Reye’s syndrome

 Liver Diseases, Metabolic Disorders  No Responses »
Aug 092011
 
An acute childhood illness, Reye’s syndrome causes fatty infiltration of the liver with concurrent hyperammonemia, encephalopathy, and increased intracranial pressure (ICP). In addition, fatty infiltration of the kidneys, brain, and myocardium may occur.
Reye’s syndrome affects children. It’s most common in patients ages 4 to 12, with a peak incidence at age 6.
The prognosis depends on the severity of central nervous system depression. Previously, mortality was as high as 90%. Today, ICP monitoring and, consequently, early treatment of increased ICP, along with other treatment measures, have cut mortality to about 20%. Death is usually a result of cerebral edema or respiratory arrest. Comatose patients who survive may have residual brain damage.
Causes
Incidence of Reye’s syndrome usually rises during influenza outbreaks and is linked to aspirin use. It almost always follows within 1 to 3 days of an acute viral infection, such as an upper respiratory tract infection, type B influenza, or varicella (chickenpox).
With Reye’s syndrome, damaged hepatic mitochondria disrupt the urea cycle, which normally changes ammonia to urea for its excretion from the body. This results in hyperammonemia, hypoglycemia, and an increase in serum short-chain fatty acids, leading to encephalopathy. Simultaneously, fatty infiltration is found in renal tubular cells, neuronal tissue, and muscle tissue, including the heart.
Signs and symptoms
Reye’s syndrome develops in five stages, but the severity of the child’s signs and symptoms varies with the degree of encephalopathy and cerebral edema. Infants may have atypical presentation.
After the initial viral infection, a brief recovery period follows when the child doesn’t seem seriously ill. A few days later, he develops intractable vomiting, lethargy, rapidly changing mental status (mild to severe agitation, confusion, irritability, delirium), hyperactive reflexes, and rising blood pressure, respiratory rate, and pulse rate.
Reye’s syndrome may progress to coma. As the coma deepens, seizures develop, followed by decreased tendon reflexes and, commonly, respiratory failure. Continue reading »
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Extrahepatic Biliary Atresia

 Liver Diseases  No Responses »
Feb 052011
 
Biliary atresia (BA), although not a common disorder, is the most common indication for pediatric liver transplantation. Current surgical intervention and medical management have dramatically improved the prognosis for this disease since its discovery in 1817. The developments of the hepatoportoenterostomy (Kasai) procedure and liver transplantation have changed biliary atresia from a universally fatal disease to a survivable condition.
Pathology
Biliary atresia results from inflammatory and progressive destruction of bile ducts, both extra- and intrahepatic, leading to fibrosis, biliary cirrhosis, and eventual liver failure. Biliary atresia has been classified into several types depending on the location and degree of atresia . The cause of BA is unknown, but the most common form is felt to be acquired rather than congenital. Infections, intrauterine and perinatal, metabolic disorders, genetic predisposition, and environmental exposures have all been implicated as potential causes, and each may be contributory in some cases. Biliary atresia also occurs in association with a variety of other congenital anomalies.  In these cases, the condition is presumed to result from abnormalities in morphogenesis and is therefore not considered an acquired lesion.
Clinical Features
The most consistent clinical feature of biliary atresia is cholestatic jaundice that appears in the second or third week of life, although some infants will be jaundiced from birth. Hypopigmented or acholic stools and darkened urine are strongly suggestive of biliary atresia. An enlarged and hard liver may be evident at the time of diagnosis, and with further progression of biliary cirrhosis, splenomegaly, ascites, and bruising from coagulopathy will occur.
Evaluation and Diagnosis
The evaluation of an infant suspected of having biliary atresia is the same as that for an infant with neonatal cholestasis . Frequently, the jaundiced infants will have a mixed hyperbilirubinemia  

with elevated serum alkaline phosphatase, GGT, and aminotransferase values. The absence of a gallbladder on sonography should raise suspicion of BA, although some affected infants will have a gallbladder. Radionuclide scans are often used to determine the presence or absence of biliary patency. Failure of excretion of radioisotope is an indication for liver biopsy and cholangiogram. Bile ductular proliferation and cholestasis are typical histopathologic findings; variable degrees of inflammation, giant-cell formation, and fibrosis are noted. The diagnosis of BA is confirmed by Continue reading »
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Total parenteral nutrition (TPN) Associated Liver Disease

 Liver Diseases  No Responses »
Dec 052010
 
Total parenteral nutrition (TPN) may cause liver injury in both pediatric and adult patients. Indications, monitoring, and nonliver complications of TPN are discussed in Sec. 17.6.2. The liver damage associated with TPN may be reversible; however, in situations in which prolonged TPN is required, cirrhosis and eventually liver failure have occurred. In fact, end-stage liver disease has replaced catheter-related sepsis and malnutrition as the leading cause of death in TPN-dependent infants with short bowel syndrome.
Infants, particularly those born preterm, are most susceptible to hepatic injury from TPN.
The most common feature of this injury is TPN-associated cholestasis, which is generally accepted to be related to multiple factors. Premature infants will often rely solely on parenteral nutrition for long periods of time because of bowel immaturity. Necrotizing enterocolitis or congenital malformations of the gut with or without surgical resection often make prolonged use of TPN a necessity. Younger gestational age, lower birth weight, and a longer duration of TPN are associated with increased likelihood of TPN-associated cholestasis. Comorbid conditions
such as sepsis, hypoxia, or immature hepatic function are commonly encountered in the preterm infant, but TPN-related factors such as taurine or carnitine deficiency may also play important roles in the development of cholestasis and subsequent hepatic disease.
The onset of TPN-associated cholestasis (TPN-AC) is usually insidious. Hepatomegaly and conjugated hyperbilirubinemia raise the suspicion of likely TPN-associated cholestasis, but other etiologies of cholestasis must be considered . Because TPN-AC is often a diagnosis of exclusion, the evaluation includes ultrasonography and possibly hepatobiliary scintigraphy, which may identify an obstructive lesion. Other considerations are inborn errors of metabolism and congenital infection. A liver biopsy may help to exclude disorders such as storage diseases; however, the histopathology seen with TPN-associated cholestasis includes portal inflammation, cholestasis, and frequently fibrosis, which are suggestive but not diagnostic findings.
Because the specific cause of liver disease associated with TPN has not been determined, Continue reading »
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