Anesthetic Management of Patients With Inborn Errors of Metabolism.

Inborn errors of metabolism (IEM) are characterized by the body's inability to convert food into energy. The pathogenetic mechanism is based on defects in a variety of cellular enzymes. In addition to impairment of energy generation, accumulation of substrates may occur, which can deposit in tissue and lead to organ dysfunction. IEM can have profound implications for perioperative management, including difficult airway management, cardiac dysfunction, aspiration risk, seizures, and metabolic dysregulation. For the anesthesiologist, comprehensive knowledge is difficult to attain because of the heterogeneity of this group and the low prevalence of specific diseases. The first part of this article reviews intermediary metabolism, whereas the second part aims to highlight important aspects in perioperative management of patients with IEM. Instead of reviewing each single disorder within the vast group of IEM, we provide a conceptual framework that will facilitate the understanding of main problems encountered in each of the disease subgroups.

Three cases of a rare disease, congenital chloride diarrhea, summons up the variation in the clinical course and significance of early diagnosis and adequate treatment in the prevention of intellectual disability.

Congenital chloride diarrhea (CLD) (OMIM #214700) is a rare, autosomal recessive disease that is characterized by increased chloride loss in stool. As a result of electrolyte loss, surviving patients might have some complications, one of them being mental retardation. Here, we present three new Turkish patients with new mutations in the SLC26A3 gene. Although the clinical picture of the patients might be similar, consequences of the disease and complications might differ greatly among patients. Pediatricians should be aware of CLD as a potentially fatal or disabling disease if untreated. History of polyhydramnios, watery diarrhea, failure to thrive, poor growth, soiling, metabolic alkalosis and hypokalemia/hypochloremia should be an alarming set of findings for the diagnosis. Salt substitution therapy started early in life prevents early complications, allows normal growth and development, and favors good long-term prognosis.

Child with '46, XX' disorder of sex development: clues to diagnose aromatase deficiency.

A diagnosis of congenital adrenal hyperplasia (CAH) in a '46, XX' newborn with ambiguous genitalia is like a 'knee jerk reaction' of the paediatrician because of its higher frequency and life-threatening consequences if remain undiagnosed and hence untreated. Aromatase deficiency (AD), a rare cause of '46, XX' disorder of sex development, mimics virilising CAH in many aspects; thus, the disease is often overlooked. Diagnosis of AD in women is much easier around puberty due to the presence of primary amenorrhoea, undeveloped breasts, androgen excess and tall stature with eunuchoid proportions. Diagnosing AD with confidence immediately after birth or during early childhood is a challenging task without genetic analysis. In resource-restricted settings, AD remains a diagnosis of exclusion particularly in this age group and history of maternal virilisation, non-progressive genital ambiguity, elevated gonadotrophins (follicle-stimulating hormone >>luteinising hormone), mildly delayed bone age with/without enlarged polycystic ovaries serve as important clues to the underlying AD.

Congenital chloride diarrhoea.

Congenital chloride diarrhoea is one of the rare causes of diarrhoea during infancy and it is infrequently reported throughout the world. It is an autosomal recessive condition which is more prevalent in Poland, Finland, Saudi Arabia and Kuwait while rarely reported in Pakistan. Our patient was 7.5-month-old baby boy who presented with diarrhoea since neonatal period. He had consanguineous parents. On examination, baby had distended abdomen, hypotonia and hyporeflexia. Investigations revealed hypochloremic hypokalemic metabolic alkalosis. Urinary electrolytes were normal. Stool electrolytes revealed increased stool chloride excretion that confirmed our diagnosis of congenital chloride diarrhoea. Patient was treated with intravenous fluids and electrolyte replacement, followed by oral potassium and sodium replacement. He was also started on butyrate, cholestyramine and proton-pump inhibitors. He started gaining weight during his hospital admission and is being followed up in clinic.

Progressive retinal dystrophy in two sisters with glutathione synthetase (GS) deficiency.

