HE is the occurrence of confusion, altered level of consciousness and potentially coma due to the influence on the brain of toxic compounds that accumulate in the blood due to the inability of the cirrhotic liver to remove them from the blood, as would occur in healthy individuals. 1
Overt HE 1,2 | Minimal/ Covert HE 2 |
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Spectrum of potentially reversible neuropsychiatric abnormalities seen in patients with liver dysfunction and/or porto-systemic shunting | Denotes subtle neuropsychometric or neuropsychological abnormalities without clinical evidence of mental change |
The impact of hepatic encephalopathy (HE) on patients
- Up to 45% of patients with cirrhosis are affected by overt HE 3
- Each overt HE episode is likely to leave patients with cumulative cognitive impairment that affects memory and learning ability 4
- Recurrent overt HE episodes have detrimental effects on physical activity, fatigue and emotional function 5
- Compared with those without, patients with previous bouts of overt HE had a significantly worsened vitality, social and physical functioning 6
Recurrent episodes of HE have a negative impact on the patient’s quality of life 5
The risk of death increases with each overt HE episode 7
- Hazard ratio (HR) for death for HE+ vs. HE- = 2.28 (95% CI 1.82-2.87)
- No p value available
- Data was selected between 1998-2012
Adapted from Morgan et al. 2014
7
Pathophysiology
Ammonia is considered by many to be central in the pathogenesis of hepatic encephalopathy (HE).
Normal Individuals 8 | Cirrhotic Patients 8,9 |
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Adapted from Clayton, M. Guide to: hepatic encephalopathy, October 2016
10
Ammonia levels correlate poorly with clinical severity suggesting that other factors are also involved in the pathogenesis of HE.
Infection and Inflammation
- Two important factors are infection and systemic inflammation. 11
- Inflammatory mediators, such as nitric oxide and cytokines produced by infection or hepatocyte necrosis, lead to further increases in cerebral blood flow and delivery of ammonia to the brain. 12
- Bacterial translocation may be increased in cirrhosis and increased systemic exposure to bacteria and bacterial toxins could potentially contribute to HE. 13
Diagnosis
HE may often go unrecognised unless it is severe. 1 HE should be regarded as a continuum ranging from unimpaired cognitive function and intact consciousness through to coma. 2
Grading of Hepatic Encephalopathy 2,14-19
Temporal and clinical detection of HE subtypes
Covert (minimal) HE
Covert HE:
Denotes neuro-psychometric or neuro-psychological abnormalities without clinical evidence of mental change, but with subtle alterations in attention, psychomotor speed, working memory and visuospatial ability. Patients remain below the clinical detection level.
2,20
Episodic or Recurrent HE
Episodic HE or Recurrent HE:
Remains clinically undetectable in between HE episodes.
2,20
Episodic HE:
Denotes an isolated bout of HE.
2,20
Recurrent HE:
Denotes bouts of HE that occur with a time interval of 6 months or less.
2,20
Persistent (chronic) HE
Persistent HE:
Denotes a pattern of behavioural alterations that are always present and interspersed with relapses of overt HE. Patients never become free of HE.
2,20
Testing cognitive function
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Psychometric hepatic encephalopathy score (PHES) / Paper & Pencil tests:Inhibitory control test (ICT):
Critical flicker (fusion) frequency (CFF) test:
Imaging: