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Portosystemic Encephalopathy
Pathology
- fibrosis blocks portal vein → portal hypertension
- collaterals develop
- umbilical
- left renal
- anal
- venous drainage of gut bypass first pass metabolism of liver
- ? ammonia
Precipitating factors
- increased dietary proteins
- GI haemorrhage (large protein meal)
- Constipation
- Infection
- Fluid and electrolyte disturbance
- diuretic therapy
- paracentesis
- Drugs
- TIPS
- Surgery
- Progressive liver damage
- Development of Hepatocellular
Carcinoma
History
Acute onset
- precipitating factor
- increasing drowsiness and confusion
Chronic onset
- history from relative
- mood disorder
- personality change
- intellectual deficit
- reversal of normal sleep rhythm
- nausea
- vomiting
- weakness
- convulsions
- coma
Examination
- irritable
- confused
- disorientated
- slow, slurred speech
- hyperventilation
- pyrexia
- fetor hepaticus
- asterixis
- constructional apraxia
- reduced mental function
- trail time increased
- serial sevens
Investigations
- LFTs confirm presence of liver disease
- EEG
- alpha waves (8-13 Hz ) decreased in frequency to delta waves (1.5-3
Hz)
- Visual evoked responses
- Arterial ammonia (if available)
Management
Acutely
- remove precipitants
- purgatives / enemas
- lactulose (30ml/day)
- reduces colonic pH → reduced ammonia absorption
- protein-free diet
- antibiotics
- stop / reduce diuretic therapy
- correct electrolyte imbalance
- IV fluids
- Treat infection
- Flumazenil
Chronically
- increase protein to level of tolerance
- lactulose
- avoid precipitants
- narcotic drugs
- over-diuresis
Prognosis
- variable, dependent on underlying disease
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