Cerebral Herniation from Hyperammonemic Cerebral Edema: A Potentially Reversible Neurological Emergency

  • Andrea LogginiEmail author
  • Raisa C. Martinez
  • Christopher L. Kramer
Practical Pearl


Hyperammonemia is a known cause of cerebral edema through multiple mechanistic pathways that ultimately converge on intracellular edema and toxic neuronal dysfunction [1, 2, 3]. Multiple causes of hyperammonemic cerebral edema (HCE) have been described in the literature, including acute hepatic failure, urea cycle defects, hepatic shunt, medications (such as valproic acid, 5-fluorouracil), hematological malignancies, gastrointestinal hemorrhages, and urinary tract infection with urease-producing bacteria [4, 5, 6, 7].

A curviform correlation exists between ammonia levels and the development of encephalopathy. Data suggest that levels of ammonia above 150 ug/dL are strongly associated with the likelihood of developing cerebral edema [8]. If left untreated, the cerebral edema in HCE can rapidly increase intracranial pressure (ICP) and precipitate cerebral herniation.

The development of cerebral edema with signs of increased ICP, and especially herniation, is a neurological...


Hypermmonemia Cerebral herniation Intracranial hypertension 


Author Contributions

AL: drafting the article. RCM: critical revision of the manuscript. CLK: critical revision of the manuscript and final approval of the version published.

Source of Support


Compliance with Ethical Standards

Conflict of interest

The authors declare that they have no conflict of interest.


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© Springer Science+Business Media, LLC, part of Springer Nature and Neurocritical Care Society 2018

Authors and Affiliations

  1. 1.Neurosciences Intensive Care Unit, Department of NeurologyUniversity of Chicago Medical CenterChicagoUSA

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