Proton magnetic resonance spectroscopy studies on human brain myo-inositol in hypo-osmolarity and hepatic encephalopathy

Gastroenterology. 1994 Nov;107(5):1475-80. doi: 10.1016/0016-5085(94)90552-5.


Background/aims: Recent in vivo studies using proton magnetic resonance (1H-MR) spectroscopy showed low levels of myo-inositol in the brain in hepatic encephalopathy; the pathogenetic relevance of this observation is unclear.

Methods: Myo-inositol and glutamine levels in the brain were studied in vivo by 1H-MR spectroscopy in patients with hypo-osmolarity and hepatic encephalopathy.

Results: A patient with severe plasma hypo-osmolarity (222 mOsm/L) had almost undetectable signals for myo-inositol and glutamine/glutamate in the brain. Both signals reappeared after normalization of plasma osmolarity, suggesting that both myo-inositol and glutamine were released as organic osmolytes from the brain. A decreased cerebral myo-inositol signal is also found in low-grade hepatic encephalopathy but is accompanied by an increased glutamine signal. Cirrhotics without hepatic encephalopathy have near-normal inositol signals, and patients with acquired immunodeficiency syndrome encephalopathy have increased inositol signals.

Conclusions: The 1H-MR spectroscopic myo-inositol signal in the human brain predominantly reflects an osmosensitive inositol pool. It is hypothesized that its depletion in latent hepatic encephalopathy points to a disturbance of cell volume homeostasis in the brain as an early pathogenetic event. This may partly be caused by a hyperammonemia-induced glutamine accumulation in the brain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acquired Immunodeficiency Syndrome / complications
  • Adult
  • Aged
  • Brain Chemistry*
  • Brain Diseases / etiology
  • Brain Diseases / metabolism
  • Female
  • Glutamine / analysis
  • Hepatic Encephalopathy / metabolism*
  • Humans
  • Inositol / analysis*
  • Liver Cirrhosis / metabolism
  • Magnetic Resonance Spectroscopy
  • Male
  • Middle Aged
  • Osmolar Concentration
  • Protons
  • Water-Electrolyte Imbalance / metabolism*


  • Protons
  • Glutamine
  • Inositol