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Monday, February 24, 2020

Liver transplantation

From Wikipedia, the free encyclopedia
 
Liver transplantation
Human Hepar.jpg
Human liver
Specialtyhepatology
ICD-9-CM50.5
MeSHD016031
MedlinePlus003006

Liver transplantation or hepatic transplantation is the replacement of a diseased liver with the healthy liver from another person (allograft). Liver transplantation is a treatment option for end-stage liver disease and acute liver failure, although availability of donor organs is a major limitation. The most common technique is orthotopic transplantation, in which the native liver is removed and replaced by the donor organ in the same anatomic position as the original liver. The surgical procedure is complex, requiring careful harvest of the donor organ and meticulous implantation into the recipient. Liver transplantation is highly regulated, and only performed at designated transplant medical centers by highly trained transplant physicians and supporting medical team. The duration of the surgery ranges from 4 to 18 hours depending on outcome. Favorable outcomes require careful screening for eligible recipient, as well as a well-calibrated live or cadaveric donor match.

Medical uses

Liver transplantation is a potential treatment for acute or chronic conditions which cause irreversible and severe ("end-stage") liver dysfunction. Since the procedure carries relatively high risks, is resource-intensive, and requires major life-modifications after surgery, it is reserved for dire circumstances. 

Judging the appropriateness/effectiveness of liver transplant on case-by-case basis is critically important, as outcomes are highly variable.

Contraindications

Although liver transplantation is the most effective treatment for many forms of end-stage liver disease, the tremendous limitation in allograft availability and widely variable post-surgical outcomes make case selection critically important. Assessment of a person's transplant eligibility is made by a multi-disciplinary team that includes surgeons, medical doctors, and other providers.

The first step in evaluation is to determine whether the patient has irreversible liver-based disease which will be cured by getting a new liver. Thus, those with diseases which are primarily based outside the liver or have spread beyond the liver are generally considered poor candidates. Some examples include:
  • someone with advanced liver cancer, with known/likely spread beyond the liver
  • active alcohol/substance abuse
  • severe heart/lung disease
  • existing high cholesterol levels in the patient
  • dyslipidemia 
Importantly, many contraindications to liver transplantation are considered reversible; a person initially deemed "transplant-ineligible" may later become a favorable candidate if their situation changes. Some examples include:
  • partial treatment of liver cancer, such that risk of spread beyond liver is decreased (for those with primary liver cancer or secondary spread to the liver, the medical team will likely rely heavily on the opinion of the patient's primary provider, the oncologist, and the radiologist)
  • cessation of substance abuse (time period of abstinence is variable)
  • improvement in heart function, e.g. by percutaneous coronary intervention or bypass surgery
  • treated HIV infection (see Special populations)
  • for those with high cholesterol or triglyceride levels or other dyslipidemias, using lifestyle changes (diet, portions, exercise) and drugs and counseling to lower one's levels, and to control any hyperglycemia or (pre-)diabetes or obesity

Risks/complications

Graft rejection

After a liver transplantation, immune-mediated rejection (also known as rejection) of the allograft may happen at any time. Rejection may present with lab findings: elevated AST, ALT, GGT; abnormal liver function values such as prothrombin time, ammonia level, bilirubin level, albumin concentration; and abnormal blood glucose. Physical findings may include encephalopathy, jaundice, bruising and bleeding tendency. Other nonspecific presentation may include malaise, anorexia, muscle ache, low fever, slight increase in white blood count and graft-site tenderness. 

Three types of graft rejection may occur: hyperacute rejection, acute rejection, and chronic rejection.
  • Hyperacute rejection is caused by preformed anti-donor antibodies. It is characterized by the binding of these antibodies to antigens on vascular endothelial cells. Complement activation is involved and the effect is usually profound. Hyperacute rejection happens within minutes to hours after the transplant procedure.
  • Acute rejection is mediated by T cells (versus B-cell-mediated hyperacute rejection). It involves direct cytotoxicity and cytokine mediated pathways. Acute rejection is the most common and the primary target of immunosuppressive agents. Acute rejection is usually seen within days or weeks of the transplant.
  • Chronic rejection is the presence of any sign and symptom of rejection after one year. The cause of chronic rejection is still unknown, but an acute rejection is a strong predictor of chronic rejections.

Technique

Before transplantation, liver-support therapy might be indicated (bridging-to-transplantation). Artificial liver support like liver dialysis or bioartificial liver support concepts are currently under preclinical and clinical evaluation. Virtually all liver transplants are done in an orthotopic fashion; that is, the native liver is removed and the new liver is placed in the same anatomic location. The transplant operation can be conceptualized as consisting of the hepatectomy (liver removal) phase, the anhepatic (no liver) phase, and the postimplantation phase. The operation is done through a large incision in the upper abdomen. The hepatectomy involves division of all ligamentous attachments to the liver, as well as the common bile duct, hepatic artery, hepatic vein and portal vein. Usually, the retrohepatic portion of the inferior vena cava is removed along with the liver, although an alternative technique preserves the recipient's vena cava ("piggyback" technique).

The donor's blood in the liver will be replaced by an ice-cold organ storage solution, such as UW (Viaspan) or HTK until the allograft liver is implanted. Implantation involves anastomoses (connections) of the inferior vena cava, portal vein, and hepatic artery. After blood flow is restored to the new liver, the biliary (bile duct) anastomosis is constructed, either to the recipient's own bile duct or to the small intestine. The surgery usually takes between five and six hours, but may be longer or shorter due to the difficulty of the operation and the experience of the surgeon.

The large majority of liver transplants use the entire liver from a non-living donor for the transplant, particularly for adult recipients. A major advance in pediatric liver transplantation was the development of reduced size liver transplantation, in which a portion of an adult liver is used for an infant or small child. Further developments in this area included split liver transplantation, in which one liver is used for transplants for two recipients, and living donor liver transplantation, in which a portion of a healthy person's liver is removed and used as the allograft. Living donor liver transplantation for pediatric recipients involves removal of approximately 20% of the liver (Couinaud segments 2 and 3).

