Episodic confusion in a haemodilaysis patient due to haemodialysis‐related portal‐systemic encephalopathy and a shunt between the left portal vein and left external iliac vein

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A 77‐year‐old woman presented with consciousness disturbance 4 years after the initiation of haemodialysis for the first time. Glasgow Coma Scale was 13, no flapping tremors. Laboratory examinations revealed hyperammonaemia (NH3 207 µg/dL: normal 30–100), but neither liver damage nor hepatitis B&C although abdominal computed tomography (CT) revealed chronic liver disease pattern. Three‐dimensional CT angiography demonstrated a long portal‐systemic shunt (PSS) from the left portal vein to the left external iliac vein, with a diameter of 14.5 mm (Fig. 1). Brain magnetic resonance imaging (MRI) did not show any abnormality. A diagnosis of haemodialysis‐related portal‐systemic encephalopathy (HRPSE)1 was made and therapy with branched‐chain amino acids and lactulose ameliorated her symptom and hyperammonaemia (29 µg/dL).
Hyperammonaemia due to the flow of ammonia‐rich portal vein blood through the PSS causes chronic portal‐systemic shunt encephalopathy (CPSE),2 and it has been demonstrated clinical symptoms occur with shunt diameters larger than 10 mm.3 Haemodialysis patients may develop CPSE through characteristic mechanisms of PSS growth due to fluid overload and an increase in back flow via the PSS to the systemic circulation as a consequence of hemodialysis‐related fluid removal, known as HRPSE.1
Haemodialysis‐related portal‐systemic encephalopathy is a very rare complication and most shunts connect the left gastric vein or splenic vein with the left renal vein4 or the inferior vena cava.4 To the best of our knowledge, this is the first case of HRPSE with a portal‐iliac shunt.
Management of this condition can be via conservative therapy as used in this case, or by closure of the shunt flow using either surgical ligation or embolization of the shunt (balloon‐occluded retrograde transvenous obliteration: B‐RTO).
It is important to suspect HRPSE, even if liver function is normal.
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