The changing epidemiology of Reye's syndrome in the United States: further evidence for a public health success

Dihydrolipoamide dehydrogenase deficiency: a still overlooked cause of recurrent acute liver failure and Reye-like syndrome

The causes of Reye-like syndrome are not completely understood. Dihydrolipoamide dehydrogenase (DLD or E3) deficiency is a rare metabolic disorder causing neurological or liver impairment. Specific changes in the levels of urinary and plasma metabolites are the hallmark of the classical form of the disease. Here, we report a consanguineous family of Algerian origin with DLD deficiency presenting without suggestive clinical laboratory and anatomopathological findings. Two children died at birth from hepatic failure and three currently adult siblings had recurrent episodes of hepatic cytolysis associated with liver failure or Reye-like syndrome from infancy. Biochemical investigation (lactate, pyruvate, aminoacids in plasma, organic acids in urine) was normal. Histologic examination of liver and muscle showed mild lipid inclusions that were only visible by electron microscopy. The diagnosis of DLD deficiency was possible only after genome-wide linkage analysis, confirmed by a homozygous mutation (p.G229C) in the DLD gene, previously reported in patients with the same geographic origin. DLD and pyruvate dehydrogenase activities were respectively reduced to 25% and 70% in skin fibroblasts of patients and were unresponsive to riboflavin supplementation. In conclusion, this observation clearly supports the view that DLD deficiency should be considered in patients with Reye-like syndrome or liver failure even in the absence of suggestive biochemical findings, with the p.G229C mutation screening as a valuable test in the Arab patients because of its high frequency. It also highlights the usefulness of genome-wide linkage analysis for decisive diagnosis advance in inherited metabolic disorders.

Infection-associated encephalopathies: their investigation, diagnosis, and treatment

Reduced level of consciousness is a common clinical finding in acutely sick patients. In the majority of cases a cause for the encephalopathy is readily identifiable,whilst in a minority the aetiology is more difficult to ascertain. Frequently the onset of encephalopathy is associated with, or follows, infection. The mechanisms through which infection leads to encephalopathy are diverse. They range from direct microbial invasion of the brain or its supporting structures, to remote, infection-triggered mechanisms such as acute disseminated encephalomyelitis. Most common however, is the encephalopathy caused through a remote effect of systemic sepsis-septic encephalopathy. This article discusses the clinical presentation and underlying pathogeneses of the acute encephalopathies associated with infection, aiming to aid both their recognition and treatment.

[Severe Reye syndrome: report of 14 cases managed in a pediatric intensive care unit over 11 years]

Idiopathic Reye syndrome is a rare disease revealed by unexplained encephalopathy and microvesicular liver steatosis. Some clinical and epidemiological studies mainly performed in English speaking countries questioned the reality of Reye syndrome because numerous know inherited metabolic diseases, and some of them unrecognized, could mimick this disorder. We focused in our study on severe forms of Reye syndrome admitted to a pediatric intensive care unit.

METHODS

Retrospective study over the last eleven years (1991-2001) included all the pediatric patients admitted to our tertiary referral center with the classical American Reye syndrome criteria (e.g. CDC). Extensive metabolic screening was performed in all cases, except for the ultimately dead patients.

RESULT

Fourteen patients (mean age 52 months) were included. Fever always occurred before their admission and aspirin (n = 12) or acetaminophen (n = 7) was prescribed. Median Glasgow scale was 7 on admission. Mean amoniac plasma level was 320 mumol/L and alanine-aminotransferase peak plasma level 1475 +/- 1387 IU/L. Mechanical ventilation was started in ten children and six of them underwent continuous venovenous hemofiltration. Three patients ultimately died and 11 survived with a mean five years follow-up without relapses or neurological impairment. Any of them demonstrated inherited metabolic disease except for one infant with hereditary fructose intolerance.

CONCLUSION

Unlike widespread opinion, severe Reye syndrome without identified metabolic disorders seems to not disappear in our country. Reye syndrome remains a potentially life threatening disease and raises for aggressive treatment of brain edema. If aspirin and Reye syndrome association are not formally documented in France, cautiousness must be kept in mind and all the aspirin adverse effects notifications should be addressed to the public drugs survey network.

