Encephalopathy /ɛnˌsɛfəˈlɒpəθi/ means disorder or
disease of the
brain.
[1] In modern usage, encephalopathy does not refer to a single
disease, but rather to a
syndrome of global brain dysfunction; this syndrome can be caused by many different illnesses.
Terminology
In some contexts it refers to permanent (or degenerative)
[2]
brain injury, and in others it is reversible. It can be due to direct
injury to the brain, or illness remote from the brain. In medical terms
it can refer to a wide variety of brain disorders with very different
etiologies, prognoses and implications. For example,
prion diseases, all of which cause
transmissible spongiform encephalopathies,
are invariably fatal, but other encephalopathies are reversible and can
be caused by nutritional deficiencies, toxins, and several other
causes.
Types
There are many types of encephalopathy. Some examples include:
- Mitochondrial encephalopathy—Metabolic
disorder caused by dysfunction of mitochondrial DNA. Can affect many
body systems, particularly the brain and nervous system.
- Glycine encephalopathy—A genetic metabolic disorder involving excess production of glycine
- Hepatic encephalopathy—Arising from advanced cirrhosis of the liver
- Hypoxic ischemic encephalopathy—Permanent or transitory encephalopathy arising from severely reduced oxygen delivery to the brain
- Static encephalopathy—Unchanging, or permanent, brain damage
- Uremic encephalopathy—Arising from high levels of toxins normally
cleared by the kidneys—rare where dialysis is readily available
- Wernicke's encephalopathy—Arising from thiamine deficiency, usually in the setting of alcoholism
- Hashimoto's encephalopathy—Arising from an auto-immune disorder
- Hypertensive encephalopathy—Arising from acutely increased blood pressure
- Chronic traumatic encephalopathy—Progressive degenerative disease associated with multiple concussions and other forms of head injury
- Lyme encephalopathy—Arising from Lyme disease bacteria, including Borrelia burgdorferi.
- Toxic encephalopathy—A form of encephalopathy caused by chemicals, often resulting in permanent brain damage
- Toxic-Metabolic encephalopathy—A catch-all for brain dysfunction caused by infection, organ failure, or intoxication
- Transmissible spongiform encephalopathy—A
collection of diseases all caused by prions, and characterized by
"spongy" brain tissue (riddled with holes), impaired locomotion or
coordination, and a 100% mortality rate. Includes bovine spongiform encephalopathy (mad cow disease), scrapie, and kuru among others.
- Neonatal encephalopathy—an obstetric form, often occurring due to lack of oxygen in bloodflow to brain-tissue of the fetus during labour or delivery
- Salmonella encephalopathy —A form of encephalopathy caused by food
poisoning (especially out of peanuts and rotten meat) often resulting in
permanent brain damage and nervous system disorders.
- Encephalomyopathy, a combination of encephalopathy and myopathy. Causes may include mitochondrial disease (particularly MELAS) or chronic hypophosphatemia, as may occur in cystinosis.[3]
Symptoms
The hallmark of encephalopathy is an altered mental state. Depending
on the type and severity of encephalopathy, common neurological symptoms
are loss of cognitive function, subtle personality changes, inability
to concentrate, lethargy, and depressed consciousness. Other
neurological signs may include
myoclonus (involuntary twitching of a muscle or group of muscles),
asterixis (abrupt loss of muscle tone, quickly restored),
nystagmus (rapid, involuntary eye movement), tremor,
seizures, jactitation (restless picking at things characteristic of severe infection), and respiratory abnormalities such as
Cheyne-Stokes respiration (cyclic waxing and waning of tidal volume), apneustic respirations and post-hypercapnic apnea.
Diagnosis
Blood tests, spinal fluid examination by
lumbar puncture, imaging studies,
electroencephalograms and similar diagnostic studies may be used to differentiate the various causes of encephalopathy.
Diagnosis is frequently clinical. That is, no set of tests give the
diagnosis, but the entire presentation of the illness with nonspecific
test results informs the experienced clinician of the diagnosis.
Therapy
Treatment varies according to the type and severity of the encephalopathy.
Anticonvulsants
may be prescribed to reduce or halt any seizures. Changes to diet and
nutritional supplements may help some patients. In severe cases,
dialysis or organ replacement surgery may be needed.
Prognosis
Treating the underlying cause of the disorder may improve or reverse
symptoms. However, in some cases, the encephalopathy may cause permanent
structural changes and irreversible damage to the brain. Some
encephalopathies can be fatal.
See also
References
Further reading
- The Diagnosis of Stupor and Coma by Plum and Posner, ISBN 0-19-513898-8, remains one the of best detailed observational references to the condition.
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Brain/
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autoimmune ( Multiple sclerosis, Neuromyelitis optica, Schilder's disease) · hereditary ( Adrenoleukodystrophy, Alexander, Canavan, Krabbe, ML, PMD, VWM, MFC, CAMFAK syndrome) · Central pontine myelinolysis · Marchiafava-Bignami disease · Alpers' disease
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Other
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Spinal cord/
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