Further advance in liver transplant involves only resection of the lobe of the liver involved in tumors and the tumor-free lobe remains within the recipient. This speeds up the recovery and the patient stay in the hospital quickly shortens to within 5–7 days.

Many major medical centers are now using radiofrequency ablation of the liver tumor as a bridge while awaiting for liver transplantation. This technique has not been used universally and further investigation is warranted.

Cooling

Between removal from donor and transplantation into the recipient, the allograft liver is stored in a temperature-cooled preservation solution. The reduced temperature slows down the process of deterioration from normal metabolic processes, and the storage solution itself is designed to counteract the unwanted effects of cold ischemia. Although this "static" cold storage method has long been standard technique, various dynamic preservation methods are under investigation. For example, systems which use a machine to pump blood through the explanted liver (after it is harvested from the body) during a transfer have met some success.

Living donor transplantation

Volume rendering image created with computed tomography, which can be used to evaluate the volume of the liver of a potential donor.

Living donor liver transplantation (LDLT) has emerged in recent decades as a critical surgical option for patients with end stage liver disease, such as cirrhosis and/or hepatocellular carcinoma often attributable to one or more of the following: long-term alcohol abuse, long-term untreated hepatitis C infection, long-term untreated hepatitis B infection. The concept of LDLT is based on (1) the remarkable regenerative capacities of the human liver and (2) the widespread shortage of cadaveric livers for patients awaiting transplant. In LDLT, a piece of healthy liver is surgically removed from a living person and transplanted into a recipient, immediately after the recipient’s diseased liver has been entirely removed.

Historically, LDLT began with terminal pediatric patients, whose parents were motivated to risk donating a portion of their compatible healthy livers to replace their children's failing ones. The first report of successful LDLT was by Christoph Broelsch at the University of Chicago Medical Center in November 1989, when two-year-old Alyssa Smith received a portion of her mother's liver. Surgeons eventually realized that adult-to-adult LDLT was also possible, and now the practice is common in a few reputable medical institutes. It is considered more technically demanding than even standard, cadaveric donor liver transplantation, and also poses the ethical problems underlying the indication of a major surgical operation (hemihepatectomy or related procedure) on a healthy human being. In various case series, the risk of complications in the donor is around 10%, and very occasionally a second operation is needed. Common problems are biliary fistula, gastric stasis and infections; they are more common after removal of the right lobe of the liver. Death after LDLT has been reported at 0% (Japan), 0.3% (USA) and <1 2006="" 2012.="" altruistic="" as="" britain="" changed="" december="" decrease="" donation="" donations="" experience="" first="" further="" gain="" in="" law="" likely="" liver="" living="" more="" non-directed="" organ="" p="" permit="" place="" procedure.="" risks="" since="" surgeons="" the="" this="" to="" took="" uk="" urope="" was="" with="">

In a typical adult recipient LDLT, 55 to 70% of the liver (the right lobe) is removed from a healthy living donor. The donor's liver will regenerate approaching 100% function within 4–6 weeks, and will almost reach full volumetric size with recapitulation of the normal structure soon thereafter. It may be possible to remove up to 70% of the liver from a healthy living donor without harm in most cases. The transplanted portion will reach full function and the appropriate size in the recipient as well, although it will take longer than for the donor.

Living donors are faced with risks and/or complications after the surgery. Blood clots and biliary problems have the possibility of arising in the donor post-op, but these issues are remedied fairly easily. Although death is a risk that a living donor must be willing to accept prior to the surgery, the mortality rate of living donors in the United States is low. The LDLT donor's immune system does diminish as a result of the liver regenerating, so certain foods which would normally cause an upset stomach could cause serious illness.

Donor requirements

CT scan performed for evaluation of a potential donor. The image shows an unusual variation of hepatic artery. The left hepatic artery supplies not only left lobe but also segment 8. The anatomy makes right lobe donation impossible. Even used as left lobe or lateral segment donation, it would be very technically challenging in anastomosing the small arteries.

Any member of the family, parent, sibling, child, spouse or a volunteer can donate their liver. The criteria for a liver donation include:
  • Being in good health
  • Having a blood type that matches or is compatible with the recipient's, although some centres now perform blood group incompatible transplants with special immunosuppression protocols
  • Having a charitable desire of donation without financial motivation
  • Being between 20 and 60 years old
  • Have an important personal relationship with the recipient
  • Being of similar or larger size than the recipient
  • Before one becomes a living donor, the donor must undergo testing to ensure that the individual is physically fit, in excellent health, and not having uncontrolled high blood pressure, liver disease, diabetes or heart disease. Sometimes CT scans or MRIs are done to image the liver. In most cases, the work up is done in 2–3 weeks.

Complications

Living donor surgery is done at a major center. Very few individuals require any blood transfusions during or after surgery. All potential donors should know there is a 0.5 to 1.0 percent chance of death. Other risks of donating a liver include bleeding, infection, painful incision, possibility of blood clots and a prolonged recovery. The vast majority of donors enjoy complete and full recovery within 2–3 months.

Pediatric transplantation

In children, due to their smaller abdominal cavity, there is only space for a partial segment of liver, usually the left lobe of the donor's liver. This is also known as a "split" liver transplant. There are four anastomoses required for a "split" liver transplant: hepaticojejunostomy (biliary drainage connecting to a roux limb of jejunum), portal venous anatomosis, hepatic arterial anastomosis, and inferior vena cava anastomosis.
 
In children, living liver donor transplantations have become very accepted. The accessibility of adult parents who want to donate a piece of the liver for their children/infants has reduced the number of children who would have otherwise died waiting for a transplant. Having a parent as a donor also has made it a lot easier for children - because both patients are in the same hospital and can help boost each other's morale.

