Encephalopathy Health Article

Definition

Encephalopathy is a condition characterized by altered brain function and structure. It is caused by diffuse brain disease.

Description

Encephalopathy may be caused by advanced and severe disease states, infections, or as a result of taking certain medications. The three main causes of encephalopathy are liver disease, kidney disease, and lack of oxygen in the brain. The associated symptoms can include subtle personality changes, inability to concentrate, lethargy, progressive loss of memory and thinking abilities, progressive loss of consciousness, and abnormal involuntary movements. Symptoms vary with the severity and type of encephalopathy.

Encephalopathy may vary in severity from only subtle changes in mental state to a more advanced state that can lead to deep coma. Cerebral edema is a common manifestation of severe encephalopathy, which causes an increase in intracranial pressure. The major related causes of death include sepsis, circulatory collapse, and brain failure related to a syndrome encompassing cerebral edema, damaged blood-brain-barrier, increased intracranial pressure, brainstem herniation, and/or neurotoxins leaking into the brain and killing brain cells. Additionally, patients with severe encephalopathy usually develop intracranial hypertension, which can produce cerebral ischemia injury and cerebral herniation.

Demographics

There is no statistical information available for encephalopathy per se. Encephalopathy can occur at any age and there seems to be no gender or racial predilection, because encephalopathy is a manifestation of a primary illness.

Causes

There is a wide variety of conditions that cause encephalopathy. Encephalopathy can be caused by infections (bacteria, viruses, or prions); lack of oxygen to the brain; liver failure; kidney failure; alcohol/drug overdose; prolonged exposure to toxic chemical (solvents, paints, industrial chemicals, drugs, radiation); metabolic diseases; brain tumor; increased intracranial pressure; and poor nutrition.

HYPOXIC ENCEPHALOPATHY Hypoxic encephalopathy refers to a lack of oxygen to the entire brain, which typically results in brain damage. Cerebral hypoxia can be caused by drowning, low blood pressure, birth injuries, cardiac arrest, strangulation, asphyxiation caused by smoke inhalation, severe hemorrhage, carbon monoxide poisoning, high altitudes, choking, tracheal compression, complications of anesthesia, paralysis of respiratory muscles, and respiratory failure.

Cardiac arrest is the most common condition that causes cerebral hypoxia. When the heart stops pumping, oxygen-rich blood cannot be delivered to vital organs such as the brain. Hypoxia to the brain causes irreversible brain damage after two minutes.

HEPATIC ENCEPHALOPATHY Hepatic encephalopathy refers to a condition of brain and nervous system damage caused by liver (hepatic) failure. Diseases that damage the liver causing impairment of the detoxification and functional capabilities of the liver can cause hepatic encephalopathy. Examples of disorders that decrease liver function are hepatitis or cirrhosis. Impairment in the detoxification capabilities of the liver causes accumulation of toxic chemicals in the blood such as ammonia, in addition to many other impurities that all collectively cause damage to the nervous system.

KIDNEY FAILURE The main function for the kidneys is to eliminate excess fluid and waste material from the blood. When the kidneys lose the ability to filter the blood, dangerous levels of waste products accumulate in the body. Chronic renal failure can be caused by diabetes, analgesic nephropathy (due to long-term use of aspirin or nonsteroidal anti-inflammatory drugs), kidney diseases (polycystic kidney disease, pyelonephritis, and glomerulonephritis), renal artery stenosis (a narrowing of the artery that supplies blood to the kidneys), and lead poisoning.

SEVERE INFECTIONS Severe infections, especially those that affect the brain, can cause encephalopathy. Infections that specifically target the brain are encephalitis, which is inflammation of the brain, typically caused by a virus, or meningitis, which is inflammation of the tissue that surrounds and protects the brain.

CHRONIC ALCOHOL USE Long-term use of alcohol not only causes destruction of brain cells but can cause cirrhosis of the liver or hepatitis, which results in the destruction of liver cells. Chronic alcoholism leads to progressive destruction of liver cells, which can cause end-stage liver failure. A subtype of hepatitis infection called hepatitis C typically causes progressive destruction to liver cells.

UREMIC ENCEPHALOPATHY Uremia describes the final stage of progressive renal insufficiency, which culminates in end-stage kidney failure with neurologic involvement. This is called uremic encephalopathy. The cause is unknown and no single metabolite or toxin is responsible for symptoms, but rather it is an accumulation of several chemicals/toxins in the blood that causes symptoms of encephalopathy.