Guidelines for diagnosis and management of congenital central hypoventilation syndrome.

BACKGROUND: Congenital Central Hypoventilation Syndrome (CCHS) is a rare condition characterized by an alveolar hypoventilation due to a deficient autonomic central control of ventilation and a global autonomic dysfunction. Paired-like homeobox 2B (PHOX2B) mutations are found in most of the patients with CCHS. In recent years, the condition has evolved from a life-threatening neonatal onset disorder to include broader and milder clinical presentations, affecting children, adults and families. Genes other than PHOX2B have been found responsible for CCHS in rare cases and there are as yet other unknown genes that may account for the disease. At present, management relies on lifelong ventilatory support and close follow up of dysautonomic progression. BODY: This paper provides a state-of-the-art comprehensive description of CCHS and of the components of diagnostic evaluation and multi-disciplinary management, as well as considerations for future research. CONCLUSION: Awareness and knowledge of the diagnosis and management of this rare disease should be brought to a large health community including adult physicians and health carers.

Proceedings of the fourth international conference on central hypoventilation.

Central hypoventilation syndromes (CHS) are rare diseases of central autonomic respiratory control associated with autonomous nervous dysfunction. Severe central hypoventilation is the hallmark and the most life-threatening feature. CHS is a group of not-fully defined disorders. Congenital CHS (CCHS) (ORPHA661) is clinically and genetically well-characterized, with the disease-causing gene identified in 2003. CCHS presents at birth in most cases, and associated with Hirschsprung's disease (ORPHA99803) and neural crest tumours in 20% and 5% of cases, respectively. The incidence of CCHS is estimated to be 1 of 200,000 live births in France, yet remains unknown for the rest of the world. In contrast, late-onset CHS includes a group of not yet fully delineated diseases. Overlap with CCHS is likely, as a subset of patients harbours PHOX2B mutations. Another subset of patients present with associated hypothalamic dysfunction. The number of these patients is unknown (less than 60 cases reported worldwide). Treatment of CHS is palliative using advanced techniques of ventilation support during lifetime. Research is ongoing to better understand physiopathological mechanisms and identify potential treatment pathways.The Fourth International Conference on Central Hypoventilation was organised in Warsaw, Poland, April 13-15, 2012, under the patronage of the European Agency for Health and Consumers and Public Health European Agency of European Community. The conference provided a state-of-the-art update of knowledge on all the genetic, molecular, cellular, and clinical aspects of these rare diseases.

Survival of patients with spinal muscular atrophy type 1.

BACKGROUND: Spinal muscular atrophy type 1 (SMA1) is a progressive disease and is usually fatal in the first year of life. METHODS: A retrospective chart review was performed of SMA1 patients and their outcomes according to the following choices: letting nature take its course (NT); tracheostomy and invasive mechanical ventilation (TV); continuous noninvasive respiratory muscle aid (NRA), including noninvasive ventilation; and mechanically assisted cough. RESULTS: Of 194 consecutively referred patients enrolled in this study (103 males, 91 females), NT, TV, and NRA were chosen for 121 (62.3%), 42 (21.7%), and 31 (16%) patients, respectively. Survival at ages 24 and 48 months was higher in TV than NRA users: 95% (95% confidence interval: 81.8%-98.8%) and 67.7% (95% confidence interval: 46.7%-82%) at age 24 months (P < .001) and 89.43% and 45% at age 48 months in the TV and NRA groups, respectively (P < .001). The choice of TV decreased from 50% (1992-1998) to 12.7% (2005-2010) (P < .005) with a nonstatistically significant increase for NT from 50% to 65%. The choice of NRA increased from 8.1% (1999-2004) to 22.7% (2005-2010) (P < .001). CONCLUSIONS: Long-term survival outcome is determined by the choice of the treatment. NRA and TV can prolong survival, with NRA showing a lower survival probability at ages 24 and 48 months.

Congenital central hypoventilation syndrome and hypoglycaemia.