Benefits

There are several advantages of living liver donor transplantation over cadaveric donor transplantation, including:
  • Transplant can be done on an elective basis because the donor is readily available
  • There are fewer possibilities for complications and death than there would be while waiting for a cadaveric organ donor
  • Because of donor shortages, UNOS has placed limits on cadaveric organ allocation to foreigners who seek medical help in the USA. With the availability of living donor transplantation, this will now allow foreigners a new opportunity to seek medical care in the USA.

Screening for donors

Living donor transplantation is a multidisciplinary approach. All living liver donors undergo medical evaluation. Every hospital which performs transplants has dedicated nurses that provide specific information about the procedure and answer questions that families may have. During the evaluation process, confidentiality is assured on the potential donor. Every effort is made to ensure that organ donation is not made by coercion from other family members. The transplant team provides both the donor and family thorough counseling and support which continues until full recovery is made.

All donors are assessed medically to ensure that they can undergo the surgery. Blood type of the donor and recipient must be compatible but not always identical. Other things assessed prior to surgery include the anatomy of the donor liver. However, even with mild variations in blood vessels and bile duct, surgeons today are able to perform transplantation without problems. The most important criterion for a living liver donor is to be in excellent health.

Post-transplant immunosuppression

Like most other allografts, a liver transplant will be rejected by the recipient unless immunosuppressive drugs are used. The immunosuppressive regimens for all solid organ transplants are fairly similar, and a variety of agents are now available. Most liver transplant recipients receive corticosteroids plus a calcineurin inhibitor such as tacrolimus or ciclosporin, (also spelled cyclosporine and cyclosporin) plus a purine antagonist such as mycophenolate mofetil. Clinical outcome is better with tacrolimus than with ciclosporin during the first year of liver transplantation. If the patient has a co-morbidity such as active hepatitis B, high doses of hepatitis B immunoglubins are administrated in liver transplant patients.

Liver transplantation is unique in that the risk of chronic rejection also decreases over time, although the great majority of recipients need to take immunosuppressive medication for the rest of their lives. It is possible to be slowly taken off anti rejection medication but only in certain cases. It is theorized that the liver may play a yet-unknown role in the maturation of certain cells pertaining to the immune system. There is at least one study by Thomas E. Starzl's team at the University of Pittsburgh which consisted of bone marrow biopsies taken from such patients which demonstrate genotypic chimerism in the bone marrow of liver transplant recipients.

Recovery and outcomes

The prognosis following liver transplant is variable, depending on overall health, technical success of the surgery, and the underlying disease process affecting the liver. There is no exact model to predict survival rates; those with transplant have a 58% chance of surviving 15 years. Failure of the new liver occurs in 10% to 15% of all cases. These percentages are contributed to by many complications. Early graft failure is probably due to preexisting disease of the donated organ. Others include technical flaws during surgery such as revascularization that may lead to a nonfunctioning graft.

History

As with many experimental models used in early surgical research, the first attempts at liver transplantation were performed on dogs. The earliest published reports of canine liver transplantations were performed in 1955 by Vittorio Staudacher at Opedale Maggiore Policlinico in Milan, Italy. This initial attempt varied significantly from contemporary techniques; for example, Staudacher reported "arterialization" of the donor portal vein via the recipient hepatic artery, and use of cholecystostomy for biliary drainage.

The first attempted human liver transplant was performed in 1963 by Thomas Starzl, although the pediatric patient died intraoperatively due to uncontrolled bleeding. Multiple subsequent attempts by various surgeons remained unsuccessful until 1967, when Starzl transplanted a 19 month old girl with hepatoblastoma who was able to survive for over 1 year before dying of metastatic disease. Despite the development of viable surgical techniques, liver transplantation remained experimental through the 1970s, with one year patient survival in the vicinity of 25%. The introduction of ciclosporin by Sir Roy Calne, Professor of Surgery Cambridge, markedly improved patient outcomes, and the 1980s saw recognition of liver transplantation as a standard clinical treatment for both adult and pediatric patients with appropriate indications. Liver transplantation is now performed at over one hundred centers in the US, as well as numerous centres in Europe and elsewhere.

The limited supply of liver allografts from non-living donors relative to the number of potential recipients spurred the development of living donor liver transplantation. The first altruistic living liver donation in Britain was performed in December 2012 in St James University Hospital Leeds.

Society and culture

Famous liver transplant recipients

Research directions

Cooling

There is increasing interest in improving methods for allograft preservation following organ harvesting. The standard "static cold storage" technique relies on decreased temperature to slow of anaerobic metabolic breakdown. This is currently being investigated at cold (hypothermic), body temperature (normothermic), and under body temperature (subnormothermic). Hypothermic machine perfusion has been used successfully at Columbia University and at the University of Zurich. A 2014 study showed that the liver preservation time could be significantly extended using a supercooling technique, which preserves the liver at subzero temperatures (-6 °C)  More recently, the first randomised controlled clinical trial comparing machine preservation with conventional cold storage showed comparable outcomes, with better early function, fewer discarded organs, and longer preservation times compared with cold stored livers.

Special populations

Alcohol dependence

The high incidence of liver transplants given to those with alcoholic cirrhosis has led to a recurring controversy regarding the eligibility of such patients for liver transplant. The controversy stems from the view of alcoholism as a self-inflicted disease and the perception that those with alcohol-induced damage are depriving other patients who could be considered more deserving. It is an important part of the selection process to differentiate transplant candidates who suffer from alcoholism as opposed to those who were susceptible to non-dependent alcohol use. The latter who gain control of alcohol use have a good prognosis following transplantation. Once a diagnosis of alcoholism has been established, however, it is necessary to assess the likelihood of future sobriety.

HIV

Historically, HIV was considered an "absolute" contraindication to liver transplantation. This was in part due to concern that the infection would be worsened by the immunosuppressive medication which is required after transplantation.

However, with the advent of highly active antiretroviral therapy (HAART), people with HIV have much improved prognosis. Transplantation may be offered selectively, although consideration of overall health and life circumstances may still be limiting. Uncontrolled HIV disease (AIDS) remains an absolute contraindication.

