Hyperammonaemic encephalopathy in adults is a rare condition in the absence of liver disease and is associated with a high mortality and risk of permanent neurological deficits. Seldomly, the condition is caused by an inborn error of metabolism in the urea cycle, triggered by an exogenic factor such as gastrointestinal haemorrhage, gastric bypass surgery, starvation, seizures, vigorous exercise, burn injuries, or drugs hampering the elimination of ammonia. Here, we present a fatal case of an unrecognized genetic ornithine transcarbamylase deficiency (OTCD) presenting with a subacute progressive encephalopathy. We review the current literature and discuss the differential diagnosis and treatment options. As swift diagnosis and initiation of treatment is vital, awareness of hyperammonaemic encephalopathy and its possible causes can help improve the prognosis of this condition.

Original languageEnglish
Article number231
JournalBrain Sciences
Issue number2
Number of pages8
Publication statusPublished - 8. Feb 2022

Bibliographical note

Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.


  • Adult onset
  • Brain oedema
  • Hyperammonaemia
  • Ornithine transcarbamylase deficiency
  • Subacute encephalopathy


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