Letter to the Editor: Hemodynamic role in hepatic encephalopathy pathogenesis following transjugular intrahepatic portosystemic shunt placement

Abstract

Hepatic encephalopathy (HE) is a common complication following transjugular intrahepatic portosystemic shunt (TIPS) placement and is thought to result from reduced hepatic detoxification of neurotoxins. However, Zhuang et al in the World Journal of Radiology demonstrate that this understanding may be incomplete through exploration of the pathophysiology from a hemodynamic perspective. They found significant changes in cerebral blood flow (CBF) and spontaneous brain activity following TIPS. Initially, CBF increased in specific areas within the first month, followed by a return to baseline at three months. These CBF changes coincided with increased spontaneous brain activity that persisted in some areas, suggesting compensation for functional loss in other regions. Together with the fact that serum ammonia remained unchanged in this cohort and prior work showing that, after three months, HE risk returns to pre-TIPS levels, these results suggest that HE may develop in individuals susceptible to these hemodynamic and adaptive changes, warranting further research.

Keywords: Arterial spin labeling; Cerebral blood flow; Hemodynamics; Hepatic encephalopathy; Digit symbol substitution test; Resting-state functional magnetic resonance imaging; Transjugular intrahepatic portosystemic shunt

Core Tip: The pathogenesis of hepatic encephalopathy (HE) following transjugular intrahepatic portosystemic shunt (TIPS) placement remains incompletely understood. While hyperammonemia is classically implicated as the driver of HE development, Zhuang et al also suggest that postoperative hemodynamic changes play a key role. Using three-dimensional arterial spin labeling and resting-state functional magnetic resonance imaging, the authors demonstrate brain-region-specific alterations in cerebral blood flow and resting spontaneous brain activity, as measured by amplitude of low-frequency fluctuation, following TIPS placement. Their findings challenge the conventional understanding of post-TIPS placement HE and highlight the diagnostic potential of resting-state functional magnetic resonance imaging for characterizing HE during the early postoperative period.