Wilson's disease

From Wikipedia, the free encyclopedia

Wilson's disease
Other namesWilson disease, hepatolenticular degeneration
Kayser-Fleischer ringArrow.jpg
A brown ring on the edge of the cornea (Kayser–Fleischer ring) is common in Wilson's disease, especially when neurological symptoms are present.
SpecialtyGastroenterology
SymptomsSwelling of the legs, yellowish skin, personality changes
Usual onsetAge 5 to 35
CausesGenetic
Differential diagnosisChronic liver disease, Parkinson's disease, multiple sclerosis, others
TreatmentDietary changes, chelating agents, zinc supplements, liver transplant
Frequency~1 per 30,000

Wilson's disease is a genetic disorder in which excess copper builds up in the body. Symptoms are typically related to the brain and liver. Liver-related symptoms include vomiting, weakness, fluid build up in the abdomen, swelling of the legs, yellowish skin and itchiness. Brain-related symptoms include tremors, muscle stiffness, trouble speaking, personality changes, anxiety and seeing or hearing things that others do not.

Wilson's disease is caused by a mutation in the Wilson disease protein (ATP7B) gene. This protein transports excess copper into bile, where it is excreted in waste products.[1] The condition is autosomal recessive; for a person to be affected, they must inherit a mutated copy of the gene from both parents. Diagnosis may be difficult and often involves a combination of blood tests, urine tests and a liver biopsy. Genetic testing may be used to screen family members of those affected.

Wilson's disease is typically treated with dietary changes and medication. Dietary changes involve eating a low-copper diet and not using copper cookware. Medications used include chelating agents such as trientine and d-penicillamine and zinc supplements.[1] Complications of Wilson's disease can include liver failure, liver cancer and kidney problems. A liver transplant may be helpful in those in whom other treatments are not effective or if liver failure occurs.

Wilson's disease occurs in about 1 in 30,000 people. Symptoms usually begin between the ages of 5 and 35 years. It was first described in 1854 by German pathologist Friedrich Theodor von Frerichs and is named after British neurologist Samuel Wilson.

Signs and symptoms

The main sites of copper accumulation are the liver and the brain, and consequently liver disease and neuropsychiatric symptoms are the main features that lead to diagnosis. People with liver problems tend to come to medical attention earlier, generally as children or teenagers, than those with neurological and psychiatric symptoms, who tend to be in their twenties or older. Some are identified only because relatives have been diagnosed with Wilson's disease; many of these, when tested, turn out to have been experiencing symptoms of the condition but have not received a diagnosis.

Liver disease

Liver disease may present itself as tiredness, increased bleeding tendency or confusion (due to hepatic encephalopathy) and portal hypertension. The latter, a condition in which the pressure in the portal vein is markedly increased, leads to esophageal varices, blood vessels in the esophagus that may bleed in a life-threatening fashion, as well as enlargement of the spleen (splenomegaly) and accumulation of fluid in the abdominal cavity (ascites). On examination, signs of chronic liver disease such as spider angiomata (small distended blood vessels, usually on the chest) may be observed. Chronic active hepatitis has caused cirrhosis of the liver in most by the time they develop symptoms. While most people with cirrhosis have an increased risk of hepatocellular carcinoma (liver cancer), this risk is relatively very low in Wilson's disease.

About 5% of all people are diagnosed only when they develop fulminant acute liver failure, often in the context of a hemolytic anemia (anemia due to the destruction of red blood cells). This leads to abnormalities in protein production (identified by deranged coagulation) and metabolism by the liver. The deranged protein metabolism leads to the accumulation of waste products such as ammonia in the bloodstream. When these irritate the brain, the person develops hepatic encephalopathy (confusion, coma, seizures and finally life-threatening swelling of the brain).

Neuropsychiatric symptoms

About half the people with Wilson's disease have neurological or psychiatric symptoms. Most initially have mild cognitive deterioration and clumsiness, as well as changes in behavior. Specific neurological symptoms usually then follow, often in the form of parkinsonism (cogwheel rigidity, bradykinesia or slowed movements and a lack of balance are the most common parkinsonian features) with or without a typical hand tremor, masked facial expressions, slurred speech, ataxia (lack of coordination) or dystonia (twisting and repetitive movements of part of the body). Seizures and migraine appear to be more common in Wilson's disease. A characteristic tremor described as "wing-beating tremor" is encountered in many people with Wilson's; this is absent at rest but can be provoked by abducting the arms and flexing the elbows toward the midline.

Cognition can also be affected in Wilson's disease. This comes in two, not mutually exclusive, categories: frontal lobe disorder (may present as impulsivity, impaired judgement, promiscuity, apathy and executive dysfunction with poor planning and decision making) and subcortical dementia (may present as slow thinking, memory loss and executive dysfunction, without signs of aphasia, apraxia or agnosia). It is suggested that these cognitive involvements are related and closely linked to psychiatric manifestations of the disease.

Psychiatric problems due to Wilson's disease may include behavioral changes, depression, anxiety disorders, and psychosis. Psychiatric symptoms are commonly seen in conjunction with neurological symptoms and are rarely manifested on their own. These symptoms are often poorly defined and can sometimes be attributed to other causes. Because of this, diagnosis of Wilson's disease is rarely made when only psychiatric symptoms are present.

Other organ systems

Medical conditions have been linked with copper accumulation in Wilson's disease:

Genetics

Wilson's disease has an autosomal recessive pattern of inheritance.

The Wilson's disease gene (ATP7B) is on chromosome 13 (13q14.3) and is expressed primarily in the liver, kidney, and placenta. The gene codes for a P-type (cation transport enzyme) ATPase that transports copper into bile and incorporates it into ceruloplasmin. Mutations can be detected in 90% of cases. Most (60%) are homozygous for ATP7B mutations (two abnormal copies), and 30% have only one abnormal copy. Ten percent have no detectable mutation.

