Cough in children with congenital central hypoventilation syndrome

Congenital central hypoventilation syndrome (CCHS) is defined as failure of the chemical (autonomic) control of breathing causing alveolar hypoventilation in the absence of pulmonary, cardiac, neuromuscular or patent brainstem lesions. Hypoventilation is predominant in non-rapid-eye-movement sleep, during which breathing is primarily under chemical control. Failure of the central integration of chemosensory inputs is proposed as the putative defect. A genetic basis for CCHS is supported by lines of evidence. In some diseases of the central nervous system there is more or less complete depression of the cough reflex, whereas spontaneous ventilation is generally preserved. Little is known regarding cough in CCHS patients. Parents consistently report that their children cough 'normally' during airway infections; in contrast, experimental lines of evidence suggest that CCHS children lack a cough response following inhalation of a tussigenic agent. Although several factors may account for the discrepancy, the possibility of a weakened or even absent cough reflex remains to be fully ascertained. Conceivably, a defective cough reflex, in conjunction with the well established lack of perception of respiratory discomfort, might result in an increased risk of potentially serious respiratory complications in CCHS patients.     

Resolution of obstructive sleep apnea syndrome after adenoidectomy in congenital central hypoventilation syndrome.

We report on a 2 1/2-year-old boy who is currently ventilated at home by positive pressure ventilation through a nasal mask during the night because of congenital central hypoventilation syndrome (CCHS). Up to age 2 he had developed normally. A reevaluation was performed because of symptoms suggestive of obstructive sleep apnea syndrome (OSAS), including snoring, nocturnal sweating, frequent nighttime awakenings, speech impairment, daytime fatigue, and failure to thrive. A sleep study indicated obstructive apnea episodes lasting up to 40 s and arterial desaturations below 50% during spontaneous sleep. During mechanical ventilation snoring persisted, and capillary PCO2 rose to 60 mm Hg. Partial upper airway obstruction, leaking around the mask, and arousal movements developed on passive flexion of the neck to 20 degrees. After adenoidectomy, symptoms of OSAS resolved. There were no more obstructive apneas during spontaneous sleep, but obstructive apneas could be provoked by neck flexion to 20 degrees. During ventilation, neck flexion of 20 degrees was tolerated, but a 40 degrees flexion led to partial obstruction. In CCHS patients, the problem of upper airway obstruction is rarely noted because most patients are ventilated through a permanent tracheostomy. Today, noninvasive ventilation strategies are becoming more common. Reduced activity of upper airway muscles and impaired reflex mechanisms could lead to upper airway obstruction during face mask positive pressure ventilation in children with CCHS. Enlarged adenoids worsened this problem in our patient, leading to insufficient ventilation and OSAS. Adenoidectomy resolved symptoms of OSAS and enabled successful nasal mask ventilation. Close follow-up of the patient avoided hypoxia and sequelae from OSAS such as pulmonary hypertension.     

Sinus vein thrombosis as presenting finding in the congenital central hypoventilation syndrome: an insight on the pathophysiology of the association

Congenital central hypoventilation syndrome (CCHS) is an increasingly recognized diagnosis causing central hypoventilation and may be definitively diagnosed by genetic testing. Previous authors reported the association between CCHS and central sinus venous thrombosis (CSVT) and hypothesized that CCHS could be secondary to CSVT. We report a case of CCHS with the typical PHOX2B mutation who also suffered from CSVT. We assume that effects, secondary to CCHS, upon the central venous system may explain the etiological connection between CSVT and CCHS including dysautoregulation, venous stasis or polycythemia. We believe that CCHS should be included in the differential diagnosis of patients with CSVT accompanied by respiratory abnormalities.     

Noninvasive ventilatory strategies in the management of a newborn infant and three children with congenital central hypoventilation syndrome

Four children with congenital central hypoventilation syndrome (CCHS) treated with noninvasive techniques of ventilation are presented. Two infants (one in the newborn period) were treated with nasal mask bilevel positive airway pressure (BiPAP), and then both were transitioned to negative pressure chamber ventilation at several years of age because of possible midface hypoplasia. Tracheostomies were not performed. Two older children were transitioned from mechanical ventilation via tracheostomy to nasal mask BiPAP, and then in one case to negative pressure chamber ventilation, and in the other to phrenic nerve pacing. Their tracheostomies were removed.     

Cardiac pacing in a patient with diaphragm pacing for congenital central hypoventilation syndrome (Ondine's curse)

Mechanical ventilation support and diaphragm pacing has improved the prognosis of patients with idiopathic congenital central hypoventilation syndrome (CCHS; Ondine's curse). However, severe bradyarrhythmias may occur. This report is about a patient who was supplied with a bilateral diaphragm pacing system at early childhood. At the age of 17 years, he experienced multiple syncopes due to sinus nodal arrest, which was successfully treated by the implantation of a dual chamber pacemaker.     

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.     

Genetic factors in sleep-disordered breathing

Sleep-disordered breathing (SDB) is characterized by repetitive episodes of decreased or arrested respiratory airflow during sleep. SDB is common and affects approximately 20% of the Japanese general population. Most traits of normal sleep and SDB show familial aggregation, suggesting significant effects of genetic factors. Obstructive sleep apnea (OSA) is the most common type of SDB and has a high heritability. Regardless of high heritability, no risk locus for OSA has reached a genome-wide level of significance (P < 5×10^?8) in linkage or candidate gene analysis. However, a recent genome-wide association study identified some genetic risks for OSA with P < 5×10^?8 for the first time. The identified genes are associated with inflammation, hypoxia signaling, and sleep pathways. The effects of genetic factors on the consequences of OSA has not been determined, although a correlation between OSA and cardiovascular disease may differ across races. Congenital central hypoventilation syndrome (CCHS) is a genetically inherited disorder caused by mutations in the paired-like homeobox 2B (PHOX2B) gene of polyalanine repeat mutations in the 20-alanine repeat or non-polyalanine repeat mutations. PHOX2B genotypes are also associated with clinical phenotypes of CCHS, including severity of hypoventilation. SDB, including obesity hypoventilation syndrome, is often seen in genetic obesity-associated disorders such as Prader-Willi syndrome. Although advances in genetics have resulted in identification of some genetic causes of SDB, further studies are required to elucidate the cellular and molecular mechanisms between genetic risks and clinical manifestations.