Bovis ISSN 2398-2993

Hepatic encephalopathy

Synonym(s): Hepatoencephalopathy

Contributor(s): Seamus O'Shea , Mark Burnell

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Introduction

  • Syndrome caused by ammonia build up secondary to liver damage.
  • Cause: severe hepatic insufficiency.
  • Signs: signs may be intermittent, slowly progressive or acute from abnormal mentation, depression to ‘sudden’ death.
  • Diagnosis: history and clinical signs suggestive; confirmation is by presence of laboratory findings indicative of liver failure.
  • Treatment: supportive.
  • Prognosis: very poor - hepatic damage is usually irreversible.

Pathogenesis

Etiology

Pathophysiology

  • Hepatic encephalopathy is characterized by abnormal mentation due to protein, and other metabolites, crossing the blood-brain barrier during severe hepatic dysfunction and leading to diffuse cerebral impairment.
  • The syndrome is incompletely understood.
  • There are multiple theories, including:
    • Systemic ammonia accumulation secondary to liver dysfunction occurs. Ammonia accumulates in the brain, acting as a neurotoxin.
    • Alteration in amino acid metabolism due to liver dysfunction results in imbalance between aromatic amino acids (AAA) and branched chain amino acids (BCAA) AAA preferentially cross blood brain barrier and act as precursor for serotonin, an inhibitory neurotransmitter. End result is diffuse cerebral impairment.
    • Hepatic dysfunction leads to systemic accumulation of metabolic byproducts, eg ammonia that causes an imbalance of fatty acids and excitatory and inhibitory neurotransmitters such as gamma amino butyric acid (GABA) or glutamate. These cross permeability-altered blood-brain barrier resulting in diffuse cerebral impairment.

Timecourse

  •  Variable- depends on underlying cause of hepatic disease.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Masoud Davoudi S (2013) Study of Hepatic Problems in livestock.  European Journal of Zoological Research 2 (4), 124-132.
  • West H J (1997) Clinical and Pathological Studies in Cattle with Hepatic Disease. Veterinary research communications 21, 169–185 VetMedResource.

Other sources of information

  •  MSD Veterinary Manual.


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