Recurrent apnoea and respiratory failure in an infant: congenital central hypoventilation syndrome with a novel PHOX2B gene variant

Airway obstruction in two children with congenital central hypoventilation syndrome and review of the literature

Congenital central hypoventilation syndrome (CCHS) is an autosomal dominant disease that is caused by heterozygous mutations in the paired-like homeobox 2B gene (PHOX2B). Madani et al. described an abnormally high degree of not only central apnea but also obstructive and mixed apnea in Phox2b27Ala/+newborn mice. Newborns with CCHS must undergo polysomnography for obstructive respiratory events in order to guide the optimal ventilation strategy if oxygen desaturation, bradycardia, and malaise persist under noninvasive ventilation. Newborns and infants with CCHS must be systematically tested for obstructive apnea, especially in cases of inefficient noninvasive ventilation.

Images: Atypical presentation of congenital central hypoventilation syndrome in an infant with central and obstructive sleep apnea

Congenital central hypoventilation syndrome (CCHS), a rare disease caused by paired-like homeobox 2B variants, affects control of breathing. We report on a 21-month-old boy with CCHS caused by a novel nonpolyalanine repeat mutation, neuroblastoma, severe obstructive and central sleep apnea, and sleep-related hypoxemia without hypoventilation. At 10 months, due to persistent central sleep apnea during serial polysomnography, bilevel positive airway pressure therapy was initiated despite the absence of hypoventilation. Nonpolyalanine repeat mutations are associated with severe phenotypes requiring continuous assisted ventilation, Hirschsprung's disease, and neural crest tumors; however, our patient had a relatively milder respiratory phenotype requiring sleep-only assisted ventilation without tracheostomy. Although alveolar hypoventilation is the hallmark of CCHS, our patient lacked hypoventilation. Bilevel positive airway pressure could be considered in some infants with CCHS requiring sleep-only assisted ventilation for tracheostomy avoidance. Our case demonstrates the expanding phenotypic spectrum in CCHS and the importance of formulating an individualized care plan.

CITATION

Fain ME, Raghunandan S, Pencheva B, Leu RM, Kasi AS. Images: atypical presentation of congenital central hypoventilation syndrome in an infant with central and obstructive sleep apnea. J Clin Sleep Med. 2024;20(3):478-481.

A narrative review of the mechanisms and consequences of intermittent hypoxia and the role of advanced analytic techniques in pediatric autonomic disorders

Disorders of autonomic functions are typically characterized by disturbances in multiple organ systems. These disturbances are often comorbidities of common and rare diseases, such as epilepsy, sleep apnea, Rett syndrome, congenital heart disease or mitochondrial diseases. Characteristic of many autonomic disorders is the association with intermittent hypoxia and oxidative stress, which can cause or exaggerate a variety of other autonomic dysfunctions, making the treatment and management of these syndromes very complex. In this review we discuss the cellular mechanisms by which intermittent hypoxia can trigger a cascade of molecular, cellular and network events that result in the dysregulation of multiple organ systems. We also describe the importance of computational approaches, artificial intelligence and the analysis of big data to better characterize and recognize the interconnectedness of the various autonomic and non-autonomic symptoms. These techniques can lead to a better understanding of the progression of autonomic disorders, ultimately resulting in better care and management.

Congenital Central Hypoventilation Syndrome: Diagnosis and Long-Term Ventilatory Outcomes

Background

Congenital central hypoventilation syndrome (CCHS), a rare disease caused by variants in the paired-like homeobox 2B (PHOX2B) gene, affects regulation of respiration necessitating lifelong assisted ventilation (AV). Most patients require full-time AV during infancy and some patients may sustain adequate spontaneous ventilation during wakefulness and change AV modalities at a later age. The aims of this study were to assess the changes in duration and modalities of AV, long-term respiratory outcomes, and to correlate them with PHOX2B genotypes.

Methods

We conducted a retrospective study of patients with CCHS treated at our institution between January 1997 and May 2022. Results analyzed included: clinical presentation, PHOX2B genotype, modality and duration of AV at diagnosis and follow-up, survival, and transition to adult care.

