Hepatic encephalopathy🎥
Hepatic Encephalopathy
Introduction
Hepatic encephalopathy (HE) is a reversible neuropsychiatric syndrome that occurs as a result of liver dysfunction. It is caused by the accumulation of neurotoxins, particularly ammonia, in the systemic circulation due to impaired hepatic clearance. The condition ranges in severity from subtle cognitive impairment to deep coma.
Peak Incidence
- Most commonly affects individuals aged 50 to 70 years.
- More frequent in patients with decompensated cirrhosis or acute liver failure.
Pathophysiology
- The failing liver cannot adequately detoxify nitrogenous substances, especially ammonia, produced by intestinal bacteria.
- Ammonia crosses the blood–brain barrier, leading to astrocyte swelling, cerebral oedema, and disrupted neurotransmission.
- Precipitating factors (e.g. infection, gastrointestinal bleeding, electrolyte disturbances) often trigger or exacerbate episodes of encephalopathy.
Symptoms
- Fatigue
- Sleep disturbances (e.g. reversed sleep–wake cycle)
- Slurred speech
- Irritability and mood changes
- Impaired attention and short-term memory
- Personality changes
Signs
- Asterixis – Flapping tremor observed when the arms are extended and wrists dorsiflexed
- Altered mental status – Confusion, disorientation, or decreased consciousness
- Constructional apraxia – Inability to perform tasks like drawing a five-pointed star
- Coma – In advanced stages
Diagnosis
Clinical Diagnosis
- Based on history, symptoms, and physical examination findings.
- Classification often follows the West Haven criteria, ranging from Grade 0 (minimal) to Grade 4 (coma).
Identify Precipitating Factors
- Common triggers include:
- Infections (e.g. spontaneous bacterial peritonitis)
- Gastrointestinal bleeding
- Constipation
- Electrolyte disturbances (e.g. hypokalaemia, hyponatraemia)
- Use of sedatives or opiates
- Transjugular intrahepatic portosystemic shunt (TIPS)
Supportive Investigations
- Serum ammonia – May be elevated, but levels do not correlate well with severity and are no longer routinely measured
- Electroencephalogram (EEG) – May show triphasic slow wave activity
- Psychometric testing – Useful for detecting minimal/covert hepatic encephalopathy in early or subclinical stages
Complications
- Cerebral oedema – Particularly in acute liver failure; may lead to raised intracranial pressure and brain herniation
- Seizures
- Aspiration pneumonia – Due to reduced consciousness
- Coma and death – In severe or untreated cases
Management
Medical Therapy
- Lactulose – First-line treatment
- Reduces ammonia absorption by acidifying colonic contents and promoting excretion via soft stools
- Dose titrated to achieve 2–3 soft stools daily
- Rifaximin – Non-absorbable antibiotic used as secondary prophylaxis
- Suppresses ammonia-producing gut flora
Treat Underlying/Precipitating Factors
- Infection – Treat appropriately (e.g. empirical antibiotics for suspected SBP)
- GI bleeding – Initiate standard resuscitation and endoscopic management
- Electrolyte disturbances – Correct hypokalaemia, hyponatraemia, and hypomagnesaemia
- Constipation – Treat with lactulose or enemas
- Review medications – Avoid sedatives, benzodiazepines, and excessive diuretics
Supportive Care
- Nutritional optimisation, including enteral feeding if required
- Consideration of shunt embolisation if recurrent HE is related to portosystemic shunts
- Liver transplantation – Consider in patients with chronic liver failure and recurrent or refractory encephalopathy
FAQ from our users
What are the common triggers of hepatic encephalopathy?
- Infection (e.g. spontaneous bacterial peritonitis)
- Gastrointestinal bleeding
- Constipation
- Electrolyte disturbances
- Certain medications – Sedatives, diuretics, and opioids
How is hepatic encephalopathy graded?
- Grade I – irritability
- Grade II – confusion, inappropriate behaviour
- Grade III – incoherent, restless
- Grade IV – coma.
Common pitfalls in a clinical setting
Common pitfalls in a clinical setting
Common pitfalls in a clinical setting
- Ammonia levels are not routinely needed for the diagnosis of hepatic encephalopathy – clinical features are more reliable.