Wernicke's encephalopathy
Encyclopedia
Wernicke encephalopathy is a syndrome
characterised by ataxia
, ophthalmoplegia, confusion, and impairment of short-term memory
.
It is caused by lesions in the medial thalamic nuclei, mammillary bodies, periaqueductal and periventricular brainstem nuclei, and superior cerebellar vermis, often resulting from inadequate intake or absorption of thiamine
(vitamin B1), especially in conjunction with carbohydrate
ingestion.
It is most commonly correlated with prolonged alcohol consumption resulting in thiamine deficiency. Alcoholics
are therefore particularly at risk, but it may also occur with thiamine deficiency states arising from other causes, particularly in patients with such gastric disorders as carcinoma
, chronic gastritis, Crohn's disease
, and repetitive vomiting, particularly after bariatric surgery
.
, confabulation
, and short-term memory loss.
The classic triad of the syndrome is confusion, ophthalmoplegia (eye paralysis), and ataxia
(loss of coordination), though these are only seen in combination in 10% of cases. Untreated it may progress to Korsakoff's psychosis, coma
and death. The pathological changes seen in Wernicke's encephalopathy are concentrated in the mammillary bodies, cranial nerve nuclei III, IV, VI and VIII, the thalamus
, hypothalamus
, periaqueductal grey, cerebellar vermis
, and the dorsal nucleus of the vagus nerve. The ataxia and ophthalmoparesis are related to lesions in the oculomotor, trochlear, abducens, and vestibular (IIIrd, IVth, VIth, and VIIIth cranial) nerve nuclei.
Despite its name, Wernicke's encephalopathy is not related to Wernicke's area, a region of the brain associated with speech and language interpretation. (See Wernicke's aphasia.) Rather, both are named for the 19th century neurologist Carl Wernicke.
death due to the effects of thiamine deficiency upon astrocyte
s. This causes alterations in their glutamate uptake, through changes in the levels of the astrocytic glutamate transporters EAAT1 and EAAT2 creating excitotoxicity
. Other changes include those to the GABA
transporter subtype GAT-3, GFAP, glutamine synthetase
, the water channel protein Aquaporin 4
. These create lactic acidosis
, brain edema, oxidative stress
, inflammation
, and white matter
damage.
of thiamine
, followed by assessment of central nervous system
and metabolic conditions. In the presence of sub-clinical thiamine deficiency, a large dose of sugar (especially glucose) can precipitate the onset of overt encephalopathy; therefore, correcting hypoglycemia should not be attempted before thiamine replenishment. Rehydration to restore blood volume
should follow, as needed.
Prognosis depends on severity. When treated early, recovery is normally rapid and complete. Established Wernicke's encephalopathy, by contrast, can have serious long-term consequences, with patients requiring permanent in-patient care.
Syndrome
In medicine and psychology, a syndrome is the association of several clinically recognizable features, signs , symptoms , phenomena or characteristics that often occur together, so that the presence of one or more features alerts the physician to the possible presence of the others...
characterised by ataxia
Ataxia
Ataxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum...
, ophthalmoplegia, confusion, and impairment of short-term memory
Short-term memory
Short-term memory is the capacity for holding a small amount of information in mind in an active, readily available state for a short period of time. The duration of short-term memory is believed to be in the order of seconds. A commonly cited capacity is 7 ± 2 elements...
.
It is caused by lesions in the medial thalamic nuclei, mammillary bodies, periaqueductal and periventricular brainstem nuclei, and superior cerebellar vermis, often resulting from inadequate intake or absorption of thiamine
Thiamine
Thiamine or thiamin or vitamin B1 , named as the "thio-vitamine" is a water-soluble vitamin of the B complex. First named aneurin for the detrimental neurological effects if not present in the diet, it was eventually assigned the generic descriptor name vitamin B1. Its phosphate derivatives are...
(vitamin B1), especially in conjunction with carbohydrate
Carbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...
ingestion.
It is most commonly correlated with prolonged alcohol consumption resulting in thiamine deficiency. Alcoholics
Alcoholism
Alcoholism is a broad term for problems with alcohol, and is generally used to mean compulsive and uncontrolled consumption of alcoholic beverages, usually to the detriment of the drinker's health, personal relationships, and social standing...
are therefore particularly at risk, but it may also occur with thiamine deficiency states arising from other causes, particularly in patients with such gastric disorders as carcinoma
Carcinoma
Carcinoma is the medical term for the most common type of cancer occurring in humans. Put simply, a carcinoma is a cancer that begins in a tissue that lines the inner or outer surfaces of the body, and that generally arises from cells originating in the endodermal or ectodermal germ layer during...
, chronic gastritis, Crohn's disease
Crohn's disease
Crohn's disease, also known as regional enteritis, is a type of inflammatory bowel disease that may affect any part of the gastrointestinal tract from mouth to anus, causing a wide variety of symptoms...
, and repetitive vomiting, particularly after bariatric surgery
Bariatric surgery
Bariatric surgery includes a variety of procedures performed on people who are obese. Weight loss is achieved by reducing the size of the stomach with an implanted medical device or through removal of a portion of the stomach or by resecting and re-routing the small intestines...
.
Presentation
Wernicke's encephalopathy begins abruptly, usually with eye movement disorders (nystagmus, gaze palsies, and ophthalmoplegia, especially of the lateral rectus muscles), gait ataxia, confusionConFusion
ConFusion is an annual science fiction convention organized by the Stilyagi Air Corps and its parent organization, the Ann Arbor Science Fiction Association. Commonly, it is held the third weekend of January. It is the oldest science fiction convention in Michigan, a regional, general SF con...