Results

We identified 30 patients with CCHS-8 with PHOX2B nonpolyalanine repeat mutations (NPARMs), 21 with polyalanine repeat mutations (PARMs), and 1 with unknown PHOX2B genotype. The median age at presentation was 0.25 months (IQR 0.1-0.7 months). At diagnosis of CCHS, 24 (80%) patients required continuous AV and 28 (93%) received AV via tracheostomy. Twenty-six patients required sleep-only AV at a median age of 9 months (IQR 6-14 months). Nine patients requiring sleep-only AV underwent tracheostomy decannulation at a median age of 11.2 years (IQR 5.9-15.7 years) and used noninvasive positive pressure ventilation or diaphragm pacing. There was insufficient evidence to conclude that patients with PARMs and NPARMs differed by age at presentation (P = .39), tracheostomy (P = .06), and transition to sleep-only AV (P = .9). Six patients transitioned to adult care, 23 continued receiving pediatric care, and 1 patient died due to complications from Hirschsprung's disease.

Conclusion

Our study demonstrates prolonged survival and good long-term respiratory outcomes possibly related to the early diagnosis of CCHS, optimizing AV strategies, and multidisciplinary care. The increasing number of patients attaining adulthood highlights the necessity for multidisciplinary care for adults with CCHS.

Images: Caffeine therapy for central sleep apnea, hypoxemia, and hypoventilation in a term neonate

The evaluation of higher-risk infants with brief resolved unexplained events and term infants with central sleep apnea can be clinically challenging due to the multitude of potential etiologies. We report a 7-day-old term neonate hospitalized for evaluation of brief resolved unexplained events with oxygen desaturations during sleep. Polysomnography showed central sleep apnea, hypoxemia, hypoventilation, periodic breathing, and mild obstructive sleep apnea. Following initial evaluations and while awaiting genetic testing, primary central sleep apnea of infancy was suspected and caffeine was initiated. Three days after initiating caffeine, polysomnography showed resolution of hypoxemia, hypoventilation, obstructive sleep apnea, and periodic breathing and improved central sleep apnea. The central apnea-hypopnea index reduced from 58 to 6.8 events/h. Although caffeine is utilized in apnea of prematurity, there is limited literature regarding caffeine in term infants with apnea. Our case demonstrates that in term infants with primary central sleep apnea of infancy, immature regulation of respiration may persist and a trial of caffeine could be considered.

CITATION

Shah AS, Leu RM, Shah SP, Martinez F, Kasi AS. Caffeine therapy for central sleep apnea, hypoxemia, and hypoventilation in a term neonate. J Clin Sleep Med. 2023;19(5):1005-1008.

Congenital Central Hypoventilation Syndrome: Optimizing Care with a Multidisciplinary Approach

Congenital central hypoventilation syndrome (CCHS) is a rare genetic disorder affecting respiratory control and autonomic nervous system function caused by variants in the paired-like homeobox 2B (PHOX2B) gene. Although most patients are diagnosed in the newborn period, an increasing number of patients are presenting later in childhood, adolescence, and adulthood. Despite hypoxemia and hypercapnia, patients do not manifest clinical features of respiratory distress during sleep and wakefulness. CCHS is a lifelong disorder. Patients require assisted ventilation throughout their life delivered by positive pressure ventilation via tracheostomy, noninvasive positive pressure ventilation, and/or diaphragm pacing. At different ages, patients may prefer to change their modality of assisted ventilation. This requires an individualized and coordinated multidisciplinary approach. Additional clinical features of CCHS that may present at different ages and require periodic evaluations or interventions include Hirschsprung’s disease, gastrointestinal dysmotility, neural crest tumors, cardiac arrhythmias, and neurodevelopmental delays. Despite an established PHOX2B genotype and phenotype correlation, patients have variable and heterogeneous clinical manifestations requiring the formulation of an individualized plan of care based on collaboration between the pulmonologist, otolaryngologist, cardiologist, anesthesiologist, gastroenterologist, sleep medicine physician, geneticist, surgeon, oncologist, and respiratory therapist. A comprehensive multidisciplinary approach may optimize care and improve patient outcomes. With advances in CCHS management strategies, there is prolongation of survival necessitating high-quality multidisciplinary care for adults with CCHS.