UNLABELLED: Congenital central hypoventilation syndrome (CCHS) is a rare genetic disorder typically presenting in infants with an impaired automatic control of breathing, particularly during sleep, and often associated with variable patterns of autonomic nervous system dysregulations. We studied three children who had CCHS associated with episodes of severe hypoglycaemia and hyperinsulinaemia; we discuss the possible relationship with impaired dopamine-beta-hydroxylase function. CONCLUSION: Hypoglycaemia and hyperinsulinaemia might be suspected in children with CCHS presenting with seizures and hyperhydrosis; though, further studies are needed to confirm this association.

Spinal muscular atrophy type 1: avoidance of hospitalization by respiratory muscle support.

OBJECTIVE: The aim of this study was to report the outcomes of an oximetry protocol using up to continuous full ventilator-setting noninvasive ventilation (NIV) and mechanically assisted coughing (MAC) to avoid episodes of acute respiratory failure and hospitalizations for children with spinal muscular atrophy type 1 under 3 yrs of age. DESIGN: This study was a retrospective chart review of 16 patients with spinal muscular atrophy type 1 under 3 yrs of age consecutively referred for respiratory decompensations resulting in continuous NIV dependence and oxyhemoglobin desaturation. An avoided hospitalization was defined by the need for continuous NIV using high span bilevel positive airway pressure and reversal of desaturations by MAC in the home setting. The protocol included training and equipping parents to use NIV, MAC, and basic life support. RESULTS: There were 49 acute episodes (1.20/patient per year), of which 43 met the criteria for an avoided hospitalization. Therefore, only six episodes (0.15/patient per year) required hospitalization, and four required endotracheal intubation (0.1/patient per year). Three of the four were extubated after 4, 9, and 15 days, respectively, to full NIV support and aggressive MAC. The fourth patient, for whom NIV could not be provided, underwent an emergency intubation at home and died at the age of 40 mos. CONCLUSIONS: A protocol including high span bilevel positive airway pressure along with MAC to expel airway secretions and normalize oxyhemoglobin saturation can be used by trained caregivers to avoid episodes of acute respiratory failure and hospitalization for children with spinal muscular atrophy type 1 under 3 yrs of age.

Daily practice of mechanical ventilation in Italian pediatric intensive care units: a prospective survey.

OBJECTIVES: To assess how children requiring endotracheal intubation are mechanically ventilated in Italian pediatric intensive care units (PICUs). DESIGN: A prospective, national, observational, multicenter, 6-month study. SETTING: Eighteen medical-surgical PICUs. PATIENTS: A total of 1943 consecutive children, aged 0-16 yrs, admitted between November 1, 2006 and April 30, 2007. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Data on cause of respiratory failure, length of mechanical ventilation (MV), mode of ventilation, use of specific interventions were recorded for all children requiring endotracheal intubation for >24 hrs. Children were stratified for age, type of patient, and cause of respiratory failure. A total of 956 (49.2%) patients required MV via an endotracheal tube; 673 (34.6%) were ventilated for >24 hrs. The median length of MV was 4.5 days for all patients. If postoperative patients were excluded, the median time was 5 days. Bronchiolitis (6.7%), pneumonia (6.7%), and upper airway obstruction (5.3%) were the most frequent causes of acute respiratory failure, and altered mental status (9.2%) was the most frequent reason for MV. The overall mortality was 6.7% with highest rates for heart disease (nonoperative), sepsis, and acute respiratory distress syndrome (26.1%, 22.2%, and 16.7% respectively). Length of stay, associated chronic disease, severity score on admission, and PICU mortality were significantly higher in children who received MV (p < .05) than in children who did not. Controlled MV and pressure support ventilation + synchronized intermittent mandatory ventilation were the most frequently used modes of ventilatory assistance during PICU stay. CONCLUSIONS: Mechanical ventilation is frequently used in Italian PICUs with almost one child of two requiring endotracheal intubation. Children treated with MV represent a more severe category of patients than children who are breathing spontaneously. Describing the standard care and how MV is performed in children can be useful for future clinical studies.

Noninvasive ventilation and low-flow veno-venous extracorporeal carbon dioxide removal as a bridge to lung transplantation in a child with refractory hypercapnic respiratory failure due to bronchiolitis obliterans.