Although 300 mutations of ATP7B have been described, in most populations the cases of Wilson's disease are due to a small number of mutations specific for that population. For instance, in Western populations the H1069Q mutation (replacement of a histidine by a glutamine at position 1069 in the protein) is present in 37–63% of cases, while in China this mutation is very uncommon and R778L (arginine to leucine at 778) is found more often. Relatively little is known about the relative impact of various mutations, although the H1069Q mutation seems to predict later onset and predominantly neurological problems, according to some studies.

A normal variation in the PRNP gene can modify the course of the disease by delaying the age of onset and affecting the type of symptoms that develop. This gene produces prion protein, which is active in the brain and other tissues and also appears to be involved in transporting copper. A role for the ApoE gene was initially suspected but could not be confirmed.

The condition is inherited in an autosomal recessive pattern. In order to inherit it, both of the parents of an individual must carry an affected gene. Most have no family history of the condition. People with only one abnormal gene are called carriers (heterozygotes) and may have mild, but medically insignificant, abnormalities of copper metabolism.

Wilson's disease is the most common from a group of hereditary diseases that cause copper overload in the liver. All can cause cirrhosis at a young age. The other members of the group are Indian childhood cirrhosis (ICC), endemic Tyrolean infantile cirrhosis and idiopathic copper toxicosis. These are not related to ATP7B mutations: for example, ICC has been linked to mutations in the KRT8 and the KRT18 gene.

Pathophysiology

Normal absorption and distribution of copper. Cu = copper, CP = ceruloplasmin, green = ATP7B carrying copper.

Copper is needed by the body for a number of functions, predominantly as a cofactor for a number of enzymes such as ceruloplasmin, cytochrome c oxidase, dopamine β-hydroxylase, superoxide dismutase and tyrosinase.

Copper enters the body through the digestive tract. A transporter protein on the cells of the small bowel, copper membrane transporter 1 (Ctr1; SLC31A1), carries copper inside the cells, where some is bound to metallothionein and part is carried by ATOX1 to an organelle known as the trans-Golgi network. Here, in response to rising concentrations of copper, an enzyme called ATP7A (Menkes' protein) releases copper into the portal vein to the liver. Liver cells also carry the CMT1 protein, and metallothionein and ATOX1 bind it inside the cell, but here it is ATP7B that links copper to ceruloplasmin and releases it into the bloodstream, as well as removing excess copper by secreting it into bile. Both functions of ATP7B are impaired in Wilson's disease. Copper accumulates in the liver tissue; ceruloplasmin is still secreted, but in a form that lacks copper (termed apoceruloplasmin) and is rapidly degraded in the bloodstream.

When the amount of copper in the liver overwhelms the proteins that normally bind it, it causes oxidative damage through a process known as Fenton chemistry; this damage eventually leads to chronic active hepatitis, fibrosis (deposition of connective tissue) and cirrhosis. The liver also releases copper into the bloodstream that is not bound to ceruloplasmin. This free copper precipitates throughout the body but particularly in the kidneys, eyes and brain. In the brain, most copper is deposited in the basal ganglia, particularly in the putamen and globus pallidus (together called the lenticular nucleus); these areas normally participate in the coordination of movement as well as playing a significant role in neurocognitive processes such as the processing of stimuli and mood regulation. Damage to these areas, again by Fenton chemistry, produces the neuropsychiatric symptoms seen in Wilson's disease.

It is not clear why Wilson's disease causes hemolysis, but various lines of evidence suggest that a high level of free (non-ceruloplasmin bound) copper has a direct effect on either oxidation of hemoglobin, inhibition of energy-supplying enzymes in the red blood cell, or direct damage to the cell membrane.

Diagnosis

Location of the basal ganglia, the part of the brain affected by Wilson's disease

Wilson's disease may be suspected on the basis of any of the symptoms mentioned above, or when a close relative has been found to have Wilson's. Most have slightly abnormal liver function tests such as a raised aspartate transaminase, alanine transaminase and bilirubin level. If the liver damage is significant, albumin may be decreased due to an inability of damaged liver cells to produce this protein; likewise, the prothrombin time (a test of coagulation) may be prolonged as the liver is unable to produce proteins known as clotting factors. Alkaline phosphatase levels are relatively low in those with Wilson's-related acute liver failure. If there are neurological symptoms, magnetic resonance imaging (MRI) of the brain is usually performed; this shows hyperintensities in the part of the brain called the basal ganglia in the T2 setting. MRI may also demonstrate the characteristic "face of the giant panda" pattern.

There is no totally reliable test for Wilson's disease, but levels of ceruloplasmin and copper in the blood, as well of the amount of copper excreted in urine during a 24-hour period, are together used to form an impression of the amount of copper in the body. The gold standard—or most ideal test—is a liver biopsy.

Ceruloplasmin

Ceruloplasmin

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as it is an acute phase protein. Low ceruloplasmin is also found in Menkes disease and aceruloplasminemia, which are related to, but much rarer than Wilson's disease.

The combination of neurological symptoms, Kayser–Fleischer rings and a low ceruloplasmin level is considered sufficient for the diagnosis of Wilson's disease. In many cases, however, further tests are needed.

Serum and urine copper

Serum copper is low, which may seem paradoxical given that Wilson's disease is a disease of copper excess. However, 95% of plasma copper is carried by ceruloplasmin which is often low in Wilson's disease. Urine copper is elevated in Wilson's disease and is collected for 24 hours in a bottle with a copper-free liner. Levels above 100 μg/24h (1.6 μmol/24h) confirm Wilson's disease, and levels above 40 μg/24h (0.6 μmol/24h) are strongly indicative. High urine copper levels are not unique to Wilson's disease; they are sometimes observed in autoimmune hepatitis and in cholestasis (any disease obstructing the flow of bile from the liver to the small bowel).

In children, the penicillamine test may be used. A 500 mg oral dose of penicillamine is administered, and urine collected for 24 hours. If this contains more than 1600 μg (25 μmol), it is a reliable indicator of Wilson's disease. This test has not been validated in adults.