Whatever happened to Reye's syndrome? Did it ever really exist?

OBJECTIVE

Reye's syndrome (RS) appeared suddenly in the 1950s and disappeared almost as quickly in the late 1980s. A number of metabolic disorders were discovered in the 1980s that could completely mimic RS. This study was undertaken to reassess the original diagnosis of RS in light of newly described metabolic disorders.

INTERVENTION

The medical records of 26 patients who had survived RS and were originally studied in Australia in the 1980s were reexamined 10 yrs later, and families were interviewed to ascertain if the diagnosis had changed. The 49 original patients with RS from Australia were also reanalyzed using more precise diagnostic criteria for RS to ascertain how many of the patients would continue to fit the more precise diagnosis of RS.

MEASUREMENTS AND MAIN RESULTS

Of 26 original patients with RS who had survived, 18 (69%) were subsequently diagnosed as having other diseases, most commonly inborn errors of metabolism. The most commonly diagnosed metabolic disorder was medium-chain acyl-coenzyme-A dehydrogenase deficiency. Of the 18 patients rediagnosed with diseases other than RS, 15 (83%) are now known to have metabolic disorders. By using more precise diagnostic criteria for RS, none of the original 49 patients with RS could be diagnosed as having certain RS. Only six patients had probable RS, two patients had possible RS, 23 patients had unlikely RS, and 18 patients were excluded as RS cases.

CONCLUSION

With better diagnostic techniques and criteria, most patients originally diagnosed with RS are now known to have metabolic disorders. The disappearance of RS was probably related to the discovery and ability to diagnose inborn errors of metabolism that mimicked RS clinically, biochemically, and pathologically.

Role of viral infections in the induction of adverse drug reactions

A spectrum of adverse drug reactions that are caused by the combined action of drugs and viruses has been described: ampicillin rash in acute infectious mononucleosis; Reye's syndrome; hypersensitivity reactions to sulphonamides in patients with HIV infection; drug-induced agranulocytosis; paracetamol (acetaminophen) hepatotoxicity; aspirin (acetylsalicyclic acid)-induced asthma; Epstein-Barr virus-associated lymphoma and methotrexate; and AIDS-related Kaposi's sarcoma and nitrite use. Changes in pharmacokinetics have been reported for: caffeine, sulfamethoxazole and fluconazole in patients with HIV infection; theophylline, following influenza and influenza vaccination; and recently, dipyrone metabolites in carriers of the hepatitis B virus. In addition increased drug- and drug metabolite-related toxicity has been observed in virally infected cells. Pathogenetic mechanisms for the interaction between drugs and viruses are varied, and include biological mechanisms (often immunological) and changes in drug metabolism. The combined effects of chemical and biological exposure provide a unique model for the study of disease induction.

The changing clinical pattern of Reye's syndrome 1982-1990

OBJECTIVE

To describe trends in the clinical pattern of Reye's syndrome in the British Isles between 1982 and 1990; and to determine the relation between any changes and the June 1986 warnings against the use of aspirin in children.

DESIGN

Development, and application to reported cases, of a scoring system designed such that patients showing the typical clinical and pathological features of 'classical' Reye's syndrome scored highly. The relations between 'Reye scores' and a number of explanatory variables were explored using multivariable analysis.

SETTING

British Isles.

SUBJECTS

445 cases fulfilling the Reye's syndrome case definition reported to the surveillance scheme between January 1982 and December 1990.

MAIN OUTCOME MEASURE

Individual 'Reye score'.

RESULTS

Cases with high scores were more likely to have occurred in the 4 1/2 year period before June 1986 compared with the subsequent period (p < 0.006). Numbers of cases in the low and intermediate score categories declined by about 50% after June 1986, whereas those in the high category fell by 79%. High scorers were more likely to have received aspirin (p < 0.0001) and were older than intermediate and low scorers (p < 0.008). No relation was identified between score and season of onset.