OBJECTIVE: To report the successful management of end-stage hypercapnic respiratory failure through the association of noninvasive mechanical ventilation and a novel automated device (Decapsmart) of low-flow veno-venous extracorporeal CO2 removal. DESIGN: Case report. SETTINGS: Pediatric intensive care unit at a tertiary care children's hospital. PATIENT: A pediatric patient affected by bronchiolitis obliterans with refractory hypercapnic respiratory failure. The patient received successful lung transplantation after respiratory support with noninvasive mechanical ventilation and a novel automated device of low-flow veno-venous extracorporeal CO2 removal. INTERVENTIONS: Treatment of end-stage hypercapnic respiratory failure with the association of noninvasive ventilation and low-flow veno-venous extracorporeal CO2 removal as a bridge to lung transplantation. MEASUREMENTS AND MAIN RESULTS: Respiratory support controlling hypercapnia, limiting volutrauma, barotraumas, and preventing the incidence of ventilator-associated pneumonia/lung colonization. CONCLUSION: Noninvasive mechanical ventilation and Decapsmart have proven efficacious in managing refractory hypercapnic respiratory failure in a pediatric patient awaiting lung transplantation.

A novel missense mutation in the PHOX2B gene is associated with late onset central hypoventilation syndrome.

We report the case of a 15-month-old male suffering from Late Onset Congenital Central Hypoventilation Syndrome and recto-sigmoid Hirschsprung's disease, an association that has not been reported thus far. Nevertheless, our patient showed a missense mutation of the PHOX2B gene already known in isolated late onset central hypoventilation, resulting in a substitution of the Ala140 residue with a Glu residue (p.A140E). The present association of LO-CHS and HSCR in a patient harboring a rare and atypical PHOX2B mutation allows to refine the mutational spectrum of this disease and suggests individualized ventilatory care along with specific surgical and oncological approaches.

Parental origin and somatic mosaicism of PHOX2B mutations in Congenital Central Hypoventilation Syndrome.

Heterozygous polyalanine repeat expansions of PHOX2B have been associated with Congenital Central Hypoventilation Syndrome, a rare neurocristopathy characterized by absence of adequate control of respiration during sleep. Here we report a PHOX2B mutational screening in 63 CCHS patients, 58 of whom presenting with poly-A expansions or frameshift, missense and nonsense mutations. To assess a somatic or germline occurrence of poly-A length variations, the relative amounts of mutant and wild type alleles have been quantified in 20 selected CCHS patients presenting with an expansion, and in their parents. Somatic mosaicism was shown in four parents, while no mosaic was found among CCHS patients. Moreover, while co-segregation analysis of the PHOX2B poly-A expansions with selected marker alleles in the same 20 CCHS trios has not demonstrated any parent-of-origin effect of the mutations, it has provided further clues to clarify the molecular mechanism underlying the expansion occurrence. Finally, the segregation of PHOX2B poly-A anomalous tracts within family members has allowed us to exclude tendency of polymorphic variations towards expansion. This strengthens the notion that expanded polyalanine tracts, identified as frequent disease-causing mutations also in other human diseases, are mitotically and meiotically stable.

Home mechanical ventilation in children: retrospective survey of a pediatric population.

BACKGROUND: Home care support is beneficial for children needing mechanical ventilation, when clinically stable. METHODS: A retrospective analysis was carried out of the long-term home ventilation management of a pediatric population with chronic respiratory failure composed of 20 ventilator-dependent children categorized according to age, diagnosis and ventilation support. Age groups consisted of 10% under 1 year, 30% between 2 and 5 years, 30% between 6 and 12 years, and 30% older than 12 years. Diagnostic categories included myopathic disorder, n = 5; congenital central hypoventilation syndrome, n = 6; chest wall disorder, n = 5; cystic fibrosis, n = 1; pulmonary hypertension, n = 1; and diaphragmatic paralysis, n = 2. RESULTS: Sixty-five percent were ventilated using non-invasive mode (NIMV): eight with nasal mask, five with full-face mask, and two children in NIMV also used negative pressure mode; 35% were ventilated using tracheostomy, one of them also used a diaphragmatic pacer. Seventy percent needed nocturnal ventilatory support, (20% 12-18 h, 10% full-day). A total of 18 children were included in the home care and follow-up program. Two children died: one because of worsening of his chronic disease and one because of septic shock. CONCLUSION: Although home care ventilation is not yet widely diffused, it represents a valid alternative to long hospitalization for children with stable chronic respiratory failure.

