- Encephalopathy is a general term that means brain disease, damage, or malfunction.
- The major symptom of encephalopathy is an altered mental state.
- The causes of encephalopathy are numerous and varied; they include infections, anoxia, metabolic problems, toxins, drugs, physiologic changes, trauma, and other causes.
- Encephalopathy is often considered a complication of a primary problem such as alcoholic cirrhosis, kidney failure, or anoxia.
- Early treatment of many types of encephalopathy can eliminate, reduce, or halt the symptoms of encephalopathy.
- Often, cases of encephalopathy can be prevented by avoiding the many primary causes.
Encephalopathy definition and overview
Encephalopathy is a term that means brain disease, damage, or malfunction. Encephalopathy can present a very broad spectrum of symptoms that range from mild, such as some memory loss or subtle personality changes, to severe, such as dementia, seizures, coma, or death. In general, encephalopathy is manifested by an altered mental state that is sometimes accompanied by physical manifestations (for example, poor coordination of limb movements).
The term encephalopathy, in most cases, is preceded by various terms that describe the reason, cause, or special conditions of the patient that leads to brain malfunction. For example, anoxic encephalopathy means brain damage due to lack of oxygen, and hepatic encephalopathy means brain malfunction due to liver disease. Additionally, some other terms either describe body conditions or syndromes that lead to a specific set of brain malfunctions. Examples of these are metabolic encephalopathy and Wernicke's encephalopathy (Wernicke's syndrome). There are over 150 different terms that modify or precede "encephalopathy" in the medical literature; the purpose of this article is to introduce the reader to the main categories of conditions that fall under the broad term of encephalopathy.
Chronic Traumatic Encephalopathy (CTE)
Getting your bell rung was once a badge of honor in sports. The ability to shake it off and not miss a play was accepted and routine. But it had been known for almost a hundred years that repeated hits to the head had long-term consequences and “dementia pugilista” was the term used for a punch drunk old fighter who had been hit in the head one too many times. The realization was slow in coming that the same injury to the brain could occur in football players, and that the most popular sport in the country could be a potential cause of psychiatric disturbances and early dementia.
A new term was born: Chronic traumatic encephalopathy (CTE) describes a gradual degeneration in brain function due to repeated head injuries that causes both concussions with symptoms and concussions that are asymptomatic (do not cause symptoms). Once the initial symptoms of concussion have faded, months and years later, new symptoms occur. CTE symptoms start slowly and creep up on the patient. Initially, there may be concentration and memory problems with episodes of disorientation and confusion, dizziness, and headache. It is as if the concussion symptoms were starting to return even without a new head injury.
What causes encephalopathy?
The causes of encephalopathy are both numerous and varied.
Some examples of causes of encephalopathy include:
- infectious (bacteria, viruses, parasites, or prions),
- anoxic (lack of oxygen to the brain, including traumatic causes),
- alcoholic (alcohol toxicity),
- hepatic (for example, liver failure or liver cancer),
- uremic (renal or kidney failure),
- metabolic diseases (hyper- or hypocalcemia, hypo- or hypernatremia, or hypo- or hyperglycemic),
- brain tumors,
- many types of toxic chemicals (mercury, lead, or ammonia),
- alterations in pressure within the brain (often from bleeding, tumors, or abscesses), and
- poor nutrition (inadequate vitamin B1 intake or alcohol withdrawal).
These examples do not cover all of the potential causes of encephalopathy but are listed to demonstrate the wide range of causes.
Although numerous causes of encephalopathy are known, the majority of cases arise from several major categories (some examples in parentheses):
- infection (HIV, Neisseria meningitides, herpes, and hepatitis B and hepatitis C),
- liver damage (alcohol and toxins),
- brain anoxia or brain cell destruction (including trauma), and
- kidney failure (uremic).
Some drugs may cause encephalopathy; for example, posterior reversible encephalopathy syndrome (PRES) may occur due to the use of drugs like tacrolimus and cyclosporine. This syndrome manifests with symptoms of headache, confusion, and seizures.
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What are the symptoms of encephalopathy?
Despite the numerous and varied causes of encephalopathy, at least one symptom present in all cases is an altered mental state. The altered mental state may be subtle and develop slowly over years (for example, in hepatitis the decreased ability to draw simple designs, termed apraxia) or be profoundly obvious and develop rapidly (for example, brain anoxia leading to coma or death in a few minutes). Often, symptoms of altered mental status can present as inattentiveness, poor judgment, or poor coordination of movements.