We report the ophthalmological findings of two sisters with severe glutathione synthetase deficiency, an autosomal recessive inborn error of metabolism resulting in very low intracellular levels of the free-radical scavenger glutathione. The patients were investigated because of declining visual acuity. The most prominent finding was progressive retinal dystrophy with hyperpigmentations and maculopathy. Generally disturbed functioning of both the outer and inner layers of the retina resulted in attenuated or nearly abolished electroretinograms. These findings agree with a rod/cone type of retinal dystrophy, and we suggest that this is due to glutathione deficiency. Treatment with antioxidants such as vitamins E and C seems to prevent the progression of CNS damage. We speculate that it might also prevent retinal dystrophy in patients with glutathione synthetase deficiency. We suggest that patients with retinal dystrophy and additional neurological signs should be investigated for a defect in glutathione metabolism. Also, we recommend that patients with low levels of glutathione should be examined for retinal dystrophy. Our results suggest that a decreased capacity for scavenging reactive oxygen species and/or increased oxidative stress may cause retinal dystrophy. If this is the case, the redox state in the retina should be a potentially useful therapeutic target to prevent reduced visual function and blindness.

Neurological implications of urea cycle disorders.

The urea cycle disorders constitute a group of rare congenital disorders caused by a deficiency of the enzymes or transport proteins required to remove ammonia from the body. Via a series of biochemical steps, nitrogen, the waste product of protein metabolism, is removed from the blood and converted into urea. A consequence of these disorders is hyperammonaemia, resulting in central nervous system dysfunction with mental status changes, brain oedema, seizures, coma, and potentially death. Both acute and chronic hyperammonaemia result in alterations of neurotransmitter systems. In acute hyperammonaemia, activation of the NMDA receptor leads to excitotoxic cell death, changes in energy metabolism and alterations in protein expression of the astrocyte that affect volume regulation and contribute to oedema. Neuropathological evaluation demonstrates alterations in the astrocyte morphology. Imaging studies, in particular (1)H MRS, can reveal markers of impaired metabolism such as elevations of glutamine and reduction of myoinositol. In contrast, chronic hyperammonaemia leads to adaptive responses in the NMDA receptor and impairments in the glutamate-nitric oxide-cGMP pathway, leading to alterations in cognition and learning. Therapy of acute hyperammonaemia has relied on ammonia-lowering agents but in recent years there has been considerable interest in neuroprotective strategies. Recent studies have suggested restoration of learning abilities by pharmacological manipulation of brain cGMP with phosphodiesterase inhibitors. Thus, both strategies are intriguing areas for potential investigation in human urea cycle disorders.

Nutritional management of patients with urea cycle disorders.

The nutritional management of patients with urea cycle disorders (UCDs) involves restriction of dietary protein along with provision of adequate protein-free energy, essential amino acid supplements, and vitamins and minerals in combination with nitrogen-scavenging drugs. The present paper discusses nutrition therapy for a range of circumstances: during an acute hyperammonaemic episode and at hospital discharge; before, during, and after surgery; and for lifelong chronic management of UCDs.

Adolescent presentations of inborn errors of metabolism.

Several studies have shown that a large percentage of inborn errors of metabolism is present in adolescent patients. Individually, each diagnosis in this category of diseases is rare; therefore, there is often a significant delay in determining the etiology of a patient's complaints. These disorders can have a wide variety of multisystemic presentations, several of which overlap with more common disorders of adolescence. This review highlights the red-flag findings on history and physical examination indicating a possible inborn error of metabolism. In addition, a systematic approach for evaluating and categorizing these disorders is introduced and demonstrated through case examples. Primary care physicians play a crucial role in the early detection and prompt treatment of patients with late-onset inborn errors of metabolism.

Neonatal type of nonketotic hyperglycinemia.

Two infants with the neonatal type of nonketotic hyperglycinemia that had manifested as early neonatal consciousness disturbance are presented. Transient hyperammonemia had been detected in both initially. High levels of glycine in plasma and cerebrospinal fluid disturb the nervous system, causing variable manifestations of this disease. Both cases were complicated by intracranial hemorrhage, which has never before been reported. After treatment with sodium benzoate and dextromethorphan, some neurologic improvement was observed, although the glycine levels did not lower. Recent clinical trials are reviewed, and because of the unfavorable outcomes, the special need for prenatal diagnosis is highlighted.

Inborn errors of metabolism: a clinical overview.

