LIVER-BRAIN AXIS
Normal brain functioning depends on several aspects of normal liver functioning.
For example,
the liver supplies certain nutrients to the brain that the brain itself cannot produce.
The liver also cleanses the blood of substances that could damage brain cells (i.e.,
neurotoxins,
for e.g.
ammonia,
manganese,
and other chemicals).
In chronic liver disease and cirrhosis,
the liver loses its capacity to remove toxic substances from the blood due to loss of functional liver cells (i.e.,
hepatocytes).
Moreover,
some of the blood that normally flows through the portal vein into the liver for cleansing is diverted directly into the general circulation without first passing through the liver,
a phenomenon known as portal–systemic shunting.
As a result,
the shunted blood is not detoxified and blood levels of toxic substances rise.
Persistently elevated neurotoxin levels can damage brain cells and cause a wide spectrum of neurocognitive decline.
NEUROLOGY OF LIVER CIRRHOSIS
A neurological syndrome associated with a liver disease may affect the CNS,
the peripheral nervous system,
or both; and,
could represent a direct complication of the disease,
or part of spectrum of pathologies that affect the brain and liver concurrently [1-6].
Boradly,
neurological disorders in cirrhosis can be attributed to:
(A) Direct effects of cirrhosis on the nervous system:
- Neuroimaging alterations with/without clinical symptoms
- Hepatic encephalopathy
- Cirrhotic or hepatic myelopathy
- Acquired hepatocerebral degeneration
- Cirrhosis-related Parkinsonism
- Cirrhosis related intracerebral hemorrhage
- Infective comlpications of cirrhosis
- Raised intracranial pressure (acute-on-chronic liver failure)
(B) Neurological complications related to chronic alcohol use:
- Osmotic demyelination syndromes
- Wernicke encephalopathy
- Marchiafava-Bignami disease
- Alcohol withdrawal syndrome
- Cerebral atrophy and cognitive dysfunction
- Alcoholic cerebellar degeneration
(C) Induced by a factor that also contributes to the (hepatic) disease:
- Wilson disease
- Hepatitis C virus infection
(D) Deficits unrelated to liver disease,
such as:
- Residual deficits of prior strokes
LIVER TRANSPLANTATION-RELATED COMPLICATIONS
Among solid organ transplant recipients,
recipients of liver transplantation have the highest incidence of neurological complications. Neurological complications following liver transplantation have an overall incidence of 13 - 47%.
These complications can be broadly classified into:
(1) Immunosuppressive neurotoxicity
(2) Opportunistic infections
(3) Osmotic demyelination
(4) Cerebrovascular complications
(5) Post transplant encephalopathy
(6) Hepatic encephalopathy
(7) Seizures
(8) Post transplant lymphoproliferative disorder