Encephalopathy
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Encephalopathy (; ) means any disorder or
disease A disease is a particular abnormal condition that adversely affects the structure or function (biology), function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical condi ...
of the
brain The brain is an organ (biology), organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It consists of nervous tissue and is typically located in the head (cephalization), usually near organs for ...
, especially chronic degenerative conditions. In modern usage, encephalopathy does not refer to a single disease, but rather to a
syndrome A syndrome is a set of medical signs and symptoms which are correlated with each other and often associated with a particular disease or disorder. The word derives from the Greek language, Greek σύνδρομον, meaning "concurrence". When a sy ...
of overall brain dysfunction; this syndrome has many possible organic and inorganic 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. * Acute necrotizing encephalopathy, rare disease that occurs following a viral infection. * Glycine encephalopathy: A genetic metabolic disorder involving excess production of glycine. *
Hepatic encephalopathy Hepatic encephalopathy (HE) is an altered level of consciousness as a result of liver failure. Its onset may be gradual or sudden. Other symptoms may include movement problems, changes in mood, or changes in personality. In the advanced stag ...
: 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, usually caused by prenatal exposure to ethanol. * 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 (B1) deficiency, usually in the setting of
alcoholism Alcoholism is the continued drinking of alcohol despite it causing problems. Some definitions require evidence of dependence and withdrawal. Problematic use of alcohol has been mentioned in the earliest historical records. The World He ...
. * Hashimoto's encephalopathy: Arising from an auto-immune disorder. * Anti-NMDA receptor encephalitis: An auto-immune encephalitis. * Hyperammonemia: A condition caused by high levels of
ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...
, which is due to inborn errors of metabolism (including urea cycle disorder or multiple carboxylase deficiency), a diet with excessive levels of
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
, deficiencies of specific nutrients such as
arginine Arginine is the amino acid with the formula (H2N)(HN)CN(H)(CH2)3CH(NH2)CO2H. The molecule features a guanidinium, guanidino group appended to a standard amino acid framework. At physiological pH, the carboxylic acid is deprotonated (−CO2−) a ...
or biotin, or organ failure. * Hypertensive encephalopathy: Arising from acutely increased blood pressure. *
Chronic traumatic encephalopathy Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease linked to repeated trauma to the head. The encephalopathy symptoms can include behavioral problems, mood problems, and problems with thinking. The disease often gets wor ...
: A progressive degenerative disease associated with repeated head trauma, often linked to
contact sports A contact sport is any sport where physical contact between competitors, or their environment, is an integral part of the game. For example, gridiron football. Contact may come about as the result of intentional or incidental actions by the playe ...
. * Lyme encephalopathy: Arising from Lyme disease bacteria, including '' Borrelia burgdorferi''. * Toxic encephalopathy: A form of encephalopathy caused by chemicals and prescription drugs, 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 (hypoxic-ischemic encephalopathy): An obstetric form, often occurring due to lack of oxygen in bloodflow to brain-tissue of the fetus during labour or delivery. *
Salmonella ''Salmonella'' is a genus of bacillus (shape), rod-shaped, (bacillus) Gram-negative bacteria of the family Enterobacteriaceae. The two known species of ''Salmonella'' are ''Salmonella enterica'' and ''Salmonella bongori''. ''S. enterica'' ...
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 In medicine, myopathy is a disease of the muscle in which the muscle fibers do not function properly. ''Myopathy'' means muscle disease ( Greek : myo- ''muscle'' + patheia '' -pathy'' : ''suffering''). This meaning implies that the primary defec ...
. Causes may include mitochondrial disease (particularly MELAS) or chronic
hypophosphatemia Hypophosphatemia is an electrolyte disorder in which there is a low level of phosphate in the blood. Symptoms may include weakness, trouble breathing, and loss of appetite. Complications may include seizures, coma, rhabdomyolysis, or soft ...
, as may occur in cystinosis. *
Creutzfeldt–Jakob disease Creutzfeldt–Jakob disease (CJD) is an incurable, always fatal neurodegenerative disease belonging to the transmissible spongiform encephalopathy (TSE) group. Early symptoms include memory problems, behavioral changes, poor coordination, visu ...
(CJD; transmissible spongiform encephalopathy). * Aicardi–Goutières syndrome, a hereditary disease caused by
mutations In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mitosi ...
in the '' TREX1, RNASEH2B, RNASEH2C, RNASEH2A, ADAR1, SAMHD1, IFIH1, LSM11'', or '' RNU7-1'' gene. * Infectious disease-associated encephalopathy (an umbrella term for encephalopathy related to infectious disease, not necessarily directly infecting the central nervous system) * HIV encephalopathy (encephalopathy associated with HIV infection and AIDS, characterized by atrophy and ill-defined white matter hyperintensity). * Sepsis-associated encephalopathy (this type can occur in the setting of apparent sepsis, trauma, severe burns, or trauma, even without clear identification of an infection). * Epileptic encephalopathies: ** Early infantile epileptic encephalopathy (acquired or congenital abnormal cortical development). ** Early myoclonic epileptic encephalopathy (possibly due to metabolic disorders). *
Gluten Gluten is a structural protein naturally found in certain Cereal, cereal grains. The term ''gluten'' usually refers to the elastic network of a wheat grain's proteins, gliadin and glutenin primarily, that forms readily with the addition of water ...
encephalopathy: Focal abnormalities of the white matter (generally area of low perfusion) are appreciated through magnetic resonance. Migraine is the most common symptom reported. * ''BRAT1'' Encephalopathy: An ultra-rare autosomal recessive neonatal encephalopathy.


