Gastroenterology

Gastroenterology

Volume 107, Issue 5, November 1994, Pages 1475-1480
Gastroenterology

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

https://doi.org/10.1016/0016-5085(94)90552-5Get rights and content
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Abstract

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 hypoosmolarity (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.

AIDS
acquired immunodeficiency syndrome
HIV
human immunodeficiency virus
1H-MR
proton magnetic resonance (spectroscopy)
NCT
number connecting test
PRESS
point resolved spectroscopy
PSE
portosystemic hepatic encephalopathy
TIPS
transjugular intrahepatic portosystemic shunting

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Supported by Deutsche Forschungsgemeinschaft through Sonderforschungsbereich 154, the Gottfried Wilhelm Leibniz-Programm, the Schilling Stiftung, and the Fonds der Chemischen Industrie.