CONTEXT: Inborn errors of metabolism cause hereditary metabolic diseases (HMD) and classically they result from the lack of activity of one or more specific enzymes or defects in the transportation of proteins. OBJECTIVES: A clinical review of inborn errors of metabolism (IEM) to give a practical approach to the physician with figures and tables to help in understanding the more common groups of these disorders. DATA SOURCE: A systematic review of the clinical and biochemical basis of IEM in the literature, especially considering the last ten years and a classic textbook (Scriver CR et al, 1995). SELECTION OF STUDIES: A selection of 108 references about IEM by experts in the subject was made. Clinical cases are presented with the peculiar symptoms of various diseases. DATA SYNTHESIS: IEM are frequently misdiagnosed because the general practitioner, or pediatrician in the neonatal or intensive care units, does not think about this diagnosis until the more common cause have been ruled out. This review includes inheritance patterns and clinical and laboratory findings of the more common IEM diseases within a clinical classification that give a general idea about these disorders. A summary of treatment types for metabolic inherited diseases is given. CONCLUSIONS: IEM are not rare diseases, unlike previous thinking about them, and IEM patients form part of the clientele in emergency rooms at general hospitals and in intensive care units. They are also to be found in neurological, pediatric, obstetrics, surgical and psychiatric clinics seeking diagnoses, prognoses and therapeutic or supportive treatment.

[Prevention of severe diseases in apparently healthy newborn infants by new neonatal diagnostic methods]. / Prevención de enfermedades graves en recién nacidos aparentemente sanos, mediante nuevos métodos de diagnóstico neonatal.

The benefit of Tamiz Neonatal Ampliado is very high in relation with its cost, which is reasonably low. The Society for Inherited Metabolic Disorders, which is the main association in the world dealing with these diseases, has recently urged the responsible ones for neonatal health, so they increase their programs about Tamiz Neonatal (personal communication), as much as possible; its use should cover all new borns.

Treatable inborn errors of metabolism presenting as cerebral palsy mimics: systematic literature review.

BACKGROUND: Inborn errors of metabolism (IEMs) have been anecdotally reported in the literature as presenting with features of cerebral palsy (CP) or misdiagnosed as 'atypical CP'. A significant proportion is amenable to treatment either directly targeting the underlying pathophysiology (often with improvement of symptoms) or with the potential to halt disease progression and prevent/minimize further damage. METHODS: We performed a systematic literature review to identify all reports of IEMs presenting with CP-like symptoms before 5 years of age, and selected those for which evidence for effective treatment exists. RESULTS: We identified 54 treatable IEMs reported to mimic CP, belonging to 13 different biochemical categories. A further 13 treatable IEMs were included, which can present with CP-like symptoms according to expert opinion, but for which no reports in the literature were identified. For 26 of these IEMs, a treatment is available that targets the primary underlying pathophysiology (e.g. neurotransmitter supplements), and for the remainder (n = 41) treatment exerts stabilizing/preventative effects (e.g. emergency regimen). The total number of treatments is 50, and evidence varies for the various treatments from Level 1b, c (n = 2); Level 2a, b, c (n = 16); Level 4 (n = 35); to Level 4-5 (n = 6); Level 5 (n = 8). Thirty-eight (57%) of the treatable IEMs mimicking CP can be identified by ready available metabolic screening tests in blood or urine, while the remaining IEMs require more specific and sometimes invasive tests. CONCLUSIONS: Limited by the rare nature of IEMs and incomplete information in the literature, we conclude that (1) A surprisingly large number of IEMs can present with CP symptoms, as 'CP mimics', (2) although individually rare, a large proportion of these diseases are treatable such that neurological damage can either be reversed or prevented, (3) clinician awareness of treatable CP mimics is important for appropriate screening, diagnosis, and early intervention, and (4) systematic studies are required to elucidate the collective frequency of treatable IEMs in CP.

[Mourning a chronic disease: diagnostic error experienced by two families]. / Faire le deuil d'une maladie chronique : vécu de l'erreur diagnostique par deux familles.

We report on two pediatric cases with a diagnosis of hereditary metabolic disease established for several years and secondarily disproved. Retrospective interviews conducted 1 year after the announcement of the absence of the illness, the psychological reactions were analyzed. Through this clinical experience, the authors suggest that the traumatism caused by the announcement of the diagnosis may be similar to that which occurred when invalidation of the disease is pronounced. Four steps predominate: relief, anger, guilt, and problems mourning the disease experienced in solitude.