Toxicity from chemotherapy

Chemotherapy medication, for example, fludarabine can cause a permanent severe global encephalopathy. Ifosfamide can cause a severe encephalopathy (but it can be reversible with stopping use of the drug and starting the use of methylene blue). Bevacizumab and other anti–vascular endothelial growth factor medication can cause posterior reversible encephalopathy syndrome.


Signs and symptoms

The hallmark of encephalopathy is an altered mental state or delirium. Characteristic of the altered mental state is impairment of the cognition, attention, orientation, sleep–wake cycle and
consciousness Consciousness, at its simplest, is awareness of a state or object, either internal to oneself or in one's external environment. However, its nature has led to millennia of analyses, explanations, and debate among philosophers, scientists, an ...
. An altered state of consciousness may range from failure of selective attention to drowsiness. Hypervigilance may be present; with or without: cognitive deficits,
headache A headache, also known as cephalalgia, is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of Depression (mood), depression in those with severe ...
,
epileptic seizure A seizure is a sudden, brief disruption of brain activity caused by abnormal, excessive, or synchronous neuronal firing. Depending on the regions of the brain involved, seizures can lead to changes in movement, sensation, behavior, awareness, o ...
s, myoclonus (involuntary twitching of a muscle or group of muscles) or asterixis ("flapping tremor" of the hand when wrist is extended). Depending on the type and severity of encephalopathy, common neurological symptoms are loss of cognitive function, subtle personality changes, and an inability to concentrate. Other neurological signs may include
dysarthria Dysarthria is a speech sound disorder resulting from neurological injury of the motor component of the motor–speech system and is characterized by poor articulation of phonemes. It is a condition in which problems effectively occur with the ...
, hypomimia, problems with movements (they can be clumsy or slow),
ataxia Ataxia (from Greek α- negative prefix+ -τάξις rder= "lack of order") is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in e ...
,
tremor A tremor is an involuntary, somewhat rhythmic muscle contraction and relaxation involving neural oscillations, oscillations or twitching movements of one or more body parts. It is the most common of all involuntary movements and can affect the h ...
. Other neurological signs may include involuntary grasping and sucking motions, nystagmus (rapid, involuntary eye movement), jactitation (restlessness while in bed), and respiratory abnormalities such as Cheyne-Stokes respiration (cyclic waxing and waning of tidal volume), apneustic respirations and post-hypercapnic
apnea Apnea (also spelled apnoea in British English) is the temporary cessation of breathing. During apnea, there is no movement of the muscles of inhalation, and the volume of the lungs initially remains unchanged. Depending on how blocked the ...
. Focal neurological deficits are less common.
Wernicke encephalopathy Wernicke encephalopathy (WE), also Wernicke's encephalopathy, or wet brain is the presence of neurological symptoms caused by biochemical lesions of the central nervous system after exhaustion of B-vitamin reserves, in particular thiamine (vi ...
can co-occur with Korsakoff alcoholic syndrome, characterized by amnestic-confabulatory syndrome:
retrograde amnesia In neurology, retrograde amnesia (RA) is the inability to access memories or information from before an injury or disease occurred. RA differs from a similar condition called anterograde amnesia (AA), which is the inability to form new memories f ...
, anterograde amnesia, confabulations (invented memories), poor recall and disorientation. Anti-NMDA receptor encephalitis is the most common autoimmune encephalitis. It can cause paranoid and
grandiose delusions Delusions of grandeur, also known as grandiose delusions (GDs) or expansive delusions, are a subtype of delusion characterized by the extraordinary belief that one is famous, omnipotent, wealthy, or otherwise very powerful or of a high status ...
, agitation,
hallucination A hallucination is a perception in the absence of an external stimulus that has the compelling sense of reality. They are distinguishable from several related phenomena, such as dreaming ( REM sleep), which does not involve wakefulness; pse ...
s (visual and auditory), bizarre behavior, fear, short-term memory loss, and confusion. HIV encephalopathy can lead to
dementia Dementia is a syndrome associated with many neurodegenerative diseases, characterized by a general decline in cognitive abilities that affects a person's ability to perform activities of daily living, everyday activities. This typically invo ...
.