Other serious symptoms that may occur include:
- muscle twitching and myalgia,
- Cheyne-Stokes respirations (an altered breathing pattern seen with brain damage and coma), and
Often the severity and type of symptoms are related to the severity and cause of the brain disease or damage. For example, alcohol-induced liver damage (alcoholic cirrhosis) can result in involuntary hand tremors (asterixis), while severe anoxia (lack of oxygen) may result in coma with no movement. Other symptoms may not be as severe and may be more localized such as cranial nerve palsies (damage to one of the 12 cranial nerves that exit the brain). Some symptoms may be very subtle and result from repeated injury to the brain tissue. For example, chronic traumatic encephalopathy (CTE), due to injury like concussions repeatedly sustained by football players and others who play contact sports, may cause slow changes over time that are not easily diagnosed. Such injury may lead to chronic depression or other personality changes that can result in life-changing consequences.
Even infants and children can suffer encephalopathy. Similar symptoms can occur in the perinatal period if the neonate had any compromise to brain blood flow during its development. Rasmussen's encephalitis is a rare disease that is seen in children that progresses to intractable seizures if untreated. It may be due to autoantibody development. Another rare form of encephalopathy that usually develops in younger people (about ages 4 to 20 years) is the MELAS syndrome ("Mitochondrial Encephalopathy, Lactic Acidosis, Stroke-like episodes") due to faulty DNA in the patient's mitochondria (a tiny part within the cell that is responsible for energy conversion).
How is encephalopathy diagnosed?
The diagnosis of encephalopathy is usually made with clinical tests done during the physical examination (mental status tests, memory tests, and coordination tests) that document an altered mental state.
In most cases, findings on clinical tests either diagnose or presumptively diagnose encephalopathy. Usually, the diagnosis occurs when the altered mental state accompanies another primary diagnosis such as chronic liver disease, kidney failure, anoxia, or many other diagnoses.
Consequently, physicians may utilize several different tests at the same time to diagnose both the primary condition (the cause of encephalopathy) and the encephalopathy itself. This approach to diagnosis is done by most physicians, because
encephalopathy is a complication that occurs because of a primary underlying health problem. The most frequently utilized tests are listed below with some of the major primary causes the tests may help diagnose:
- Complete blood count or CBC (infections or loss of blood)
- Blood pressure (high or low blood pressure)
- Metabolic tests (blood levels of electrolytes, glucose, lactate, ammonia, oxygen, and liver enzymes)
- Drugs or toxin levels (alcohol, cocaine, amphetamines, and many others)
- Blood and body fluid cultures and analyses (infections of many types)
- Creatinine (kidney function)
- CT and MRI scans (brain swelling, anatomical abnormalities, or infections)
- Doppler ultrasound (abnormal blood flow to tissues or abscesses)
- Encephalogram or EEG (brain damage or abnormal brain wave patterns)
- Autoantibody analysis (dementia caused by antibodies that destroy neurons)
- Review of the person's medications as some medications (for example, cyclosporine) may be responsible for symptoms
This list is not exhaustive, and not all of the above tests need to be done
on every patient. Specific testing is usually ordered by the treating physician according to the symptoms and history of the patient.
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What is the treatment for encephalopathy?
Treatment of encephalopathy varies with the primary cause of the symptoms. Consequently, not all cases of encephalopathy are treated the same.
Some examples of different "encephalopathy treatments" for different causes:
- Short-term anoxia (usually less than two minutes): oxygen therapy
- Long-term anoxia: rehabilitation
- Short-term alcohol toxicity: IV fluids or no therapy
- Long-term alcohol abuse (cirrhosis or chronic liver failure): oral lactulose, low-protein diet, antibiotics
- Uremic encephalopathy (due to kidney failure): correct the underlying physiologic cause, dialysis, kidney transplant
- Diabetic encephalopathy: administer glucose to treat hypoglycemia, insulin to treat hyperglycemia
- Hypo- or hypertensive encephalopathy: medications to raise (for hypotensive) or reduce (for hypertensive) blood pressure
The key to treatment of any encephalopathy is to understand the basic cause and thus design a treatment plan to reduce or eliminate the cause(s). There is one type of encephalopathy that is difficult or impossible to treat; it is static encephalopathy (an altered mental state or brain damage that is permanent). The best that can be done with static encephalopathy is, if possible, to prevent further damage and implement rehabilitation to allow the individual to perform at his or her highest possible functional level.