Liver biopsy

Once other investigations have indicated Wilson's disease, the ideal test is the removal of a small amount of liver tissue through a liver biopsy. This is assessed microscopically for the degree of steatosis and cirrhosis, and histochemistry and quantification of copper are used to measure the severity of the copper accumulation. A level of 250 μg of copper per gram of dried liver tissue confirms Wilson's disease. Occasionally, lower levels of copper are found; in that case, the combination of the biopsy findings with all other tests could still lead to a formal diagnosis of Wilson's.

In the earlier stages of the disease, the biopsy typically shows steatosis (deposition of fatty material), increased glycogen in the nucleus, and areas of necrosis (cell death). In more advanced disease, the changes observed are quite similar to those seen in autoimmune hepatitis, such as infiltration by inflammatory cells, piecemeal necrosis and fibrosis (scar tissue). In advanced disease, finally, cirrhosis is the main finding. In acute liver failure, degeneration of the liver cells and collapse of the liver tissue architecture is seen, typically on a background of cirrhotic changes. Histochemical methods for detecting copper are inconsistent and unreliable, and taken alone are regarded as insufficient to establish a diagnosis.

Genetic testing

Mutation analysis of the ATP7B gene, as well as other genes linked to copper accumulation in the liver, may be performed. Once a mutation is confirmed, it is possible to screen family members for the disease as part of clinical genetics family counseling. Regional distributions of genes associated with Wilson's disease are important to follow, as this can help clinicians design appropriate screening strategies. Since mutations of the WD gene vary between populations, research and genetic testing done in countries like the USA or United Kingdom can pose problems as they tend to have more mixed populations.

Treatment

Diet

In general, a diet low in copper-containing foods is recommended with the avoidance of mushrooms, nuts, chocolate, dried fruit, liver, sesame seeds and sesame oil, and shellfish.

Medication

Medical treatments are available for Wilson's disease. Some increase the removal of copper from the body, while others prevent the absorption of copper from the diet.

Generally, penicillamine is the first treatment used. This binds copper (chelation) and leads to excretion of copper in the urine. Hence, monitoring of the amount of copper in the urine can be done to ensure a sufficiently high dose is taken. Penicillamine is not without problems: about 20% experience a side effect or complication of penicillamine treatment, such as drug-induced lupus (causing joint pains and a skin rash) or myasthenia (a nerve condition leading to muscle weakness). In those who presented with neurological symptoms, almost half experience a paradoxical worsening in their symptoms. While this phenomenon is observed in other treatments for Wilson's, it is usually taken as an indication for discontinuing penicillamine and commencing second-line treatment. Those intolerant to penicillamine may instead be commenced on trientine hydrochloride, which also has chelating properties. Some recommend trientine as first-line treatment, but experience with penicillamine is more extensive. A further agent, under clinical investigation by Wilson Therapeutics, with known activity in Wilson's disease is tetrathiomolybdate. This is regarded as experimental, though some studies have shown a beneficial effect.

Once all results have returned to normal, zinc (usually in the form of a zinc acetate prescription called Galzin) may be used instead of chelators to maintain stable copper levels in the body. Zinc stimulates metallothionein, a protein in gut cells that binds copper and prevents their absorption and transport to the liver. Zinc therapy is continued unless symptoms recur or if the urinary excretion of copper increases.

In rare cases where none of the oral treatments are effective, especially in severe neurological disease, dimercaprol (British anti-Lewisite) is occasionally necessary. This treatment is injected intramuscularly (into a muscle) every few weeks and has unpleasant side effects such as pain.

People who are asymptomatic (for instance, those diagnosed through family screening or only as a result of abnormal test results) are generally treated, as the copper accumulation may cause long-term damage in the future. It is unclear whether these people are best treated with penicillamine or zinc acetate.

Physical and occupational therapies

Physiotherapy and occupational therapy are beneficial for patients with the neurologic form of the disease. The copper chelating treatment may take up to six months to start working, and these therapies can assist in coping with ataxia, dystonia, and tremors, as well as preventing the development of contractures that can result from dystonia.

Transplantation

Liver transplantation is an effective cure for Wilson's disease but is used only in particular scenarios because of the risks and complications associated with the procedure. It is used mainly in people with fulminant liver failure who fail to respond to medical treatment or in those with advanced chronic liver disease. Liver transplantation is avoided in severe neuropsychiatric illness, in which its benefit has not been demonstrated.

Prognosis

Left untreated, Wilson's disease tends to become progressively worse and is eventually fatal. With early detection and treatment, most of those affected can live relatively normal lives. Liver and neurologic damage that occurs prior to treatment may improve, but it is often permanent.

History

The disease bears the name of the British physician Samuel Alexander Kinnier Wilson (1878–1937), a neurologist who described the condition, including the pathological changes in the brain and liver, in 1912. Wilson's work had been predated by, and drew on, reports from German neurologist Carl Westphal (in 1883), who termed it "pseudosclerosis"; by the British neurologist William Gowers (in 1888); by the Finnish neuropathologist Ernst Alexander Homén (in 1889-1892), who noted the hereditary nature of the disease; and by Adolph Strümpell (in 1898), who noted hepatic cirrhosis. Neuropathologist John Nathaniel Cumings made the link with copper accumulation in both the liver and the brain in 1948. The occurrence of hemolysis was noted in 1967.

Cumings, and simultaneously the New Zealand neurologist Derek Denny-Brown, working in the United States, first reported effective treatment with metal chelator British anti-Lewisite in 1951. This treatment had to be injected but was one of the first therapies available in the field of neurology, a field that classically was able to observe and diagnose but had few treatments to offer. The first effective oral chelation agent, penicillamine, was discovered in 1956 by British neurologist John Walshe. In 1982, Walshe also introduced trientine, and was the first to develop tetrathiomolybdate for clinical use. Zinc acetate therapy initially made its appearance in the Netherlands, where physicians Schouwink and Hoogenraad used it in 1961 and in the 1970s, respectively, but it was further developed later by Brewer and colleagues at the University of Michigan.