Noninvasive ventilation in a child affected by achondroplasia respiratory difficulty syndrome.

Achondroplasia can result in respiratory difficulty in early infancy, from anatomical abnormalities such as mid-facial hypoplasia and/or adenotonsillar hypertrophy, leading to obstructive apnea, or to pathophysiological changes occurring in nasopharyngeal or glossal muscle tone, related to neurological abnormalities (foramen magnum and/or hypoglossal canal problems, hydrocephalus), leading to central apnea. More often, the two respiratory components (central and obstructive) are both evident in mixed apnea. Polysomnographic recording should be used during preoperative and postoperative assessment of achondroplastic children and in the subsequent follow-up to assess the adequacy of continuing home respiratory support, including supplemental oxygen, bilevel positive airway pressure, or assisted ventilation.

Brainstem anomalies in two patients affected by congenital central hypoventilation syndrome.

Congenital central hypoventilation syndrome (CCHS) is a rare neurocristopathy characterized by absence of automatic control of respiration; decreased sensibility to hypoxia and hypercapnia, mainly during sleep; and autosomal dominant inheritance due to heterozygous polyalanine expansions and frameshift mutations in the PHOX2B gene. Because the CCHS phenotype could hide other neurologic diseases, the American Thoracic Society established that the initial evaluation of suspected CCHS should exclude neuroanatomic impairments as the structural basis of the reduced autonomic system function. In this work, we describe the clinical history of two unrelated patients with hypoventilation during sleep and harboring hypoplasia of the pons and a Chiari I malformation, respectively. In both patients, CCHS was diagnosed by detection of PHOX2B polyalanine expansion, suggesting that the American Thoracic Society diagnostic criteria may be too restrictive. Moreover, to exclude a putative role of PHOX2B in non-CCHS neurologic diseases, we have performed PHOX2B mutation screening in a group of individuals with Chiari I malformation, confirming the exclusive role of PHOX2B in the pathogenesis of CCHS.

Sudden death in an infant revealing atypical Kawasaki disease.

We present a case of a 4-month-old girl referred to the emergency department with a provisional diagnosis of acute life-threatening event with a recent episode of heart block and a history of long-lasting fever. Soon after admission, the child suddenly deteriorated rapidly; she became pulseless with complete heart block and died despite intensive resuscitation efforts. Postmortem examination showed coronary arteritis with aneurysmal dilatation and coronary thrombosis, revealing atypical Kawasaki disease. With this case presentation, we discuss the importance of early recognition and treatment of atypical and/or incomplete forms of Kawasaki disease, which are most common in young infants and may lead, if untreated, to coronary artery abnormalities with a potential for myocardial infarctions, aneurysm formation, and sudden death. In addition, the relevance of postmortem examination in a case of sudden and undiagnosed infant death is underlined.

How wide is the ocular spectrum of Delleman syndrome?

We describe a patient with cerebral and cutaneous features typical of oculocerebrocutaneous syndrome. The ocular anomalies observed have not been previously reported in patients affected with this syndrome.

Mutational analysis of the RNX gene in congenital central hypoventilation syndrome.

Congenital central hypoventilation syndrome (CCHS) is a rare syndrome characterized by failure of autonomic respiratory control, often presenting with other dysfunctions of the autonomic nervous system. Segregation analysis suggested a complex model of inheritance with a major locus involved. Disruption of the Rnx gene, a member of the Hox11 family of homeobox genes, in embryonic stem cells produced mice showing a phenotype similar to CCHS. Based on this observation, we have carried out mutation screening of the RNX gene in a set of 13 patients affected with CCHS, 2 of whom showing association with Hirschsprung disease. Single-strand conformational polymorphism analysis and direct sequencing of the whole coding portion of the RNX gene and of 1,311 bp of 5' flanking region were performed. No sequence variant was identified, with the exception of a private nucleotide change at position -874 bp from the ATG codon in two siblings affected with isolated CCHS. A functional test, performed by using the luciferase gene reporter system, has not shown any significant difference in the activity of the promoter region carrying this latter nucleotide change with respect to the wild-type allele. We conclude that RNX, and presumably its expression, are not altered in our index cases of CCHS.