Encephalopathy means disorder or disease of the brain.
In modern usage, encephalopathy does not refer to a single disease, but rather to a syndrome
of global brain dysfunction; this syndrome can have many different organic and inorganic
causes.
Terminology In some contexts it refers to permanent 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, impaired locomotion or coordination, and a
100% mortality rate.
Includes bovine spongiform encephalopathy, 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 often resulting in
permanent brain damage and nervous system disorders.
Encephalomyopathy: A combination of encephalopathy and myopathy.
Causes may include mitochondrial disease or chronic hypophosphatemia, as may occur in
cystinosis.
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, asterixis, nystagmus, tremor, seizures, jactitation,
and respiratory abnormalities such as Cheyne-Stokes respiration, apneustic respirations and post-hypercapnic
apnea.
Diagnosis Blood tests, cerebrospinal fluid examination
by lumbar puncture, brain 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.
These permanent deficits can be considered a form of stable dementia.
Some encephalopathies can be fatal.
See also Brain damage
Neurobiology Neurobiological brain disorder
Chronic traumatic encephalopathy References
Adapted from: Office of Communications and Public Liaison.
"NINDS Encephalopathy Information Page".
National Institute of Neurological Disorders and Stroke, National Institutes of Health.
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.