The genetic basis of Wilson's disease and linkage to ATP7B mutations was elucidated in the 1980s and 1990s by several research groups.

Other animals

Hereditary copper accumulation has been described in Bedlington Terriers, where it generally only affects the liver. It is due to mutations in the COMMD1 (or MURR1) gene. Despite this findings, COMMD1 mutations could not be detected in humans with non-Wilsonian copper accumulation states (such as Indian childhood cirrhosis) to explain their genetic origin.

Tardive dyskinesia

From Wikipedia, the free encyclopedia

Tardive dyskinesia
Other namesLinguofacial dyskinesia, tardive dystonia, tardive oral dyskinesia
Dopamine-3d-CPK.png
Tardive dyskinesia is believed to involve the neurotransmitter dopamine.
Pronunciation
SpecialtyNeurology, psychiatry
SymptomsInvoluntary, repetitive body movements
CausesNeuroleptic medications (antipsychotics, metoclopramide)
Diagnostic methodBased on symptoms after ruling out other potential causes
Differential diagnosisHuntington's disease, cerebral palsy, Tourette syndrome, dystonia
PreventionUsing lowest possible dose of neuroleptic medication
TreatmentStopping neuroleptic medication if possible, switching to clozapine
MedicationValbenazine, tetrabenazine, botulinum toxin
PrognosisVariable
Frequency20% (atypical antipsychotics) 30% (typical antipsychotics)

Tardive dyskinesia (TD) is a disorder that results in involuntary, repetitive body movements, which may include grimacing, sticking out the tongue, or smacking the lips. Additionally, there may be rapid jerking movements or slow writhing movements. In about 20% of people, the disorder interferes with daily functioning.

Tardive dyskinesia occurs in some people as a result of long-term use of dopamine-receptor-blocking medications such as antipsychotics and metoclopramide. These medications are usually used for mental illness but may also be given for gastrointestinal or neurological problems. The condition typically develops only after months to years of use. The diagnosis is based on the symptoms after ruling out other potential causes.

Efforts to prevent the condition include either using the lowest possible dose or discontinuing use of neuroleptics. Treatment includes stopping the neuroleptic medication if possible or switching to clozapine. Other medications such as valbenazine, tetrabenazine, or botulinum toxin may be used to lessen the symptoms. With treatment, some see a resolution of symptoms, while others do not.

Rates in those on atypical antipsychotics are about 20%, while those on typical antipsychotics have rates of about 30%. The risk of acquiring the condition is greater in older people. The term "tardive dyskinesia" first came into use in 1964.

Signs and symptoms

Tardive dyskinesia is characterized by repetitive, involuntary movements. Some examples of these types of involuntary movements include:

Rapid, involuntary movements of the limbs, torso, and fingers may also occur. In some cases, an individual's legs can be so affected that walking becomes difficult or impossible. These symptoms are the opposite of people who are diagnosed with Parkinson's disease. People with Parkinson's have difficulty moving, whereas people with tardive dyskinesia have difficulty not moving.

Respiratory irregularity, such as grunting and difficulty breathing, is another symptom associated with tardive dyskinesia, although studies have shown that the rate of people affected is relatively low.

Tardive dyskinesia is often misdiagnosed as a mental illness rather than a neurological disorder, and as a result, people are prescribed neuroleptic drugs, which increase the probability that the person will develop a severe and disabling case, and shortening the typical survival period.

Other closely related neurological disorders have been recognized as variants of tardive dyskinesia. Tardive dystonia is similar to standard dystonia but permanent. Tardive akathisia involves painful feelings of inner tension and anxiety and a compulsive drive to move the body. In some extreme cases, afflicted individuals experience so much internal torture that they lose their ability to sit still. Tardive tourettism is a tic disorder featuring the same symptoms as Tourette syndrome. The two disorders are extremely close in nature and often can only be differentiated by the details of their respective onsets. Tardive myoclonus, a rare disorder, presents as brief jerks of muscles in the face, neck, trunk, and extremities.

"AIMS Examination": This test is used when psychotropic medications have been prescribed because people sometimes develop tardive dyskinesia due to prolonged use of antipsychotic medications. The Abnormal Involuntary Movement Scale (AIMS) examination is a test used to identify the symptoms of tardive dyskinesia (TD). The test is not meant to tell whether there is an absence or presence of tardive dyskinesia. It just scales to level of symptoms indicated by the actions observed. The levels range from none to severe. The AIMS examination was constructed in the 1970s to measure involuntary facial, trunk, and limb movements. It is best to do this test before and after the administration of the psychotropic drugs. Taking the AIMS consistently can help to track severity of TD over time.

Causes

Tardive dyskinesia was first described in the 1950s shortly after the introduction of chlorpromazine and other antipsychotic drugs. However, the exact mechanism of the disorder remains largely uncertain. The most compelling line of evidence suggests that tardive dyskinesia may result primarily from neuroleptic-induced dopamine supersensitivity in the nigrostriatal pathway, with the D2 dopamine receptor being most affected. Neuroleptics act primarily on this dopamine system, and older neuroleptics, which have greater affinity for the D2 binding site, are associated with high risk for tardive dyskinesia. The D2 hypersensitivity hypothesis is also supported by evidence of a dose–response relationship, withdrawal effects, studies on D2 agonists and antagonists, animal studies, and genetic polymorphism research.

Given similar doses of the same neuroleptic, differences among individuals still exist in the likelihood of developing tardive dyskinesia. Such individual differences may be due to genetic polymorphisms, which code for D2 receptor binding site affinity, or prior exposure to environmental toxins. Decreased functional reserve or cognitive dysfunction, associated with aging, mental retardation, alcohol and drug abuse, or traumatic head injuries, has also been shown to increase risk of developing the disorder among those treated with neuroleptics. Antipsychotic drugs can sometimes camouflage the signs of tardive dyskinesia from occurring in the early stages; this can happen from the individual having an increased dose of an antipsychotic drug. Often the symptoms of tardive dyskinesia are not apparent until the individual comes off of the antipsychotic drugs; however, when tardive dyskinesia worsens, the signs become visible.