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What are the complications of encephalopathy?
Complications of encephalopathy vary from none to profound mental impairments that lead to death. The complications can be similar in some cases. Also, many investigators consider encephalopathy itself to be a complication that arises from a primary health problem or primary diagnosis.
Complications depend on the primary cause of encephalopathy and can be illustrated by citing a few examples from the wide variety of causes:
- Hepatic (liver) encephalopathy (brain swelling with herniation, coma, death)
- Metabolic encephalopathy (irritability, lethargy, depression, tremors; occasionally, coma or death)
- Anoxic encephalopathy (wide range of complications, from none in short-term anoxia to personality changes, severe brain damage to death in long-term anoxic events)
- Uremic encephalopathy (lethargy, hallucinations, stupor, muscle twitching, seizures, death)
- Hashimoto's encephalopathy (confusion, heat intolerance, dementia)
- Wernicke's encephalopathy (mental confusion, memory loss, decreased ability to move eyes)
- Bovine spongiform encephalopathy (BSE) or "mad cow disease" (ataxia, dementia, and myoclonus or muscle twitching without any rhythm or pattern)
- Shigella encephalopathy (headache, stiff neck, delirium, seizures, coma)
- Infectious causes of pediatric encephalopathy (irritability, poor feeding, hypotonia or floppy baby syndrome, seizures, death)
The best way to understand potential complications is to discuss these with the diagnosing doctor who can discuss the possible problems associated with the specific cause(s) of the type of encephalopathy.
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What is the prognosis (outlook) for encephalopathy?
The prognosis for a patient with encephalopathy depends on the initial causes and, in general, the length of time it takes to reverse, stop, or inhibit those causes. Consequently, the prognosis varies from patient to patient and ranges from complete recovery to a poor prognosis that often leads to permanent brain damage or death. This highly variable prognosis is exemplified by patients that get encephalopathy from hypoglycemia. If patients with hypoglycemia are given glucose at the first signs of encephalopathy (for example, irritability, mild confusion), most patients recover completely. Delays in correcting hypoglycemia (hours to days) may lead to seizures or coma, which may be halted by treatment with complete or partial recovery (minimal permanent brain damage). A long delay or multiple delays in treatment can lead to a poor prognosis with extensive brain damage, coma, or death.
Although the symptoms and time frame vary widely from patient to patient and according to the initial causes of encephalopathy (see above sections for examples of causes), the prognosis of each case usually follows the pattern described in the hypoglycemic example above and depends upon the extent and rapidity with which the underlying cause is treated. The doctor or team of doctors treating the underlying cause of encephalopathy can offer the best information on the individual's prognosis.
Can encephalopathy be prevented?
Many cases of encephalopathy can be prevented. The key to prevention is to stop or limit the chance of developing any of the multitudes of causes of encephalopathy. If encephalopathy develops, the quicker the underlying cause is treated, the more likely that severe encephalopathy can be prevented.
Examples of prevention (and situations to avoid) are listed below:
- Diabetic encephalopathy: Follow your prescribed diabetes management plan, including taking glucose measurements when appropriate. Take all medications as directed.
- Hepatic encephalopathy: Avoid alcohol intoxication, drug overdoses, and IV injections of illegal drugs.
- Anoxic encephalopathy: Prevent choking on food. Avoid risky behavior that could lead to head and neck trauma. Avoid exposure to carbon monoxide.
- Hypertensive encephalopathy: Monitor blood pressure; take antihypertensive medication as directed and do not stop medications or change medication without consulting a doctor.
- Infectious encephalopathy: Avoid physical contact with individuals known to be infected with organisms that may cause encephalopathy such as N. meningitidis or Shigella.
- Uremic encephalopathy: Do not skip or avoid scheduled dialysis. Take all medications as directed and have frequent assessments of mental status.
Methods for prevention of encephalopathy are about as numerous as the underlying causes; however, some cases of encephalopathy may not be preventable (for example, congenital and accidental traumatic encephalopathy).
A concussion is a traumatic brain injury.
For more information on types of encephalopathy
Medically Reviewed on 8/13/2018
Medically reviewed by Jon Glass, MD; Board Certificate: Neurology
"Definition of Encephalitis." eMedicineHealth. 19 Mar. 2012.
Shiel, William C. and Frederick Hecht. "MELAS Syndrome." 19 July 2006.
Wedro, Benjamin and Charles Patrick Davis. "Encephalopathy." eMedicineHealth. 6 Oct. 2009.