CONCLUSIONS

The decline in Reye's syndrome after the aspirin warnings cannot be explained entirely, as has been proposed, by improved diagnosis of 'Reye-like' inherited metabolic and other disorders: this would not account for the greater decline of the high scoring subgroup which also contained those cases most likely to resemble 'classical' Reye's syndrome and to have received aspirin. This study provides further evidence for the role of aspirin in a subset of cases meeting the standard diagnostic criteria for Reye's syndrome and supports the need to consider this disorder as a heterogeneous group of conditions including Reye-like inherited metabolic disorders.

The phenylpropionic acid load test: experience with 72 children at-risk for beta-oxidation disorders

The urinary excretion of metabolites of orally administered phenylpropionic acid (PPA) in 72 children, aged 2 days to 16 years, thought to be at-risk of medium acyl CoA dehydrogenase deficiency has been studied. Forty had presented as Reye Syndrome, 9 as a Reye-like syndrome and 24 were sibs of decreased RS, sibs of RLS cases or sibs of infants who had died suddenly and without explanation where an autopsy revealed the presence of very heavy fatty infiltration of the liver. These studies demonstrated that PPA metabolites are maximally excreted during the 3 hours following the oral load and that this urine collection should be diagnostic. PPA loading is a relatively simple, safe test which is part of the investigation of a patient suspected of having an inborn error of metabolism.

Reye's syndrome in Olmsted County, Minnesota: did it exist before 1963?

In this study, our goals were to determine whether Reye's syndrome existed before the first published report of this entity in 1963 and to describe the long-term incidence and trend of this syndrome. Medical and pathologic records and pathologic specimens for Mayo Clinic patients, including those who were residents of Olmsted County, Minnesota, were reviewed through the facilities of the Rochester Epidemiology Project. On review, 12 cases were identified for the period 1920 through 1962; 2 of these cases were in Olmsted County residents. Of the 12 cases identified before 1963, 10 were in patients younger than 5 years of age. In addition to the aforementioned two cases, five others in Olmsted County were diagnosed between 1963 and 1989. Incidence rates were computed for the Olmsted County population. The number of cases and rates per 100,000 persons younger than 18 years of age in that population were 2 cases (0.3) for 1920 through 1962, 4 cases (0.7) for 1963 through 1980, and 1 case (0.4) for 1981 through 1989. Although cases found during the earlier periods may have included disorders that mimic Reye's syndrome, the recommended criteria from the Centers for Disease Control were applied to review of medical records and supported by pathologic findings in the liver. The data showed an age distribution tending toward young patients and no seasonality of occurrence. The incidence rates in Olmsted County, Minnesota, showed an increase for 1963 through 1980 over previous decades, followed by a decrease. The small numbers preclude any conclusion about trends in the incidence rates.

Biochemical relationships between Reye's and Reye's-like metabolic and toxicological syndromes

Reye's syndrome is a hepatic encephalopathy with fatty infiltration of the liver and is due to mitochondrial dysfunction. Knowledge of the mechanisms causing Reye's syndrome has been gained from the study of Reye's syndrome-like diseases, including inborn errors of mitochondrial energy production, viral disease and toxicological injury. Entry of fatty acids into mitochondria or beta-oxidation itself may be impaired. Toxins such as hypoglycin, pentanoate, valproate, salicylate, and their metabolites inhibit beta-oxidation pathways and can produce Reye's syndrome-like presentations. Biochemical manifestations of the diverse causes of Reye's syndrome-like disorders are similar and include: hypoglycaemia due to impaired gluconeogenesis, accumulation of fatty acids, fatty acyl CoAs, and acyl carnitines with depletion of free CoA and carnitine. Accumulated products may further injure mitochondria and exacerbate impaired beta-oxidation, uncouple oxidative phosphorylation or increase mitochondrial permeability. Mitochondrial swelling and steatosis of hepatic cells are the histological result. With the advances of biochemical techniques for the study of organic acid excretion patterns, serum fatty acid patterns and identification of enzymatic deficiencies in cells from patients with Reye's syndrome-like presentations, it is clear that Reye's syndrome is, in part, a collection of various inborn errors and toxicological states. Circumstances such as viral disease, prolonged fasting and drugs may precipitate clinical expression of these deficiencies as Reye's syndrome. As work progresses, further causes of Reye's syndrome will be identified.