Other dopamine antagonists and antiemetics can cause tardive dyskinesia, such as metoclopramide and promethazine, used to treat gastrointestinal disorders. Atypical antipsychotics are considered lower-risk for causing TD than their typical counterparts with their relative rates of TD of 13.1% and 32.4% respectively in short-term trials with haloperidol being the main typical antipsychotic utilised in said trials.[18] Quetiapine and clozapine are considered the lowest risk agents for precipitating TD.[18] From 2008, there have been reported cases of the anti-psychotic medication aripiprazole, a partial agonist at D2 receptors, leading to tardive dyskinesia.[19] As of 2013, reports of tardive dyskinesia in aripiprazole have grown in number.[20] The available research seems to suggest that the concurrent prophylactic use of a neuroleptic and an antiparkinsonian drug is useless to avoid early extrapyramidal side-effects and may render the person more sensitive to tardive dyskinesia. Since 1973 the use of these drugs has been found to be associated with the development of tardive dyskinesia.[21][22]

Risk factors

An increased risk of tardive dyskinesia has been associated with smoking in some studies, although a negative study does exist. There seems to be a cigarette smoke-exposure-dependent risk for TD in people who are antipsychotic-treated . Elderly peoples are also at a heightened risk for developing TD, as are females and those with organic brain injuries or diabetes mellitus and those with the negative symptoms of schizophrenia. TD is also more common in those that experience acute neurological side effects from antipsychotic drug treatment. Racial discrepancies in TD rate also exist, with Africans and African Americans having higher rates of TD after exposure to antipsychotics. Certain genetic risk factors for TD have been identified including polymorphisms in the genes encoding the D3, 5-HT2A and 5-HT2C receptors.

Prevention

Prevention of tardive dyskinesia is achieved by using the lowest effective dose of a neuroleptic for the shortest time. However, with diseases of chronic psychosis such as schizophrenia, this strategy must be balanced with the fact that increased dosages of neuroleptics are more beneficial in preventing recurrence of psychosis. If tardive dyskinesia is diagnosed, the causative drug should be discontinued. Tardive dyskinesia may persist after withdrawal of the drug for months, years or even permanently. Some studies suggest that physicians should consider using atypical antipsychotics as a substitute to typical antipsychotics for people requiring medication. These agents are associated with fewer neuromotor side effects and a lower risk of developing tardive dyskinesia.

Studies have tested the use of melatonin, high dosage vitamins, and different antioxidants in concurrence with antipsychotic drugs (often used to treat schizophrenia) as a way of preventing and treating tardive dyskinesia. Although further research is needed, studies reported a much lower percentage of individuals developing tardive dyskinesia than the current rate of people for those taking antipsychotic drugs. Tentative evidence supports the use of vitamin E for prevention.

Treatment

Valbenazine was approved by the FDA for tardive dyskinesia in April 2017. Tetrabenazine, which is a dopamine depleting drug, is sometimes used to treat tardive dyskinesia and other movement disorders (e.g. Huntington's chorea). Deutetrabenazine, an isotopic isomer of tetrabenazine, was approved by the FDA for tardive dyskinesia in August 2017. Vitamin B6 has been reported to be an effective treatment for TD in two randomised double-blind placebo-controlled trials, but the overall evidence for its effectiveness is considered "weak." Clonidine may also be useful in the treatment of TD, although dose-limiting hypotension and sedation may hinder its usage. Botox injections are used for minor focal dystonia, but not in more advanced tardive dyskinesia. As of 2018 evidence is insufficient to support the use of benzodiazepines, baclofen, progabide, sodium valproate, gaboxadol, or calcium channel blockers (e.g. diltiazem).

Epidemiology

Tardive dyskinesia most commonly occurs in people with psychiatric conditions who are treated with antipsychotic medications for many years. The average rate of people affected has been estimated to be around 30% for individuals taking antipsychotic medication, such as that used to treat schizophrenia. A study being conducted at the Yale University School of Medicine has estimated that "32% of people develop persistent tics after 5 years on major tranquilizers, 57% by 15 years, and 68% by 25 years." More drastic data was found during a longitudinal study conducted on individuals 45 years of age and older who were taking antipsychotic drugs. According to this research study, 26% of people developed tardive dyskinesia after just one year on the medication. Another 60% of this at-risk group developed the disorder after 3 years, and 23% developed severe cases of tardive dyskinesia within 3 years. According to these estimates, the majority of people will eventually develop the disorder if they remain on the drugs long enough.

Elderly people are more prone to develop tardive dyskinesia, and elderly women are more at-risk than elderly men. The risk is much lower for younger men and women, and also more equal across the sexes. People who have undergone electroconvulsive therapy or have a history of diabetes or alcohol abuse also have a higher risk of developing tardive dyskinesia.

Several studies have recently been conducted comparing the number of people affected of tardive dyskinesia with second generation, or more modern, antipsychotic drugs to that of first generation drugs. The newer antipsychotics appear to have a substantially reduced potential for causing tardive dyskinesia. However, some studies express concern that the number of people affected has decreased far less than expected, cautioning against the overestimation of the safety of modern antipsychotics.

A physician can evaluate and diagnose a person with tardive dyskinesia by conducting a systematic examination. The physician should ask the person to relax, and look for symptoms like facial grimacing, eye or lip movements, tics, respiratory irregularities, and tongue movements. In some cases, people experience nutritional problems, so a physician can also look for a gain or loss in weight.

Apart from the underlying psychiatric disorder, tardive dyskinesia may cause afflicted people to become socially isolated. It also increases the risk of body dysmorphic disorder (BDD) and can even lead to suicide. Emotional or physical stress can increase the severity of dyskinetic movements, whereas relaxation and sedation have the opposite effect.

Mathematical universe hypothesis

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