Diagnosis

Blood test A blood test is a medical laboratory, laboratory analysis performed on a blood sample that is usually extracted from a vein in the arm using a hypodermic needle, or via fingerprick. Multiple tests for specific blood components, such as a glucose ...
s,
cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless Extracellular fluid#Transcellular fluid, transcellular body fluid found within the meninges, meningeal tissue that surrounds the vertebrate brain and spinal cord, and in the ventricular system, ven ...
examination by lumbar puncture (also known as spinal tap), brain imaging studies,
electroencephalography Electroencephalography (EEG) is a method to record an electrogram of the spontaneous electrical activity of the brain. The biosignal, bio signals detected by EEG have been shown to represent the postsynaptic potentials of pyramidal neurons in ...
(EEG), neuropsychological testing 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.


Treatment

Treatment varies according to the type and severity of the encephalopathy.
Anticonvulsant Anticonvulsants (also known as antiepileptic drugs, antiseizure drugs, or anti-seizure medications (ASM)) are a diverse group of pharmacological agents used in the treatment of epileptic seizures. Anticonvulsants are also used in the treatme ...
s may be prescribed to reduce or halt any seizures. Changes to diet and nutritional supplements may help some people. In severe cases, dialysis or organ replacement surgery may be needed. Sympathomimetic drugs can increase
motivation Motivation is an mental state, internal state that propels individuals to engage in goal-directed behavior. It is often understood as a force that explains why people or animals initiate, continue, or terminate a certain behavior at a particul ...
,
cognition Cognition is the "mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, thought, ...
, motor performance and alertness in persons with encephalopathy caused by
brain injury Brain injury (BI) is the destruction or degeneration of brain cells. Brain injuries occur due to a wide range of internal and external factors. In general, brain damage refers to significant, undiscriminating trauma-induced damage. A common ...
, chronic infections, strokes,
brain tumor A brain tumor (sometimes referred to as brain cancer) occurs when a group of cells within the Human brain, brain turn cancerous and grow out of control, creating a mass. There are two main types of tumors: malignant (cancerous) tumors and benign ...
s. When the encephalopathy is caused by untreated
celiac disease Coeliac disease (British English) or celiac disease (American English) is a long-term autoimmune disorder, primarily affecting the small intestine. Patients develop intolerance to gluten, which is present in foods such as wheat, rye, spel ...
or
non-celiac gluten sensitivity Non-celiac gluten sensitivity (NCGS) or gluten sensitivity is a controversial disorder which can cause both gastrointestinal and other problems. NCGS is included in the spectrum of gluten-related disorders. The definition and diagnostic criteria ...
, the gluten-free diet stops the progression of brain damage and improves the headaches.


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 Dementia is a syndrome associated with many neurodegenerative diseases, characterized by a general decline in cognitive abilities that affects a person's ability to perform activities of daily living, everyday activities. This typically invo ...
. Some encephalopathies can be fatal.


Terminology

Encephalopathy is a difficult term because it can be used to denote either a disease or finding (i.e., an observable sign in a person). When referring to a finding, encephalopathy refers to permanent (or degenerative) brain injury, or a reversible one. It can be due to direct injury to the brain, or illness remote from the brain. The individual findings that cause a clinician to refer to a person as having encephalopathy include intellectual disability, irritability, agitation, delirium, confusion, somnolence, stupor, coma and psychosis. As such, describing a person as having a clinical picture of encephalopathy is not a very specific description. When referring to a disease, encephalopathy refers to a wide variety of brain disorders with very different etiologies, prognoses and implications. For example,
prion A prion () is a Proteinopathy, misfolded protein that induces misfolding in normal variants of the same protein, leading to cellular death. Prions are responsible for prion diseases, known as transmissible spongiform encephalopathy (TSEs), w ...
diseases, all of which cause
transmissible spongiform encephalopathies Transmissible spongiform encephalopathies (TSEs), also known as prion diseases, are a group of progressive, incurable, and fatal conditions that are associated with the prion hypothesis and affect the brain and nervous system of many animals, in ...
, are invariably fatal, but other encephalopathies are reversible and can have a number of causes including nutritional deficiencies and toxins.


See also

*
Brain damage Brain injury (BI) is the destruction or degeneration of brain cells. Brain injuries occur due to a wide range of internal and external factors. In general, brain damage refers to significant, undiscriminating trauma-induced damage. A common ...
*
Neuroscience Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions, and its disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, ...
*
Neurological disorder Neurological disorders represent a complex array of medical conditions that fundamentally disrupt the functioning of the nervous system. These disorders affect the brain, spinal cord, and nerve networks, presenting unique diagnosis, treatment, and ...
* Psychoorganic syndrome


References

* Adapted from:


Further reading

* ''The Diagnosis of Stupor and Coma'' by Plum and Posner, , remains one of the best detailed observational references to the condition. {{Organ failure Brain disorders