Encephalopathy pathophysiology On the Web
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Encephalopathy may be due to damage to blood brain barrier with accumulation of toxic substances (Hepatic encephalopathy), low oxygen (Hypoxic encephalopathy), low levels of vitamins such as vitamin B1 (Wernicke encephalopathy) and sepsis (Septic encephalopathy).
Encephalopathy is a broad term given to numerous condition's which cause dysfunction of the brain. There are various underlying mechanisms:
The brain is protected from the circulatory toxins by the blood brain barrier lined by astrocytes. In cases of hepatic failure due to any reason, the detoxifying capacity of liver is drastically reduced. This causes an increase in the concentration of circulatory toxins like ammonia, mercaptans, manganese. Circulatory toxins damage the barrier made by astrocytes and cause pathological changes in the cells. This alters blood brain barrier and toxins gain access into the brain tissues.
The brain needs a large oxygen supply owing to its high metabolic activity. When oxygen is deprived from the brain, energy stores of the neuronal cells is decreased rapidly resulting in neuronal injury and encephalopathy.
Normal neuronal activity requires a balanced environment of electrolytes, water and lots of substrates. In case of dehydration and renal diseases causing electrolyte abnormalities this equilibrium is disturbed. This results in dysfunction of the brain.
This is a disorder of diencephalic brain tissue around the third and fourth ventricle. It results of deficiency of vitamin B1, thiamine. It is the most under recognized cause of encephalopathy in intensive care units. Thiamine is an important co-factor for enzyme required for glucose utilization in brain. If this is deficient it automatically goes into a low energy state and performs suboptimally.
- Septic encephalopathy