, confabulation
Confabulation
Confabulation is the process in which a memory is remembered falsely. Confabulations are indicative of a complicated and intricate process that can be led astray at any given point during encoding, storage, or recall of a memory. Two distinct types of confabulation are often distinguished...
, and short-term memory loss.
The classic triad of the syndrome is confusion, ophthalmoplegia (eye paralysis), and ataxia
Ataxia
Ataxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum...
(loss of coordination), though these are only seen in combination in 10% of cases. Untreated it may progress to Korsakoff's psychosis, coma
Coma
In medicine, a coma is a state of unconsciousness, lasting more than 6 hours in which a person cannot be awakened, fails to respond normally to painful stimuli, light or sound, lacks a normal sleep-wake cycle and does not initiate voluntary actions. A person in a state of coma is described as...
and death. The pathological changes seen in Wernicke's encephalopathy are concentrated in the mammillary bodies, cranial nerve nuclei III, IV, VI and VIII, the thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
, hypothalamus
Hypothalamus
The Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions...
, periaqueductal grey, cerebellar vermis
Cerebellar vermis
The cerebellar vermis is located in the medial, cortico-nuclear zone of the cerebellum, residing in the posterior fossa of the cranium. The primary fissure in the vermis curves ventrolaterally to the superior surface of the cerebellum, dividing it into anterior and posterior lobes....
, and the dorsal nucleus of the vagus nerve. The ataxia and ophthalmoparesis are related to lesions in the oculomotor, trochlear, abducens, and vestibular (IIIrd, IVth, VIth, and VIIIth cranial) nerve nuclei.
Despite its name, Wernicke's encephalopathy is not related to Wernicke's area, a region of the brain associated with speech and language interpretation. (See Wernicke's aphasia.) Rather, both are named for the 19th century neurologist Carl Wernicke.
Cause
The neuropathy of Wernicke's encephalopathy causes neuronNeuron
A neuron is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core components of the nervous...
death due to the effects of thiamine deficiency upon astrocyte
Astrocyte
Astrocytes , also known collectively as astroglia, are characteristic star-shaped glial cells in the brain and spinal cord...
s. This causes alterations in their glutamate uptake, through changes in the levels of the astrocytic glutamate transporters EAAT1 and EAAT2 creating excitotoxicity
Excitotoxicity
Excitotoxicity is the pathological process by which nerve cells are damaged and killed by excessive stimulation by neurotransmitters such as glutamate and similar substances. This occurs when receptors for the excitatory neurotransmitter glutamate such as the NMDA receptor and AMPA receptor are...
. Other changes include those to the GABA
Gabâ
Gabâ or gabaa, for the people in many parts of the Philippines), is the concept of a non-human and non-divine, imminent retribution. A sort of negative karma, it is generally seen as an evil effect on a person because of their wrongdoings or transgressions...
transporter subtype GAT-3, GFAP, glutamine synthetase
Glutamine synthetase
Glutamine synthetase is an enzyme that plays an essential role in the metabolism of nitrogen by catalyzing the condensation of glutamate and ammonia to form glutamine:Glutamate + ATP + NH3 → Glutamine + ADP + phosphate...
, the water channel protein Aquaporin 4
Aquaporin 4
Aquaporin 4 also known as AQP4 is protein which in humans is encoded by the AQP4 gene. AQP4 belongs to the aquaporin family of integral membrane proteins that conduct water through the cell membrane.- Function :...
. These create lactic acidosis
Lactic acidosis
Lactic acidosis is a physiological condition characterized by low pH in body tissues and blood accompanied by the buildup of lactate especially D-lactate, and is considered a distinct form of metabolic acidosis. The condition typically occurs when cells receive too little oxygen , for example...
, brain edema, oxidative stress
Oxidative stress
Oxidative stress represents an imbalance between the production and manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage...
, inflammation
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
, and white matter
White matter
White matter is one of the two components of the central nervous system and consists mostly of myelinated axons. White matter tissue of the freshly cut brain appears pinkish white to the naked eye because myelin is composed largely of lipid tissue veined with capillaries. Its white color is due to...
damage.
Treatment
Treatment begins with intravenous or intramuscular injectionInjection (medicine)
An injection is an infusion method of putting fluid into the body, usually with a hollow needle and a syringe which is pierced through the skin to a sufficient depth for the material to be forced into the body...
of thiamine
Thiamine
Thiamine or thiamin or vitamin B1 , named as the "thio-vitamine" is a water-soluble vitamin of the B complex. First named aneurin for the detrimental neurological effects if not present in the diet, it was eventually assigned the generic descriptor name vitamin B1. Its phosphate derivatives are...
, followed by assessment of central nervous system
Central nervous system
The central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
and metabolic conditions. In the presence of sub-clinical thiamine deficiency, a large dose of sugar (especially glucose) can precipitate the onset of overt encephalopathy; therefore, correcting hypoglycemia should not be attempted before thiamine replenishment. Rehydration to restore blood volume
Blood volume
Blood volume is the volume of blood in the circulatory system of an individual.-Humans:A typical adult has a blood volume of approximately between 4.7 and 5 liters, with females generally having less blood volume than males....
should follow, as needed.
Prognosis depends on severity. When treated early, recovery is normally rapid and complete. Established Wernicke's encephalopathy, by contrast, can have serious long-term consequences, with patients requiring permanent in-patient care.
External links
- The Merck Manual, Wernicke's encephalopathy
- Images of Wernicke's encephalopathy MR and Gross Brain Pictures