIONS
  The cerebral oxygen concentration is poorly reactive in response to tasks among cirrhotic patients without overt HE but having abnormal electroencephalography findings. These impaired responses in regional cerebral oxy-Hb concentration may be related to the latent impairment of brain activity seen in MHE.
authors.affiliation: Department of Gastroenterology and Hepatology, Musashino Red Cross Hospital, Musashino, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Nakanishi
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kurosaki
authors.forename: Kaoru
authors.initials: K
authors.lastname: Nakanishi
authors.forename: Kaoru
authors.initials: K
authors.lastname: Tsuchiya
authors.forename: Takamasa
authors.initials: T
authors.lastname: Noda
authors.forename: Nobuharu
authors.initials: N
authors.lastname: Tamaki
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Yasui
authors.forename: Takanori
authors.initials: T
authors.lastname: Hosokawa
authors.forename: Ken
authors.initials: K
authors.lastname: Ueda
authors.forename: Jun
authors.initials: J
authors.lastname: Itakura
authors.forename: Kimitaka
authors.initials: K
authors.lastname: Anami
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Asahina
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Enomoto
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Higuchi
authors.forename: Namiki
authors.initials: N
authors.lastname: Izumi
keywords: hepatic encephalopathy; near-infrared spectroscopy